- Email: [email protected]
CAM labial and lingual appliances: A retrospective cohort study
Accepted Manuscript
Accuracy of digital predictions with CAD/CAM labial and lingual appliances: A retrospective cohort study Mirna G. Awad BDS , Skander Ellouze , Smith Ashley BD.c.(Hons),MDSc , Nikhilesh Vaid BDS, MDS , Laith Makki BDS, MSc , Donald J. Ferguson DMD, MSD PII: DOI: Reference:
S1073-8746(18)30062-8 https://doi.org/10.1053/j.sodo.2018.10.004 YSODO 550
To appear in:
Seminars in Orthodontics
Please cite this article as: Mirna G. Awad BDS , Skander Ellouze , Smith Ashley BD.c.(Hons),MDSc , Nikhilesh Vaid BDS, MDS , Laith Makki BDS, MSc , Donald J. Ferguson DMD, MSD , Accuracy of digital predictions with CAD/CAM labial and lingual appliances: A retrospective cohort study, Seminars in Orthodontics (2018), doi: https://doi.org/10.1053/j.sodo.2018.10.004
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT Title: Accuracy of digital predictions with CAD/CAM labial and lingual appliances: A retrospective cohort study
Authors:
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Mirna G. Awad, BDS Orthodontic Graduate Resident European University College
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Skander Ellouze Total Health Orthodontics Specialist
Visiting Professor at Bordeaux University & Valencia University
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Toowoomba , Australia
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Orthodontist Private Practice,
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Smith Ashley BD.c.(Hons),MDSc
Nikhilesh Vaid, BDS, MDS
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Professor of Orthodontics
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European University College,
Laith Makki, BDS, MSc Instructor, Advanced Orthodontic Program European University College
Donald J. Ferguson, DMD, MSD Dean & Professor of Orthodontics
ACCEPTED MANUSCRIPT European University College
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Donald J. Ferguson, DMD, MSD Professor & Dean European University College Dubai Healthcare City, UAE Ibn Sina Building, Block D, 3rd Floor, Office 302 PO Box 53382, Dubai, UAE email: [email protected] mobile: +971 50 149 2375 tele: +971 4 362 4788 fax: +971 4 362 4793
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Corresponding author:
Title: Accuracy of digital predictions with CAD/CAM labial and lingual appliances: A retrospective cohort study
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Authors: Mirna G. Awad, Elouse Skander, Smith Ashley, Nikhilesh Vaid, Laith Makki, Donald J. Ferguson
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ABSTRACT
Purpose: To compare the treatment efficacy and efficiency of the two CAD/CAM
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customized bracket systems Incognito (lingual) and Insignia (labial) for differences in: 1) ABO Cast and Radiograph Evaluation system scores, 2) efficiency as assessed by
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three clinical measures of efficiency, and 3) final treatment outcome and the virtual set up. Materials & Methods: Consecutive patients treated with Insignia (n=21) and
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Incognito (n=16) treatment systems had STL Images evaluated at pretreatment, post treatment and virtual set-up (predicted outcome); predicted and post treatment STL images were superimposed upon each other and differences were recorded. Results: Incognito patients had fewer emergency appointments. ABO scores were also better for Incognito in 4 of the 8 categories and in total score; a “pass” total score of <27 was achieved in 87.5% on Incognito cases versus 42.9% of Insignia cases. Predicted versus actual outcomes assessment showed the following: right-left symmetry for incognito (95.2%) and Insignia (75.0%), more efficacious linear tooth movements of <0.5 mm for
ACCEPTED MANUSCRIPT Incognito (78.6% vs 57.1%), more efficacious angular tooth movements of <2.0 degrees for Insignia (21.4% vs 7.1%). Incognito was more effective with linear predicted versus actual outcomes and more efficaciousness especially in remaining within clinical significance guidelines. Incognito out performed Insignia in the maxilla, especially by staying within the clinical significant guidelines, and Incognito also out performed Insignia in the mandible, except for mandibular tip discrepancies. Conclusions: Based upon the conditions of the present study, the Incognito treatment system was more
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efficacious than Insignia when the two treatment systems were critically compared.
ACCEPTED MANUSCRIPT INTRODUCTION Goal directed orthodontics with customized appliance systems is aimed at improving, both the efficacy and efficiency of orthodontic mechanotherapy. The incorporation of CAD/CAM technology in the fabrication of these appliance systems is to achieve both precision and efficiency. Orthodontic treatment should be not only effective1, i.e. able to produce a desired or intended result, but also efficient in terms of total treatment time
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and number of appointments (Brown 2015)2.Laboratory-fabricated indirect bonding protocols enable easy and accurate placement of brackets on a handheld model in preparation for precise bracket transfer to the patient’s own teeth. While indirect bonding techniques have demonstrated good bond strength, the accuracy of the indirect
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bracket transfer techniques has varied.2
Customized orthodontic treatment systems are designed to facilitate orthodontists in appliance placement by simplifying clinical procedures. Once placed, these customized treatment systems provide prescription outcomes based upon the unique features of the specific malocclusion of the patient thereby streamlining mechanics toward pre-
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established goal posts or end points. CAD/CAM techniques start by creating a setup of the desired outcome that serves as a diagnostic aid and a road map outlining the steps
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Incognito
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for robotically bending arch-wires that will achieve the desired outcome.
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The Incognito treatment system (3M-Unitek, Monrovia, CA, USA)3,4 combines individualization of bracket bases, bracket slots and arch wires to create fully
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customized lingual orthodontic appliances. Bracket bases are individualized to the tooth anatomy and initial position of the tooth in the dental arch. Bracket slots are customized to produce ideal tooth movement, and wires are formed to minimize the overall thickness of the appliance in the mouth. Impressions/intra oral scans are acquired before treatment and a setup (either laboratory or virtual) is created. Based on an optical scan of the laboratory setup or on the digital setup, custom bracket bases are created and attached to virtual bracket
ACCEPTED MANUSCRIPT bodies. The position of the bracket body on the digital setup is optimized to achieve ideal tooth movement and maximum comfort. A three-dimensional printer produces wax patterns of the customized brackets and these are cast in a gold alloy. A series of robotically bent wires are formed according to the position of the brackets’ slots in the virtual setup. An indirect bonding tray is created in order to transfer the virtual position of the bracket to the patient’s mouth. Orthodontic treatment will proceed by arch wire progression. The claimed advantages include optimum esthetic appearance, great
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accuracy in final results, fewer incidences of white spot lesions, less discomfort over other lingual systems, and relatively easy and precise direct rebonding of inadvertently debonded brackets because of good adaptation of the custom bracket bases. Disadvantages include potential for error in bracket positioning during placement of the
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indirect bonding tray, and need to re-order any lost bracket or fractured wire. Insignia
The Insignia treatment system is comprised of indirect bonded CAD/CAM self-ligating
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appliances (Ormco, Orange, CA, USA)5 and uses a customized slot that is cut into the bracket at the desired position. The clinician creates a virtual design of the final
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occlusion and alignment using computer-assisted technology with reverse-engineered brackets and arch wires used to obtain the intended result. Bracket bases are standard;
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slots are custom created to produce the desired tooth movement via arch wire progression to a straight final arch wire. Some customization, in terms of arch form, is
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also incorporated into the wire based on the width of the dental arch at the beginning of
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treatment.
Digital models are generated from impressions/scans are acquired before treatment. These are used to create a virtual setup of the desired outcome. This setup is sent to the orthodontist for refinement and approval. Once approved, brackets without slots are placed virtually on the teeth. The slots are cut into the actual brackets based on their position on the tooth in the setup. This will allow for insertion of a straight final full-size wire. The relative position of a bracket to its tooth is recorded on the setup and transferred to the initial model. An indirect bonding tray composed of bracket transfer
ACCEPTED MANUSCRIPT jigs is created to transfer the virtual position of the bracket to the patient’s mouth. Orthodontic treatment will proceed by arch wire progression. The main supposed advantage of the Insignia system is the customization of the bracket slot. The movement of the tooth no longer depends on the position of the bracket, but on the position of the slot. The treatment theoretically can be achieved with straight wires that, if needed, allow sliding of teeth along the wire. Disadvantages include the
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potential for error in bracket positioning, either virtually or during transfer to the mouth. Given that a customized bracket is used, if a bracket is lost, a new one must be ordered.
Weber investigated a commercially available CAD/CAM orthodontic system comparing
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treatment effectiveness and efficiency of the customized appliances to traditional twin appliances. The study reported significantly lower American Board of Orthodontic (ABO) scores, fewer archwire appointments, and shorter overall treatment times in the CAD/CAM group.6 Although these findings were promising, the study did not distinguish
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actual customized brackets.
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whether the clinical benefits were due to indirect bonding in the CAD/CAM group or the
Brown compared ABO scores and clinical efficiency between CAD/CAM group, indirect bonding group and direct bonding group. The study reported that CAD/CAM group was
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more efficient in regard to treatment duration but ABO scores were better in the direct
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bonding group.2
Penning investigated the clinical efficiency between Insignia customized and Damon
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non-customized orthodontic systems and reported treatment clinical quality was comparable between two groups. Treatment with a customized appliance required significantly more planning time from the orthodontist and was associated with a higher number of visits due to lose brackets and was not associated with any significant reduction in treatment duration.7 Only one study has investigated the accuracy of tooth positioning in the Incognito system by superimposition of the virtual set up on the actual treatment outcome;
ACCEPTED MANUSCRIPT Grauer reported fully customized lingual orthodontic appliances were accurate in achieving the goals planned at the initial setup, except for the full amount of planned expansion and the inclination at the second molars.8 No study has investigated orthodontic treatment outcome quality generated by the software system of the labial customized bracket system. A systematic review by Papageorgiou compared the clinical effects of labial and lingual
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orthodontic fixed appliances and he recommended comparison of clinical quality between labial and lingual bracket system using the ABO grading system.9 Accurate assessment of technological applications can be made only if achieved treatment results are compared to planned simulations using an accurate and validated measurement 3D coordinate system that can assess accurate differences between different planned and
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actual tooth movements.8 The present study attempts to do that, and to compare a labial and lingual customized appliance system using matched samples. ABO Cast-Radiograph Evaluation System
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A commission of the American board of orthodontics (ABO) directors was formed in 1994 to develop a system that could be used to quantify tooth position more exactly.
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And in 1997 the ABO completed its Objective Grading System (OGS) for scoring post treatment case records which was later renamed the Cast-Radiograph Evaluation System. This system included 8 criteria: alignment, marginal ridges, buccolingual
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inclination, occlusal relationship, occlusal contact, overjet, interproximal contact and root angulation. The system used special gauge to make the measurement standardized
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by the examiners. The validity and reliability of the ABO OGS were confirmed and used for evaluation of the orthodontic records, The ABO OGS provides and methods for an
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objective assessment of the outcome and achievement of the orthodontic treatment.10 Others found that the ABO OGS involves more rigorous standards then the PAR or the index of complexity, outcome, and the need for assessing the outcome of the orthodontic treatments.11 eModel™ 9.0 “Compare” Software (Geodigm) Digital models offer a clear advantage over dental casts in assessing longitudinal changes given that they can be registered and superimposed in space.12,13 Among other
ACCEPTED MANUSCRIPT methods of treatment results assessment in orthodontics, outcomes in orthodontics also can be assessed by comparing the obtained outcome with the planned setup. Spatial registration of the setup model on the final digital models is achieved by an iterative closest point (ICP) algorithm or “best fit” of surfaces. Using Compare software, Grauer evaluated the reliability of the ICP registration of setup models to their homologous final outcome model. He concluded that surface-to-surface registration of final orthodontic digital models to planned setup models also is reproducible.14 This software had been used
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in many studies of Invisalign15 and Incognito lingual appliances.8 Purpose and Hypotheses
The purposes of this study were to compare the treatment efficacy and efficiency of the
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two CAD/CAM customized bracket systems Incognito (lingual) and Insignia (labial) as follows:
1. Differences in ABO Cast and Radiograph grading system scores. 2. Differences in efficiency as assessed by three clinical measures of efficiency.
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3. Differences between the final treatment outcome and the virtual set up. The null hypotheses tested were as follows:
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1. No differences in treatment outcome quality as determined using the ABO CastRadiograph Evaluation system.
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2. No differences in treatment efficiency using three measures of clinical efficiency; number of appointments, number of emergencies and overall length of active
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orthodontic treatment.
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3. No differences in predicted versus actual treatment outcomes.
MATERIALS and METHODS Sample
The research design was a retrospective cohort study. Ethical approval was obtained from
the European University College IRB Committee.
ACCEPTED MANUSCRIPT The sample was comprised of 37 patient-subjects separated by treatment methods: Insignia patient-subjects with 14 females and 7 males (n=21) were treated with the customized labial Insignia appliance; Incognito patient-subjects with 12 females and 4 males (n=16) were treated with the customized lingual Incognito appliance. All patients evaluated for a given appliance type were treated by a single experienced operator with
Criteria for sample selection were as follows: Inclusion criteria: 1) consecutively treated non extraction cases,
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the appliance.
2) complete maxillary and mandibular fixed appliances used (7-7),
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3) only intraoral, intra-arch or inter-arch mechanics,
4) complete chart entries, including number of appointments, emergencies, treatment time, and
5) availability of pretreatment and post-treatment digital casts, treatment prediction
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digital casts, pre treatment and post-treatment panoramic radiographs. Exclusion criteria for sample selection were as follows:
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1) previous orthodontic treatment,
2) treatment involving functional appliances, growth modification, extractions,
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temporary skeletal anchorage, extra oral appliances, or orthognathic surgery, 3) impacted teeth except for third molars,
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4) restorative treatment required following post orthodontic therapy, 5) incomplete pretreatment or post-treatment records,
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6) chronic medications affecting bone metabolism, i.e. NSAIDS, steroids, antiinflammatory, etc., and
7) lack of compliance defined as no appointment for 3 consecutive months.
Procedures Treatment Efficiency Using Clinical Practice Data 1. Demographic data for the study participants was collected including gender and age at the beginning of treatment.
ACCEPTED MANUSCRIPT 2. Treatment data was collected consisting of the number of treatment appointments (bonding, arch-wire adjustments, emergencies, and de-bonding), duration of treatment (months); records gathered were initial and final cephalometric and panoramic radiographs, and e-Model (stereolithography or STL) digital casts (GeoDigm Corp, Falcon Height, MN). 3. Emergencies were counted as appointments if brackets were replaced or wires changed, but not if long wires extending out of molar tubes were clipped. efficiency was
assessed
using
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parameters:
number
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4. Treatment
of
appointments, number of emergencies and overall length of active orthodontic treatment time. Treatment Efficacy Using ABO Grading System
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Before data collection, the investigator was trained and calibrated on both the ABO Discrepancy Index and the ABO Cast-Radiograph Evaluation techniques. The investigator performed all measurements and case analyses which also included PAR index scoring.
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1. The ABO Discrepancy Index (DI) was used to grade/score the pre-treatment digital casts using 3Shape Ortho Analyser software program. DI score established a numeric
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value correlating to the relative severity of the orthodontic problems of each subject. 2. The post-treatment STL study casts were 3D printed using EDEN260VS dental
advantage (Stratasys-3D future technology) in order to be able to manually assess
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them according to the ABO Cast and Radiograph Evaluation system scoring using the ABO special gauge; final panoramic radiographs were included to objectively
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quantify the treatment outcome of each patient. ABO criteria include the following: alignment, marginal ridges, bucco-lingual inclination, occlusal contact, occlusal
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relationship, overjet, interproximal contact and root angulation.
3. Treatment efficacy using ABO grading scores was assessed using the eight ABO
criteria plus total score as well as number of cases with total score <27.
Treatment Efficacy Using Prediction Versus Actual Outcome 1. All digital models were de-identified and soft tissues were digitally removed to ensure that evaluation was based solely on tooth-surface features.
ACCEPTED MANUSCRIPT 2. The maxillary setup model was registered to the maxillary final model using eModel™ 9.0 “Compare” software (Geodigm Corporation, Chanhassen, MN) to combine both models in the same coordinate system. The same process was followed for the mandibular setup model.15
3. The surface-to-surface registration of the setup dental arch to the final arch was independently performed for both arches. Fifty (50) iterations were automatically performed until the best fit of the surfaces was obtained (Figure 1A).
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4. The virtual set up models were segmented to isolate each tooth as a separate object and compared with the un-segmented post treatment plan models using the same software.
5. After the dental arches were first aligned globally, the software then superimposed individual teeth from the segmented virtual set up on the corresponding teeth in the un-segmented post
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treatment model using best-fit surface-based registration (Figure 1B).
6. Based on the transformation of axes required to fit each tooth, the software quantified the differences or discrepancies between achieved and predicted position for each tooth in the following six directions: mesial-distal, facial-lingual, occlusal-gingival, tip, torque, and rotation.
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The differences were expressed with respect to the center of resistance.
7. Treatment efficacy using predicted versus actual outcomes was assessed by
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comparing right-left sides of both maxilla and mandible, linear absolute values <0.5 mm and angular absolute values <2 degrees and differences in predicted versus
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Insert Figure 1
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actual means by treatment system.
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Statistical Analysis
Data was collected and stored (Excel, Microsoft, Seattle, WA) and later transformed for use for analysis by SPSS (SPSS software v.15.0.1, IBM, Armonk, NY). The 0.05 probability level of significance was used for all testing purposes (P≤.05). Distributions of samples were evaluated for equality of variances; non-parametric tests were used if variances were found unequal and when nominal or ordinal data was evaluated. Parametric paired t test was used for intra-group the comparisons between pre-treatment and post-treatment; unpaired t-tests were used to compare mean ABO scores of treatment
ACCEPTED MANUSCRIPT outcomes. Clinical significance for tooth movements followed the ABO guidelines of >.05 mm for linear movements and >2.0 degrees for angular measurements. Technique reliability/reproducibility was evaluated. One week after completion of the data collection, the ABO Discrepancy Index and Cast-Radiograph Evaluation were repeated on 10 randomly selected subjects to assess Intra-examiner reliability. Dahlberg’s test was used to assess whether or not the examiner is reliable. Validity of Analyzer and e-model16 Compare 8.1 software17 programs.
RESULTS
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Treatment Efficiency
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measurement technique has been validated in scholarly literature for both 3Shape Ortho
As described immediately below, severity of initial Insignia and Incognito malocclusions were assessed as no different using the ABO Discrepancy Index. The number of emergency visits was significantly less for Incognito (0.7 vs 2.2, P=.002). For Insignia
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and Incognito, mean treatment times were 16.5 and 15.1 months and number of
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appointments were 16.3 and 22.6, respectively and both insignificant (P>.05). (Table 1) Insert Table 1:
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Treatment Efficacy – ABO Cast-Radiograph Evaluation Initial severity of malocclusion for Insignia and Incognito were respectively 5.6 and 5.7
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(P>.05) using ABO Discrepancy Index. However, using PAR index for assessment of initial malocclusion, Insignia demonstrated a significantly more severe malocclusion
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than Incognito, i.e. 23.8 and 17.8, P=.044, respectively. Four of the eight grades/scores used in the ABO Cast-Radiograph Evaluation system were found significantly lower for Incognito, i.e. alignment, occlusal contact, occlusal relationship and overjet. ABO Cast-Radiograph Evaluation total score was also significantly lower for incognito (18.3 vs 28.3, P=.000) (Table 2) Moreover,14 of 16 Incognito cases (87.5%)scored below the ABO pass score of 27 compared to9 of 21 (42.9%)Insignia cases with total score <27. (not shown)
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Insert Table 2: Treatment Efficacy – Predicted Outcome Versus Actual Treatment Outcomes As described previously, the patient’s actual outcome STL image was superimposed upon the STL image representing the outcome predicted by the treatment system. This data represented the difference between the two STL images. Paired t-tests were used
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to compare right-left data on each tooth for each movement per jaw. For Incognito, significant (P<.05) right-left differences were demonstrated for 4 variables affecting 3 teeth; one was in the maxilla (rotation) and 3 were in the mandible (mesial-distal and rotation). For Insignia, significant right-left differences were demonstrated for 21 variables with near equal distribution in the maxilla and mandible; 11 variables with
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right-left differences (P>.05) were linear (mesial-distal, buccal-lingual and occlusalgingival) and 10 variables were angular (rotation, tip and torque). Right-left Insignia differences were greatest for the mandibular first premolar, i.e. mesial-distal, occlusalgingival and rotation variables were significantly different. (Table 3)
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Insert Table 3:
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Right-left data were pooled for each treatment system per tooth per tooth movement per jaw. ABO guidelines as measures of clinical significance for linear measurements
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was>0.5 mm and >2.0 degrees for angular measurements. Discrepancies between predicted and actual outcome values for tooth movements that exceeded these clinical
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significance guidelines were indentified. For linear tooth movements in the mandible, Incognito exceeded the guideline of >0.5 mm 3 of 21 times (14.3%) and Insignia
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exceeded 9 of 21 times (42.9%). In the maxilla, Incognito mean linear tooth movements exceeded the guideline 6 of 21 times (28.6%) and Insignia exceeded 9 of 21 times (42.9%). (Table 4) Insert Table 4: Discrepancies between predicted and actual outcome values for angular tooth movements in the mandible for Incognito exceeded the angular tooth movement clinical
ACCEPTED MANUSCRIPT significance guideline of >2 degrees 16 times (76.2%) and Incognito exceeded 18 times (85.7%). In the maxilla, 17 of 21 (81.0%) of angular tooth movements were deemed clinically significant for Insignia and Incognito was clinically significant 100% of the time, i.e. 21 of 21 means differed. (Table 5) Insert Table 5:
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One of the aims of the present study was to compare and contrast Insignia and Incognito treatment systems. The pooled predicted versus actual outcome discrepancies were compared by treatment system; statistically significant differences were identified and plotted relative to clinically significant guidelines. For maxillary linear discrepancies, only the buccal-lingual discrepancies differed statistically. All seven buccal-lingual
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predicted versus actual outcome discrepancies differed statistically, and 6 of 7 Insignia discrepancies exceeded the ABO clinical guideline of ±0.5 mm. The predicted versus actual discrepancy error for Insignia was buccal (positive) for maxillary central and lateral and lingual (negative) for first premolar through second molar. In other words,
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the Insignia treatment system showed tooth crowns discrepant from buccal to lingual and the discrepancies were progressive from anterior to posterior teeth; all but canine
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buccal-lingual predicted versus actual discrepancies were clinically significant, i.e.
Insert Figure 2:
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exceeded ±0.5 mm. (Figure 2)
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For maxillary angular discrepancies, 3 torque, 3 tip and 4 rotation discrepancies differed statistically between the two treatment systems. The torque discrepancies were positive
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(buccal) for maxillary central, second premolar and first molar and the three discrepancies clinically significant (exceeded 2.0 degrees) for Insignia. In contrast, there were three statistically significant tip discrepancies with Incognito exceeding mesial (positive) clinical guidelines in two, i.e. maxillary canine and second premolar. Maxillary rotation discrepancies differed statistically for central, canine, second premolar and first molar, and Insignia exceeded distal (negative) clinical guidelines (-2.0 degrees) in two, i.e. canine and first molar (Figure 3)
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Insert Figure3: In the mandible, there were and total of 14 linear predicted versus actual discrepancies that differed statically. All buccal-lingual discrepancies differed except mandibular canine, and Insignia exceeded clinical guidelines in 5 of the 6; discrepancies for central and lateral incisor crowns exceeded 0.5 mm (buccal) and discrepancies for second
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premolar through second molar exceeded -0.5 mm (lingual). (Figure 4) Insert Figure 4:
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Insert Figure 5:
For mandibular angular predicted versus actual discrepancies compared by treatment system, statistically significant differences were found for five tip (central incisor
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through second premolar) and two (canine and first premolar) angular discrepancies. Discrepancies were clinically significant for Incognito lateral incisor through second
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premolar tip discrepancies and for Insignia canine. Insignia demonstrated clinical
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Insert Figure 6:
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significance for canine and first premolar rotations. (Figure 6)
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DISCUSSION
The main goal of CAD/CAM orthodontic appliances is to improve the final outcomes. Intuitively, these systems should reduce the effects of human error during orthodontic treatment, account for anatomic variations in tooth shape, and improve the overall finished treatment quality.2 To our knowledge the present study is the first study comparing accuracy of two fully customized bracket treatment systems, labial versus lingual, i.e. Insignia versus
ACCEPTED MANUSCRIPT Incognito. The three types of comparisons included: 1) clinical efficiency, i.e. treatment time period and convenience to the treating clinician, 2) efficacy of treatment outcome, i.e. the quality of the result using ABO criteria, and 3) efficacy of the treatment system itself, i.e. ability of the predicted outcome to match the actual treatment outcome. Most other studies comparing labial and the lingual appliances focused on oral discomfort, speech difficulty and incidence of white spot legions.18-21
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Since introduction of lingual appliances by Fujita progress has been seen in their design, manufacturing, and mechanotherapy.22 There are several publications comparing the difference in treatment outcomes between the labial and lingual appliances but the labial treatment systems were not customized.9 Deguchi used the PAR index and cephalometric analysis to compare between labial and lingual appliances but he limited
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the investigation to Class II extraction cases; the lingual appliance used is different from the present study.23
A few publications have compared the Insignia treatment system with another labial
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treatment appliance. Weber compared the Insignia with Roth conventional bracket system and reported Insignia more efficient that the conventional labial bracket system,
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i.e. shorter treatment time and fewer emergency appointments. Moreover, Weber reported better ABO scores resulting from Insignia treatment.6 Another investigator compared two self-ligating bracket systems (direct and indirect bonding) with Insignia
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bracket system and concluded that Insignia was more efficient in regards to the treatment duration; similar outcomes were reported for treatment outcome
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comparisons using the ABO Cast-Radiograph Evaluation system.2
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Penning reported results from a randomized controlled trial aimed to evaluate the duration and the outcome of orthodontic treatment between customized fixed appliance Insignia and the non-customized Damon system; he concluded that the customized treatment system had significantly more loose brackets, a longer planning time, and more complaints (P<.05).7 The Insignia treatment system was not associated with significantly reduced treatment duration, and treatment quality was comparable between the two appliance systems studied.
ACCEPTED MANUSCRIPT The present study compared labial to lingual customized CAD/CAM bracket systems with a focus on clinical efficiency, treatment outcomes and accuracy of predicted versus actual outcomes. Clinical Efficiency Of the three clinical efficiency measures used in the study, Incognito had significantly fewer emergency appointments than Insignia (2.2 vs 0.7, P=.002). Numbers of
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appointments were insignificantly fewer for Insignia (16.3 vs 22.6) and overall treatment time was insignificantly shorter for Incognito (15.1 vs 16.5 months). From a clinical perspective, customization and incorporation of technology for the same is the gold standard in lingual orthodontics, due to multiple factors; including accessibility to bonding surfaces and variable lingual anatomy. However, for the vestibular surface, the
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benefits of technology for customization haven’t yet been comprehensively proven in scholarly literature.24 Penning, in-fact, has observed more loose brackets in the customized appliance group, when they compared them to non-customized group. Our findings also indicate significantly more emergency appointments for the vestibular
Efficacy of Treatment Outcome
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customized group, compared to the lingual group.7
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The present study demonstrated substantially improved treatment outcomes with Incognito compared to Insignia. Incognito treatment patients scored significantly
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(P<.05) lower in 4 of 8 ABO criteria using the ABO Cast-Radiograph Evaluation system, i.e. alignment, occlusal contact, occlusal relationship and overjet, and total score was
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significantly lower for Incognito (18.3 vs 28.3, P=.000). Using an ABO “pass” total score of <27 to signify successful orthodontic treatment outcome, 87.5% Incognito patients
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succeeded while only 42.9% of Insignia patients succeeded. These results are compelling because ABO Discrepancy Index scores measuring severity of initial malocclusion were not different (P>.05). It is interesting to point out that Insignia had a significantly higher initial malocclusion PAR Index score compared to Incognito (23.8 and 17.8, P=.044) but results of scoring with the ABO Cast-Radiograph Evaluation system showed Incognito superior. This finding was interesting but not really surprising given the fact that PAR and DI indices use different scoring criteria. Using quality of treatment outcome as measured by the ABO Cast-Radiograph Evaluation system,
ACCEPTED MANUSCRIPT Incognito was clearly more efficacious than Insignia in the present study, when digital models were prepared by scans on the same day as the debonding in both groups. Efficacy of Predicted Outcome Versus Actual Outcome A comparison of predicted outcome versus actual outcomes were inconsistent was assessed in three ways. The first was to compare mean data from right and left sides within each of the two groups. Doing so is a reflection upon the bilateral nature of how
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well predicted outcome matches actual outcome and suggests that no difference between right and left sides is a measure of symmetrical treatment effectiveness. Incognito clearly demonstrated better symmetrical treatment effectiveness with no difference in 80 of 84 (95.2%) right-to-left tooth movements while Insignia showed no difference in 63 of 84 (75.0%) right-left sides. There appeared to be relatively even
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distribution of right-left differences with no particular pattern emerging. (see Table 3) The second evaluative assessment of predicted outcome versus actual outcome was a within-group comparison with guidelines for clinical significance, i.e. <±0.5 mm for
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linear tooth movements and <±2.0 degrees for angular tooth movements. Incognito was clearly more efficacious for linear discrepancies demonstrating only 14.3% predicted vs
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actual outcomes discrepancies >0.5 mm in the mandible while Insignia showed 42.9%. The same was found for linear tooth movements in the maxilla; Incognito showed 28.6% and Insignia showed again 42.9%. For angular tooth movements, Insignia showed fewer
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predicted versus actual outcomes discrepancies >2.0 degrees than Incognito in both the mandible (76.2% vs 85.7%) and in the maxilla (81.0% vs 100%). In summary, the
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Insignia treatment system was more efficacious for angular predicted outcome versus actual outcome discrepancies while Incognito was more efficacious for linear
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discrepancies.
Thirdly, right-left pooled predicted versus actual outcome discrepancies were compared by Incognito and Insignia treatment system. For maxillary linear discrepancies, statistically significant differences were demonstrated for all maxillary buccal-lingual discrepancies and Insignia discrepancies exceeded the 0.5 mm clinically significant guideline in 6 of 7 of those buccal-lingual differences. For maxillary angular discrepancies, statistically significant differences were demonstrated three torque, three
ACCEPTED MANUSCRIPT tip and four rotation discrepancies; clinically significant (2.0 degrees) guidelines were exceed by Insignia for 5 of 10 discrepancies and Incognito exceed 2.0 degrees for 2 of 10. To summarized maxillary performance, Incognito out performed Insignia, especially by staying within the clinical significant guidelines. For mandibular linear discrepancies, statistically significant differences were demonstrated for all mandibular buccal-lingual discrepancies except canine; again, as in
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the maxilla, Insignia exceeded 0.5 mm clinical guidelines in 5 of 6 discrepancies while Incognito exceeded none. In contrast with maxillary linear discrepancies, there were five mesial-distal (central incisor through second premolar) and three occlusal-gingival (central incisor through canine) mandibular angular discrepancies statistically different with two of the Insignia occlusal-gingival discrepancies assessed as clinical significant.
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Mandibular angular predicted versus actual outcome discrepancies differed statistically for five tip (central incisor through second premolar) and two rotation (canine and first premolar) discrepancies; 4 of 5 tip discrepancies for Incognito exceeded clinical guidelines and, for Insignia, 1 of 5 tip discrepancies was clinically significant. Two of
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three rotation discrepancies were clinically significant for Insignia. In summarizing mandibular comparisons, Incognito out performed Insignia, except of mandibular tip
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discrepancies.
Viewed from a broad perspective, results of the ABO Cast-Radiograph Evaluation system
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assessment were arguably the most compelling in concluding that the Incognito treatment system is the more efficacious of the two treatment systems. The Incognito
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treatment system demonstrated better right-left predicted versus actual outcome symmetry effectiveness and was more effective with linear predicted versus actual
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outcomes. Moreover, the Incognito treatment system was more efficaciousness especially in remaining within clinical significance guidelines. The Insignia treatment system was more effective with angular predicted outcome versus actual outcomes. Difficulties encountered in performing the present study were the intensive labor and expense to gather and assemble STL files suitable for assessment using the Compare software and to produce 3D printed study casts. Hence, one limitations of the study was the small size of the samples, i.e. n=16 for Incognito and n=21 for Insignia. The second
ACCEPTED MANUSCRIPT limitation of this study was that Incognito and Insignia treatments were performed by different orthodontist clinicians; this confounding factor may have had an influence on finishing protocols. Clinical Significance The limitations of our study are consistent with any retrospective study that evaluates matched samples, and the risk of confounding variables can influence treatment results.
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The lingual Incognito appliance evaluated in the present study used significantly different bracket–arch wire geometry and ligation techniques in the finishing stages compared to the vestibular Insignia appliance that uses “passive” self ligation brackets. This possibly could have been a factor that influenced the efficacy of results.
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A recent trial comparing customized vestibular appliances with direct bonded ones comprehensively outlined the role of the treating clinician in planning and execution of treatment, affecting both treatment duration and quality.7 Critiques of technology often cite the cost-benefit ratio of technology (a variable not applied in the present study) as a
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possible impediment to incorporation of technology as laboratory costs with a customized appliance are significantly more costly. While this might seem a justifiable
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expense for lingual orthodontics due to the lingual surface anatomy and complex lingual biomechanics, scholarly literature has not been able to justify the benefits for vestibular appliances yet. Based upon the conditions of the present study, results of the present
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study indicate a similar phenomenon. Future trials to comprehensively evaluate digital systems should include an aesthetic outcome evaluation and a cost-benefit audit of the
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systems as well.
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CONCLUSION
Differences in clinical efficiency were compared for 16 patients treated with the Incognito treatment system and 21 patients treated with the Insignia treatment system. Patient treatment outcomes were also scored using the ABO Cast-Radiograph Evaluation system assessment after STL images were converted to 3D printed casts. Moreover, Compare software was used to superimpose predicated outcome (virtual set-up) and actual outcome; discrepancies between predicted and actual outcomes served as a basis
ACCEPTED MANUSCRIPT for also comparing treatment effectiveness between the Insignia and Incognito treatment systems. Important results of the present study were as follows: Incognito had fewer emergency appointments than Insignia. Actual patient treatment outcomes were significantly better for Incognito in ABO Cast-Radiograph Evaluation system assessment categories alignment, occlusal
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contact, occlusal relationship and overjet as well as total score.
Using an ABO “pass” total score of <27 to signify successful orthodontic treatment outcome, success rate for Incognito was 87.5%and 42.9% for Insignia.
Symmetry of right-left predicted versus actual outcomes was higher for Incognito (95.2%) compared to Insignia (75.0%).
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Incognito was more efficacious for linear tooth movements demonstrating 78.6% (33 of 42) predicted vs actual outcomes <0.5 mm while Insignia showed 57.1%. Insignia was more efficacious for angular tooth movements demonstrating 21.4% (9 of 42) predicted vs actual outcomes <2.0 degrees while Incognito showed only 7.1%.
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Incognito was more effective with linear predicted versus actual outcomes and more efficaciousness especially in remaining within clinical significance guidelines.
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Incognito out performed Insignia in the maxilla, especially by staying within the clinical significant guidelines.
Incognito out performed Insignia in the mandible, except of mandibular tip
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discrepancies.
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Based upon the conditions of the present study, the Incognito treatment system was the
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more efficacious of the two treatment systems. ACKNOWLEDGEMENTS Dr. Smith Ashley is thanked for his support and for providing the study sample of Insignia and we thank Dr. Elouse Skander for providing the samples of Incognito. Thanks to Mr. Mike Marshall, Marshall Technologies, LLC, for providing technical assistance with the use of Compare software. We acknowledge University of Minnesota for allowing permission and
ACCEPTED MANUSCRIPT use of the Compare software and 3D Future Technologies, Mumbai, India for printing the 3D models for ABO Cast-Radiograph Evaluation system analysis.
REFERENCES
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1. Müller-Hartwich R, Prager TM, Jost-Brinkmann PG. SureSmile—CAD/CAM system for orthodontic treatment planning, simulation and fabrication of customized archwires. Int J Comput Dent 2007;10:53-62.
2. Brown MW, Koroluk L, Ko CC, Zhang K, Chen M, Nguyen T. Effectiveness and efficiency of a
CAD/CAM orthodontic bracket system. Am J Orthod Dentofacial Orthop 2015;148(6):1067–1074.
3. Wiechmann D. A new bracket system for lingual orthodontic treatment. Part 1: Theoretical
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background and development. J Orofac Orthop 2002;63:234-245.
4. Wiechmann D. A new bracket system for lingual orthodontic treatment. Part 2: First clinical experiences and further development. J Orofac Orthop 2003;64:372-388. 5. Gracco A, Tracey S. The insignia system: customized orthodontics. J Clin Orthod 2011;45(8):442–
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6. Weber DJ II, Koroluk LD, Phillips C, Nguyen T, Proffit WR. Clinical effectiveness and efficiency of
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customized vs. conventional pre-adjusted bracket systems. J Clin Orthod 2013;47:261-6.
7. Penning EW, Peerlings RHJ, Govers JDM, Rischen RJ, Zinad K, Bronkhorst EM, Breuning KH,
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Kuijpers-Jagtman AM. Orthodontics with customized versus non-customized appliances: A randomized controlled clinical trial. J Dent Res 2017;96(13);1498–1504.
8. Grauer D; Proffit WR. Accuracy in tooth positioning with a fully customized lingual orthodontic
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appliance. Am J Orthod Dentofacial Orthop 2011;140(3): 433-443.
9. Papageorgiou SN, G€olz L, Jager A, Eliades T, Bourauel C. Lingual vs. labial fixed orthodontic
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appliances: systematic review and meta-analysis of treatment effects. Eur J Oral Sci 2016;124:105–118.
10. Casko JS, Vaden JL, Kokich VG, Damone J, James RD, Cangialosi TJ, et al. Objective grading system for dental casts and panoramic radiograph Am J Orthod Dentofacial Orthop 1998;114:589-599.
11. Onyeaso CO, Begole EA. Relationship between index of complexity, outcome and need, dental aesthetic index, peer assessment rating index, and American Board of Orthodontics Objective grading system. Am J Orthod Dentofacial Orthod 2007;131:248-52.
ACCEPTED MANUSCRIPT 12. Jang I, Tanaka M, Koga Y, Iijima S, Yozgatian JH, Cha BK, Yoshida N.A novel method for the assessment of three-dimensional tooth movement during orthodontic treatment. Angle Orthod 2009;79:447-453.
13. Choi DS, Jeong YM, Jang I, Jost-Brinkmann PG, Cha BK. Accuracy and reliability of palatal superimposition of three-dimensional digital models. Angle Orthod 2010;80:497-503.
14. Grauer D, Cevidanes LH, Tyndall D, Styner MA, Flood PM, Proffit WR. Registration of orthodontic digital models. Craniofac Growth Ser 2011;48:377-391.
tooth positions achieved? Angle Orthod 2017;87(6):809-815.
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15. Grünheid T, Loh C, Larson BE. How accurate is Invisalign in nonextraction cases? Are predicted
16. Czarnota J, Hey J, Fuhrmann R. Measurements using orthodontic analysis software on digital models obtained by 3D scans of plaster casts : Intrarater reliability and validity. J Orofac Orthop 2016;77:22-30.
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17. Haque S, Sandler J, Cobourne MT, Bassett P, DiBiase AT. A retrospective study comparing the loss of anchorage following the extraction of maxillary first or second premolars during orthodontic treatment with fixed appliances in adolescent patients. J Orthod 2017; 44:268-276. 18. Gorman JC, Smith RJ. Comparison of treatment effects with labial and lingual fixed appliances.Am J Orthod Dentofacial Orthop 1991;99(3):202-209.
19. Caniklioglu C, Oztürk Y.Patient discomfort: a comparison between lingual and labial fixed
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appliances. Angle Orthod 2005;75(1):86-91.
20. Khattab TZ, FARAH H, AL-Sabbagh R, Hajeer MY, Hajhamed Y. Speech performance and oral
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impairments with lingual and labial orthodontic appliances in the first stage of fixed treatment. Angle Orthod 2013;83:519–526.
21. Karttab TZ, Hajeer MY, Farah H, AL-Sabbagh R. Maxillary dental arch changes following the
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leveling and alignment stage with lingual and labial orthodontic appliances: a preliminary report of a randomized controlled trial. J Contemp Dent Pract 2014;15:561–566.
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22. Fujita K. New orthodontic treatment with lingual bracket and mushroom arch wire appliance. Am J Orthod 1979;76:657–675.
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23. Deguchi T, Terao F, Aonuma T, Kataoka T, Sugawara Y, Yamashiro T, Takano-Yamamoto T. Outcome assessment of lingual and labial appliances compared with cephalometric analysis, peer assessment rating, and objective grading system in Angle Class II extraction cases. Angle Orthod 2015;85:400–407.
24. Lee W, Vaid N. Incognito™ lite lingual orthodontic appliance: Enhancing the scope of targeted mechanics with customized computer-aided design/computer-aided manufacturing therapy. APOS Trends Orthod 2015;5(3):120-123.
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Figure 1: (A) The surface-to-surface registration of the setup dental arch to the final arch was independently performed; (B) superimposed individual teeth from the segmented virtual set up on the corresponding teeth in the unsegmented post treatment model using best-fit surface-based registration.
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Figure 2: Maxillary linear predicted versus actual discrepancies were compared by treatment system and statistically significant differences were first identified and then plotted relative to the ±0.5 mm clinically significant guideline. Only the buccal-lingual (BL) linear discrepancies differed statistically and of these, discrepancies were clinically significant for Insignia for maxillary central (1x), lateral (2x), first premolar (4x) through second molar (7x). Amounts of discrepancy were indicated within the bar only if the clinical significance guideline was exceeded.
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Figure3: Maxillary angular predicted versus actual discrepancies compared by treatment system showed 10 discrepancies statistically different. Clinical significance was demonstrated by Insignia for the three toque (Tor) discrepancies and 2 of 4 rotation (Rot) discrepancies. Incognito showed 2 of 3 tip (Tip) discrepancies as clinically significant.
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Figure 4: Mandibular linear predicted versus actual discrepancies compared by treatment system showed that 6 of 7 buccal-lingual discrepancies differed statistically. Clinical significance was demonstrated by Insignia for 5 of 6 buccal-lingual discrepancies. Figure 5: Mandibular (n) linear predicted versus actual discrepancies compared by treatment system showed 5 mesial-distal and 3 occlusal-gingival discrepancies that differed statistically. Clinical significance was demonstrated by Insignia for central and lateral incisor occlusal-gingival discrepancies.
ACCEPTED MANUSCRIPT Figure 6: Mandibular angular predicted versus actual discrepancies were compared by treatment system. Statistically different were 5 tip (central incisor through second premolar) and 2 rotation (canine and first premolar) discrepancies. Clinical significance was demonstrated by Incognito for tip lateral incisor through second premolar; Insignia demonstrated clinical significance canine tip and rotation and first premolar rotation discrepancies.
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Table 1: A comparison of Insignia and Incognito samples for treatment time, number of appointments and emergency visit. Non-parametric Mann-Whitney U test demonstrated a significantly higher number of emergency appoints for Insignia than Incognito.
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Efficiency measures Insignia Incognito P signif treatment time (months) 16.5 15.1 NS number of appointments 16.3 22.6 NS emergency visits 2.2 0.7 .002
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Table 2: MannWhitney U tests demonstrated significantly lower ABO Cast-Radiograph Evaluation system scores for Incognito for alignment, occlusal contact, occlusal relationship, overjet and total score. Incognito (n=16) Insignia (n=21) ABO criteria mean ±SD mean ±SD mean dif P sig alignment 2.6 ±1.4 6.2 ±1.8 -3.6 .000 marginal ridge 5.0 ±2.1 5.1 ±2.1 -.1 NS buccolingual inclination 5.8 ±3.5 3.9 ±3.3 1.8 NS occlusal contact 0.7 ±1.0 3.9 ±2.5 -3.2 .000 occlusal relationship 1.3 ±2.8 3.6 ±3.4 -2.3 .013 overjet 1.8 ±1.7 4.0 ±2.8 -2.2 .011 interproximal contact 0.0 ±0.0 0.0 ±0.0 0.0 NS root angulation 1.1 ±1.1 1.5 ±1.8 -.4 NS Total score 18.3 ±6.3 28.3 ±6.3 -10.0 .000
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Table 3: Paired t-tests demonstrated significant right-left side differences. Note that a greater number of right-left side differences were found for Insignia than for Incognito (20 vs4), respectively. (Mx=maxilla; Mn=mandible; MD=mesial-distal; BL=buccallingual; OG=occlusal-gingival; Rot=rotation; Tor=torque) Incognito Insignia
central Mx Mn MD BL Rot
lateral Mx Mn MD Rot BL Rot Tor
canine Mx Mn OG Tor
OG
1st premolar Mx Mn OG
MD OG Rot
2nd premolar Mx Mn Rot MD
OG Tip
1st molar Mx Mn
2nd molar Mx Mn
MD Rot
Rot
OG Tor
Tor
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Table 4: Clinical significance guidelines for linear tooth movements (>0.5 mm) were exceeded in the mandible by Incognito 3 times and by Insignia 9 times. For maxilla, linear tooth movement guidelines were exceeded by Incognito 6 times and by Insignia 9 times. BL=buccal-lingual, OG=occlusal-gingival, MD=mesial-distal, 1=central, 2=lateral, etc. 7=second molar. Mandible – Linear Maxilla – Linear Insignia Incognito Insignia Incognito BL1 MD7 MD7 BL2 MD6 MD6 BL5 BL1 BL1 BL6 BL6 BL2 BL7 BL7 BL4 OG1 BL5 OG2 BL6 BL6 OG8 BL7 BL7 OG7 OG7 OG7 OG7
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9 of 21 (42.9%) 3 of 21 (14.3%) 9 of 21 (42.9%) 6 of 21 (28.6%)
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Table 5: Clinical significance guidelines for angular tooth movements (>2.0 degrees) were exceeded in the mandible by Insignia 16 times and by Incognito 18 times. For maxilla, linear tooth movement guidelines were exceeded by Insignia17 times and by 21 of 21 (1005) by Incognito. Tip=tip, Tor=torque, Rot=rotation, 1=central, 2=lateral, etc., 7=second molar Mandible – Angular
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Tip3
Tip7 Tor1 Tor2 Tor3 Tor4 Tor5 Tor6 Tor7 Rot1 Rot2
Tip7 Tor1 Tor2 Tor3 Tor4 Tor5 Tor6 Tor7
Rot4 Rot5 Rot6 Rot7
Rot4 Rot5 Rot6 Rot7
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Incognito Tip1 Tip2 Tip3 Tip4 Tip5
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Insignia
Rot3
Rot2
Maxilla – Angular Insignia Incognito Tip1 Tip2 Tip2 Tip3 Tip3 Tip4 Tip5 Tip6 Tip7 Tip7 Tor1 Tor1 Tor2 Tor2 Tor3 Tor3 Tor4 Tor4 Tor5 Tor5 Tor6 Tor6 Tor7 Tor7 Rot1 Rot1 Rot2 Rot2 Rot3
Rot4 Rot5 Rot6 Rot7
Rot3
Rot4 Rot5 Rot6 Rot7
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16 of 21 (76.2%) 18 of 21 (85.7%) 17 of 21 (81.0%) 21 of 21 (100%)
Accuracy of digital predictions with CAD/CAM labial and lingual appliances: A retrospective cohort study Mirna G. Awad BDS , Skander Ellouze , Smith Ashley BD.c.(Hons),MDSc , Nikhilesh Vaid BDS, MDS , Laith Makki BDS, MSc , Donald J. Ferguson DMD, MSD PII: DOI: Reference:
S1073-8746(18)30062-8 https://doi.org/10.1053/j.sodo.2018.10.004 YSODO 550
To appear in:
Seminars in Orthodontics
Please cite this article as: Mirna G. Awad BDS , Skander Ellouze , Smith Ashley BD.c.(Hons),MDSc , Nikhilesh Vaid BDS, MDS , Laith Makki BDS, MSc , Donald J. Ferguson DMD, MSD , Accuracy of digital predictions with CAD/CAM labial and lingual appliances: A retrospective cohort study, Seminars in Orthodontics (2018), doi: https://doi.org/10.1053/j.sodo.2018.10.004
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT Title: Accuracy of digital predictions with CAD/CAM labial and lingual appliances: A retrospective cohort study
Authors:
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Mirna G. Awad, BDS Orthodontic Graduate Resident European University College
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Skander Ellouze Total Health Orthodontics Specialist
Visiting Professor at Bordeaux University & Valencia University
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Toowoomba , Australia
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Orthodontist Private Practice,
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Smith Ashley BD.c.(Hons),MDSc
Nikhilesh Vaid, BDS, MDS
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Professor of Orthodontics
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European University College,
Laith Makki, BDS, MSc Instructor, Advanced Orthodontic Program European University College
Donald J. Ferguson, DMD, MSD Dean & Professor of Orthodontics
ACCEPTED MANUSCRIPT European University College
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Donald J. Ferguson, DMD, MSD Professor & Dean European University College Dubai Healthcare City, UAE Ibn Sina Building, Block D, 3rd Floor, Office 302 PO Box 53382, Dubai, UAE email: [email protected] mobile: +971 50 149 2375 tele: +971 4 362 4788 fax: +971 4 362 4793
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Corresponding author:
Title: Accuracy of digital predictions with CAD/CAM labial and lingual appliances: A retrospective cohort study
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Authors: Mirna G. Awad, Elouse Skander, Smith Ashley, Nikhilesh Vaid, Laith Makki, Donald J. Ferguson
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ABSTRACT
Purpose: To compare the treatment efficacy and efficiency of the two CAD/CAM
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customized bracket systems Incognito (lingual) and Insignia (labial) for differences in: 1) ABO Cast and Radiograph Evaluation system scores, 2) efficiency as assessed by
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three clinical measures of efficiency, and 3) final treatment outcome and the virtual set up. Materials & Methods: Consecutive patients treated with Insignia (n=21) and
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Incognito (n=16) treatment systems had STL Images evaluated at pretreatment, post treatment and virtual set-up (predicted outcome); predicted and post treatment STL images were superimposed upon each other and differences were recorded. Results: Incognito patients had fewer emergency appointments. ABO scores were also better for Incognito in 4 of the 8 categories and in total score; a “pass” total score of <27 was achieved in 87.5% on Incognito cases versus 42.9% of Insignia cases. Predicted versus actual outcomes assessment showed the following: right-left symmetry for incognito (95.2%) and Insignia (75.0%), more efficacious linear tooth movements of <0.5 mm for
ACCEPTED MANUSCRIPT Incognito (78.6% vs 57.1%), more efficacious angular tooth movements of <2.0 degrees for Insignia (21.4% vs 7.1%). Incognito was more effective with linear predicted versus actual outcomes and more efficaciousness especially in remaining within clinical significance guidelines. Incognito out performed Insignia in the maxilla, especially by staying within the clinical significant guidelines, and Incognito also out performed Insignia in the mandible, except for mandibular tip discrepancies. Conclusions: Based upon the conditions of the present study, the Incognito treatment system was more
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efficacious than Insignia when the two treatment systems were critically compared.
ACCEPTED MANUSCRIPT INTRODUCTION Goal directed orthodontics with customized appliance systems is aimed at improving, both the efficacy and efficiency of orthodontic mechanotherapy. The incorporation of CAD/CAM technology in the fabrication of these appliance systems is to achieve both precision and efficiency. Orthodontic treatment should be not only effective1, i.e. able to produce a desired or intended result, but also efficient in terms of total treatment time
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and number of appointments (Brown 2015)2.Laboratory-fabricated indirect bonding protocols enable easy and accurate placement of brackets on a handheld model in preparation for precise bracket transfer to the patient’s own teeth. While indirect bonding techniques have demonstrated good bond strength, the accuracy of the indirect
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bracket transfer techniques has varied.2
Customized orthodontic treatment systems are designed to facilitate orthodontists in appliance placement by simplifying clinical procedures. Once placed, these customized treatment systems provide prescription outcomes based upon the unique features of the specific malocclusion of the patient thereby streamlining mechanics toward pre-
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established goal posts or end points. CAD/CAM techniques start by creating a setup of the desired outcome that serves as a diagnostic aid and a road map outlining the steps
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Incognito
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for robotically bending arch-wires that will achieve the desired outcome.
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The Incognito treatment system (3M-Unitek, Monrovia, CA, USA)3,4 combines individualization of bracket bases, bracket slots and arch wires to create fully
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customized lingual orthodontic appliances. Bracket bases are individualized to the tooth anatomy and initial position of the tooth in the dental arch. Bracket slots are customized to produce ideal tooth movement, and wires are formed to minimize the overall thickness of the appliance in the mouth. Impressions/intra oral scans are acquired before treatment and a setup (either laboratory or virtual) is created. Based on an optical scan of the laboratory setup or on the digital setup, custom bracket bases are created and attached to virtual bracket
ACCEPTED MANUSCRIPT bodies. The position of the bracket body on the digital setup is optimized to achieve ideal tooth movement and maximum comfort. A three-dimensional printer produces wax patterns of the customized brackets and these are cast in a gold alloy. A series of robotically bent wires are formed according to the position of the brackets’ slots in the virtual setup. An indirect bonding tray is created in order to transfer the virtual position of the bracket to the patient’s mouth. Orthodontic treatment will proceed by arch wire progression. The claimed advantages include optimum esthetic appearance, great
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accuracy in final results, fewer incidences of white spot lesions, less discomfort over other lingual systems, and relatively easy and precise direct rebonding of inadvertently debonded brackets because of good adaptation of the custom bracket bases. Disadvantages include potential for error in bracket positioning during placement of the
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indirect bonding tray, and need to re-order any lost bracket or fractured wire. Insignia
The Insignia treatment system is comprised of indirect bonded CAD/CAM self-ligating
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appliances (Ormco, Orange, CA, USA)5 and uses a customized slot that is cut into the bracket at the desired position. The clinician creates a virtual design of the final
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occlusion and alignment using computer-assisted technology with reverse-engineered brackets and arch wires used to obtain the intended result. Bracket bases are standard;
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slots are custom created to produce the desired tooth movement via arch wire progression to a straight final arch wire. Some customization, in terms of arch form, is
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also incorporated into the wire based on the width of the dental arch at the beginning of
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treatment.
Digital models are generated from impressions/scans are acquired before treatment. These are used to create a virtual setup of the desired outcome. This setup is sent to the orthodontist for refinement and approval. Once approved, brackets without slots are placed virtually on the teeth. The slots are cut into the actual brackets based on their position on the tooth in the setup. This will allow for insertion of a straight final full-size wire. The relative position of a bracket to its tooth is recorded on the setup and transferred to the initial model. An indirect bonding tray composed of bracket transfer
ACCEPTED MANUSCRIPT jigs is created to transfer the virtual position of the bracket to the patient’s mouth. Orthodontic treatment will proceed by arch wire progression. The main supposed advantage of the Insignia system is the customization of the bracket slot. The movement of the tooth no longer depends on the position of the bracket, but on the position of the slot. The treatment theoretically can be achieved with straight wires that, if needed, allow sliding of teeth along the wire. Disadvantages include the
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potential for error in bracket positioning, either virtually or during transfer to the mouth. Given that a customized bracket is used, if a bracket is lost, a new one must be ordered.
Weber investigated a commercially available CAD/CAM orthodontic system comparing
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treatment effectiveness and efficiency of the customized appliances to traditional twin appliances. The study reported significantly lower American Board of Orthodontic (ABO) scores, fewer archwire appointments, and shorter overall treatment times in the CAD/CAM group.6 Although these findings were promising, the study did not distinguish
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actual customized brackets.
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whether the clinical benefits were due to indirect bonding in the CAD/CAM group or the
Brown compared ABO scores and clinical efficiency between CAD/CAM group, indirect bonding group and direct bonding group. The study reported that CAD/CAM group was
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more efficient in regard to treatment duration but ABO scores were better in the direct
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bonding group.2
Penning investigated the clinical efficiency between Insignia customized and Damon
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non-customized orthodontic systems and reported treatment clinical quality was comparable between two groups. Treatment with a customized appliance required significantly more planning time from the orthodontist and was associated with a higher number of visits due to lose brackets and was not associated with any significant reduction in treatment duration.7 Only one study has investigated the accuracy of tooth positioning in the Incognito system by superimposition of the virtual set up on the actual treatment outcome;
ACCEPTED MANUSCRIPT Grauer reported fully customized lingual orthodontic appliances were accurate in achieving the goals planned at the initial setup, except for the full amount of planned expansion and the inclination at the second molars.8 No study has investigated orthodontic treatment outcome quality generated by the software system of the labial customized bracket system. A systematic review by Papageorgiou compared the clinical effects of labial and lingual
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orthodontic fixed appliances and he recommended comparison of clinical quality between labial and lingual bracket system using the ABO grading system.9 Accurate assessment of technological applications can be made only if achieved treatment results are compared to planned simulations using an accurate and validated measurement 3D coordinate system that can assess accurate differences between different planned and
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actual tooth movements.8 The present study attempts to do that, and to compare a labial and lingual customized appliance system using matched samples. ABO Cast-Radiograph Evaluation System
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A commission of the American board of orthodontics (ABO) directors was formed in 1994 to develop a system that could be used to quantify tooth position more exactly.
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And in 1997 the ABO completed its Objective Grading System (OGS) for scoring post treatment case records which was later renamed the Cast-Radiograph Evaluation System. This system included 8 criteria: alignment, marginal ridges, buccolingual
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inclination, occlusal relationship, occlusal contact, overjet, interproximal contact and root angulation. The system used special gauge to make the measurement standardized
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by the examiners. The validity and reliability of the ABO OGS were confirmed and used for evaluation of the orthodontic records, The ABO OGS provides and methods for an
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objective assessment of the outcome and achievement of the orthodontic treatment.10 Others found that the ABO OGS involves more rigorous standards then the PAR or the index of complexity, outcome, and the need for assessing the outcome of the orthodontic treatments.11 eModel™ 9.0 “Compare” Software (Geodigm) Digital models offer a clear advantage over dental casts in assessing longitudinal changes given that they can be registered and superimposed in space.12,13 Among other
ACCEPTED MANUSCRIPT methods of treatment results assessment in orthodontics, outcomes in orthodontics also can be assessed by comparing the obtained outcome with the planned setup. Spatial registration of the setup model on the final digital models is achieved by an iterative closest point (ICP) algorithm or “best fit” of surfaces. Using Compare software, Grauer evaluated the reliability of the ICP registration of setup models to their homologous final outcome model. He concluded that surface-to-surface registration of final orthodontic digital models to planned setup models also is reproducible.14 This software had been used
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in many studies of Invisalign15 and Incognito lingual appliances.8 Purpose and Hypotheses
The purposes of this study were to compare the treatment efficacy and efficiency of the
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two CAD/CAM customized bracket systems Incognito (lingual) and Insignia (labial) as follows:
1. Differences in ABO Cast and Radiograph grading system scores. 2. Differences in efficiency as assessed by three clinical measures of efficiency.
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3. Differences between the final treatment outcome and the virtual set up. The null hypotheses tested were as follows:
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1. No differences in treatment outcome quality as determined using the ABO CastRadiograph Evaluation system.
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2. No differences in treatment efficiency using three measures of clinical efficiency; number of appointments, number of emergencies and overall length of active
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orthodontic treatment.
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3. No differences in predicted versus actual treatment outcomes.
MATERIALS and METHODS Sample
The research design was a retrospective cohort study. Ethical approval was obtained from
the European University College IRB Committee.
ACCEPTED MANUSCRIPT The sample was comprised of 37 patient-subjects separated by treatment methods: Insignia patient-subjects with 14 females and 7 males (n=21) were treated with the customized labial Insignia appliance; Incognito patient-subjects with 12 females and 4 males (n=16) were treated with the customized lingual Incognito appliance. All patients evaluated for a given appliance type were treated by a single experienced operator with
Criteria for sample selection were as follows: Inclusion criteria: 1) consecutively treated non extraction cases,
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the appliance.
2) complete maxillary and mandibular fixed appliances used (7-7),
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3) only intraoral, intra-arch or inter-arch mechanics,
4) complete chart entries, including number of appointments, emergencies, treatment time, and
5) availability of pretreatment and post-treatment digital casts, treatment prediction
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digital casts, pre treatment and post-treatment panoramic radiographs. Exclusion criteria for sample selection were as follows:
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1) previous orthodontic treatment,
2) treatment involving functional appliances, growth modification, extractions,
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temporary skeletal anchorage, extra oral appliances, or orthognathic surgery, 3) impacted teeth except for third molars,
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4) restorative treatment required following post orthodontic therapy, 5) incomplete pretreatment or post-treatment records,
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6) chronic medications affecting bone metabolism, i.e. NSAIDS, steroids, antiinflammatory, etc., and
7) lack of compliance defined as no appointment for 3 consecutive months.
Procedures Treatment Efficiency Using Clinical Practice Data 1. Demographic data for the study participants was collected including gender and age at the beginning of treatment.
ACCEPTED MANUSCRIPT 2. Treatment data was collected consisting of the number of treatment appointments (bonding, arch-wire adjustments, emergencies, and de-bonding), duration of treatment (months); records gathered were initial and final cephalometric and panoramic radiographs, and e-Model (stereolithography or STL) digital casts (GeoDigm Corp, Falcon Height, MN). 3. Emergencies were counted as appointments if brackets were replaced or wires changed, but not if long wires extending out of molar tubes were clipped. efficiency was
assessed
using
three
parameters:
number
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4. Treatment
of
appointments, number of emergencies and overall length of active orthodontic treatment time. Treatment Efficacy Using ABO Grading System
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Before data collection, the investigator was trained and calibrated on both the ABO Discrepancy Index and the ABO Cast-Radiograph Evaluation techniques. The investigator performed all measurements and case analyses which also included PAR index scoring.
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1. The ABO Discrepancy Index (DI) was used to grade/score the pre-treatment digital casts using 3Shape Ortho Analyser software program. DI score established a numeric
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value correlating to the relative severity of the orthodontic problems of each subject. 2. The post-treatment STL study casts were 3D printed using EDEN260VS dental
advantage (Stratasys-3D future technology) in order to be able to manually assess
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them according to the ABO Cast and Radiograph Evaluation system scoring using the ABO special gauge; final panoramic radiographs were included to objectively
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quantify the treatment outcome of each patient. ABO criteria include the following: alignment, marginal ridges, bucco-lingual inclination, occlusal contact, occlusal
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relationship, overjet, interproximal contact and root angulation.
3. Treatment efficacy using ABO grading scores was assessed using the eight ABO
criteria plus total score as well as number of cases with total score <27.
Treatment Efficacy Using Prediction Versus Actual Outcome 1. All digital models were de-identified and soft tissues were digitally removed to ensure that evaluation was based solely on tooth-surface features.
ACCEPTED MANUSCRIPT 2. The maxillary setup model was registered to the maxillary final model using eModel™ 9.0 “Compare” software (Geodigm Corporation, Chanhassen, MN) to combine both models in the same coordinate system. The same process was followed for the mandibular setup model.15
3. The surface-to-surface registration of the setup dental arch to the final arch was independently performed for both arches. Fifty (50) iterations were automatically performed until the best fit of the surfaces was obtained (Figure 1A).
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4. The virtual set up models were segmented to isolate each tooth as a separate object and compared with the un-segmented post treatment plan models using the same software.
5. After the dental arches were first aligned globally, the software then superimposed individual teeth from the segmented virtual set up on the corresponding teeth in the un-segmented post
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treatment model using best-fit surface-based registration (Figure 1B).
6. Based on the transformation of axes required to fit each tooth, the software quantified the differences or discrepancies between achieved and predicted position for each tooth in the following six directions: mesial-distal, facial-lingual, occlusal-gingival, tip, torque, and rotation.
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The differences were expressed with respect to the center of resistance.
7. Treatment efficacy using predicted versus actual outcomes was assessed by
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comparing right-left sides of both maxilla and mandible, linear absolute values <0.5 mm and angular absolute values <2 degrees and differences in predicted versus
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Insert Figure 1
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actual means by treatment system.
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Statistical Analysis
Data was collected and stored (Excel, Microsoft, Seattle, WA) and later transformed for use for analysis by SPSS (SPSS software v.15.0.1, IBM, Armonk, NY). The 0.05 probability level of significance was used for all testing purposes (P≤.05). Distributions of samples were evaluated for equality of variances; non-parametric tests were used if variances were found unequal and when nominal or ordinal data was evaluated. Parametric paired t test was used for intra-group the comparisons between pre-treatment and post-treatment; unpaired t-tests were used to compare mean ABO scores of treatment
ACCEPTED MANUSCRIPT outcomes. Clinical significance for tooth movements followed the ABO guidelines of >.05 mm for linear movements and >2.0 degrees for angular measurements. Technique reliability/reproducibility was evaluated. One week after completion of the data collection, the ABO Discrepancy Index and Cast-Radiograph Evaluation were repeated on 10 randomly selected subjects to assess Intra-examiner reliability. Dahlberg’s test was used to assess whether or not the examiner is reliable. Validity of Analyzer and e-model16 Compare 8.1 software17 programs.
RESULTS
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Treatment Efficiency
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measurement technique has been validated in scholarly literature for both 3Shape Ortho
As described immediately below, severity of initial Insignia and Incognito malocclusions were assessed as no different using the ABO Discrepancy Index. The number of emergency visits was significantly less for Incognito (0.7 vs 2.2, P=.002). For Insignia
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and Incognito, mean treatment times were 16.5 and 15.1 months and number of
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appointments were 16.3 and 22.6, respectively and both insignificant (P>.05). (Table 1) Insert Table 1:
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Treatment Efficacy – ABO Cast-Radiograph Evaluation Initial severity of malocclusion for Insignia and Incognito were respectively 5.6 and 5.7
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(P>.05) using ABO Discrepancy Index. However, using PAR index for assessment of initial malocclusion, Insignia demonstrated a significantly more severe malocclusion
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than Incognito, i.e. 23.8 and 17.8, P=.044, respectively. Four of the eight grades/scores used in the ABO Cast-Radiograph Evaluation system were found significantly lower for Incognito, i.e. alignment, occlusal contact, occlusal relationship and overjet. ABO Cast-Radiograph Evaluation total score was also significantly lower for incognito (18.3 vs 28.3, P=.000) (Table 2) Moreover,14 of 16 Incognito cases (87.5%)scored below the ABO pass score of 27 compared to9 of 21 (42.9%)Insignia cases with total score <27. (not shown)
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Insert Table 2: Treatment Efficacy – Predicted Outcome Versus Actual Treatment Outcomes As described previously, the patient’s actual outcome STL image was superimposed upon the STL image representing the outcome predicted by the treatment system. This data represented the difference between the two STL images. Paired t-tests were used
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to compare right-left data on each tooth for each movement per jaw. For Incognito, significant (P<.05) right-left differences were demonstrated for 4 variables affecting 3 teeth; one was in the maxilla (rotation) and 3 were in the mandible (mesial-distal and rotation). For Insignia, significant right-left differences were demonstrated for 21 variables with near equal distribution in the maxilla and mandible; 11 variables with
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right-left differences (P>.05) were linear (mesial-distal, buccal-lingual and occlusalgingival) and 10 variables were angular (rotation, tip and torque). Right-left Insignia differences were greatest for the mandibular first premolar, i.e. mesial-distal, occlusalgingival and rotation variables were significantly different. (Table 3)
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Insert Table 3:
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Right-left data were pooled for each treatment system per tooth per tooth movement per jaw. ABO guidelines as measures of clinical significance for linear measurements
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was>0.5 mm and >2.0 degrees for angular measurements. Discrepancies between predicted and actual outcome values for tooth movements that exceeded these clinical
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significance guidelines were indentified. For linear tooth movements in the mandible, Incognito exceeded the guideline of >0.5 mm 3 of 21 times (14.3%) and Insignia
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exceeded 9 of 21 times (42.9%). In the maxilla, Incognito mean linear tooth movements exceeded the guideline 6 of 21 times (28.6%) and Insignia exceeded 9 of 21 times (42.9%). (Table 4) Insert Table 4: Discrepancies between predicted and actual outcome values for angular tooth movements in the mandible for Incognito exceeded the angular tooth movement clinical
ACCEPTED MANUSCRIPT significance guideline of >2 degrees 16 times (76.2%) and Incognito exceeded 18 times (85.7%). In the maxilla, 17 of 21 (81.0%) of angular tooth movements were deemed clinically significant for Insignia and Incognito was clinically significant 100% of the time, i.e. 21 of 21 means differed. (Table 5) Insert Table 5:
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One of the aims of the present study was to compare and contrast Insignia and Incognito treatment systems. The pooled predicted versus actual outcome discrepancies were compared by treatment system; statistically significant differences were identified and plotted relative to clinically significant guidelines. For maxillary linear discrepancies, only the buccal-lingual discrepancies differed statistically. All seven buccal-lingual
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predicted versus actual outcome discrepancies differed statistically, and 6 of 7 Insignia discrepancies exceeded the ABO clinical guideline of ±0.5 mm. The predicted versus actual discrepancy error for Insignia was buccal (positive) for maxillary central and lateral and lingual (negative) for first premolar through second molar. In other words,
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the Insignia treatment system showed tooth crowns discrepant from buccal to lingual and the discrepancies were progressive from anterior to posterior teeth; all but canine
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buccal-lingual predicted versus actual discrepancies were clinically significant, i.e.
Insert Figure 2:
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exceeded ±0.5 mm. (Figure 2)
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For maxillary angular discrepancies, 3 torque, 3 tip and 4 rotation discrepancies differed statistically between the two treatment systems. The torque discrepancies were positive
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(buccal) for maxillary central, second premolar and first molar and the three discrepancies clinically significant (exceeded 2.0 degrees) for Insignia. In contrast, there were three statistically significant tip discrepancies with Incognito exceeding mesial (positive) clinical guidelines in two, i.e. maxillary canine and second premolar. Maxillary rotation discrepancies differed statistically for central, canine, second premolar and first molar, and Insignia exceeded distal (negative) clinical guidelines (-2.0 degrees) in two, i.e. canine and first molar (Figure 3)
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Insert Figure3: In the mandible, there were and total of 14 linear predicted versus actual discrepancies that differed statically. All buccal-lingual discrepancies differed except mandibular canine, and Insignia exceeded clinical guidelines in 5 of the 6; discrepancies for central and lateral incisor crowns exceeded 0.5 mm (buccal) and discrepancies for second
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premolar through second molar exceeded -0.5 mm (lingual). (Figure 4) Insert Figure 4:
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Insert Figure 5:
For mandibular angular predicted versus actual discrepancies compared by treatment system, statistically significant differences were found for five tip (central incisor
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through second premolar) and two (canine and first premolar) angular discrepancies. Discrepancies were clinically significant for Incognito lateral incisor through second
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premolar tip discrepancies and for Insignia canine. Insignia demonstrated clinical
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Insert Figure 6:
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significance for canine and first premolar rotations. (Figure 6)
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DISCUSSION
The main goal of CAD/CAM orthodontic appliances is to improve the final outcomes. Intuitively, these systems should reduce the effects of human error during orthodontic treatment, account for anatomic variations in tooth shape, and improve the overall finished treatment quality.2 To our knowledge the present study is the first study comparing accuracy of two fully customized bracket treatment systems, labial versus lingual, i.e. Insignia versus
ACCEPTED MANUSCRIPT Incognito. The three types of comparisons included: 1) clinical efficiency, i.e. treatment time period and convenience to the treating clinician, 2) efficacy of treatment outcome, i.e. the quality of the result using ABO criteria, and 3) efficacy of the treatment system itself, i.e. ability of the predicted outcome to match the actual treatment outcome. Most other studies comparing labial and the lingual appliances focused on oral discomfort, speech difficulty and incidence of white spot legions.18-21
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Since introduction of lingual appliances by Fujita progress has been seen in their design, manufacturing, and mechanotherapy.22 There are several publications comparing the difference in treatment outcomes between the labial and lingual appliances but the labial treatment systems were not customized.9 Deguchi used the PAR index and cephalometric analysis to compare between labial and lingual appliances but he limited
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the investigation to Class II extraction cases; the lingual appliance used is different from the present study.23
A few publications have compared the Insignia treatment system with another labial
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treatment appliance. Weber compared the Insignia with Roth conventional bracket system and reported Insignia more efficient that the conventional labial bracket system,
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i.e. shorter treatment time and fewer emergency appointments. Moreover, Weber reported better ABO scores resulting from Insignia treatment.6 Another investigator compared two self-ligating bracket systems (direct and indirect bonding) with Insignia
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bracket system and concluded that Insignia was more efficient in regards to the treatment duration; similar outcomes were reported for treatment outcome
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comparisons using the ABO Cast-Radiograph Evaluation system.2
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Penning reported results from a randomized controlled trial aimed to evaluate the duration and the outcome of orthodontic treatment between customized fixed appliance Insignia and the non-customized Damon system; he concluded that the customized treatment system had significantly more loose brackets, a longer planning time, and more complaints (P<.05).7 The Insignia treatment system was not associated with significantly reduced treatment duration, and treatment quality was comparable between the two appliance systems studied.
ACCEPTED MANUSCRIPT The present study compared labial to lingual customized CAD/CAM bracket systems with a focus on clinical efficiency, treatment outcomes and accuracy of predicted versus actual outcomes. Clinical Efficiency Of the three clinical efficiency measures used in the study, Incognito had significantly fewer emergency appointments than Insignia (2.2 vs 0.7, P=.002). Numbers of
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appointments were insignificantly fewer for Insignia (16.3 vs 22.6) and overall treatment time was insignificantly shorter for Incognito (15.1 vs 16.5 months). From a clinical perspective, customization and incorporation of technology for the same is the gold standard in lingual orthodontics, due to multiple factors; including accessibility to bonding surfaces and variable lingual anatomy. However, for the vestibular surface, the
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benefits of technology for customization haven’t yet been comprehensively proven in scholarly literature.24 Penning, in-fact, has observed more loose brackets in the customized appliance group, when they compared them to non-customized group. Our findings also indicate significantly more emergency appointments for the vestibular
Efficacy of Treatment Outcome
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customized group, compared to the lingual group.7
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The present study demonstrated substantially improved treatment outcomes with Incognito compared to Insignia. Incognito treatment patients scored significantly
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(P<.05) lower in 4 of 8 ABO criteria using the ABO Cast-Radiograph Evaluation system, i.e. alignment, occlusal contact, occlusal relationship and overjet, and total score was
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significantly lower for Incognito (18.3 vs 28.3, P=.000). Using an ABO “pass” total score of <27 to signify successful orthodontic treatment outcome, 87.5% Incognito patients
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succeeded while only 42.9% of Insignia patients succeeded. These results are compelling because ABO Discrepancy Index scores measuring severity of initial malocclusion were not different (P>.05). It is interesting to point out that Insignia had a significantly higher initial malocclusion PAR Index score compared to Incognito (23.8 and 17.8, P=.044) but results of scoring with the ABO Cast-Radiograph Evaluation system showed Incognito superior. This finding was interesting but not really surprising given the fact that PAR and DI indices use different scoring criteria. Using quality of treatment outcome as measured by the ABO Cast-Radiograph Evaluation system,
ACCEPTED MANUSCRIPT Incognito was clearly more efficacious than Insignia in the present study, when digital models were prepared by scans on the same day as the debonding in both groups. Efficacy of Predicted Outcome Versus Actual Outcome A comparison of predicted outcome versus actual outcomes were inconsistent was assessed in three ways. The first was to compare mean data from right and left sides within each of the two groups. Doing so is a reflection upon the bilateral nature of how
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well predicted outcome matches actual outcome and suggests that no difference between right and left sides is a measure of symmetrical treatment effectiveness. Incognito clearly demonstrated better symmetrical treatment effectiveness with no difference in 80 of 84 (95.2%) right-to-left tooth movements while Insignia showed no difference in 63 of 84 (75.0%) right-left sides. There appeared to be relatively even
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distribution of right-left differences with no particular pattern emerging. (see Table 3) The second evaluative assessment of predicted outcome versus actual outcome was a within-group comparison with guidelines for clinical significance, i.e. <±0.5 mm for
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linear tooth movements and <±2.0 degrees for angular tooth movements. Incognito was clearly more efficacious for linear discrepancies demonstrating only 14.3% predicted vs
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actual outcomes discrepancies >0.5 mm in the mandible while Insignia showed 42.9%. The same was found for linear tooth movements in the maxilla; Incognito showed 28.6% and Insignia showed again 42.9%. For angular tooth movements, Insignia showed fewer
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predicted versus actual outcomes discrepancies >2.0 degrees than Incognito in both the mandible (76.2% vs 85.7%) and in the maxilla (81.0% vs 100%). In summary, the
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Insignia treatment system was more efficacious for angular predicted outcome versus actual outcome discrepancies while Incognito was more efficacious for linear
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discrepancies.
Thirdly, right-left pooled predicted versus actual outcome discrepancies were compared by Incognito and Insignia treatment system. For maxillary linear discrepancies, statistically significant differences were demonstrated for all maxillary buccal-lingual discrepancies and Insignia discrepancies exceeded the 0.5 mm clinically significant guideline in 6 of 7 of those buccal-lingual differences. For maxillary angular discrepancies, statistically significant differences were demonstrated three torque, three
ACCEPTED MANUSCRIPT tip and four rotation discrepancies; clinically significant (2.0 degrees) guidelines were exceed by Insignia for 5 of 10 discrepancies and Incognito exceed 2.0 degrees for 2 of 10. To summarized maxillary performance, Incognito out performed Insignia, especially by staying within the clinical significant guidelines. For mandibular linear discrepancies, statistically significant differences were demonstrated for all mandibular buccal-lingual discrepancies except canine; again, as in
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the maxilla, Insignia exceeded 0.5 mm clinical guidelines in 5 of 6 discrepancies while Incognito exceeded none. In contrast with maxillary linear discrepancies, there were five mesial-distal (central incisor through second premolar) and three occlusal-gingival (central incisor through canine) mandibular angular discrepancies statistically different with two of the Insignia occlusal-gingival discrepancies assessed as clinical significant.
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Mandibular angular predicted versus actual outcome discrepancies differed statistically for five tip (central incisor through second premolar) and two rotation (canine and first premolar) discrepancies; 4 of 5 tip discrepancies for Incognito exceeded clinical guidelines and, for Insignia, 1 of 5 tip discrepancies was clinically significant. Two of
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three rotation discrepancies were clinically significant for Insignia. In summarizing mandibular comparisons, Incognito out performed Insignia, except of mandibular tip
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discrepancies.
Viewed from a broad perspective, results of the ABO Cast-Radiograph Evaluation system
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assessment were arguably the most compelling in concluding that the Incognito treatment system is the more efficacious of the two treatment systems. The Incognito
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treatment system demonstrated better right-left predicted versus actual outcome symmetry effectiveness and was more effective with linear predicted versus actual
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outcomes. Moreover, the Incognito treatment system was more efficaciousness especially in remaining within clinical significance guidelines. The Insignia treatment system was more effective with angular predicted outcome versus actual outcomes. Difficulties encountered in performing the present study were the intensive labor and expense to gather and assemble STL files suitable for assessment using the Compare software and to produce 3D printed study casts. Hence, one limitations of the study was the small size of the samples, i.e. n=16 for Incognito and n=21 for Insignia. The second
ACCEPTED MANUSCRIPT limitation of this study was that Incognito and Insignia treatments were performed by different orthodontist clinicians; this confounding factor may have had an influence on finishing protocols. Clinical Significance The limitations of our study are consistent with any retrospective study that evaluates matched samples, and the risk of confounding variables can influence treatment results.
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The lingual Incognito appliance evaluated in the present study used significantly different bracket–arch wire geometry and ligation techniques in the finishing stages compared to the vestibular Insignia appliance that uses “passive” self ligation brackets. This possibly could have been a factor that influenced the efficacy of results.
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A recent trial comparing customized vestibular appliances with direct bonded ones comprehensively outlined the role of the treating clinician in planning and execution of treatment, affecting both treatment duration and quality.7 Critiques of technology often cite the cost-benefit ratio of technology (a variable not applied in the present study) as a
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possible impediment to incorporation of technology as laboratory costs with a customized appliance are significantly more costly. While this might seem a justifiable
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expense for lingual orthodontics due to the lingual surface anatomy and complex lingual biomechanics, scholarly literature has not been able to justify the benefits for vestibular appliances yet. Based upon the conditions of the present study, results of the present
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study indicate a similar phenomenon. Future trials to comprehensively evaluate digital systems should include an aesthetic outcome evaluation and a cost-benefit audit of the
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systems as well.
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CONCLUSION
Differences in clinical efficiency were compared for 16 patients treated with the Incognito treatment system and 21 patients treated with the Insignia treatment system. Patient treatment outcomes were also scored using the ABO Cast-Radiograph Evaluation system assessment after STL images were converted to 3D printed casts. Moreover, Compare software was used to superimpose predicated outcome (virtual set-up) and actual outcome; discrepancies between predicted and actual outcomes served as a basis
ACCEPTED MANUSCRIPT for also comparing treatment effectiveness between the Insignia and Incognito treatment systems. Important results of the present study were as follows: Incognito had fewer emergency appointments than Insignia. Actual patient treatment outcomes were significantly better for Incognito in ABO Cast-Radiograph Evaluation system assessment categories alignment, occlusal
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contact, occlusal relationship and overjet as well as total score.
Using an ABO “pass” total score of <27 to signify successful orthodontic treatment outcome, success rate for Incognito was 87.5%and 42.9% for Insignia.
Symmetry of right-left predicted versus actual outcomes was higher for Incognito (95.2%) compared to Insignia (75.0%).
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Incognito was more efficacious for linear tooth movements demonstrating 78.6% (33 of 42) predicted vs actual outcomes <0.5 mm while Insignia showed 57.1%. Insignia was more efficacious for angular tooth movements demonstrating 21.4% (9 of 42) predicted vs actual outcomes <2.0 degrees while Incognito showed only 7.1%.
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Incognito was more effective with linear predicted versus actual outcomes and more efficaciousness especially in remaining within clinical significance guidelines.
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Incognito out performed Insignia in the maxilla, especially by staying within the clinical significant guidelines.
Incognito out performed Insignia in the mandible, except of mandibular tip
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discrepancies.
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Based upon the conditions of the present study, the Incognito treatment system was the
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more efficacious of the two treatment systems. ACKNOWLEDGEMENTS Dr. Smith Ashley is thanked for his support and for providing the study sample of Insignia and we thank Dr. Elouse Skander for providing the samples of Incognito. Thanks to Mr. Mike Marshall, Marshall Technologies, LLC, for providing technical assistance with the use of Compare software. We acknowledge University of Minnesota for allowing permission and
ACCEPTED MANUSCRIPT use of the Compare software and 3D Future Technologies, Mumbai, India for printing the 3D models for ABO Cast-Radiograph Evaluation system analysis.
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17. Haque S, Sandler J, Cobourne MT, Bassett P, DiBiase AT. A retrospective study comparing the loss of anchorage following the extraction of maxillary first or second premolars during orthodontic treatment with fixed appliances in adolescent patients. J Orthod 2017; 44:268-276. 18. Gorman JC, Smith RJ. Comparison of treatment effects with labial and lingual fixed appliances.Am J Orthod Dentofacial Orthop 1991;99(3):202-209.
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22. Fujita K. New orthodontic treatment with lingual bracket and mushroom arch wire appliance. Am J Orthod 1979;76:657–675.
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23. Deguchi T, Terao F, Aonuma T, Kataoka T, Sugawara Y, Yamashiro T, Takano-Yamamoto T. Outcome assessment of lingual and labial appliances compared with cephalometric analysis, peer assessment rating, and objective grading system in Angle Class II extraction cases. Angle Orthod 2015;85:400–407.
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Figure 1: (A) The surface-to-surface registration of the setup dental arch to the final arch was independently performed; (B) superimposed individual teeth from the segmented virtual set up on the corresponding teeth in the unsegmented post treatment model using best-fit surface-based registration.
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Figure 2: Maxillary linear predicted versus actual discrepancies were compared by treatment system and statistically significant differences were first identified and then plotted relative to the ±0.5 mm clinically significant guideline. Only the buccal-lingual (BL) linear discrepancies differed statistically and of these, discrepancies were clinically significant for Insignia for maxillary central (1x), lateral (2x), first premolar (4x) through second molar (7x). Amounts of discrepancy were indicated within the bar only if the clinical significance guideline was exceeded.
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Figure3: Maxillary angular predicted versus actual discrepancies compared by treatment system showed 10 discrepancies statistically different. Clinical significance was demonstrated by Insignia for the three toque (Tor) discrepancies and 2 of 4 rotation (Rot) discrepancies. Incognito showed 2 of 3 tip (Tip) discrepancies as clinically significant.
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Figure 4: Mandibular linear predicted versus actual discrepancies compared by treatment system showed that 6 of 7 buccal-lingual discrepancies differed statistically. Clinical significance was demonstrated by Insignia for 5 of 6 buccal-lingual discrepancies. Figure 5: Mandibular (n) linear predicted versus actual discrepancies compared by treatment system showed 5 mesial-distal and 3 occlusal-gingival discrepancies that differed statistically. Clinical significance was demonstrated by Insignia for central and lateral incisor occlusal-gingival discrepancies.
ACCEPTED MANUSCRIPT Figure 6: Mandibular angular predicted versus actual discrepancies were compared by treatment system. Statistically different were 5 tip (central incisor through second premolar) and 2 rotation (canine and first premolar) discrepancies. Clinical significance was demonstrated by Incognito for tip lateral incisor through second premolar; Insignia demonstrated clinical significance canine tip and rotation and first premolar rotation discrepancies.
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Table 1: A comparison of Insignia and Incognito samples for treatment time, number of appointments and emergency visit. Non-parametric Mann-Whitney U test demonstrated a significantly higher number of emergency appoints for Insignia than Incognito.
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Efficiency measures Insignia Incognito P signif treatment time (months) 16.5 15.1 NS number of appointments 16.3 22.6 NS emergency visits 2.2 0.7 .002
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Table 2: MannWhitney U tests demonstrated significantly lower ABO Cast-Radiograph Evaluation system scores for Incognito for alignment, occlusal contact, occlusal relationship, overjet and total score. Incognito (n=16) Insignia (n=21) ABO criteria mean ±SD mean ±SD mean dif P sig alignment 2.6 ±1.4 6.2 ±1.8 -3.6 .000 marginal ridge 5.0 ±2.1 5.1 ±2.1 -.1 NS buccolingual inclination 5.8 ±3.5 3.9 ±3.3 1.8 NS occlusal contact 0.7 ±1.0 3.9 ±2.5 -3.2 .000 occlusal relationship 1.3 ±2.8 3.6 ±3.4 -2.3 .013 overjet 1.8 ±1.7 4.0 ±2.8 -2.2 .011 interproximal contact 0.0 ±0.0 0.0 ±0.0 0.0 NS root angulation 1.1 ±1.1 1.5 ±1.8 -.4 NS Total score 18.3 ±6.3 28.3 ±6.3 -10.0 .000
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Table 3: Paired t-tests demonstrated significant right-left side differences. Note that a greater number of right-left side differences were found for Insignia than for Incognito (20 vs4), respectively. (Mx=maxilla; Mn=mandible; MD=mesial-distal; BL=buccallingual; OG=occlusal-gingival; Rot=rotation; Tor=torque) Incognito Insignia
central Mx Mn MD BL Rot
lateral Mx Mn MD Rot BL Rot Tor
canine Mx Mn OG Tor
OG
1st premolar Mx Mn OG
MD OG Rot
2nd premolar Mx Mn Rot MD
OG Tip
1st molar Mx Mn
2nd molar Mx Mn
MD Rot
Rot
OG Tor
Tor
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Table 4: Clinical significance guidelines for linear tooth movements (>0.5 mm) were exceeded in the mandible by Incognito 3 times and by Insignia 9 times. For maxilla, linear tooth movement guidelines were exceeded by Incognito 6 times and by Insignia 9 times. BL=buccal-lingual, OG=occlusal-gingival, MD=mesial-distal, 1=central, 2=lateral, etc. 7=second molar. Mandible – Linear Maxilla – Linear Insignia Incognito Insignia Incognito BL1 MD7 MD7 BL2 MD6 MD6 BL5 BL1 BL1 BL6 BL6 BL2 BL7 BL7 BL4 OG1 BL5 OG2 BL6 BL6 OG8 BL7 BL7 OG7 OG7 OG7 OG7
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9 of 21 (42.9%) 3 of 21 (14.3%) 9 of 21 (42.9%) 6 of 21 (28.6%)
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Table 5: Clinical significance guidelines for angular tooth movements (>2.0 degrees) were exceeded in the mandible by Insignia 16 times and by Incognito 18 times. For maxilla, linear tooth movement guidelines were exceeded by Insignia17 times and by 21 of 21 (1005) by Incognito. Tip=tip, Tor=torque, Rot=rotation, 1=central, 2=lateral, etc., 7=second molar Mandible – Angular
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Tip3
Tip7 Tor1 Tor2 Tor3 Tor4 Tor5 Tor6 Tor7 Rot1 Rot2
Tip7 Tor1 Tor2 Tor3 Tor4 Tor5 Tor6 Tor7
Rot4 Rot5 Rot6 Rot7
Rot4 Rot5 Rot6 Rot7
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Incognito Tip1 Tip2 Tip3 Tip4 Tip5
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Rot3
Rot2
Maxilla – Angular Insignia Incognito Tip1 Tip2 Tip2 Tip3 Tip3 Tip4 Tip5 Tip6 Tip7 Tip7 Tor1 Tor1 Tor2 Tor2 Tor3 Tor3 Tor4 Tor4 Tor5 Tor5 Tor6 Tor6 Tor7 Tor7 Rot1 Rot1 Rot2 Rot2 Rot3
Rot4 Rot5 Rot6 Rot7
Rot3
Rot4 Rot5 Rot6 Rot7
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AN US
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16 of 21 (76.2%) 18 of 21 (85.7%) 17 of 21 (81.0%) 21 of 21 (100%)