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Accuracy and precision of 3D-printed implant surgical guides with different implant systems: An in vitro study
RESEARCH AND EDUCATION
Accuracy and precision of 3D-printed implant surgical guides with different implant systems: An in vitro study Matthew Yeung, DDS,a Aous Abdulmajeed, BDS, PhD,b Caroline K. Carrico, PhD,c George R. Deeb, DDS, MD,d and Sompop Bencharit, DDS, MS, PhDe
ABSTRACT Statement of problem. Implant guided surgery systems promise implant placement accuracy and precision beyond straightforward nonguided surgery. Recently introduced in-office stereolithography systems allow clinicians to produce implant surgical guides themselves. However, different implant designs and osteotomy preparation protocols may produce accuracy and precision differences among the different implant systems. Purpose. The purpose of this in vitro study was to measure the accuracy and precision of 3 implant systems, Tapered Internal implant system (BioHorizons) (BH), NobelReplace Conical (Nobel Biocare) (NB), and Tapered Screw-Vent (Zimmer Biomet) (ZB) when in-office fabricated surgical guides were used. Material and methods. A cone beam computed tomography (CBCT) data set of an unidentified patient missing a maxillary right central incisor and intraoral scans of the same patient were used as a model. A software program (3Shape Implant Studio) was used to plan the implant treatment with the 3 implant systems. Three implant surgical guides were fabricated by using a 3D printer (Form 2), and 30 casts were printed. A total of 10 implants for each system were placed in the dental casts by using the manufacturer’s recommended guided surgery protocols. After implant placement, postoperative CBCT images were made. The CBCT cast and implant images were superimposed onto the treatment-planning image. The implant positions, mesiodistal, labiopalatal, and vertical, as well as implant angulations were measured in the labiolingual and mesiodistal planes. The displacements from the planning in each dimension were recorded. ANOVA with the Tukey adjusted post hoc pairwise comparisons were used to examine the accuracy and precision of the 3 implant systems (a=.05). Results. The overall implant displacements were −0.02 ±0.13 mm mesially (M), 0.07 ±0.14 mm distally (D), 0.43 ±0.57 mm labially (L), and 1.26 ±0.80 mm palatally (P); 1.20 ±3.01 mm vertically in the mesiodistal dimension (VMD); 0.69 ±2.03 mm vertically in the labiopalatal dimension (VLP); 1.69 ±1.02 degrees in mesiodistal angulation (AMD); and 1.56 ±0.92 degrees in labiopalatal angulation (ALP). Statistically significant differences (ANOVA) were found in M (P=.026), P (P=.001), VMD (P=.009), AMD (P=.001), and ALP (P=.001). ZB showed the most displacements in the M and vertical dimensions and the least displacements in the P angulation (P<.05), suggesting statistically significant differences among the M, VMD, VLP, AMD, and ALP. NB had the most M variation. ZB had the least P deviation. NB had the fewest vertical dimension variations but the most angulation variations. Conclusions. Dimensional and angulation displacements of guided implant systems by in-office 3D-printed fabrication were within clinically acceptable limits: <0.1 mm in M-D, 0.5 to 1 mm in L-P, and 1 to 2 degrees in angulation. However, the vertical displacement can be as much as 2 to 3 mm. Different implant guided surgery systems have strengths and weaknesses as revealed in the dimensional and angulation implant displacements. (J Prosthet Dent 2019;-:---)
S.B. is a lecturer for Zimmer Biomet Institute; his research was partly supported by Zimmer Biomet; lectures for Formlabs and 3Shape. BioHorizon, Nobel Biocare, and Zimmer Biomet provided implant fixtures used for this study. Funding for the study was provided in part through the American Association of Dental Research Student Fellowship and the Virginia Commonwealth University A.D. Williams Dental Student Research Fellowship (to M.Y. under the supervision of S.B.). a Former doctoral student, Department of General Practice, School of Dentistry, Virginia Commonwealth University, Richmond, Va. b Assistant Professor and Director of Biomaterials, Department of General Practice, School of Dentistry, Virginia Commonwealth University, Richmond, Va. c Assistant Professor, Department of Oral Health Promotion and Community Outreach, School of Dentistry, Virginia Commonwealth University, Richmond, Va; and Assistant Professor, Department of Biostatistics, School of Medicine, Virginia Commonwealth University, Richmond, Va. d Professor, Department of Oral and Maxillofacial Surgery, School of Dentistry, Virginia Commonwealth University, Richmond, Va. e Associate Professor and Director of Digital Dentistry Technologies, Department of General Practice and Department of Oral & Maxillofacial Surgery, School of Dentistry, Virginia Commonwealth University, Richmond, Va; and Associate Professor, Department of Biomedical Engineering, College of Engineering, Virginia Commonwealth University, Richmond, Va.
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Clinical Implications Each implant guided surgical system has strengths and weaknesses that clinicians must learn to accommodate. In general, limited mesiodistal and labiopalatal dimensional and angulation displacements are expected in guided surgery. However, clinicians should be careful with the vertical depth of implant placement and should check the depth of the osteotomy before placing an implant. Clinicians should recognize the range of implant deviation upon placement of the system used; therefore, clinicians should be trained in each implant system to compensate for these possible deviations.
The recent introduction of in-office stereolithographic 3D printers has popularized their clinical applications, especially for guided implant surgery. Their use has reduced the cost of surgical guides and provides direct access for clinicians throughout the workflow, from intraoral scanning to implant treatment planning, surgical implant placement, restorative design, and fabrication.1-3 Guided implant surgery promises improved placement accuracy and precision compared with conventional nonguided implant surgery.4-13 Moreover, guided surgery allows conservative flapless surgery and therefore limits surgical complications.6,14-16 Guided implant surgery has been reported to be more accurate and precise than conventional surgical guides or free-hand implant placement.2,9-11,17,18 However, most of these studies compared only within the same implant surgical system. Information comparing the precision and accuracy of different guided implant surgery systems is lacking.9,10,18 Different drill designs, sizes, protocols, as well as implant fixture designs may influence the effectiveness of each guided implant system. More importantly, as clinicians are moving toward in-office implant guide fabrication for guided surgery, information is required on how different implant systems may behave in terms of accuracy and precision when in-office stereolithographic fabrication is used. The main objectives of this study were to define the range of dimensional and angulation deviations of implant placements from the planned implant positions, referred to as placement accuracy; to define the variables in the range of implant placement deviations, referred to as placement precision; and to give clinical recommendations for improving guided implant surgery for 3 commonly used implant systems. The accuracy of implant placement is most often referred to as the mean implant deviation, comparing the actual implant placement with the planned implant position. The precision of
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implant placement is referred to as the variation or variance of implant deviation.5,6 The research hypothesis was that each implant-guided system would have its own unique implant deviations, and therefore, implant dimensional and angulation deviations would be specific to each system. Specifically, the accuracy and the precision would be different among different implant surgical systems when in-office 3D printing was used in guide fabrication. Defining the specific strengths and weaknesses of implant systems through implant deviations would allow better clinical recommendations for improving in-office implant guide fabrication, implant guided surgery, implant prosthetic design, and implant treatment outcome. MATERIAL AND METHODS Three implant systems were chosen: Tapered Internal implant system (BioHorizons, BH), NobelReplace Conical (Nobel Biocare, NB), and Tapered Screw-Vent (Zimmer Biomet, ZB). A cone beam computed tomography (CBCT) data set and intraoral scans obtained from the implant clinic database of an unidentified patient missing a maxillary right central incisor were used. The CBCT scans were obtained by using the following protocol: i-CAT FLX V10 (Imaging Sciences International LLC) with standard implant scan parameters (16 cm in depth, 10 cm in height, 0.3-mm voxel size, 8.9-second scan time, 3.7-second exposure time, 120 kVP, 5 mA, and 501.3 mGy/cm2).5 The intraoral scans were made by using the TRIOS Intraoral Scanner (3Shape). By using the CBCT and intraoral scans, the implant treatment planning to replace the maxillary right central incisor was carried out by using the Implant Studio 2017 (3Shape). Three treatment plans were made by using a BH (4.6×12 mm), NB (4.3×13 mm), or ZB (3.7×13 mm) implant. The implant positions were approximately the same in terms of positioning and angulation, but with slightly differences in implant fixture lengths and widths. The protocol for fabricating the dental cast and surgical guide is similar to those of previous studies.4,5 The intraoral scan was imported into a software program (Dental System v2017; 3Shape), in which the dental cast and surgical guide were designed.4 The cast was exported in the standard tessellation language (STL) format and was used to print 30 dental casts (Form 2; Formlabs) (Fig. 1). Dental Model resin (Formlabs) was used to print at a resolution of 0.1 mm, lying flat on the base without the fabrication of printing supports. The cast was later used for implant placement. Three implant surgical guide designs, one for each implant system, were exported into a software program (PreForm; Formlabs) in the STL format. The casts were oriented, and appropriate structural printing supports were designed. The guides were printed in resin (Dental SG; Formlabs) at a resolution of
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Figure 1. Study workflow. CBCT, cone beam computed tomography. *Length of drill refers to depth of osteotomy preparation.
0.05 mm.1,4 After the guides had been printed, the print supports were removed. The guides were then rinsed twice in isopropanol and air-dried, and the surgical guide tubes were placed. Finally, the surgical guides were postprocessed by light-polymerization for 1 hour and sterilized in an autoclave.1,4,5 For each implant system, 10 dental casts and 10 implants were used. The same surgical guide and implant surgical kit were used for each system to control the variations of guide fitting and drills. The implants were placed based on the manufacturer’s recommendation. All osteotomy sites were prepared through surgical guides. The osteotomes were evaluated for depth and width before implant placement. Then, BH and NB implants were placed through the surgical guide, while ZB implants were placed after the removal of the surgical guide. Figure 1 illustrates the workflow used in the study. Postoperative CBCT scans were made by using a postoperative scanning protocol similar to that of a previous study.5 The dimensions and angulations of the implant position were determined in the mesiodistal and labiopalatal planes, similar to previous studies.4,5,7 The distances between the most cervical part of the planned implant Yeung et al
and the closest adjacent natural tooth root surfaces mesially and distally were recorded as M and D, respectively. The distances between the most cervical part of the planned implant and the outer surface dental cast labially and palatially were recorded as L and P, respectively. The vertical distance between the most cervical part of the implant and the soft tissue in the mesiodistal and labiopalatal planes was recorded as VMD and VLP, respectively. The mesiodistal implant angulation in relation to the left maxillary central incisor and the labiopalatal implant angulation in relation to the palatal plane of the cast were recorded as AMD and ALP, respectively, (Fig. 2). Similar to the preoperative measurement, the postoperative positions of the placed implants were measured by using a previous published protocol.4,5,7 The postoperative CBCT scans were superimposed onto the planned implant position. The implant positions, mesiodistally, labiopalatally, and vertically, as well as the implant angulations in the labiopalatal and mesiodistal planes were measured and compared with the planned positions. The differences between the planned and placed implant positions in each dimension and at each angulation were THE JOURNAL OF PROSTHETIC DENTISTRY
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Figure 2. Measurements for planned and placed implant positions. A, Measurements for BH. B, Measurements for NB. C, Measurements for ZB. BH, BioHorizons; NB, Nobel Biocare; ZB, Zimmer Biomet.
recorded. Accuracy of implant placement refers to the mean implant placement deviations. To examine the differences in the accuracy among the implant systems, ANOVA (a=.05) was used. In the cases of unequal variance, the Welch ANOVA was used. If a statistically significant difference was found based on ANOVA, post hoc pairwise comparisons were used to compare the differences in accuracy of each pair of implant systems. All post hoc pairwise comparisons were performed by using the Tukey adjusted P values to account for multiple comparisons. To examine the precision of each implant system, the Levene test for differences in variance was used to examine a pair of implant systems in each dimension and at each angulation. RESULTS The overall implant displacements were −0.02 ±0.13 mm mesially (M), 0.07 ±0.14 mm distally (D), 0.43 ±0.57 mm labially (L), and 1.26 ±0.80 mm palatally (P); 1.20 ±3.01 mm vertically in the mesiodistal dimension THE JOURNAL OF PROSTHETIC DENTISTRY
(VMD); 0.69 ±2.03 mm vertically in the labiopalatal dimension (VLP); 1.69 ±1.02 degrees in mesiodistal angulation (AMD); and 1.56 ±0.92 degrees in labiopalatal angulation (ALP). Table 1 demonstrates the mean, standard deviation, range, minimum (Min), Q1 (first quartile), Q3 (third quartile), and maximum (Max) values for each implant system, as well as the P values. Figure 3 demonstrates the box plots of each dimension and angulation deviation overall and for each implant system. In terms of accuracy, referring to the deviations from the planned implant position, there were statistically significant differences (ANOVA) in M (P=.026), P (P<.001), VMD (P<.001), AMD (P<.001), and ALP (P<.001). In the M dimension, ZB showed the most displacements, while no statistically significant differences were found in NB and BH. In the vertical displacements (VMD and VLP), ZB showed statistically higher displacements than NB and BH. In the angulation displacements, ZB showed the fewest displacements in P (0.56 ±0.57 mm), AMD (0.83 ±0.28 mm), and ALP (0.77 Yeung et al
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Table 1. Implant placement deviations and statistical analyses Tukey Adjusted Post Hoc Pairwise Comparisons, P* Dimension (mm)/Angulation ( )
Implant System
Mean
SD
Range
Min
Max
ANOVA (P)*
M
BH
0.06
0.09
0.30
-0.12
0.18
.026
t-test
NB
-0.03
0.18
0.54
-0.29
0.25 .663
t-test
N/A
N/A
N/A
.076
t-test
N/A
N/A
N/A
.001
t-test
.462
<.001
.003
.009
t-test
.339
.01
<.001
.258
t-test
.001
t-test
.116
<.001
.003
.001
t-test
.324
<.001
.005
D
L
P
VMD
VLP
AMD
ALP
ZB
-0.09
0.06
0.18
-0.16
0.02
BH
0.05
0.16
0.49
-0.18
0.31
NB
0.10
0.12
0.37
-0.12
0.25
ZB
0.05
0.14
0.42
-0.20
0.22
BH
0.37
0.50
1.52
-0.49
1.03
NB
0.74
0.68
1.90
-0.23
1.67
ZB
0.18
0.39
1.28
-0.45
0.83
BH
1.62
0.47
1.37
0.76
2.13
NB
1.59
0.85
1.85
0.47
2.32 1.30
ZB
0.56
0.57
1.70
-0.40
BH
-0.21
3.93
12.60
-8.48
4.12
NB
0.35
1.34
4.48
-2.55
1.93
ZB
3.46
1.83
5.80
-0.51
5.29
BH
-0.12
2.18
7.46
-4.69
2.77
NB
0.81
1.10
4.17
-0.87
3.30
ZB
1.38
2.46
7.00
-2.28
4.72
BH
1.84
0.34
1.07
1.42
2.49
NB
2.39
1.33
3.21
0.61
3.82
ZB
0.83
0.28
0.86
0.42
1.28
BH
1.86
0.33
1.03
1.45
2.48
NB
2.05
1.22
3.16
0.55
3.71
ZB
0.77
0.26
0.71
0.48
1.19
BH-NB
BH-ZB
NB-ZB
.210
.021
.503
N/A
N/A
N/A
*Statistically significant P values shown in bold.
±0.26 mm), with statistically significant difference (See P values in Table 1). In terms of precision, referring to the consistency of displacement or the least variation in deviations, the Levene tests for differences in variance (a=.05) suggested statistically significant differences in the M, P, VMD, VLP, AMD, and ALP. ZB and BH had statistically fewer variations in M than NB. ZB had statistically fewer variations in the P deviation than BH and NB. NB and ZB had statistically fewer variations in VMD. NB had statistically significantly fewer variations than BH and ZB in VLP. NB, however, had statistically more variations in the angulations (AMD and ALP). DISCUSSION The results support the research hypothesis that when an in-office stereolithographic fabricated guide is used, each implant guided surgery system has unique strengths and weaknesses. Overall, guided implant surgery performed by using in-office 3D-printed guides has a similar range of accuracy and precision as previous studies.4,5 Note that the vertical depth of placement in this study could induce an error of approximately 3 mm or more in some systems. The M dimension has the highest accuracy, approximately 0.1 mm in BH and ZB and approximately 0.2 mm in NB. The D dimension also has similar Yeung et al
accuracy, approximately 0.1 to 0.3 mm. While there was a statistically significant difference in M displacement among the 3 implant systems, the displacement values were in the range of those of other studies and likely to have little clinical significance.4,5,13 In the L dimension, all implants displaced slightly labially, reflecting a clinical situation of limited labial or buccal bone. Clinicians should pay attention to this trend of labial or buccal displacement when performing flapless surgery. Angulation of the drill and other techniques such as bone tapping have been suggested to limit labial or buccal directional and angulation displacements.19-22 The ZB system showed the least P displacement. This may be related to the way the implant was placed and the size of the implant fixture and threads. With the BH and NB systems, the implant fixtures were placed through the guide, making it more difficult to lean on the palatal bone and keep the implant fixture palatally. In addition, the sizes of the NB fixture and threads were much larger than the osteotomy sites. In the ZB situation, after the osteotomy site had been completely prepared (through the surgical guide), the implant fixture was placed without the guide, and clinicians could then direct the fixture against the palatal bone. Therefore, clinicians should pay particular attention to placement of the implant when fully guided surgery is performed and try to keep the implant fixture engaged with the palatal bone or perform bone tapping.4,23 THE JOURNAL OF PROSTHETIC DENTISTRY
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0.
0.
0.
0.
0
0.
mm
mm
0.
–0. –0. –0.
–0. Overall
BioHorizon
Nobel
–0.
Zimmer
BioHorizon
1.
1.5
1
1
mm
2
0.
Nobel
Zimmer
B
D
2
0.5 0
0 –0.
Overall
A
M
mm
0
Overall
BioHorizon
Nobel
–0.5
Zimmer
Overall
BioHorizon
C
L
Nobel
Zimmer
D
P
10
6 4
5
mm
mm
2 0
–2
–5 –10
0
–4 Overall
BioHorizon
Nobel
–6
Zimmer
Overall
E
VMD
BioHorizon
Nobel
Zimmer
F
VLP 4
4 3
Degree
Degree
3 2
1
1 0
2
Overall
BioHorizon
AMD
Nobel
0
Zimmer
G
Overall
BioHorizon
ALP
Nobel
Zimmer
H
Figure 3. Box plots for dimensional and angulation implant deviations showing first and third quartile box plots and maximal and minimal values. A, M. B, D. C, L. D, P. E, VMD. F, VLP. G, AMD. H, ALP. ALP, angulation in labiopalatal dimension; AMD, angulation in mesiodistal direction; D, distal; L, labial; M, mesial; P, palatal; VLP, vertical in labiopalatal dimension; VMD, vertical in mesiodistal direction.
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While ZB performs well in most dimensions compared with other systems, the partially guided protocol, preparing for an osteotomy with the surgical guide but placing the implant without the surgical guide, leads to a lack of vertical control, and, therefore, the ZB implant displacement can be more than 3 mm. While the manufacturer recommends placing the implant without the guide, a previous study suggests fully guiding ZB implants through the guide to provide better vertical accuracy clinically.5 In terms of angulation deviation, ZB systems demonstrated the least angulation deviation, which may be a result of less deviation from thin labial bone and angulation at placement similar to that of the P displacement. However, the overall angulation deviations of all 3 systems were consistent with those of previous studies.4,5 In terms of precision, NB appeared to have the highest variability, which may be the result of the vertical stopper used in the guide system and the larger size of the implant fixture and threads than the osteotomy site. While BH and ZB osteotomy preparations are performed by using the entire drill length, the NB system uses a stopper that may result in less precision. This in vitro study has limitations similar to those of previous work.4 First, the fitting of the guide and dental casts may not be the same as in the patient’s mouth. Clinically, there may be some minor movements of natural teeth and soft tissue. However, previous in vitro and in vivo studies4,5 demonstrated that the range of implant deviations in resin 3D-printed models4 was similar to that in humans.5 Second, the nature of drill deviations when drilling through a homogenous polymethyl methacrylate may be different from that when drilling through nonhomogenous alveolar bone. Third, the dental casts used in this study did not have soft tissue. Thus, some deviations of the implant fixture may occur as a result of lack of soft tissue in the cervical portion of the implant fixture. Finally, the implant systems chosen were of different widths and lengths, and direct comparison of these implants may not reflect a side-by-side comparison but only a general overview of the system. The influence of different drills used in guided surgery may be observed when performing trephination-based implant guided surgery which can standardize the initial osteotomy site, except for the final implant drill that is specific to each implant system.24 In addition to these limitations, the deviations themselves were assumed to be independent and were all analyzed individually. There may be inherent correlations among the deviations that were not considered in this analysis. Future studies should include analysis of implant deviations in humans with different locations in the mouth, different types of bone, as well as different implant systemespecific deviations when a universal implant guided system such as trephination-based implant guided surgery is used. Yeung et al
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CONCLUSIONS Based on the findings of this in vitro study, the following conclusions were drawn: 1. When guide fabrication is performed in office by using a desktop stereolithographic printer, clinicians should recognize the limitations of the guide, such as the guide fit and depth of placement. 2. When performing fully or partially guided surgery, clinicians need to be aware of potential vertical and palatal displacements. 3. When a long drill is used with a surgical stopper, clinicians should recognize that the implant placement may have less precision and that the fit of all surgical components is essential during osteotomy preparation. REFERENCES 1. Whitley D 3rd, Eidson RS, Rudek I, Bencharit S. In-office fabrication of dental implant surgical guides using desktop stereolithographic printing and implant treatment planning software: A clinical report. J Prosthet Dent 2017;118:256-63. 2. Hultin M, Svensson KG, Trulsson M. Clinical advantages of computerguided implant placement: a systematic review. Clin Oral Implants Res 2012;23:124-35. 3. Marchack CB, Moy PK. Computed tomography-based, template-guided implant placement and immediate loading: an 8-year clinical report. J Prosthet Dent 2014;112:1319-23. 4. Deeb GR, Allen RK, Hall VP, Whitley D 3rd, Laskin DM, Bencharit S. How accurate are implant surgical guides produced with desktop stereolithographic 3-dimentional printers? J Oral Maxillofac Surg 2017;75: 2559.e1-8. 5. Bencharit S, Staffen A, Yeung M, Whitley D 3rd, Laskin DM, Deeb GR. In vivo tooth-supported implant surgical guides fabricated with desktop stereolithographic printers: Fully guided surgery is more accurate than partially guided surgery. J Oral Maxillofac Surg 2018;76: 1431-9. 6. Deeb JG, Bencharit S, Loschiavo CA, Yeung M, Laskin D, Deeb GR. Do implant surgical guides allow an adequate zone of keratinized tissue for flapless surgery? J Oral Maxillofac Surg 2018;76:2540-50. 7. Deeb G, Koerich L, Whitley D 3rd, Bencharit S. Computer-guided implant removal: A clinical report. J Prosthet Dent 2018;120:796-800. 8. Seo C, Juodzbalys G. Accuracy of guided surgery via stereolithographic mucosa-supported surgical guide in implant surgery for edentulous patient: a systematic review. J Oral Maxillofac Res 2018;9:e1. 9. Colombo M, Mangano C, Mijiritsky E, Krebs M, Hauschild U, Fortin T. Clinical applications and effectiveness of guided implant surgery: a critical review based on randomized controlled trials. BMC Oral Health 2017;17:150. 10. Zhou W, Liu Z, Song L, Kuo C-L, Shafer DM. Clinical factors affecting the accuracy of guided implant surgery-A systematic review and meta-analysis. J Evid Based Dent Pract 2018;18:28-40. 11. Choi W, Nguyen B-C, Doan A, Girod S, Gaudilliere B, Gaudilliere D. Freehand versus guided surgery: factors influencing accuracy of dental implant placement. Implant Dent 2017;26:500-9. 12. Pettersson A, Komiyama A, Hultin M, Näsström K, Klinge B. Accuracy of virtually planned and template guided implant surgery on edentate patients. Clin Implant Dent Relat Res 2010;14:527-37. 13. Pozzi A, Polizzi G, Moy PK. Guided surgery with tooth-supported templates for single missing teeth: A critical review. Eur J Oral Implantol 2016;9 Suppl 1: S135-53. 14. Bedard JF, Cullum DR. Diagnosis and Treatment Planning for Minimally Invasive Dental Implant Treatment. In: Cullum DR, Deporter D, editors. Minimally invasive dental implant surgery. Hoboken: John Wiley & Sons; 2016. p. 3-27. 15. Orentlicher G, Horowitz A, Abboud M. Minimally Invasive Implant Surgery Using Computer-Guided Technology. In: Cullum DR, Deporter D, editors. Minimally invasive dental implant surgery. Hoboken: John Wiley & Sons; 2016. p. 169-89. 16. Yong LT, Moy PK. Complications of computer-aided-design/computeraided-machining-guided (NobelGuide) surgical implant placement: an
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evaluation of early clinical results. Clin Implant Dent Relat Res 2008;10: 123-7. Block MS, Chandler C. Computed tomography-guided surgery: complications associated with scanning, processing, surgery, and prosthetics. J Oral Maxillofac Surg 2009;67:13-22. Schneider D, Marquardt P, Zwahlen M, Jung RE. A systematic review on the accuracy and the clinical outcome of computer-guided template-based implant dentistry. Clin Oral Implants Res 2009;20: 73-86. Givens E Jr, Bencharit S, Byrd WC, Phillips C, Hosseini B, Tyndall D. Immediate placement and provisionalization of implants into sites with periradicular infection with and without antibiotics: An exploratory study. J Oral Implantol 2015;41:299-305. Hosseini B, Byrd WC, Preisser JS, Khan A, Duggan D, Bencharit S. Effects of antibiotics on bone and soft-tissue healing following immediate singletooth implant placement into sites with apical pathology. J Oral Implantol 2015;41:e202-11. Bencharit S, Byrd WC, Hosseini B. Immediate placement of a poroustantalum, trabecular metal-enhanced titanium dental implant with demineralized bone matrix into a socket with deficient buccal bone: a clinical report. J Prosthet Dent 2015;113:262-9.
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22. Bencharit S, Allen RK, Whitley D 3rd. Utilization of demineralized bone matrix to restore missing buccal bone during single implant placement: Clinical report. J Oral Implantol 2016;42:490-7. 23. Bencharit S, Byrd WC, Altarawneh S, Hosseini B, Leong A, Reside G, et al. Development and applications of porous tantalum trabecular metal-enhanced titanium dental implants. Clin Implant Dent Relat Res 2013;16:817-26. 24. Suriyan N, Sarinnaphakorn L, Deeb GR, Bencharit S. Trephination-based, guided surgical implant placement: A clinical study. J Prosthet Dent 2019;121: 411-6. Corresponding author: Dr Sompop Bencharit Department of General Practice School of Dentistry Virginia Commonwealth University 520 N 12th Street, Richmond, VA 23298-0566 Email: [email protected] Copyright © 2019 by the Editorial Council for The Journal of Prosthetic Dentistry. https://doi.org/10.1016/j.prosdent.2019.05.027
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Accuracy and precision of 3D-printed implant surgical guides with different implant systems: An in vitro study Matthew Yeung, DDS,a Aous Abdulmajeed, BDS, PhD,b Caroline K. Carrico, PhD,c George R. Deeb, DDS, MD,d and Sompop Bencharit, DDS, MS, PhDe
ABSTRACT Statement of problem. Implant guided surgery systems promise implant placement accuracy and precision beyond straightforward nonguided surgery. Recently introduced in-office stereolithography systems allow clinicians to produce implant surgical guides themselves. However, different implant designs and osteotomy preparation protocols may produce accuracy and precision differences among the different implant systems. Purpose. The purpose of this in vitro study was to measure the accuracy and precision of 3 implant systems, Tapered Internal implant system (BioHorizons) (BH), NobelReplace Conical (Nobel Biocare) (NB), and Tapered Screw-Vent (Zimmer Biomet) (ZB) when in-office fabricated surgical guides were used. Material and methods. A cone beam computed tomography (CBCT) data set of an unidentified patient missing a maxillary right central incisor and intraoral scans of the same patient were used as a model. A software program (3Shape Implant Studio) was used to plan the implant treatment with the 3 implant systems. Three implant surgical guides were fabricated by using a 3D printer (Form 2), and 30 casts were printed. A total of 10 implants for each system were placed in the dental casts by using the manufacturer’s recommended guided surgery protocols. After implant placement, postoperative CBCT images were made. The CBCT cast and implant images were superimposed onto the treatment-planning image. The implant positions, mesiodistal, labiopalatal, and vertical, as well as implant angulations were measured in the labiolingual and mesiodistal planes. The displacements from the planning in each dimension were recorded. ANOVA with the Tukey adjusted post hoc pairwise comparisons were used to examine the accuracy and precision of the 3 implant systems (a=.05). Results. The overall implant displacements were −0.02 ±0.13 mm mesially (M), 0.07 ±0.14 mm distally (D), 0.43 ±0.57 mm labially (L), and 1.26 ±0.80 mm palatally (P); 1.20 ±3.01 mm vertically in the mesiodistal dimension (VMD); 0.69 ±2.03 mm vertically in the labiopalatal dimension (VLP); 1.69 ±1.02 degrees in mesiodistal angulation (AMD); and 1.56 ±0.92 degrees in labiopalatal angulation (ALP). Statistically significant differences (ANOVA) were found in M (P=.026), P (P=.001), VMD (P=.009), AMD (P=.001), and ALP (P=.001). ZB showed the most displacements in the M and vertical dimensions and the least displacements in the P angulation (P<.05), suggesting statistically significant differences among the M, VMD, VLP, AMD, and ALP. NB had the most M variation. ZB had the least P deviation. NB had the fewest vertical dimension variations but the most angulation variations. Conclusions. Dimensional and angulation displacements of guided implant systems by in-office 3D-printed fabrication were within clinically acceptable limits: <0.1 mm in M-D, 0.5 to 1 mm in L-P, and 1 to 2 degrees in angulation. However, the vertical displacement can be as much as 2 to 3 mm. Different implant guided surgery systems have strengths and weaknesses as revealed in the dimensional and angulation implant displacements. (J Prosthet Dent 2019;-:---)
S.B. is a lecturer for Zimmer Biomet Institute; his research was partly supported by Zimmer Biomet; lectures for Formlabs and 3Shape. BioHorizon, Nobel Biocare, and Zimmer Biomet provided implant fixtures used for this study. Funding for the study was provided in part through the American Association of Dental Research Student Fellowship and the Virginia Commonwealth University A.D. Williams Dental Student Research Fellowship (to M.Y. under the supervision of S.B.). a Former doctoral student, Department of General Practice, School of Dentistry, Virginia Commonwealth University, Richmond, Va. b Assistant Professor and Director of Biomaterials, Department of General Practice, School of Dentistry, Virginia Commonwealth University, Richmond, Va. c Assistant Professor, Department of Oral Health Promotion and Community Outreach, School of Dentistry, Virginia Commonwealth University, Richmond, Va; and Assistant Professor, Department of Biostatistics, School of Medicine, Virginia Commonwealth University, Richmond, Va. d Professor, Department of Oral and Maxillofacial Surgery, School of Dentistry, Virginia Commonwealth University, Richmond, Va. e Associate Professor and Director of Digital Dentistry Technologies, Department of General Practice and Department of Oral & Maxillofacial Surgery, School of Dentistry, Virginia Commonwealth University, Richmond, Va; and Associate Professor, Department of Biomedical Engineering, College of Engineering, Virginia Commonwealth University, Richmond, Va.
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Clinical Implications Each implant guided surgical system has strengths and weaknesses that clinicians must learn to accommodate. In general, limited mesiodistal and labiopalatal dimensional and angulation displacements are expected in guided surgery. However, clinicians should be careful with the vertical depth of implant placement and should check the depth of the osteotomy before placing an implant. Clinicians should recognize the range of implant deviation upon placement of the system used; therefore, clinicians should be trained in each implant system to compensate for these possible deviations.
The recent introduction of in-office stereolithographic 3D printers has popularized their clinical applications, especially for guided implant surgery. Their use has reduced the cost of surgical guides and provides direct access for clinicians throughout the workflow, from intraoral scanning to implant treatment planning, surgical implant placement, restorative design, and fabrication.1-3 Guided implant surgery promises improved placement accuracy and precision compared with conventional nonguided implant surgery.4-13 Moreover, guided surgery allows conservative flapless surgery and therefore limits surgical complications.6,14-16 Guided implant surgery has been reported to be more accurate and precise than conventional surgical guides or free-hand implant placement.2,9-11,17,18 However, most of these studies compared only within the same implant surgical system. Information comparing the precision and accuracy of different guided implant surgery systems is lacking.9,10,18 Different drill designs, sizes, protocols, as well as implant fixture designs may influence the effectiveness of each guided implant system. More importantly, as clinicians are moving toward in-office implant guide fabrication for guided surgery, information is required on how different implant systems may behave in terms of accuracy and precision when in-office stereolithographic fabrication is used. The main objectives of this study were to define the range of dimensional and angulation deviations of implant placements from the planned implant positions, referred to as placement accuracy; to define the variables in the range of implant placement deviations, referred to as placement precision; and to give clinical recommendations for improving guided implant surgery for 3 commonly used implant systems. The accuracy of implant placement is most often referred to as the mean implant deviation, comparing the actual implant placement with the planned implant position. The precision of
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implant placement is referred to as the variation or variance of implant deviation.5,6 The research hypothesis was that each implant-guided system would have its own unique implant deviations, and therefore, implant dimensional and angulation deviations would be specific to each system. Specifically, the accuracy and the precision would be different among different implant surgical systems when in-office 3D printing was used in guide fabrication. Defining the specific strengths and weaknesses of implant systems through implant deviations would allow better clinical recommendations for improving in-office implant guide fabrication, implant guided surgery, implant prosthetic design, and implant treatment outcome. MATERIAL AND METHODS Three implant systems were chosen: Tapered Internal implant system (BioHorizons, BH), NobelReplace Conical (Nobel Biocare, NB), and Tapered Screw-Vent (Zimmer Biomet, ZB). A cone beam computed tomography (CBCT) data set and intraoral scans obtained from the implant clinic database of an unidentified patient missing a maxillary right central incisor were used. The CBCT scans were obtained by using the following protocol: i-CAT FLX V10 (Imaging Sciences International LLC) with standard implant scan parameters (16 cm in depth, 10 cm in height, 0.3-mm voxel size, 8.9-second scan time, 3.7-second exposure time, 120 kVP, 5 mA, and 501.3 mGy/cm2).5 The intraoral scans were made by using the TRIOS Intraoral Scanner (3Shape). By using the CBCT and intraoral scans, the implant treatment planning to replace the maxillary right central incisor was carried out by using the Implant Studio 2017 (3Shape). Three treatment plans were made by using a BH (4.6×12 mm), NB (4.3×13 mm), or ZB (3.7×13 mm) implant. The implant positions were approximately the same in terms of positioning and angulation, but with slightly differences in implant fixture lengths and widths. The protocol for fabricating the dental cast and surgical guide is similar to those of previous studies.4,5 The intraoral scan was imported into a software program (Dental System v2017; 3Shape), in which the dental cast and surgical guide were designed.4 The cast was exported in the standard tessellation language (STL) format and was used to print 30 dental casts (Form 2; Formlabs) (Fig. 1). Dental Model resin (Formlabs) was used to print at a resolution of 0.1 mm, lying flat on the base without the fabrication of printing supports. The cast was later used for implant placement. Three implant surgical guide designs, one for each implant system, were exported into a software program (PreForm; Formlabs) in the STL format. The casts were oriented, and appropriate structural printing supports were designed. The guides were printed in resin (Dental SG; Formlabs) at a resolution of
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Figure 1. Study workflow. CBCT, cone beam computed tomography. *Length of drill refers to depth of osteotomy preparation.
0.05 mm.1,4 After the guides had been printed, the print supports were removed. The guides were then rinsed twice in isopropanol and air-dried, and the surgical guide tubes were placed. Finally, the surgical guides were postprocessed by light-polymerization for 1 hour and sterilized in an autoclave.1,4,5 For each implant system, 10 dental casts and 10 implants were used. The same surgical guide and implant surgical kit were used for each system to control the variations of guide fitting and drills. The implants were placed based on the manufacturer’s recommendation. All osteotomy sites were prepared through surgical guides. The osteotomes were evaluated for depth and width before implant placement. Then, BH and NB implants were placed through the surgical guide, while ZB implants were placed after the removal of the surgical guide. Figure 1 illustrates the workflow used in the study. Postoperative CBCT scans were made by using a postoperative scanning protocol similar to that of a previous study.5 The dimensions and angulations of the implant position were determined in the mesiodistal and labiopalatal planes, similar to previous studies.4,5,7 The distances between the most cervical part of the planned implant Yeung et al
and the closest adjacent natural tooth root surfaces mesially and distally were recorded as M and D, respectively. The distances between the most cervical part of the planned implant and the outer surface dental cast labially and palatially were recorded as L and P, respectively. The vertical distance between the most cervical part of the implant and the soft tissue in the mesiodistal and labiopalatal planes was recorded as VMD and VLP, respectively. The mesiodistal implant angulation in relation to the left maxillary central incisor and the labiopalatal implant angulation in relation to the palatal plane of the cast were recorded as AMD and ALP, respectively, (Fig. 2). Similar to the preoperative measurement, the postoperative positions of the placed implants were measured by using a previous published protocol.4,5,7 The postoperative CBCT scans were superimposed onto the planned implant position. The implant positions, mesiodistally, labiopalatally, and vertically, as well as the implant angulations in the labiopalatal and mesiodistal planes were measured and compared with the planned positions. The differences between the planned and placed implant positions in each dimension and at each angulation were THE JOURNAL OF PROSTHETIC DENTISTRY
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Figure 2. Measurements for planned and placed implant positions. A, Measurements for BH. B, Measurements for NB. C, Measurements for ZB. BH, BioHorizons; NB, Nobel Biocare; ZB, Zimmer Biomet.
recorded. Accuracy of implant placement refers to the mean implant placement deviations. To examine the differences in the accuracy among the implant systems, ANOVA (a=.05) was used. In the cases of unequal variance, the Welch ANOVA was used. If a statistically significant difference was found based on ANOVA, post hoc pairwise comparisons were used to compare the differences in accuracy of each pair of implant systems. All post hoc pairwise comparisons were performed by using the Tukey adjusted P values to account for multiple comparisons. To examine the precision of each implant system, the Levene test for differences in variance was used to examine a pair of implant systems in each dimension and at each angulation. RESULTS The overall implant displacements were −0.02 ±0.13 mm mesially (M), 0.07 ±0.14 mm distally (D), 0.43 ±0.57 mm labially (L), and 1.26 ±0.80 mm palatally (P); 1.20 ±3.01 mm vertically in the mesiodistal dimension THE JOURNAL OF PROSTHETIC DENTISTRY
(VMD); 0.69 ±2.03 mm vertically in the labiopalatal dimension (VLP); 1.69 ±1.02 degrees in mesiodistal angulation (AMD); and 1.56 ±0.92 degrees in labiopalatal angulation (ALP). Table 1 demonstrates the mean, standard deviation, range, minimum (Min), Q1 (first quartile), Q3 (third quartile), and maximum (Max) values for each implant system, as well as the P values. Figure 3 demonstrates the box plots of each dimension and angulation deviation overall and for each implant system. In terms of accuracy, referring to the deviations from the planned implant position, there were statistically significant differences (ANOVA) in M (P=.026), P (P<.001), VMD (P<.001), AMD (P<.001), and ALP (P<.001). In the M dimension, ZB showed the most displacements, while no statistically significant differences were found in NB and BH. In the vertical displacements (VMD and VLP), ZB showed statistically higher displacements than NB and BH. In the angulation displacements, ZB showed the fewest displacements in P (0.56 ±0.57 mm), AMD (0.83 ±0.28 mm), and ALP (0.77 Yeung et al
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Table 1. Implant placement deviations and statistical analyses Tukey Adjusted Post Hoc Pairwise Comparisons, P* Dimension (mm)/Angulation ( )
Implant System
Mean
SD
Range
Min
Max
ANOVA (P)*
M
BH
0.06
0.09
0.30
-0.12
0.18
.026
t-test
NB
-0.03
0.18
0.54
-0.29
0.25 .663
t-test
N/A
N/A
N/A
.076
t-test
N/A
N/A
N/A
.001
t-test
.462
<.001
.003
.009
t-test
.339
.01
<.001
.258
t-test
.001
t-test
.116
<.001
.003
.001
t-test
.324
<.001
.005
D
L
P
VMD
VLP
AMD
ALP
ZB
-0.09
0.06
0.18
-0.16
0.02
BH
0.05
0.16
0.49
-0.18
0.31
NB
0.10
0.12
0.37
-0.12
0.25
ZB
0.05
0.14
0.42
-0.20
0.22
BH
0.37
0.50
1.52
-0.49
1.03
NB
0.74
0.68
1.90
-0.23
1.67
ZB
0.18
0.39
1.28
-0.45
0.83
BH
1.62
0.47
1.37
0.76
2.13
NB
1.59
0.85
1.85
0.47
2.32 1.30
ZB
0.56
0.57
1.70
-0.40
BH
-0.21
3.93
12.60
-8.48
4.12
NB
0.35
1.34
4.48
-2.55
1.93
ZB
3.46
1.83
5.80
-0.51
5.29
BH
-0.12
2.18
7.46
-4.69
2.77
NB
0.81
1.10
4.17
-0.87
3.30
ZB
1.38
2.46
7.00
-2.28
4.72
BH
1.84
0.34
1.07
1.42
2.49
NB
2.39
1.33
3.21
0.61
3.82
ZB
0.83
0.28
0.86
0.42
1.28
BH
1.86
0.33
1.03
1.45
2.48
NB
2.05
1.22
3.16
0.55
3.71
ZB
0.77
0.26
0.71
0.48
1.19
BH-NB
BH-ZB
NB-ZB
.210
.021
.503
N/A
N/A
N/A
*Statistically significant P values shown in bold.
±0.26 mm), with statistically significant difference (See P values in Table 1). In terms of precision, referring to the consistency of displacement or the least variation in deviations, the Levene tests for differences in variance (a=.05) suggested statistically significant differences in the M, P, VMD, VLP, AMD, and ALP. ZB and BH had statistically fewer variations in M than NB. ZB had statistically fewer variations in the P deviation than BH and NB. NB and ZB had statistically fewer variations in VMD. NB had statistically significantly fewer variations than BH and ZB in VLP. NB, however, had statistically more variations in the angulations (AMD and ALP). DISCUSSION The results support the research hypothesis that when an in-office stereolithographic fabricated guide is used, each implant guided surgery system has unique strengths and weaknesses. Overall, guided implant surgery performed by using in-office 3D-printed guides has a similar range of accuracy and precision as previous studies.4,5 Note that the vertical depth of placement in this study could induce an error of approximately 3 mm or more in some systems. The M dimension has the highest accuracy, approximately 0.1 mm in BH and ZB and approximately 0.2 mm in NB. The D dimension also has similar Yeung et al
accuracy, approximately 0.1 to 0.3 mm. While there was a statistically significant difference in M displacement among the 3 implant systems, the displacement values were in the range of those of other studies and likely to have little clinical significance.4,5,13 In the L dimension, all implants displaced slightly labially, reflecting a clinical situation of limited labial or buccal bone. Clinicians should pay attention to this trend of labial or buccal displacement when performing flapless surgery. Angulation of the drill and other techniques such as bone tapping have been suggested to limit labial or buccal directional and angulation displacements.19-22 The ZB system showed the least P displacement. This may be related to the way the implant was placed and the size of the implant fixture and threads. With the BH and NB systems, the implant fixtures were placed through the guide, making it more difficult to lean on the palatal bone and keep the implant fixture palatally. In addition, the sizes of the NB fixture and threads were much larger than the osteotomy sites. In the ZB situation, after the osteotomy site had been completely prepared (through the surgical guide), the implant fixture was placed without the guide, and clinicians could then direct the fixture against the palatal bone. Therefore, clinicians should pay particular attention to placement of the implant when fully guided surgery is performed and try to keep the implant fixture engaged with the palatal bone or perform bone tapping.4,23 THE JOURNAL OF PROSTHETIC DENTISTRY
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0.
0.
0.
0.
0
0.
mm
mm
0.
–0. –0. –0.
–0. Overall
BioHorizon
Nobel
–0.
Zimmer
BioHorizon
1.
1.5
1
1
mm
2
0.
Nobel
Zimmer
B
D
2
0.5 0
0 –0.
Overall
A
M
mm
0
Overall
BioHorizon
Nobel
–0.5
Zimmer
Overall
BioHorizon
C
L
Nobel
Zimmer
D
P
10
6 4
5
mm
mm
2 0
–2
–5 –10
0
–4 Overall
BioHorizon
Nobel
–6
Zimmer
Overall
E
VMD
BioHorizon
Nobel
Zimmer
F
VLP 4
4 3
Degree
Degree
3 2
1
1 0
2
Overall
BioHorizon
AMD
Nobel
0
Zimmer
G
Overall
BioHorizon
ALP
Nobel
Zimmer
H
Figure 3. Box plots for dimensional and angulation implant deviations showing first and third quartile box plots and maximal and minimal values. A, M. B, D. C, L. D, P. E, VMD. F, VLP. G, AMD. H, ALP. ALP, angulation in labiopalatal dimension; AMD, angulation in mesiodistal direction; D, distal; L, labial; M, mesial; P, palatal; VLP, vertical in labiopalatal dimension; VMD, vertical in mesiodistal direction.
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While ZB performs well in most dimensions compared with other systems, the partially guided protocol, preparing for an osteotomy with the surgical guide but placing the implant without the surgical guide, leads to a lack of vertical control, and, therefore, the ZB implant displacement can be more than 3 mm. While the manufacturer recommends placing the implant without the guide, a previous study suggests fully guiding ZB implants through the guide to provide better vertical accuracy clinically.5 In terms of angulation deviation, ZB systems demonstrated the least angulation deviation, which may be a result of less deviation from thin labial bone and angulation at placement similar to that of the P displacement. However, the overall angulation deviations of all 3 systems were consistent with those of previous studies.4,5 In terms of precision, NB appeared to have the highest variability, which may be the result of the vertical stopper used in the guide system and the larger size of the implant fixture and threads than the osteotomy site. While BH and ZB osteotomy preparations are performed by using the entire drill length, the NB system uses a stopper that may result in less precision. This in vitro study has limitations similar to those of previous work.4 First, the fitting of the guide and dental casts may not be the same as in the patient’s mouth. Clinically, there may be some minor movements of natural teeth and soft tissue. However, previous in vitro and in vivo studies4,5 demonstrated that the range of implant deviations in resin 3D-printed models4 was similar to that in humans.5 Second, the nature of drill deviations when drilling through a homogenous polymethyl methacrylate may be different from that when drilling through nonhomogenous alveolar bone. Third, the dental casts used in this study did not have soft tissue. Thus, some deviations of the implant fixture may occur as a result of lack of soft tissue in the cervical portion of the implant fixture. Finally, the implant systems chosen were of different widths and lengths, and direct comparison of these implants may not reflect a side-by-side comparison but only a general overview of the system. The influence of different drills used in guided surgery may be observed when performing trephination-based implant guided surgery which can standardize the initial osteotomy site, except for the final implant drill that is specific to each implant system.24 In addition to these limitations, the deviations themselves were assumed to be independent and were all analyzed individually. There may be inherent correlations among the deviations that were not considered in this analysis. Future studies should include analysis of implant deviations in humans with different locations in the mouth, different types of bone, as well as different implant systemespecific deviations when a universal implant guided system such as trephination-based implant guided surgery is used. Yeung et al
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CONCLUSIONS Based on the findings of this in vitro study, the following conclusions were drawn: 1. When guide fabrication is performed in office by using a desktop stereolithographic printer, clinicians should recognize the limitations of the guide, such as the guide fit and depth of placement. 2. When performing fully or partially guided surgery, clinicians need to be aware of potential vertical and palatal displacements. 3. When a long drill is used with a surgical stopper, clinicians should recognize that the implant placement may have less precision and that the fit of all surgical components is essential during osteotomy preparation. REFERENCES 1. Whitley D 3rd, Eidson RS, Rudek I, Bencharit S. In-office fabrication of dental implant surgical guides using desktop stereolithographic printing and implant treatment planning software: A clinical report. J Prosthet Dent 2017;118:256-63. 2. Hultin M, Svensson KG, Trulsson M. Clinical advantages of computerguided implant placement: a systematic review. Clin Oral Implants Res 2012;23:124-35. 3. Marchack CB, Moy PK. Computed tomography-based, template-guided implant placement and immediate loading: an 8-year clinical report. J Prosthet Dent 2014;112:1319-23. 4. Deeb GR, Allen RK, Hall VP, Whitley D 3rd, Laskin DM, Bencharit S. How accurate are implant surgical guides produced with desktop stereolithographic 3-dimentional printers? J Oral Maxillofac Surg 2017;75: 2559.e1-8. 5. Bencharit S, Staffen A, Yeung M, Whitley D 3rd, Laskin DM, Deeb GR. In vivo tooth-supported implant surgical guides fabricated with desktop stereolithographic printers: Fully guided surgery is more accurate than partially guided surgery. J Oral Maxillofac Surg 2018;76: 1431-9. 6. Deeb JG, Bencharit S, Loschiavo CA, Yeung M, Laskin D, Deeb GR. Do implant surgical guides allow an adequate zone of keratinized tissue for flapless surgery? J Oral Maxillofac Surg 2018;76:2540-50. 7. Deeb G, Koerich L, Whitley D 3rd, Bencharit S. Computer-guided implant removal: A clinical report. J Prosthet Dent 2018;120:796-800. 8. Seo C, Juodzbalys G. Accuracy of guided surgery via stereolithographic mucosa-supported surgical guide in implant surgery for edentulous patient: a systematic review. J Oral Maxillofac Res 2018;9:e1. 9. Colombo M, Mangano C, Mijiritsky E, Krebs M, Hauschild U, Fortin T. Clinical applications and effectiveness of guided implant surgery: a critical review based on randomized controlled trials. BMC Oral Health 2017;17:150. 10. Zhou W, Liu Z, Song L, Kuo C-L, Shafer DM. Clinical factors affecting the accuracy of guided implant surgery-A systematic review and meta-analysis. J Evid Based Dent Pract 2018;18:28-40. 11. Choi W, Nguyen B-C, Doan A, Girod S, Gaudilliere B, Gaudilliere D. Freehand versus guided surgery: factors influencing accuracy of dental implant placement. Implant Dent 2017;26:500-9. 12. Pettersson A, Komiyama A, Hultin M, Näsström K, Klinge B. Accuracy of virtually planned and template guided implant surgery on edentate patients. Clin Implant Dent Relat Res 2010;14:527-37. 13. Pozzi A, Polizzi G, Moy PK. Guided surgery with tooth-supported templates for single missing teeth: A critical review. Eur J Oral Implantol 2016;9 Suppl 1: S135-53. 14. Bedard JF, Cullum DR. Diagnosis and Treatment Planning for Minimally Invasive Dental Implant Treatment. In: Cullum DR, Deporter D, editors. Minimally invasive dental implant surgery. Hoboken: John Wiley & Sons; 2016. p. 3-27. 15. Orentlicher G, Horowitz A, Abboud M. Minimally Invasive Implant Surgery Using Computer-Guided Technology. In: Cullum DR, Deporter D, editors. Minimally invasive dental implant surgery. Hoboken: John Wiley & Sons; 2016. p. 169-89. 16. Yong LT, Moy PK. Complications of computer-aided-design/computeraided-machining-guided (NobelGuide) surgical implant placement: an
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evaluation of early clinical results. Clin Implant Dent Relat Res 2008;10: 123-7. Block MS, Chandler C. Computed tomography-guided surgery: complications associated with scanning, processing, surgery, and prosthetics. J Oral Maxillofac Surg 2009;67:13-22. Schneider D, Marquardt P, Zwahlen M, Jung RE. A systematic review on the accuracy and the clinical outcome of computer-guided template-based implant dentistry. Clin Oral Implants Res 2009;20: 73-86. Givens E Jr, Bencharit S, Byrd WC, Phillips C, Hosseini B, Tyndall D. Immediate placement and provisionalization of implants into sites with periradicular infection with and without antibiotics: An exploratory study. J Oral Implantol 2015;41:299-305. Hosseini B, Byrd WC, Preisser JS, Khan A, Duggan D, Bencharit S. Effects of antibiotics on bone and soft-tissue healing following immediate singletooth implant placement into sites with apical pathology. J Oral Implantol 2015;41:e202-11. Bencharit S, Byrd WC, Hosseini B. Immediate placement of a poroustantalum, trabecular metal-enhanced titanium dental implant with demineralized bone matrix into a socket with deficient buccal bone: a clinical report. J Prosthet Dent 2015;113:262-9.
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22. Bencharit S, Allen RK, Whitley D 3rd. Utilization of demineralized bone matrix to restore missing buccal bone during single implant placement: Clinical report. J Oral Implantol 2016;42:490-7. 23. Bencharit S, Byrd WC, Altarawneh S, Hosseini B, Leong A, Reside G, et al. Development and applications of porous tantalum trabecular metal-enhanced titanium dental implants. Clin Implant Dent Relat Res 2013;16:817-26. 24. Suriyan N, Sarinnaphakorn L, Deeb GR, Bencharit S. Trephination-based, guided surgical implant placement: A clinical study. J Prosthet Dent 2019;121: 411-6. Corresponding author: Dr Sompop Bencharit Department of General Practice School of Dentistry Virginia Commonwealth University 520 N 12th Street, Richmond, VA 23298-0566 Email: [email protected] Copyright © 2019 by the Editorial Council for The Journal of Prosthetic Dentistry. https://doi.org/10.1016/j.prosdent.2019.05.027
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