The International Journal of Oral & Maxillofacial Implants, 01/2023

Purpose: To study whether the use of preventive antibiotic therapy reduces the sinus graft infection and/or dental implant failure rates in maxillary sinus elevation surgeries (primary outcome), and to identify the associated best protocol (secondary outcome). Materials and Methods: The MEDLINE (via PubMed), Web of Science, Scopus, LILACS, and OpenGrey databases were searched between December 2006 and December 2021. Prospective and retrospective comparative clinical studies with at least 50 patients and published in English were included. Animal studies, systematic reviews and meta-analyses, narrative literature reviews, books, case reports, letters to the editor, and commentaries were excluded. Assessment of the identified studies, data extraction, and risk of bias were performed independently by two reviewers. Authors were contacted if required. Collected data were reported by descriptive methods. Results: A total of 12 studies fulfilled the inclusion criteria. The only retrospective study comparing the use of antibiotics vs no use of them showed no statistically significant differences for implant failure; however, no data were reported for sinus infection rates. The only randomized clinical trial comparing different courses of antibiotics (only the day of surgery vs 7 additional postoperative days) reported no statistically significant differences between groups in terms of sinus infection rate. Conclusion: Not enough evidence is available to support either the use or nonuse of preventive antibiotic therapy for sinus elevation surgeries or to support the superiority of any protocol over others. Int J Oral Maxillofac Implants 2023;38:19–28. doi: 10.11607/jomi.9930 Keywords: antibiotic prophylaxis, antibiotics, graft infection, preventive antibiotic therapy, sinus floor augmentation, sinus elevation surgery

Purpose: To evaluate the effectiveness of extra-short implants compared to standard-length implants in graft regions at different longitudinal follow-up times. Materials and Methods: A systematic review was performed, following PRISMA criteria. LILACS, MEDLINE/PubMed, Cochrane Library, and Embase databases, including gray literature and manual searches, were conducted without language or date restrictions. Study selection, risk of bias (Rob 2.0), quality of evidence (GRADE), and data collection were performed by two independent reviewers. Disagreements were resolved by a third reviewer. Data were combined using the random-effects model. Results: A total of 1,383 publications were identified, including 11 publications from 4 randomized clinical trials that evaluated 567 implants (276 extra-short and 291 regular implants with graft) in 186 patients. The meta-analysis showed that losses (risk ratio [RR]: 1.24; 95% CI: 0.53 to 2.89; P = .62; I2: 0%) and prosthetic complications (RR: 0.89; 95% CI: 0.31 to 2.59; P = .83; I2: 0%) were similar in both groups. Biologic complications were significantly higher in regular implants with graft (RR: 0.48; CI: 0.29 to 0.77; P = .003; I2: 18%), which also had lower peri-implant bone stability in the mandible at the 12-month follow-up (mean deviation [MD]: –0.25; CI: –0.36 to 0.15; P < .00001; I2 = 0%). Conclusion: Extra-short implants showed similar effictiveness compared to standard-length implants placed in grafted regions at different longitudinal follow-up times and present reduced biologic complications, shorter treatment times, and greater peri-implant bone crest stability. Int J Oral Maxillofac Implants 2023;38:29–36. doi: 10.11607/jomi.9990 Keywords: biomechanical phenomena, bone grafting, dental implants, implant-supported dental prosthesis, metaanalysis, systematic review

Purpose: To evaluate hard and soft tissue response and mechanical integrity for screw-retained layered zirconia crowns bonded to titanium nitride–coated titanium (TiN) CAD/CAM abutments supported by implants at 1- and 2-year followups. Materials and Methods: A total of 46 patients were restored with a total of 102 free-standing implant-supported layered zirconia crowns, which were bonded to their respective abutments in the dental laboratory and delivered as a one-piece screw-retained crown. Baseline, 1-year, and 2-year data were collated on pocket probing depth, bleeding on probing, marginal bone levels, and mechanical complications. Results: Of the 46 patients, 4 patients with one implant each were not followed-up. These patients were not included in the analysis. Of the remaining 98 implants, due to failed appointments during the global pandemic, soft tissue measurements were recorded for 94 implants at year 1 and 86 implants at year 2, with a mean buccal/lingual pocket probing depth of 1.80/1.95 mm and 2.09/2.17 mm, respectively. Mean bleeding on probing was 0.50 and 0.53 at 1 and 2 years, which represents somewhere between no bleeding and a spot bleed according to the study protocol. Radiographic data were available for 74 implants at year 1 and 86 implants at year 2. The mean marginal bone change from baseline was +0.11 mm mesially and +0.19 mm distally at 1 year and +0.24 mm mesially and +0.16 mm distally at 2 years. The final bone level with respect to the reference point was +0.49 mm mesially and +0.19 mm distally at the end of the study period. Mechanical complications involving a slight misfit of the crown margin were recorded for one unit (1%), porcelain fracture for 16 units (16%), and a loss of preload for 12 units (12%) of < 5 Ncm (< 20% of initial preload). Conclusion: The biologic and mechanical stability of ceramic crowns bonded to CAD/ CAM screw-retained abutments using angulated screw access was considered to be high, with overall bone gain, excellent soft tissue health, and only limited mechanical complications related to generally small fractures of the porcelain and a clinically insignificant loss of preload. Int J Oral Maxillofac Implants 2023;38:37–45. doi: 10.11607/jomi.9856 Keywords: abutments, computer assisted, computer milled, dental implants, marginal bone levels, soft tissue health

Purpose: To investigate and assess the differences in crestal bone loss (CBL) between wide-diameter, external-hexagon– connection implants restored with platform-switching (PS) and platform-matching (PM) restorations with a follow-up of 10 years. Materials and Methods: This study retrospectively analyzed the updated and enlarged dataset of a 5-year prospective clinical study at 10-year follow-up. The data concerns 182 healthy adult subjects treated in a private dental practice who received a single wide-diameter implant with an external hexagon connection in the molar area, restored with either a PS restoration (test) or PM restoration (control). The amount of CBL was radiographically measured at each annual follow-up, as well as after 5 and 10 years of implant loading. In evaluating the association between the two types of abutments and bone loss (including change over time), a linear mixed effects model was run for longitudinal data. Results: Implants connected with PS restorations exhibited significantly lower reduction (0.25 mm) in CBL than those joined to PM restorations (P < .001; 95% CI from 0.22 to 0.29). However, both groups presented a higher increase in bone loss during the first year (0.58 mm in PS and 0.83 mm in PM) and a linear increment thereafter until the 10-year followup (0.046 mm/year; P < .001; 95% CI from .042 to .049). Conclusion: Notwithstanding the limitations of this study, it can be concluded that after 10 years of follow-up, the implant with a wide diameter and external-hexagon connection restored with a PS abutment seems to be more effective in reducing bone loss compared with the PM abutment. Int J Oral Maxillofac Implants 2023;38:46–52. doi: 10.11607/jomi.9744 Keywords: crestal bone loss, external connection, implant-supported fixed dental prostheses, platform-matching, platform-switching

Purpose: To evaluate the clinical outcomes of posterior implants with surveyed crowns in implant-assisted removable partial dentures (IARPDs). Materials and Methods: Internal-connection implants were inserted and restored with surveyed crowns at the most posterior molar regions of Kennedy class I or II in partially edentulous patients between 2007 and 2018. IARPDs were fabricated and functioned with or without clasps on the surveyed implant crowns. Clinical outcomes of biologic problems, mechanical problems, and marginal bone loss (MBL) through periapical and panoramic views were recorded and measured. The effects of sex, Kennedy classification, opposing dentition, and clasp existence on MBL were analyzed using Mann-Whitney test, and the implant length, crown-to-implant (C/I) ratio, and function period on MBL were analyzed using a multiple regression analysis at α = .05. Results: A total of 32 posterior implants were restored with a surveyed crown for IARPDs in 16 patients (7 men, 9 women; mean age: 69.3 ± 6.0 years). A total of 15 IARPDs were for the mandible (1 maxilla), and 13 were Kennedy class I (3 class II) before implant insertion. All internal-connection implants (15 bone-level and 17 tissue-level) with 7-mm (n = 12), 8.5-mm (n = 18), and 9-mm (n = 2) lengths were restored for 3 surveyed premolar crowns and 29 molar crowns (15 first molar and 14 second molar). The mean C/I ratio was 1.48. The mean function period of the implants was 60.9 ± 40.2 months (range: 14 to 155), and the mean MBL was 0.11 ± 0.36 mm. Only Kennedy class II showed significantly more MBL (P = .002). The implant survival and success rates were 96.9% and 90.6%, respectively. Conclusion: Within the limitations of this retrospective clinical study, mainly in mandibular IARPDs, implants with surveyed crowns showed high survival and success rates during short- to medium-term functions. Posterior implants with surveyed crowns appear to be a reliable alternative for free-end removable partial denture (RPD) patients. Int J Oral Maxillofac Implants 2023;38:53–61. doi: 10.11607/jomi.9761 Keywords: dental implant, implant-assisted removable partial denture, marginal bone loss, surveyed crown, survival rate

Purpose: To evaluate the effect of insertion depth, bone type, and implant diameter on the primary stability of short implants. Materials and Methods: Commercial dental implants with different lengths (6 and 8 mm; BLX, Straumann) were inserted into artificial bone specimens of good and poor quality at three different depth positions: equicrestal, 1-mm subcrestal, and 2-mm subcrestal. Insertion torque values were recorded spontaneously during the implant procedure. Both maximum insertion torque values (MITVs) and final insertion torque values (FITVs) were recorded. Subsequently, Periotest values (PTVs) and implant stability quotients (ISQs) were measured for all specimens. Results: The mean MITVs of all groups ranged from 31.8 to 46.2 Ncm. However, the mean FITVs of all groups ranged from 8.8 to 29 Ncm. Torque values decreased significantly when the implants were inserted into their final positions. When insertion depth was increased, the PTV and ISQ decreased. Long implants and implants inserted into good-quality bone yielded greater primary stability, and bone quality appeared to have a greater effect on primary stability. Conclusion: When 6-mm short implants are inserted in a subcrestal position, low primary stability may be yielded, particularly in poor-quality bone. Int J Oral Maxillofac Implants 2023;38:62–70. doi: 10.11607/jomi.9769 Keywords: artificial bone, implant stability quotient, insertion depth, insertion torque value, Periotest value, primary stability, short dental implant

Purpose: To investigate the effect of incisive papilla on esthetic ratings and lip support for patients who are treated with implant-supported fixed prostheses on edentulous maxillae. Materials and Methods: A study population of 118 patients with maxillomandibular edentulism was identified. A self-administered questionnaire was used to evaluate treatment outcomes through a patient perspective. Also, clinical factors such as smile line, maxillary resorption, incisive papilla position, and lip support were evaluated. Results: Lip support has a significant effect on the facial esthetic scores of patients, while smile line and incisive papilla localization have not had a proven statistically significant effect on esthetic and facial esthestic scores of patients treated with implant-supported fixed prostheses on maxillae. Conclusion: Although the patients were diagnosed with disadvantageous clinical factors such as crestally localized incisive papilla, they still noted higher esthetic scores with their fixed prostheses. Factors that affect the esthetic perception of patients or their priorities should be investigated more to understand the reasons for patient satisfaction with prostheses. Int J Oral Maxillofac Implants 2023;38:71–76. doi: 10.11607/jomi.9829 Keywords: diagnostic procedure, edentulous, full edentulism, patient satisfaction, prostheses

Notice of Retraction: The article “The Effects of Clockwise and Counterclockwise Conventional and Osseodensification Drilling on the Dimensions, Density, and Biomechanical Properties of Bone,” by Daneshparvar et al, which was published in the January/February issue (Int J Oral Maxillofac Implants 2023;38:77–83. doi: 10.11607.jomi.9555), has been retracted at the authors’ request. Purpose: To compare the effects of regular implant drills to osseodensifying drills used in clockwise and counterclockwise motions on bone dimension change and primary implant stability. Materials and Methods: A total of 40 bone models were made (20 × 15 × 4 mm) from porcine tibia to represent implants placed in soft bone. Implant osteotomies were prepared in the bone models using one of the following techniques: (1) regular implant drills in a clockwise direction (group A), (2) regular implant drills in a counterclockwise direction (group B), (3) osseodensifying drills in a clockwise direction (group C), and (4) osseodensifying drills in a counterclockwise direction (group D). Bone-level tapered titanium alloy implants (4.1 × 10 mm) were placed following osteotomy creation. The implant stability quotient (ISQ) was measured after implant placement. Each bone model was scanned with an optical scanner to convert to Standard Tessellation Language (STL) files before and after the osteotomy creation. Presurgical and postsurgical STL files were superimposed, and the dimensional changes were measured at 1, 3, and 7 mm from the crestal bone. Histomorphometric analysis was done, and bone-to-implant contact percentage (BIC%) was calculated. Results: There were no significant differences in ISQ values (P = .239) between any of the groups. Histomorphometric analysis showed implants in group D had significantly higher BIC% than groups A (P = .020) and B (P = .009). The amount of bone expansion decreased with distance from the crest (P < .001). Groups B (P = .039) and D (P = .001) showed significant expansions at all levels compared with group A. No other statistically significant differences in dimensional change were found between groups. Conclusion: Both regular and osseodensification burs used in a counterclockwise motion contribute to expansion of bone dimension compared to conventional drilling methods. Int J Oral Maxillofac Implants 2023;38:77–83. doi: 10.11607/jomi.9555 Keywords: bone expansion, Densah, implant stability, osseodensification, osteotomy

Purpose: To evaluate the implant survival and the prevalence of biologic and mechanical complications in edentulous patients restored with complete-arch implant-supported fixed dental prostheses (IFDPs). Materials and Methods: Patients restored with complete-arch screw-retained IFDPs between January 2012 and December 2019 with a minimum 2-year follow-up were included. Outcome measures were cumulative survival rate (CSR) for implants and prostheses, biologic complications, and mechanical complications. A generalized estimating equation model was used to estimate potential risk factors for mechanical complications. Patient satisfaction was investigated using a standardized questionnaire. Results: A total of 44 prostheses supported by 268 implants in 30 patients were included for a mean duration of 4.8 years (range: 2 to 9 years). Eighteen of the prostheses were zirconia-ceramic (group ZC), and 26 were titanium-ceramic (group TC). The CSR for the implants and IFDPs was 99.3% (95% CI: 98.2% to 100.3%) and 92.5% (95% CI: 84.2% to 100.8%), respectively. The most common biologic complication was peri-implant mucositis (4.5%), followed by peri-implantitis (3.0%). The most common mechanical complication was ceramic chipping (45.5%), followed by crown debonding (13.6%) and framework fracture (4.5%). There was no significant difference in the prevalence of complications between groups TC and ZC (P > .050). The presence of cantilever (OR = 5.54, P = .048) and maxillary arch (OR = 5.94, P = .041) were significantly associated with mechanical complications. Patient satisfaction scores were generally high, but some continued to be bothered by speech problems (13.6%). Conclusion: Complete-arch IFDPs presented reliable clinical outcomes for edentulous patients with a high implant survival rate and a high level of patient satisfaction. However, a high incidence of mechanical complications occurred in the long term. Int J Oral Maxillofac Implants 2023;38:84–93. doi: 10.11607/jomi.9808 Keywords: dental implants, fixed prosthesis, full edentulism, implant survival, mechanical complications

Purpose: To evaluate the effect of cooling on the reverse torque values of different abutments in bone-level and tissue-level implants. The null hypothesis was that there would be no difference in reverse torque values of abutment screws when cooled and uncooled implant abutments were compared. Materials and Methods: Bone-level and tissue-level implants (Straumann, each n = 36) were placed in synthetic bone blocks and subdivided into three groups (each n = 12) based on the abutment type (titanium base, cementable abutment, abutment for screw-retained restorations). All abutment screws were tightened to 35 Ncm torque. In half of the implants, a dry ice rod was applied on the abutments close to the implant-abutment connection for 60 seconds before untightening the abutment screw. The remaining implant-abutment pairs were not cooled. The maximum reverse torque values were recorded using a digital torque meter. The tightening and untightening procedure was repeated three times for each implant including cooling for the test groups, resulting in 18 reverse torque values per group. Two-way analysis of variance (ANOVA) was used to analyze the effect of cooling and abutment type on the measurements. Post hoc t tests were used to make group comparisons (α = .05). The P values of post hoc tests were corrected for multiple testing using the Bonferroni-Holm method. Results: The null hypothesis was rejected. Cooling and abutment type significantly affected the reverse torque values in bone-level implants (P = .004) but not in tissue-level implants (P = .051). The reverse torque values of bone-level implants significantly decreased after cooling (20.31 ± 2.55 Ncm vs 17.61 ± 2.49 Ncm). Overall mean reverse torque values were significantly higher in bonelevel implants compared to tissue-level implants (18.96 ± 2.84 Ncm vs 16.13 ± 3.17 Ncm; P < .001). Conclusion: Cooling of the implant abutment led to a significant decrease in reverse torque values in bone-level implants and may therefore be recommended as a pretreatment before the application of procedures to remove a stuck implant part. Int J Oral Maxillofac Implants 2023;38:94–100. doi: 10.11607/jomi.9499 Keywords: abutment screw, blocked implants, cryo-mechanical, maintenance, technical complications

Purpose: To compare different assessment methods for peri-implant inflammation to evaluate potential risk factors and to generate a comprehensive algorithm for clinical staging, treatment, and evaluation of success in periorbital implants. Materials and Methods: In this hospital-based cross-sectional study, 111 periorbital implants in 40 patients with orbital defects after exenteration were clinically analyzed. Skin reaction according to Holgers (SRH), probing depth (PD) , and sulcus fluid flow rate (SFFR), as well as patient-specific data, such as age, sex, smoking and irradiation status, cleaning agent and frequency, defect etiology, implant system, implant location, time span since implantation, and type of retention, were assessed and statistically analyzed via mixed-model calculations. Success was defined as the absence of necessary invasive or antibiotic treatment. Results: A total of 62 implants (55.9%) had been placed in male patients and 49 implants (44.1%) in female patients. There were 18 patients (52 implants, 46.8%) who had received radiotherapy. Mean inflammation levels were low. PD and SFFR were highly correlated, whereby PD increased significantly with time after implantation. SRH ≥ 2 was correlated significantly with higher PD and SFFR values. While 80% of the implants did not require invasive or antibiotic treatment, 45% of the patients presented at least one affected implant. The data gathered allowed for the definition of a staging and treatment algorithm for peri-implantitis in periorbital implants. No patient-specific factors showed a significant impact on peri-implant inflammation. Conclusion: Periorbital implant restorations with magnetic abutments are a safe treatment option for orbital defects. PD and SRH were proven to be valuable quick assessment tools and should be complemented by SFFR, if inconclusive. The established parameters for the staging of peri-implant tissue health and clinical success can serve as a viable tool for reliable and comparable assessment in clinical and scientific settings. Further studies are necessary to assess the suggested treatment algorithm. Int J Oral Maxillofac Implants 2023;38:101–110. doi: 10.11607/jomi.9698 Keywords: clinical parameters, clinical success, craniofacial implants, orbital defects, peri-implantitis, staging, treatment algorithm

Purpose: To propose and evaluate a novel method for achieving a favorable bone-to-implant contact (BIC) area for zygomatic implants (ZIs). Materials and Methods: Patients who needed ZIs to restore a severely atrophied maxilla were recruited. In preoperative virtual planning, an algorithm was utilized to find the ZI trajectory that would achieve the largest BIC area with a predefined entry point on the alveolar ridge. The surgery was conducted according to the preoperative plan with the assistance of real-time navigation. Area BIC (A-BIC), linear BIC (L-BIC), distance from implant to infraorbital margin (DIO), distance from implant to infratemporal fossa (DIT), implant exit section, and deviation of the real-time navigated surgery were measured and compared between the preoperative plan and the placed ZIs. The patients were followed up for 6 months. Results: Overall, 11 patients with 21 ZIs were included. The A-BICs and L-BICs were significantly higher in the preoperative plan than in the placed implants (P < .05). Meanwhile, there were no significant differences in DIO or DIT. The planned-placed deviation was 2.31 ± 1.26 mm for the entry, 3.41 ± 1.77 mm for the exit, and 3.06 ± 1.68 degrees for the angle. All ZIs survived to the 6-month follow-up. Conclusion: This novel method can virtually calculate the trajectory of ZIs and transfer the preoperative plan to surgery to acquire a favorable BIC area. The actual positions of placed ZIs were slightly deviated from the ideal due to navigation errors. Int J Oral Maxillofac Implants 2023;38:111–119. doi: 10.11607/jomi.9824 Keywords: accuracy, bone-to-implant contact, maxilla, real-time surgical navigation system, zygomatic implants

Purpose: To examine how the accuracy (linear and angular deviation) of implants placed using computer-guided surgery varies in relation to the type of surgical technique (fully guided, half-guided, vs freehand implant placement), bone density (type D1 to D4 bone), and type of support surface (tooth- vs mucosa-supported). Materials and Methods: A total of 32 mandible models were produced (16 partially edentulous and 16 edentulous) using acrylic resin, each calibrated to a different bone density (D1 to D4). Four implants planned using Mguide software were placed in each acrylic resin mandible. A total of 128 implants were placed, distributed according to bone density (D1 to D4, n = 32), the degree of intervention in the surgery (fully guided [FG] = 80, half-guided [HG] = 32, and freehand surgery [F] = 16), and the type of support surface (tooth-supported: n = 64 and mucosa-supported: n = 64). To determine the linear, vertical, and angular deviations between the planned three-dimensional position and the actual position of the implants, the linear and angular difference between them was calculated, with the analysis performed through preoperative and postoperative CBCT scans. The effect was analyzed using parametric tests and linear regression models. Results: All parameters of linear and angular discrepancy in the various regions analyzed (neck, body, and apex) were primarily influenced by the technique and, to a lesser extent, by the bone type, although both variables were predictive and highly significant. These discrepancies tend to increase in completely edentulous models. The regression models show that linear deviations increase by between 630.2 μm at neck level in the buccolingual direction and 836.7 μm at apex level in the mesiodistal direction when comparing the FG and HG techniques. This increase is accumulative when comparing the HG and F techniques. Regarding the effect of bone density, the regression models found that linear discrepancies increase by between 132.6 μm in the axial direction and 199.0 μm at the apex of the implant in the buccolingual direction with each reduction in bone density (D1 to D4). Conclusion: According to this in vitro study, the highest implant placement predictability is found among dentate models with high bone density and a fully guided surgical technique. Int J Oral Maxillofac Implants 2023;38:120–129. doi: 10.11607/jomi.9794 Keywords: bone density, computer-assisted manufacturing, computer-assisted surgery, dental implants, guided implant surgery

Purpose: To compare the matrix metalloproteinase-8 (MMP-8) levels in the peri-miniscrew implant crevicular fluid (PMCF) of immediate-loaded and delayed-loaded miniscrew implants at different time intervals. Materials and Methods: Titanium orthodontic miniscrews were placed bilaterally in the attached gingiva of 15 patients between the maxillary second premolar and maxillary first molar for en masse retraction. This split-mouth study was designed to have an immediate-loaded miniscrew on one side and a delayed-loaded miniscrew on the other side that was loaded 8 days after miniscrew placement. PMCF was collected from the mesiobuccal aspects of the immediate-loaded implants at 24 hours, 8 days, and 28 days after loading, and from the delayed-loaded miniscrew implants at 24 hours and 8 days before loading and 24 hours and 28 days after loading. An enzyme-linked immunosorbent assay kit was used to assess MMP-8 levels in the PMCF samples. Unpaired t test, ANOVA F-test, and Tukey post hoc test were used to evaluate data at the P < .05 level. Results: Although there were slight alterations in the MMP-8 levels in the PMCF over time, there was no statistically significant difference in the MMP-8 levels between groups. There was a statistically significant decrease in the levels of MMP-8 between 24 hours after miniscrew placement and 28 days after loading on the delayed-loaded side (P < .05). Conclusion: The MMP-8 levels did not vary much between immediate-loaded and delayed-loaded miniscrew implants as a result of the force application. However, there was no significant difference between immediate loading and delayed loading in terms of biologic response to mechanical stress. The increase in MMP-8 levels after 24 hours post-miniscrew insertion, as well as the subsequent gradual reduction over the course of the study period in both immediate and delayed groups after loading, is probably due to the bone adapting to stimuli. Int J Oral Maxillofac Implants 2023;38:130–135. doi: 10.11607/jomi.9705 Keywords: delayed loading, immediate loading, matrix metalloproteinase-8, mini-screws, peri-miniscrew crevicular fluid, stability

Purpose: To compare the osteoblastic activity around dental implants placed via adaptive osteotomy and osseodensification techniques using bone scintigraphy in human subjects. Materials and Methods: A single-blinded, split-mouth design was conducted on two sites in each of the 10 subjects, with the adaptive osteotomy (n = 10) and osseodensification (n = 10) techniques for implant placement performed on either side of the D3-type bone in the posterior mandible. All participants were subjected to a multiphase bone scintigraphy test on the 15th, 45th, and 90th days after implant placement to evaluate the osteoblastic activity. Results: The mean values obtained on the 15th, 45th, and 90th days in the adaptive osteotomy group were 51.14% ± 3.93%, 51.40% ± 3.41%, and 50.73% ± 1.51%, respectively, while the osseodensification group values were 48.88% ± 3.94%, 48.78% ± 3.38%, and 49.29% ± 1.56%, respectively. The intragroup and intergroup analyses revealed no significant difference between the mean values of the adaptive osteotomy and osseodensification groups on the tested days (P > .05). Conclusions: Osseodensification and adaptive osteotomy techniques improved primary stability of D3-type bone and accelerated the osteoblastic activity after implant placement, with no superiority of one method over the other. Int J Oral Maxillofac Implants 2023;38:136–141. doi: 10.11607/jomi.9722 Keywords: adaptive osteotomy, endosseous dental implantation, osseodensification, osteoblast, osteotomy

Purpose: To develop, analyze, and optimize a dental implant by considering square threads and varying the thread dimensions to obtain an optimal shape. Materials and Methods: For this study, finite element analysis (FEA) and numerical optimization method were integrated to develop a mathematical model. The critical parameters of dental implants were studied, and an optimized shape was obtained using response surface method (RSM) and design of experiment (DOE). The simulated results were then compared to the predicted values under optimal conditions. Results: Using the one-factor RSM design model for the dental implant and a vertical compressive load of 450 N for testing, the optimal depth to width ratio for the thread was 0.7 in order to achieve the minimum von Mises and shear stress. Conclusion: The buttress thread was found to be the optimal shape for achieving the lowest von Mises and shear stress compared to square threads, and the thread parameters were calculated accordingly, with a thread depth 0.45 times the pitch, a width 0.3 times the pitch, and a thread angle of 17 degrees. Also, due to the constant diameter of the implant, common 4-mm diameter abutments can be used interchangeably. Int J Oral Maxillofac Implants 2023;38:142–149. doi: 10.11607/jomi.9785 Keywords: ANSYS, dental implant, design of experiment, finite element analysis, response surface method

Purpose: To evaluate the accuracy and clinical usability of an identification model using ensemble deep learning for 130 dental implant types. Materials and Methods: A total of 28,112 panoramic radiographs were obtained from 30 domestic and foreign dental clinics. From these panoramic radiographs, 45,909 implant fixture images were extracted and labeled based on electronic medical records. Dental implants were classified into 130 types according to the manufacturer, the manufacturer’s implant system, and the diameter and length of the implant fixture. Regions of interest were manually cropped, and data augmentation was performed. According to the minimum number of images collected per implant type, the datasets were classified into three sets: an overall total of 130 and two subsets that consisted of 79 and 58 types. EfficientNet and Res2Next algorithms were used for image classification in deep learning. After testing the performance of the two models, the ensemble learning technique was applied to improve accuracy. The top-1 accuracy, top-5 accuracy, precision, recall, and F1 scores were calculated according to algorithms and datasets. Results: For the 130 types, the top-1 accuracy, top-5 accuracy, precision, recall, and F1 scores were 75.27, 95.02, 78.84, 75.27, and 74.89, respectively. In all cases, the ensemble model performed better than EfficientNet and Res2Next. When using the ensemble model, the accuracy increased as the number of types decreased. Conclusion: The ensemble deep learning model for the identification of 130 types of dental implants showed higher accuracy than the existing algorithms. To further improve the performance and clinical usability of the model, images with higher quality and fine-tuned algorithms optimized for implant identification are required. Int J Oral Maxillofac Implants 2023;38:150–156. doi: 10.11607/jomi.9818 Keywords: artificial intelligence, convolutional neural networks, deep learning, dental implants

Purpose: To assess the accuracy of totally guided implant placement with static surgical splints in relation to the different types of supporting tissues (tooth, mucosa, or bone). Materials and Methods: This review was carried out following the PRISMA guidelines. An electronic search was done of the MEDLINE (PubMed), Embase, and Cochrane Library databases, without publication year or language restrictions. Results: The literature search yielded a total of 877 articles; 18 were included in the qualitative synthesis, and 16 of these articles were included in the quantitative analysis. The included studies presented a high risk of bias, except for one randomized clinical trial. The strength of the recommendations is therefore weak. In the angular deviation treatment, statistically significant differences were observed in the accuracy of the implants with tooth vs bone support: Bone support yielded 1.31 degrees greater deviation vs tooth support (SD = 0.43; 95% CI: 0.47, 2.15, P = .002). No significant differences were observed in the linear deviations. Conclusion: Tooth support proved to be significantly more precise than bone support splints. There were no differences referring to horizontal coronal deviation, horizontal apical deviation, or vertical deviation according to the type of splint support used. Int J Oral Maxillofac Implants 2023;38:157–168. doi: 10.11607/jomi.9796 Keywords: accuracy, computer-assisted surgery, dental implant, guided surgery, precision, splint support

Purpose: To address the hypothesis that the tissue processing methods of solvent dehydration and freeze-drying would differentially affect the physicochemical characteristics of four commercially available bone allografts and the adhesion and differentiation of human bone marrow–derived mesenchymal stromal cells (hBMSCs) on such substrates in vitro. Materials and Methods: The surface morphology, surface area, and elemental composition of four commercially available cancellous bone allografts were examined using SEM, Brunauer-Emmett-Teller (BET) gas adsorption, and inductively coupled plasma (ICP) analyses. SEM was also employed to compare the allograft surfaces to that of human bone exposed by in vitro osteoclastic resorption. The allografts were seeded with hBMSCs, and the number of adhered cells was assessed at 3 and 7 days. Alkaline phosphatase (ALP) activity was quantified as a measure of osteogenic differentiation after 21 days. Results: Marked differences were seen between the physicochemical characteristics of the solvent-dehydrated and freezedried allografts, as well as between their resulting bone microarchitectures and that of osteoclast-resorbed human bone. Increased hBMSC adhesion and differentiation were observed on the solvent-dehydrated allografts compared to freezedried allografts, which suggests a higher putative osteogenic potential. The latter was attributed to better preservation of the bone collagen microarchitecture integrity, which may provide not only a more complex substrate architecture, but also a more favorable microenvironment to allow nutrients and oxygen to flow to the adhered cells. Conclusion: Commercially available cancellous bone allografts significantly differ in their physicochemical characteristics, stemming from differences in tissue processing and sterilization methods undertaken by tissue banks. These differences impact the response of MSCs in vitro and may alter the biologic performance of the grafts in vivo. Therefore, it is important to consider these characteristics when choosing a bone substitute for clinical application, as the physicochemical properties of the grafts play a crucial role in their interactions with the biologic environment and subsequent incorporation into the native bone. Int J Oral Maxillofac Implants 2023;38:169–180. doi: 10.11607/jomi.9781

Purpose: To evaluate the marginal accuracy of soft-milled cobalt-chromium (Co-Cr) compared to other construction methods/restorative materials in tooth/implant-supported restorations. Materials and Methods: PICO questions were defined, and a systematic search was conducted in six electronic databases. Titles and abstracts were collected and screened by two independent reviewers. After removing duplicate articles, the full texts of relevant articles were gathered, and the required information and data were extracted. Risk of bias was assessed and meta-analyses of the collected data were conducted using STATA software version 16. Results: A total of 1,914 experimental and clinical articles were reviewed, and 18 studies were selected for qualitative analysis. The 16 studies that were included in the meta-analysis showed no significant marginal gap differences between soft-milled Co-Cr and the following methods/materials: hardmilled Co-Cr (I2 = 92.9%, P = .86), casting wax (I2 = 90.9%, P = .42), laser-sintered Co-Cr (I2 = 93.3%, P = .46), and zirconia (I2 = 0.00%, P = .47). However, a significantly higher marginal accuracy of soft-milled Co-Cr was observed when compared to milled-wax casting (I2 = 93.1%, P < .001). Conclusion: The marginal gap of soft-milled Co-Cr restorations is within the acceptable clinical range and provides an accuracy similar to other available methods/materials for both the prepared implant abutment and tooth. Int J Oral Maxillofac Implants 2023;38:181–191. doi: 10.11607/jomi.9782 Keywords: chromium alloys, CAD/CAM, computer-aided design and computer-aided manufacturing, dental prosthesis, dental marginal adaptation