- Email: [email protected]
Influence of lip retraction on the cone beam computed tomography assessment of bone and gingival tissues of the anterior maxilla
Accepted Manuscript Influence of Lip Retraction on the CBCT Assessment of Bone and Gingival Tissues of the Anterior Maxilla Jesca Neftali Nogueira Silva, MSc, Priscila Ferreira de Andrade, MSc, Bruno Salles Sotto-Maior, PhD, Neuza Maria Souza Picorelli Assis, PhD, Antônio Carlos Pires Carvalho, PhD, Karina Lopes Devito, PhD PII:
S2212-4403(17)30064-0
DOI:
10.1016/j.oooo.2017.02.005
Reference:
OOOO 1708
To appear in:
Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology
Received Date: 17 August 2016 Revised Date:
20 December 2016
Accepted Date: 7 February 2017
Please cite this article as: Silva JNN, Andrade PFd, Sotto-Maior BS, Souza Picorelli Assis NM, Pires Carvalho AC, Devito KL, Influence of Lip Retraction on the CBCT Assessment of Bone and Gingival Tissues of the Anterior Maxilla, Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology (2017), doi: 10.1016/j.oooo.2017.02.005. 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 INFLUENCE OF LIP RETRACTION ON THE CBCT ASSESSMENT OF BONE AND GINGIVAL TISSUES OF THE ANTERIOR MAXILLA
Authors:
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Jesca Neftali Nogueira Silva
MSc, School of Dentistry, Federal University of Juiz de Fora, Juiz de Fora, MG, Brazil - [email protected] Priscila Ferreira de Andrade
Brazil - [email protected]
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Bruno Salles Sotto-Maior
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MSc, School of Dentistry, Federal University of Juiz de Fora, Juiz de Fora, MG,
PhD, Department of Restorative Dentistry, School of Dentistry, Federal University of Juiz de Fora, Juiz de Fora, MG, Brazil - [email protected] Neuza Maria Souza Picorelli Assis
PhD, Department of Dental Clinic, School of Dentistry, Federal University of Juiz de Fora, Juiz de Fora, MG, Brazil - [email protected]
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Antônio Carlos Pires Carvalho
PhD, Department of Radiology, School of Medicine, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil - [email protected] Karina Lopes Devito
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PhD, Department of Dental Clinic, School of Dentistry, Federal University of Juiz
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de Fora, Juiz de Fora, MG, Brazil - [email protected]
Corresponding author: Karina Lopes Devito
Department of Dental Clinic, School of Dentistry, Federal University of Juiz de Fora Campus Universitário, s/n, CEP: 36036-900 - Juiz de Fora, MG, Brazil E-mail: [email protected]
Disclosures: “This paper consists of unpublished work which is not under consideration for publication elsewhere. All authors participated fully in the implementation of the
ACCEPTED MANUSCRIPT study, definition of the methodology and writing of the manuscript. Moreover, there is no conflict of interest regarding this work, or any funding source, and the publication was approved by all authors.”
Word count - manuscript: 3856 words Number of references: 27 Number of tables: 2
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Number of figures: 4
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Word count - abstract: 206 words
Statement of Clinical Relevance:
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The use of lip retractors during CBCT exams is a simple and reliable technique, which allows the measurement of gingival tissues in addition to bone tissue
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assessment.
ACCEPTED MANUSCRIPT INFLUENCE OF LIP RETRACTION ON THE CBCT ASSESSMENT OF BONE AND GINGIVAL TISSUES OF THE ANTERIOR MAXILLA
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ABSTRACT Objective: To evaluate the influence of lip retraction on cone beam computed tomography (CBCT) assessment of bone and gingival tissues on the labial surface of
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the anterior maxilla.
Study Design: A retrospective study was conducted using measurements of bone
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and gingival tissues collected from 120 maxillary incisors. The thicknesses of the bone and gingival tissues of different regions were measured on CBCT images, with and without a lip retractor. The thicknesses of the gingival tissues obtained from CBCT were correlated with measurements performed by clinical probing.
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Results: The thickness of bone in the more cervical region presented a higher mean value for exams performed with a lip retractor (p=0.021). The thickness of bone showed a significant correlation with the thickness of the gingiva (p≤0.020) with a lip
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retractor in CBCT exams. The thickness of the gingival tissue obtained from CBCT scans with lip retraction showed significant correlations with those obtained clinically
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(p≤0.001).
Conclusion: The use of lip retractors is a simple and reliable practice that allows the measurement of gingival tissues on CBCT images. This practice can exempt a patient from an invasive clinical procedure for measuring the thickness of the gingival tissue for implant cases of the anterior segment.
KEYWORDS: cone beam computed tomography; gingival thickness; implantology; cosmetic dentistry.
ACCEPTED MANUSCRIPT INTRODUCTION With the growing demand for aesthetic rehabilitation treatment, it has become necessary to determine parameters that offer greater predictability of peri-implant
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results, especially regarding the placement of immediate dental implants in the anterior maxilla. To ensure an aesthetically favorable result, a careful assessment is required of both the bone and gingival tissue at the implant receptor site, especially
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when the labial socket wall and the tissue biotype are thin. Thin tissue biotype is considered a major risk factor for advanced mid-buccal recession in immediate dental
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implant placement.1 Therefore, knowledge of the thickness of soft tissue and the labial bone plate of teeth to be extracted is imperative.
Assessment of gingival tissue has been restricted to clinical examinations, whereas bone tissue has been evaluated mainly by imaging examinations. Currently,
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the examination of choice is cone beam computed tomography (CBCT), as it provides accurate measurements of bone quantity, guiding the selection of potential sites for implant placement.2, 3
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Some studies have applied CBCT for measurement of soft tissues, such as the thickness of the buccal or lingual gingiva.4-7 However, other contiguous soft
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tissues, e.g., the lips and cheeks, may be confused with the gingival tissue, making visualization difficult or impossible, especially on the labial surface. In an attempt to minimize this limitation, plastic lip retractors and wooden spatulas can be used while conducting imaging exams to permit the assessment of periodontal soft tissues. This simple and non-invasive technique provides retraction of the lips and cheek, favoring observation of soft tissues and measurements of the thickness of the facial and lingual gingiva.4, 5
ACCEPTED MANUSCRIPT The objective of this study was to evaluate the influence of lip retraction on the CBCT assessment of bone and gingival tissues in the anterior maxilla and to correlate the measurements obtained from clinical probing with the tomographic
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measurements of the gingiva.
ACCEPTED MANUSCRIPT MATERIALS AND METHODS A retrospective cross-sectional clinical-CBCT study was performed in which records from 30 patients treated at the postgraduate clinic for implant dentistry,
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School of Dentistry, Federal University of Juiz de Fora (UFJF), were selected randomly. The data obtained from these records included anamnesis, clinical
examination, and imaging examinations. This study used only the clinical data
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regarding the conditions of the gingival tissue of the anterior maxilla and the CBCT exams.
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The four maxillary incisors of all patients included in the study were analyzed. In this study, the tooth is used as the unit of measurement (n = 120, 60 central incisors and 60 lateral incisors). Records of the patients were enrolled sequentially by convenience sample until data for at least 120 teeth were acquired. This study was
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approved by the Research Ethics Committee of UFJF (Opinion No. 563.860). Only records that presented maxillary CBCT scans performed previously with and without a lip retractor on the same patients and complete information on gingival
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tissue conditions were included. It is important to note that the patients did not receive additional radiation exposure for the purpose of this investigation. The
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selected patients had already been scanned with and without the lip retractor. Only the records of patients who had four healthy upper incisors (central and lateral) were included. Patients who presented abnormalities or bone defects in the maxilla, craniofacial abnormalities, bone grafting, gingival surgery, and orthognathic or other maxillary surgery were excluded.
Assessment of the clinical data
ACCEPTED MANUSCRIPT For the measurement of labial gingival thickness, three clinical measures were used, represented in this study by the letters "GC (gingival-clinical)", as follows: GC1 - 1 mm above the gingival margin; GC3 - 3 mm above the gingival margin; and GC5 -
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5 mm above the gingival margin (Figure 1). Thicknesses of the labial gingival tissues were obtained in the most central region of each maxillary incisor.
Measurements of gingival thickness were taken after applying topical and local
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anesthetic that was deposited at the depth of the vestibule to avoid any increase in gingival thickness at the sites to be measured. A millimeter probe was inserted
measures were excluded.
Assessment of the CBCT data
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transgingivally to contact the tooth or bone plate. Patients with incomplete clinical
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Images were acquired using the i-CAT Next Generation dental CBCT scanner (Imaging Sciences International, Hatfield, PA, USA) with the following acquisition protocol: 0.25 mm voxel, 26.9 s rotation time, and a FOV varying between 7 x 23 cm
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and 10 x 23 cm. The examinations were conducted with (Figure 2) and without the
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use of an acrylic lip retractor (Arcflex, FGM, Joinvile, SC, Brazil).
The images of the parasagittal sections were analyzed with the i-CAT Vision
software (Imaging Sciences International, Hatfield, PA, USA) by an oral radiologist experienced in image interpretation, properly trained and calibrated. The process of calibration included the evaluation of 15 CBCT scans that were not included in this study. Thicknesses of the buccal bone and gingival tissues were obtained in the most central parasagittal section of each maxillary incisor. The same images were
ACCEPTED MANUSCRIPT reevaluated after a 15-day interval, showing excellent agreement among evaluations (ICC - intraclass correlation coefficient = 0.87; p<0.001).
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To measure the thickness of the labial bone, four measurements were obtained perpendicular to the long axis of the tooth on the CBCT image, represented by the letters "OT (osseous-tomography)", as follows: OT1 - 1 mm above the alveolar
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bone crest; OT3 - 3 mm above the alveolar bone crest; OT5 - 5 mm above the alveolar bone crest; and OTT - measurement obtained at the greatest bone thickness
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(Figure 3).
To measure the thickness of the labial gingival tissue, four tomographic measurements were obtained perpendicular to the long axis of the tooth and corresponding to the bone measurements described above. These measurements,
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used to correlate bone thickness with gingival thickness obtained by CBCT, are represented by "GT (gingival-tomography)" as follows: GT1 - 1 mm above the alveolar bone crest; GT3 - 3 mm above the alveolar bone crest; GT5 - 5 mm above
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the alveolar bone crest; and GTT - measurement obtained at the greatest gingival thickness (Figure 3).
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To correlate the gingival thickness obtained in CBCT images with the data from the clinical probe, new measurements of gingival tissue were obtained in the tomography exams: GT1G - 1 mm above the gingival margin; GT3G - 3 mm above the gingival margin; and GT5G - 5 mm above the gingival margin (Figure 3). These tomographic measurements were performed in the regions corresponding to the clinical measurements.
ACCEPTED MANUSCRIPT Data analysis The means for bone and gingival thicknesses obtained in CBCT examinations with and without a lip retractor were compared using a paired t-test. The Pearson
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correlation coefficient was used to correlate the tomographic measurements of bone and gingival thicknesses and the thicknesses of gingival tissues obtained by CBCT scans and the clinical probe. The data obtained were statistically analyzed using the
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Statistical Package for Social Sciences (SPSS) program version 13.0 for Windows
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RESULTS
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(Chicago, IL, USA). A 5% significance level was adopted.
The comparison of bone plate thickness at 1 mm above the alveolar bone
crest (OT1), obtained in examinations performed with (1.08 ± 0.14 mm) and without (1.03 ± 0.21 mm) the lip retractor, showed a significantly higher mean for the examinations performed with the lip retractor (p = 0.021). The correlations of bone plate thickness with gingival tissue thickness obtained in examinations performed with a lip retractor were significant for the
ACCEPTED MANUSCRIPT measurements taken at 1 mm above the alveolar bone crest (OT1 x GT1) and at the greatest bone and gingival thicknesses (OTT x GTT) (Table 1). It was not possible to identify the image of the labial gingival tissue when the CBCT examinations were
without a lip retractor are shown in Figure 4.
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performed without a lip retractor. Parasagittal CBCT sections obtained with and
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The correlation of gingival tissue thickness obtained in CBCT examinations using a lip retractor with the gingival thickness obtained clinically indicated significant
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correlations for measurements obtained at 1 mm (GT1G x GC1) and 3 mm (GT3G x
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GC3) above the gingival margin (Table 2).
ACCEPTED MANUSCRIPT DISCUSSION Awareness of the thicknesses of the bone and gingival tissues is of utmost importance in dental procedures, especially in aesthetic regions such as the anterior
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maxilla, as they directly affect rehabilitation success. Various specialty fields, including periodontics, cosmetic dentistry, prosthodontics, orthodontics, and
implantology, are increasingly concerned with the quantity and quality of labial
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tissues, aiming to meet an increasing level of aesthetic demand.
In the implantology field, assessing the quality and quantity of bone tissue
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becomes even more essential because without the analysis of these parameters, implant placement would be impossible. However, to ensure better predictability of peri-implant esthetics, the assessment of gingival tissue in the implant site is critical.8, 9
The different gingival biotypes and the soft tissue morphology have been described
as key elements for achieving successful results in the placement and maintenance
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of implants, especially immediate implants in esthetic areas.10-13 There has been a concern that recession of the marginal peri-implant mucosa may occur, which, in
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turn, may have an adverse effect on the final esthetic outcome.14 Thin labial bone and soft tissue are considered important risk factors for advanced mid-buccal
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recession.1 Recent studies of immediate implant placement, after tooth extraction, imposed specific selection criteria, including thick tissue biotype and an intact labial socket wall.15
Studies show that the bone measurements obtained by CBCT are accurate,
and their measurements help ensure greater safety for surgery, reducing the risk of failures or surgical complications.16-18 However, CBCT exams have several limitations, mainly regarding the assessment of soft tissues, particularly because the
ACCEPTED MANUSCRIPT images present low contrast resolution.19 In addition, due to the proximity of the gingival tissues with other soft tissues such as the lips and cheek, which would all be visualized with the same radiographic density, it is impossible to discriminate
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between these structures. Unlike fan-shaped multidetector computed tomography (MDCT), which has its own window for assessing non-mineralized tissues4, CBCT was indicated, initially, only for bone tissue visualization. This drawback restricts the
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assessment and measurement of peri-implant soft tissue in clinical examinations. The most common method of clinical assessment of the thickness of the
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gingival tissue is the clinical probe, which is an invasive method and requires local anesthesia, causing discomfort for the patient and possibly damaging the gingival tissue, which is highly susceptible to minimal intervention, especially in thin tissues.20 In an attempt to withdraw the lip and cheek and assess gingival tissue by CBCT, a number of clinicians have used a plastic lip retractor during the examination, and with
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this simple and non-invasive technique, have been able to view the labial gingiva4 and the lingual mucosa.5
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Taking into consideration the increasing applicability of CBCT in implantology planning, it would be most advantageous to use a technique that would expand the
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use of this examination, serving for the assessment of both bone and soft tissues. This would ensure better use of tomographic images and spare the patient from the discomfort of a clinical probe. The literature clearly demonstrates the accuracy of bone tissue assessment in CBCT, but research is lacking that confirms the application of this examination for gingival assessment. Few studies have performed labial gingival tissue measurements using CBCT images. Januário et al.4 presented their results based on the comparison of CBCT images from three patients, each
ACCEPTED MANUSCRIPT subjected to two examinations, one with and one without a lip retractor. Fu et al.6 concluded that CBCT measurements are accurate representations of the thicknesses of both bone and gingival tissues, but their study was conducted on cadavers, not on
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patient images. In this context, the present study was conducted to evaluate the thickness of the bone plate and the gingival tissue in CBCT images obtained with and without a lip
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retractor. The measurements obtained in the imaging tests with a retractor were correlated with clinical data obtained by probing, demonstrating the accuracy of
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CBCT, with a retractor, for soft tissue for measurement.
The results of the comparison of bone thicknesses obtained from images acquired with and without a lip retractor showed that the most cervical measure (OT1) exhibited a significantly higher mean for examinations performed with a lip
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retractor. This result can directly affect the aesthetic expectation for an implant because the cervical area is the largest area visible in the smile line. Ghassemian et al.21 conducted a study to measure the thickness of the buccal bone plate and
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affirmed that in the anterior maxillary region, this structure is predominantly thin, thus a thorough and accurate assessment is essential prior to placing implants in this
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region. Wood et al.22 investigated the factors that affect the measurement precision of the buccal bone tissue in CBCT images and observed that in the absence of soft tissue, the images appear clearer for viewing the contours of bone tissue. To determine the relationship between the labial bone plate and the
associated gingival tissue using CBCT examinations, correlations were performed at three different cervical-apical heights. Significant correlations were observed for measurements obtained at 1 mm above the alveolar bone crest and at the largest
ACCEPTED MANUSCRIPT bone and gingival thicknesses, affirming that thicker bone tissue is associated with thicker gingival tissue. Le and Borzabadi-Farahani23 also examined the relationship between labial bone thickness and gingival tissue thickness in the anterior maxilla
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using CBCT scans and affirmed that bone and gingival thicknesses were highly associated in the anterior region of the maxilla in sites with implants. Cook et al.11, who evaluated the relationship between the gingival biotypes and the labial bone plate of the anterior maxilla using CBCT images, stated that there is a significant
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correlation between these variables. Fu et al.6 also recognized this correlation in an
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assessment conducted on cadavers. Studies using radiographs obtained with the profile technique also observed correlations of the dimensions of gingival and bone tissues in the assessment of anterior teeth.24-26 However, La Rocca et al.27 found no correlations between gingival tissue thickness measured clinically and bone tissue
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measured in CBCT scans.
It is emphasized that the visualization of gingival tissue was possible only in the tests performed with a lip retractor. In other words, through a very simple
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technique, without compromising image quality, the use of CT scans can be expanded, allowing them to measure both bone and gingival tissues. To confirm that
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CBCT is a reliable examination method for assessing soft tissue, the gingival thicknesses obtained clinically and by CBCT scans were correlated. Significant correlations were observed for measurements at 1 mm and 3 mm above the gingival margin, i.e., CBCT proved to be a reliable method for measuring soft tissue, especially in the areas involved in patient aesthetics. It is noteworthy that the use of retractors allows a quantitative assessment of labial soft tissue but not a qualitative assessment. It is not possible to discriminate specific tissue characteristics, such as
ACCEPTED MANUSCRIPT discriminating inflamed gingiva from healthy gingiva, just as it is not possible to distinguish different types of soft tissue, such as epithelial tissue and connective tissue.4
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This study was not conducted on edentulous implant regions, but we believe that, indirectly, the impact of the present study can also be extended to the
edentulous regions. In edentulous ridges there may be adequate bone tissue for
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implant installation; however, there may be insufficient quantity and quality of soft tissue, which would lead to the need for grafts. As with dentate patients, the use of
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the retractor in edentulous patients allows assessment of the soft tissue thickness remaining on the healed ridge, without overlapping of the cheek and lip. Given the positive results found for images taken with a lip retractor, the technique's ease of use, and the clinical importance of the combined assessment of
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bone and gingival tissues as a determining factor in dental implant planning, it can be concluded that the use of lip retractors in CBCT examinations is a useful and
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applicable choice for implant placement in the anterior segment.
ACCEPTED MANUSCRIPT FUNDING SOURCES This research did not receive any specific grant from funding agencies in the public,
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commercial, or not-for-profit sectors.
ACCEPTED MANUSCRIPT REFERENCES 1. Kan JY, Rungcharassaeng K, Lozada JL, Zimmerman G. Facial gingival tissue stability following immediate placement and provisionalization of maxillary
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anterior single implants: a 2- to 8-year follow-up. Int J Oral Maxillofac
2. Guerrero ME, Jacobs R, Loubele M, Schutyser F, Suetens P, van
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Steenberghe D. State of the art on cone beam CT imaging for preoperative planning of implant placement. Clin Oral Investig. 2006;10(1):1-7.
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3. Chan HL, Misch K, Wang HL. Dental imaging in implant treatment planning. Implant Dent. 2010;19(4):288-298.
4. Januário AL, Barriviera M, Duarte WR. Soft tissue cone-beam computed tomography: a novel method for the measurement of gingival tissue and the
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6. Fu JH, Yeh CY, Chan HL, Tatarakis N, Leong DJ, Wang HL. Tissue biotype and its relation to the underlying bone morphology. J Periodontol. 2010;81(4):569-574.
7. Ueno D, Sekiguchi R, Morita M, et al. Palatal mucosal measurements in a Japanese population using cone‐beam computed tomography. J Esthet Restor Dent. 2014;26(1):48-58.
ACCEPTED MANUSCRIPT 8. Kao RT, Fagan MC, Conte GJ. Thick vs. thin gingival biotypes: a key determinant in treatment planning for dental implants. J Calif Dent Assoc. 2008;36(3):193-198.
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9. Lee A, Fu J, Wang H. Soft tissue biotype affects implant success. Implant Dent. 2011;20(3):e38-47.
10. De Rouck T, Eghbali R, Collys K, Bruyns H, Cosyn J. The gingival biotype
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revisited: transparency of the periodontal probe through the gingival margin as a method to discriminate thin from thick gingiva. J Clin Periodontol.
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2009;36(5):428-433.
11. Cook DR, Mealey BL, Verrett RG, et al. Relationship between clinical periodontal biotype and labial plate thickness: an in vivo study. Int J Periodont Restorat Dent. 2011;31(4):345-354.
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12. Raes F, Cosyn J, Crommelinck E, Coessens P, De Bruyn H. Immediate and, conventional single implant treatment in the anterior maxilla: 1-year results of a case series on hard and soft tissue response and aesthetics. J Clin
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Periodontol. 2011;38(4):385-394. 13. Cabello G, Rioboo M, Fábrega JG. Immediate placement and restoration of
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implants in the aesthetic zone with a trimodal approach: soft tissue alterations and its relation to gingival biotype. Clin Oral Impl Res. 2013;24(10):1094-1100.
ACCEPTED MANUSCRIPT 14. Arora H, Ivanovski S. Correlation between pre-operative buccal bone thickness and soft tissue changes around immediately placed and restored implants in the maxillary anterior region: a 2-year prospective study. Clin Oral
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Implants Res. 2016 Jul 29. doi: 10.1111/clr.12939. 15. Chen ST, Buser D. Esthetic outcomes following immediate and early implant placement in the anterior maxilla - a systematic review. Int J Oral Maxillofac
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Implants. 2014;29 Suppl:186-215.
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tomography in the practice of oral and maxillofacial surgery. J Oral Maxillofac
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Dent. 2011;31(3):215-225.
18. Patcas R, Muller L, Ullrich O, Peltomaki T. Accuracy of cone-beam computed
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tomography at different resolutions assessed on the bony covering of the mandibular anterior teeth. Am J Orthod Dentofacial Orthop. 2012;141(1):41-
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20. Lee DW, Kim CK, Park KH, Cho KS, Moo SM. Non-invasive method to measure the length of soft tissue from the top of the papilla to the crestal bone. J Periodontol. 2005;76(8):1311-1314.
ACCEPTED MANUSCRIPT 21. Ghassemian M, Nowzari H, Lajolo C, Verdugo F, Pirronti T, D’Addona A. The thickness of facial alveolar bone overlying healthy maxillary anterior teeth. J Periodontol. 2012;83(2):187-197.
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22. Wood R, Sun Z, Chaudhry J, et al. Factors affecting the accuracy of buccal alveolar bone height measurements from cone‐beam computed tomography images. Am J Orthod Dentofacial Orthop. 2013;143(3):353‐363.
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23. Le BT, Borzabadi-Farahani A. Labial bone thickness in area of anterior
maxillary implants associated with crestal labial soft tissue thickness. Implant
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Dent. 2012;21(5):406-410.
24. Alpiste-Illueca F. Dimensions of the dentogingival unit in maxillary anterior teeth: a new exploration technique (parallel profile radiograph). Int J Periodontics Restorative Dent. 2004;24(4):386-396.
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25. Stein JM, Nils L, Hammacher C, Kasaj A, Tamm M, Hanisch O. The gingival biotype: measurement of soft and hard tissue dimensions - a radiographic morphometric study. J Clin Periodontol. 2013;40(12):1132-1139.
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26. Rossell J, Puigdollers A, Girabent-Farrés M. A simple method for measuring thickness of gingival and labial bone of mandibular incisors. Quintessence Int.
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2015;46(3):265‐271.
27. La Rocca AP, Alemany AS, Levi PJr, Juan MV, Molina JN, Weisgold AS. Anterior maxillary and mandibular biotype: relationship between gingival thickness and width with respect to underlying bone thickness. Implant Dent. 2012;21(6):507-515.
ACCEPTED MANUSCRIPT FIGURE LEGENDS Figure 1. Illustrative image of clinical probing. GC1 - 1 mm above the gingival margin;
Figure 2. Patient with an acrylic lip retractor
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GC3 - 3 mm above the gingival margin; and GC5 - 5 mm above the gingival margin.
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Figure 3. CBCT parasagittal sections representative of the measurement of bone and gingival tissues. (A). OT1 - 1 mm above the alveolar bone crest; OT3 - 3 mm above
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the alveolar bone crest; and OT5 - 5 mm above the alveolar bone crest. (B). GT1 - 1 mm above the alveolar bone crest; GT3 - 3 mm above the alveolar bone crest; and GT5 - 5 mm above the alveolar bone crest. (C). GT1G - 1 mm above the gingival margin; GT3G - 3 mm above the gingival margin; and GT5G - 5 mm above the
gingiva thickness.
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gingival margin. (D). OTT - greatest labial bone thickness and GTT - greatest labial
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Figure 4. Representative parasagittal sections of the CBCT images obtained (A). without a lip retractor and (B). with a lip retractor. White arrows indicate the labial
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gingival tissue.
ACCEPTED MANUSCRIPT Table 1. Correlation between bone plate thickness and gingival tissue thickness, obtained from examinations conducted with a lip retractor Gingival tissue thickness
0.359
Sig. (2-tailed)
0.005*
N
120
Pearson Correlation Sig. (2-tailed) N
OT5
0.103 120
Pearson Correlation
0.068
Sig. (2-tailed)
0.604
N
120
Pearson Correlation
0.301
Sig. (2-tailed)
0.020*
N
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OTT
GTT
-0.212
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Bone plate thickness
OT3
Pearson Correlation
GT5
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OT1
GT3
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GT1
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* Statistically significant correlation using Pearson’s test (P≤0.05).
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GT - thickness of the gingival tissue: GT1 - 1 mm above the alveolar bone crest; GT3 - 3 mm above the alveolar bone crest; GT5 - 5 mm above the alveolar bone crest; GTT - greatest gingival thickness. OT - thickness of the bone plate: OT1 - 1 mm above the alveolar bone crest; OT3 - 3 mm above the alveolar bone crest; OT5 - 5 mm above the alveolar bone crest; OTT - greatest bone thickness.
ACCEPTED MANUSCRIPT Table 2. Correlation between the measurements of gingival tissue thicknesses obtained in CBCT exams with a lip retractor and those obtained clinically Gingival tissue thickness obtained clinically
Sig. (2-tailed)
0.000*
N
120
Pearson Correlation Sig. (2-tailed) N
GT5G
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0.443
GC5
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GT3G
Pearson Correlation
0.552
0.000*
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GT1G
GC3
120
Pearson Correlation
0.184
Sig. (2-tailed)
0.159
N
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Gingival tissue thickness obtained in CBCT
GC1
* Statistically significant correlation using Pearson’s test (P≤0.05).
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GC - thickness of the gingival tissue obtained clinically: GC1 - 1 mm above the gingival margin; GC3 - 3 mm above the gingival margin; GC5 - 5 mm above the gingival margin.
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GTG - thickness of the gingival tissue obtained in CBCT: GT1G - 1 mm above the gingival margin; GT3G - 3 mm above the gingival margin; GT5G - 5 mm above the gingival margin.
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S2212-4403(17)30064-0
DOI:
10.1016/j.oooo.2017.02.005
Reference:
OOOO 1708
To appear in:
Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology
Received Date: 17 August 2016 Revised Date:
20 December 2016
Accepted Date: 7 February 2017
Please cite this article as: Silva JNN, Andrade PFd, Sotto-Maior BS, Souza Picorelli Assis NM, Pires Carvalho AC, Devito KL, Influence of Lip Retraction on the CBCT Assessment of Bone and Gingival Tissues of the Anterior Maxilla, Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology (2017), doi: 10.1016/j.oooo.2017.02.005. 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 INFLUENCE OF LIP RETRACTION ON THE CBCT ASSESSMENT OF BONE AND GINGIVAL TISSUES OF THE ANTERIOR MAXILLA
Authors:
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Jesca Neftali Nogueira Silva
MSc, School of Dentistry, Federal University of Juiz de Fora, Juiz de Fora, MG, Brazil - [email protected] Priscila Ferreira de Andrade
Brazil - [email protected]
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Bruno Salles Sotto-Maior
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MSc, School of Dentistry, Federal University of Juiz de Fora, Juiz de Fora, MG,
PhD, Department of Restorative Dentistry, School of Dentistry, Federal University of Juiz de Fora, Juiz de Fora, MG, Brazil - [email protected] Neuza Maria Souza Picorelli Assis
PhD, Department of Dental Clinic, School of Dentistry, Federal University of Juiz de Fora, Juiz de Fora, MG, Brazil - [email protected]
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Antônio Carlos Pires Carvalho
PhD, Department of Radiology, School of Medicine, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil - [email protected] Karina Lopes Devito
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PhD, Department of Dental Clinic, School of Dentistry, Federal University of Juiz
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de Fora, Juiz de Fora, MG, Brazil - [email protected]
Corresponding author: Karina Lopes Devito
Department of Dental Clinic, School of Dentistry, Federal University of Juiz de Fora Campus Universitário, s/n, CEP: 36036-900 - Juiz de Fora, MG, Brazil E-mail: [email protected]
Disclosures: “This paper consists of unpublished work which is not under consideration for publication elsewhere. All authors participated fully in the implementation of the
ACCEPTED MANUSCRIPT study, definition of the methodology and writing of the manuscript. Moreover, there is no conflict of interest regarding this work, or any funding source, and the publication was approved by all authors.”
Word count - manuscript: 3856 words Number of references: 27 Number of tables: 2
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Number of figures: 4
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Word count - abstract: 206 words
Statement of Clinical Relevance:
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The use of lip retractors during CBCT exams is a simple and reliable technique, which allows the measurement of gingival tissues in addition to bone tissue
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assessment.
ACCEPTED MANUSCRIPT INFLUENCE OF LIP RETRACTION ON THE CBCT ASSESSMENT OF BONE AND GINGIVAL TISSUES OF THE ANTERIOR MAXILLA
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ABSTRACT Objective: To evaluate the influence of lip retraction on cone beam computed tomography (CBCT) assessment of bone and gingival tissues on the labial surface of
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the anterior maxilla.
Study Design: A retrospective study was conducted using measurements of bone
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and gingival tissues collected from 120 maxillary incisors. The thicknesses of the bone and gingival tissues of different regions were measured on CBCT images, with and without a lip retractor. The thicknesses of the gingival tissues obtained from CBCT were correlated with measurements performed by clinical probing.
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Results: The thickness of bone in the more cervical region presented a higher mean value for exams performed with a lip retractor (p=0.021). The thickness of bone showed a significant correlation with the thickness of the gingiva (p≤0.020) with a lip
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retractor in CBCT exams. The thickness of the gingival tissue obtained from CBCT scans with lip retraction showed significant correlations with those obtained clinically
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(p≤0.001).
Conclusion: The use of lip retractors is a simple and reliable practice that allows the measurement of gingival tissues on CBCT images. This practice can exempt a patient from an invasive clinical procedure for measuring the thickness of the gingival tissue for implant cases of the anterior segment.
KEYWORDS: cone beam computed tomography; gingival thickness; implantology; cosmetic dentistry.
ACCEPTED MANUSCRIPT INTRODUCTION With the growing demand for aesthetic rehabilitation treatment, it has become necessary to determine parameters that offer greater predictability of peri-implant
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results, especially regarding the placement of immediate dental implants in the anterior maxilla. To ensure an aesthetically favorable result, a careful assessment is required of both the bone and gingival tissue at the implant receptor site, especially
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when the labial socket wall and the tissue biotype are thin. Thin tissue biotype is considered a major risk factor for advanced mid-buccal recession in immediate dental
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implant placement.1 Therefore, knowledge of the thickness of soft tissue and the labial bone plate of teeth to be extracted is imperative.
Assessment of gingival tissue has been restricted to clinical examinations, whereas bone tissue has been evaluated mainly by imaging examinations. Currently,
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the examination of choice is cone beam computed tomography (CBCT), as it provides accurate measurements of bone quantity, guiding the selection of potential sites for implant placement.2, 3
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Some studies have applied CBCT for measurement of soft tissues, such as the thickness of the buccal or lingual gingiva.4-7 However, other contiguous soft
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tissues, e.g., the lips and cheeks, may be confused with the gingival tissue, making visualization difficult or impossible, especially on the labial surface. In an attempt to minimize this limitation, plastic lip retractors and wooden spatulas can be used while conducting imaging exams to permit the assessment of periodontal soft tissues. This simple and non-invasive technique provides retraction of the lips and cheek, favoring observation of soft tissues and measurements of the thickness of the facial and lingual gingiva.4, 5
ACCEPTED MANUSCRIPT The objective of this study was to evaluate the influence of lip retraction on the CBCT assessment of bone and gingival tissues in the anterior maxilla and to correlate the measurements obtained from clinical probing with the tomographic
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measurements of the gingiva.
ACCEPTED MANUSCRIPT MATERIALS AND METHODS A retrospective cross-sectional clinical-CBCT study was performed in which records from 30 patients treated at the postgraduate clinic for implant dentistry,
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School of Dentistry, Federal University of Juiz de Fora (UFJF), were selected randomly. The data obtained from these records included anamnesis, clinical
examination, and imaging examinations. This study used only the clinical data
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regarding the conditions of the gingival tissue of the anterior maxilla and the CBCT exams.
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The four maxillary incisors of all patients included in the study were analyzed. In this study, the tooth is used as the unit of measurement (n = 120, 60 central incisors and 60 lateral incisors). Records of the patients were enrolled sequentially by convenience sample until data for at least 120 teeth were acquired. This study was
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approved by the Research Ethics Committee of UFJF (Opinion No. 563.860). Only records that presented maxillary CBCT scans performed previously with and without a lip retractor on the same patients and complete information on gingival
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tissue conditions were included. It is important to note that the patients did not receive additional radiation exposure for the purpose of this investigation. The
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selected patients had already been scanned with and without the lip retractor. Only the records of patients who had four healthy upper incisors (central and lateral) were included. Patients who presented abnormalities or bone defects in the maxilla, craniofacial abnormalities, bone grafting, gingival surgery, and orthognathic or other maxillary surgery were excluded.
Assessment of the clinical data
ACCEPTED MANUSCRIPT For the measurement of labial gingival thickness, three clinical measures were used, represented in this study by the letters "GC (gingival-clinical)", as follows: GC1 - 1 mm above the gingival margin; GC3 - 3 mm above the gingival margin; and GC5 -
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5 mm above the gingival margin (Figure 1). Thicknesses of the labial gingival tissues were obtained in the most central region of each maxillary incisor.
Measurements of gingival thickness were taken after applying topical and local
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anesthetic that was deposited at the depth of the vestibule to avoid any increase in gingival thickness at the sites to be measured. A millimeter probe was inserted
measures were excluded.
Assessment of the CBCT data
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transgingivally to contact the tooth or bone plate. Patients with incomplete clinical
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Images were acquired using the i-CAT Next Generation dental CBCT scanner (Imaging Sciences International, Hatfield, PA, USA) with the following acquisition protocol: 0.25 mm voxel, 26.9 s rotation time, and a FOV varying between 7 x 23 cm
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and 10 x 23 cm. The examinations were conducted with (Figure 2) and without the
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use of an acrylic lip retractor (Arcflex, FGM, Joinvile, SC, Brazil).
The images of the parasagittal sections were analyzed with the i-CAT Vision
software (Imaging Sciences International, Hatfield, PA, USA) by an oral radiologist experienced in image interpretation, properly trained and calibrated. The process of calibration included the evaluation of 15 CBCT scans that were not included in this study. Thicknesses of the buccal bone and gingival tissues were obtained in the most central parasagittal section of each maxillary incisor. The same images were
ACCEPTED MANUSCRIPT reevaluated after a 15-day interval, showing excellent agreement among evaluations (ICC - intraclass correlation coefficient = 0.87; p<0.001).
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To measure the thickness of the labial bone, four measurements were obtained perpendicular to the long axis of the tooth on the CBCT image, represented by the letters "OT (osseous-tomography)", as follows: OT1 - 1 mm above the alveolar
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bone crest; OT3 - 3 mm above the alveolar bone crest; OT5 - 5 mm above the alveolar bone crest; and OTT - measurement obtained at the greatest bone thickness
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(Figure 3).
To measure the thickness of the labial gingival tissue, four tomographic measurements were obtained perpendicular to the long axis of the tooth and corresponding to the bone measurements described above. These measurements,
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used to correlate bone thickness with gingival thickness obtained by CBCT, are represented by "GT (gingival-tomography)" as follows: GT1 - 1 mm above the alveolar bone crest; GT3 - 3 mm above the alveolar bone crest; GT5 - 5 mm above
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the alveolar bone crest; and GTT - measurement obtained at the greatest gingival thickness (Figure 3).
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To correlate the gingival thickness obtained in CBCT images with the data from the clinical probe, new measurements of gingival tissue were obtained in the tomography exams: GT1G - 1 mm above the gingival margin; GT3G - 3 mm above the gingival margin; and GT5G - 5 mm above the gingival margin (Figure 3). These tomographic measurements were performed in the regions corresponding to the clinical measurements.
ACCEPTED MANUSCRIPT Data analysis The means for bone and gingival thicknesses obtained in CBCT examinations with and without a lip retractor were compared using a paired t-test. The Pearson
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correlation coefficient was used to correlate the tomographic measurements of bone and gingival thicknesses and the thicknesses of gingival tissues obtained by CBCT scans and the clinical probe. The data obtained were statistically analyzed using the
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Statistical Package for Social Sciences (SPSS) program version 13.0 for Windows
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RESULTS
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(Chicago, IL, USA). A 5% significance level was adopted.
The comparison of bone plate thickness at 1 mm above the alveolar bone
crest (OT1), obtained in examinations performed with (1.08 ± 0.14 mm) and without (1.03 ± 0.21 mm) the lip retractor, showed a significantly higher mean for the examinations performed with the lip retractor (p = 0.021). The correlations of bone plate thickness with gingival tissue thickness obtained in examinations performed with a lip retractor were significant for the
ACCEPTED MANUSCRIPT measurements taken at 1 mm above the alveolar bone crest (OT1 x GT1) and at the greatest bone and gingival thicknesses (OTT x GTT) (Table 1). It was not possible to identify the image of the labial gingival tissue when the CBCT examinations were
without a lip retractor are shown in Figure 4.
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performed without a lip retractor. Parasagittal CBCT sections obtained with and
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The correlation of gingival tissue thickness obtained in CBCT examinations using a lip retractor with the gingival thickness obtained clinically indicated significant
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correlations for measurements obtained at 1 mm (GT1G x GC1) and 3 mm (GT3G x
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GC3) above the gingival margin (Table 2).
ACCEPTED MANUSCRIPT DISCUSSION Awareness of the thicknesses of the bone and gingival tissues is of utmost importance in dental procedures, especially in aesthetic regions such as the anterior
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maxilla, as they directly affect rehabilitation success. Various specialty fields, including periodontics, cosmetic dentistry, prosthodontics, orthodontics, and
implantology, are increasingly concerned with the quantity and quality of labial
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tissues, aiming to meet an increasing level of aesthetic demand.
In the implantology field, assessing the quality and quantity of bone tissue
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becomes even more essential because without the analysis of these parameters, implant placement would be impossible. However, to ensure better predictability of peri-implant esthetics, the assessment of gingival tissue in the implant site is critical.8, 9
The different gingival biotypes and the soft tissue morphology have been described
as key elements for achieving successful results in the placement and maintenance
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of implants, especially immediate implants in esthetic areas.10-13 There has been a concern that recession of the marginal peri-implant mucosa may occur, which, in
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turn, may have an adverse effect on the final esthetic outcome.14 Thin labial bone and soft tissue are considered important risk factors for advanced mid-buccal
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recession.1 Recent studies of immediate implant placement, after tooth extraction, imposed specific selection criteria, including thick tissue biotype and an intact labial socket wall.15
Studies show that the bone measurements obtained by CBCT are accurate,
and their measurements help ensure greater safety for surgery, reducing the risk of failures or surgical complications.16-18 However, CBCT exams have several limitations, mainly regarding the assessment of soft tissues, particularly because the
ACCEPTED MANUSCRIPT images present low contrast resolution.19 In addition, due to the proximity of the gingival tissues with other soft tissues such as the lips and cheek, which would all be visualized with the same radiographic density, it is impossible to discriminate
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between these structures. Unlike fan-shaped multidetector computed tomography (MDCT), which has its own window for assessing non-mineralized tissues4, CBCT was indicated, initially, only for bone tissue visualization. This drawback restricts the
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assessment and measurement of peri-implant soft tissue in clinical examinations. The most common method of clinical assessment of the thickness of the
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gingival tissue is the clinical probe, which is an invasive method and requires local anesthesia, causing discomfort for the patient and possibly damaging the gingival tissue, which is highly susceptible to minimal intervention, especially in thin tissues.20 In an attempt to withdraw the lip and cheek and assess gingival tissue by CBCT, a number of clinicians have used a plastic lip retractor during the examination, and with
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this simple and non-invasive technique, have been able to view the labial gingiva4 and the lingual mucosa.5
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Taking into consideration the increasing applicability of CBCT in implantology planning, it would be most advantageous to use a technique that would expand the
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use of this examination, serving for the assessment of both bone and soft tissues. This would ensure better use of tomographic images and spare the patient from the discomfort of a clinical probe. The literature clearly demonstrates the accuracy of bone tissue assessment in CBCT, but research is lacking that confirms the application of this examination for gingival assessment. Few studies have performed labial gingival tissue measurements using CBCT images. Januário et al.4 presented their results based on the comparison of CBCT images from three patients, each
ACCEPTED MANUSCRIPT subjected to two examinations, one with and one without a lip retractor. Fu et al.6 concluded that CBCT measurements are accurate representations of the thicknesses of both bone and gingival tissues, but their study was conducted on cadavers, not on
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patient images. In this context, the present study was conducted to evaluate the thickness of the bone plate and the gingival tissue in CBCT images obtained with and without a lip
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retractor. The measurements obtained in the imaging tests with a retractor were correlated with clinical data obtained by probing, demonstrating the accuracy of
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CBCT, with a retractor, for soft tissue for measurement.
The results of the comparison of bone thicknesses obtained from images acquired with and without a lip retractor showed that the most cervical measure (OT1) exhibited a significantly higher mean for examinations performed with a lip
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retractor. This result can directly affect the aesthetic expectation for an implant because the cervical area is the largest area visible in the smile line. Ghassemian et al.21 conducted a study to measure the thickness of the buccal bone plate and
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affirmed that in the anterior maxillary region, this structure is predominantly thin, thus a thorough and accurate assessment is essential prior to placing implants in this
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region. Wood et al.22 investigated the factors that affect the measurement precision of the buccal bone tissue in CBCT images and observed that in the absence of soft tissue, the images appear clearer for viewing the contours of bone tissue. To determine the relationship between the labial bone plate and the
associated gingival tissue using CBCT examinations, correlations were performed at three different cervical-apical heights. Significant correlations were observed for measurements obtained at 1 mm above the alveolar bone crest and at the largest
ACCEPTED MANUSCRIPT bone and gingival thicknesses, affirming that thicker bone tissue is associated with thicker gingival tissue. Le and Borzabadi-Farahani23 also examined the relationship between labial bone thickness and gingival tissue thickness in the anterior maxilla
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using CBCT scans and affirmed that bone and gingival thicknesses were highly associated in the anterior region of the maxilla in sites with implants. Cook et al.11, who evaluated the relationship between the gingival biotypes and the labial bone plate of the anterior maxilla using CBCT images, stated that there is a significant
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correlation between these variables. Fu et al.6 also recognized this correlation in an
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assessment conducted on cadavers. Studies using radiographs obtained with the profile technique also observed correlations of the dimensions of gingival and bone tissues in the assessment of anterior teeth.24-26 However, La Rocca et al.27 found no correlations between gingival tissue thickness measured clinically and bone tissue
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measured in CBCT scans.
It is emphasized that the visualization of gingival tissue was possible only in the tests performed with a lip retractor. In other words, through a very simple
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technique, without compromising image quality, the use of CT scans can be expanded, allowing them to measure both bone and gingival tissues. To confirm that
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CBCT is a reliable examination method for assessing soft tissue, the gingival thicknesses obtained clinically and by CBCT scans were correlated. Significant correlations were observed for measurements at 1 mm and 3 mm above the gingival margin, i.e., CBCT proved to be a reliable method for measuring soft tissue, especially in the areas involved in patient aesthetics. It is noteworthy that the use of retractors allows a quantitative assessment of labial soft tissue but not a qualitative assessment. It is not possible to discriminate specific tissue characteristics, such as
ACCEPTED MANUSCRIPT discriminating inflamed gingiva from healthy gingiva, just as it is not possible to distinguish different types of soft tissue, such as epithelial tissue and connective tissue.4
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This study was not conducted on edentulous implant regions, but we believe that, indirectly, the impact of the present study can also be extended to the
edentulous regions. In edentulous ridges there may be adequate bone tissue for
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implant installation; however, there may be insufficient quantity and quality of soft tissue, which would lead to the need for grafts. As with dentate patients, the use of
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the retractor in edentulous patients allows assessment of the soft tissue thickness remaining on the healed ridge, without overlapping of the cheek and lip. Given the positive results found for images taken with a lip retractor, the technique's ease of use, and the clinical importance of the combined assessment of
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bone and gingival tissues as a determining factor in dental implant planning, it can be concluded that the use of lip retractors in CBCT examinations is a useful and
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applicable choice for implant placement in the anterior segment.
ACCEPTED MANUSCRIPT FUNDING SOURCES This research did not receive any specific grant from funding agencies in the public,
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commercial, or not-for-profit sectors.
ACCEPTED MANUSCRIPT REFERENCES 1. Kan JY, Rungcharassaeng K, Lozada JL, Zimmerman G. Facial gingival tissue stability following immediate placement and provisionalization of maxillary
Implants. 2011;26(1):179-187.
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anterior single implants: a 2- to 8-year follow-up. Int J Oral Maxillofac
2. Guerrero ME, Jacobs R, Loubele M, Schutyser F, Suetens P, van
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Steenberghe D. State of the art on cone beam CT imaging for preoperative planning of implant placement. Clin Oral Investig. 2006;10(1):1-7.
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3. Chan HL, Misch K, Wang HL. Dental imaging in implant treatment planning. Implant Dent. 2010;19(4):288-298.
4. Januário AL, Barriviera M, Duarte WR. Soft tissue cone-beam computed tomography: a novel method for the measurement of gingival tissue and the
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dimensions of the dentogingival unit. J Esthet Restor Dent. 2008;20(6):366-
5. Barriviera M, Januário AL, Duarte WR, Bezerra ACB. A new method to assess
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and measure palatal masticatory mucosa by cone-beam computerized tomography. J Clin Periodontol. 2009;36(7):564-568.
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6. Fu JH, Yeh CY, Chan HL, Tatarakis N, Leong DJ, Wang HL. Tissue biotype and its relation to the underlying bone morphology. J Periodontol. 2010;81(4):569-574.
7. Ueno D, Sekiguchi R, Morita M, et al. Palatal mucosal measurements in a Japanese population using cone‐beam computed tomography. J Esthet Restor Dent. 2014;26(1):48-58.
ACCEPTED MANUSCRIPT 8. Kao RT, Fagan MC, Conte GJ. Thick vs. thin gingival biotypes: a key determinant in treatment planning for dental implants. J Calif Dent Assoc. 2008;36(3):193-198.
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9. Lee A, Fu J, Wang H. Soft tissue biotype affects implant success. Implant Dent. 2011;20(3):e38-47.
10. De Rouck T, Eghbali R, Collys K, Bruyns H, Cosyn J. The gingival biotype
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revisited: transparency of the periodontal probe through the gingival margin as a method to discriminate thin from thick gingiva. J Clin Periodontol.
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2009;36(5):428-433.
11. Cook DR, Mealey BL, Verrett RG, et al. Relationship between clinical periodontal biotype and labial plate thickness: an in vivo study. Int J Periodont Restorat Dent. 2011;31(4):345-354.
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12. Raes F, Cosyn J, Crommelinck E, Coessens P, De Bruyn H. Immediate and, conventional single implant treatment in the anterior maxilla: 1-year results of a case series on hard and soft tissue response and aesthetics. J Clin
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Periodontol. 2011;38(4):385-394. 13. Cabello G, Rioboo M, Fábrega JG. Immediate placement and restoration of
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implants in the aesthetic zone with a trimodal approach: soft tissue alterations and its relation to gingival biotype. Clin Oral Impl Res. 2013;24(10):1094-1100.
ACCEPTED MANUSCRIPT 14. Arora H, Ivanovski S. Correlation between pre-operative buccal bone thickness and soft tissue changes around immediately placed and restored implants in the maxillary anterior region: a 2-year prospective study. Clin Oral
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Implants Res. 2016 Jul 29. doi: 10.1111/clr.12939. 15. Chen ST, Buser D. Esthetic outcomes following immediate and early implant placement in the anterior maxilla - a systematic review. Int J Oral Maxillofac
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Implants. 2014;29 Suppl:186-215.
16. Quereshy FA, Savell TA, Palomo JM. Applications of cone beam computed
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tomography in the practice of oral and maxillofacial surgery. J Oral Maxillofac
17. Miyamoto Y, Obama T. Dental cone beam computed tomography analyses of postoperative labial bone thickness in maxillary anterior implants: comparing immediate and delayed implant placement. Int J Periodontics Restorative
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Dent. 2011;31(3):215-225.
18. Patcas R, Muller L, Ullrich O, Peltomaki T. Accuracy of cone-beam computed
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tomography at different resolutions assessed on the bony covering of the mandibular anterior teeth. Am J Orthod Dentofacial Orthop. 2012;141(1):41-
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19. Suomalainen A, Pakbaznejad Esmaeili EP, Robinson S. Dentomaxillofacial imaging with panoramic views and cone beam CT. Insights Imaging.
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20. Lee DW, Kim CK, Park KH, Cho KS, Moo SM. Non-invasive method to measure the length of soft tissue from the top of the papilla to the crestal bone. J Periodontol. 2005;76(8):1311-1314.
ACCEPTED MANUSCRIPT 21. Ghassemian M, Nowzari H, Lajolo C, Verdugo F, Pirronti T, D’Addona A. The thickness of facial alveolar bone overlying healthy maxillary anterior teeth. J Periodontol. 2012;83(2):187-197.
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22. Wood R, Sun Z, Chaudhry J, et al. Factors affecting the accuracy of buccal alveolar bone height measurements from cone‐beam computed tomography images. Am J Orthod Dentofacial Orthop. 2013;143(3):353‐363.
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23. Le BT, Borzabadi-Farahani A. Labial bone thickness in area of anterior
maxillary implants associated with crestal labial soft tissue thickness. Implant
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Dent. 2012;21(5):406-410.
24. Alpiste-Illueca F. Dimensions of the dentogingival unit in maxillary anterior teeth: a new exploration technique (parallel profile radiograph). Int J Periodontics Restorative Dent. 2004;24(4):386-396.
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25. Stein JM, Nils L, Hammacher C, Kasaj A, Tamm M, Hanisch O. The gingival biotype: measurement of soft and hard tissue dimensions - a radiographic morphometric study. J Clin Periodontol. 2013;40(12):1132-1139.
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26. Rossell J, Puigdollers A, Girabent-Farrés M. A simple method for measuring thickness of gingival and labial bone of mandibular incisors. Quintessence Int.
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2015;46(3):265‐271.
27. La Rocca AP, Alemany AS, Levi PJr, Juan MV, Molina JN, Weisgold AS. Anterior maxillary and mandibular biotype: relationship between gingival thickness and width with respect to underlying bone thickness. Implant Dent. 2012;21(6):507-515.
ACCEPTED MANUSCRIPT FIGURE LEGENDS Figure 1. Illustrative image of clinical probing. GC1 - 1 mm above the gingival margin;
Figure 2. Patient with an acrylic lip retractor
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GC3 - 3 mm above the gingival margin; and GC5 - 5 mm above the gingival margin.
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Figure 3. CBCT parasagittal sections representative of the measurement of bone and gingival tissues. (A). OT1 - 1 mm above the alveolar bone crest; OT3 - 3 mm above
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the alveolar bone crest; and OT5 - 5 mm above the alveolar bone crest. (B). GT1 - 1 mm above the alveolar bone crest; GT3 - 3 mm above the alveolar bone crest; and GT5 - 5 mm above the alveolar bone crest. (C). GT1G - 1 mm above the gingival margin; GT3G - 3 mm above the gingival margin; and GT5G - 5 mm above the
gingiva thickness.
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gingival margin. (D). OTT - greatest labial bone thickness and GTT - greatest labial
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Figure 4. Representative parasagittal sections of the CBCT images obtained (A). without a lip retractor and (B). with a lip retractor. White arrows indicate the labial
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gingival tissue.
ACCEPTED MANUSCRIPT Table 1. Correlation between bone plate thickness and gingival tissue thickness, obtained from examinations conducted with a lip retractor Gingival tissue thickness
0.359
Sig. (2-tailed)
0.005*
N
120
Pearson Correlation Sig. (2-tailed) N
OT5
0.103 120
Pearson Correlation
0.068
Sig. (2-tailed)
0.604
N
120
Pearson Correlation
0.301
Sig. (2-tailed)
0.020*
N
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OTT
GTT
-0.212
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Bone plate thickness
OT3
Pearson Correlation
GT5
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OT1
GT3
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GT1
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* Statistically significant correlation using Pearson’s test (P≤0.05).
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GT - thickness of the gingival tissue: GT1 - 1 mm above the alveolar bone crest; GT3 - 3 mm above the alveolar bone crest; GT5 - 5 mm above the alveolar bone crest; GTT - greatest gingival thickness. OT - thickness of the bone plate: OT1 - 1 mm above the alveolar bone crest; OT3 - 3 mm above the alveolar bone crest; OT5 - 5 mm above the alveolar bone crest; OTT - greatest bone thickness.
ACCEPTED MANUSCRIPT Table 2. Correlation between the measurements of gingival tissue thicknesses obtained in CBCT exams with a lip retractor and those obtained clinically Gingival tissue thickness obtained clinically
Sig. (2-tailed)
0.000*
N
120
Pearson Correlation Sig. (2-tailed) N
GT5G
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0.443
GC5
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GT3G
Pearson Correlation
0.552
0.000*
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GT1G
GC3
120
Pearson Correlation
0.184
Sig. (2-tailed)
0.159
N
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Gingival tissue thickness obtained in CBCT
GC1
* Statistically significant correlation using Pearson’s test (P≤0.05).
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GC - thickness of the gingival tissue obtained clinically: GC1 - 1 mm above the gingival margin; GC3 - 3 mm above the gingival margin; GC5 - 5 mm above the gingival margin.
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GTG - thickness of the gingival tissue obtained in CBCT: GT1G - 1 mm above the gingival margin; GT3G - 3 mm above the gingival margin; GT5G - 5 mm above the gingival margin.
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