The International Journal of Oral & Maxillofacial Implants, 02/2023

Time-to-event (survival) analysis is an integral tool in the wheelhouse of the dental researcher. While there are many references available for the study of time-to-event analysis, they tend to be written for audiences trained in statistical methodology. Moreover, the canonical examples offered by most time-to-event analysis references are focused on outcomes that do not translate directly to dentistry. This article provides a tutorial of time-to-event analysis for the specific context of dental research. Our tutorial assumes no statistical training or computing experience. Using real data from a dental study as our extended example, we explain foundational concepts, including median survival, Nth-year survival, the log-rank test, and the Cox model. Keywords: time-to-event analysis, survival analysis, dental tesearch, crown margin repair

Purpose: To compare different socket sealing approaches for alveolar ridge preservation and assess the dimensional changes and histologic characteristics of soft and hard tissues in a 4- to 6-month period. Material and Methods: A total of 22 patients with indicated single-tooth extraction in the maxillary nonmolar region were eligible for this study. After CBCT scanning and minimally traumatic tooth extraction, the alveolar sockets were filled with demineralized bovine bone mineral with collagen (DBBM-C) in patients from all groups except for those in the control group. Patients were divided into groups for socket sealing as follows: unsealed/spontaneous healing (control; n = 6), collagen matrix (n = 5), collagen membrane (n = 5), and autogenous graft (n = 6). A second CBCT scan was taken 4 to 6 months after extraction, and a trephine biopsy of soft and hard tissues was collected during implant placement. Tomographic dimensional changes were compared between groups. Intragroup tomographic evaluation and histological analysis were also performed. Results: Analysis of dimensional changes did not detect differences between the socket sealing groups (P > .05). In an intragroup evaluation, the height of the buccal bone and cross-sectional area of the alveolar ridge were significantly lower 4 to 6 months after extraction for the control group (P = .031). Histological analysis revealed that the socket sealing approach had no impact on hard and soft tissue formation. Conclusion: The data from the present study suggest that socket sealing with a collagen matrix, a collagen membrane exposed to the oral cavity, or an autogenous punch graft had no difference in the effects on volumetric maintenance and tissue formation in a period of 4 to 6 months. Keywords: alveolar process, alveolar ridge preservation, biomaterials, histology, periodontology, randomized clinical trial, socket sealing, tomographic analysis, tooth extraction, tooth socket

Purpose: To systematically analyze the outcomes of immediate implant placement (IIP) with bone grafting in the esthetic area. Materials and Methods: PubMed, Embase, and Cochrane CENTRAL were searched. Prospective studies reporting midfacial soft tissue recession (primary outcome) of single-tooth IIP with bone grafting in the esthetic area were included. Risks of bias were assessed. Meta-analysis, sensitivity analysis, and meta-regression were undertaken. Results: A total of 13 studies and 421 patients were included, with a follow-up length of 1 to 10 years in function. The weighted mean (95% CI) of midfacial soft tissue recession was 0.33 (0.21, 0.46) mm and 0.54 (0.16, 0.93) mm after 1 year and 5 years in function. Meta-regression indicated that after 1 year in function, there was 0.33 mm less midfacial soft tissue recession with soft tissue grafting (P = .021), while there was 0.58 mm more soft tissue recession (P = .007) in defect extraction sockets. Implant survival was 97.8%, and all failures were early failures. Peri-implant soft and hard tissue stability, peri-implant health, esthetic outcomes, and patient satisfaction were predictable within the follow-up period. Conclusion: Midfacial soft tissue recession showed an ongoing status in IIP with bone grafting in the esthetic area within 5 years in function. For extraction sockets with a thin gingival biotype or deficient buccal bone wall, soft tissue grafting was recommended. Keywords: immediate implant placement, midfacial soft tissue recession, systematic review

Purpose: To retrospectively evaluate the clinical outcomes of immediately loaded zygomatic implants combined with anterior regular implants (hybrid zygoma) for the fixed rehabilitation of atrophic maxillae. Materials and Methods: A total of 18 patients were enrolled in this study and treated with the hybrid zygoma concept by an experienced surgeon. Follow-up visits were planned after 1 week, 3 weeks, 4 months, 6 months, then annually. At the last follow-up appointment (mean: 36 months after surgery; range: 24 to 52 months), the prostheses were unscrewed and the implants and peri-implant tissues were examined. The primary outcome evaluated was implant success. Following the criteria proposed by Aparicio et al, implant success was classified in five grades, with grade I representing the best condition and grade V representing a failure. At the annual check-up, patients were asked to fill out a questionnaire to evaluate their satisfaction with their oral rehabilitation. Results: A total of 80 implants (34 zygomatic and 46 regular) were inserted. One zygomatic implant was lost in one patient, and two regular implants failed in two other patients. Of the zygomatic implants, 24 (70.6%) presented a success grade I, 9 (26.5%) a success grade II, and 1 (2.9%) a grade V. Sinusitis was the most common biologic complication, occurring in two patients (5.6%). Two patients showed unilateral upper lip paresthesia that was persistent at the last follow-up appointment. According to the annual follow-up visit questionnaire data, 72%, 89%, and 94% of patients declared that they were satisfied with their phonetic ability, chewing ability, and esthetics, respectively. Conclusion: Although zygomatic implants combined with anterior regular implants present a higher risk of complications than traditional implantology, they allow for immediately loaded full-arch fixed rehabilitation of patients with advanced atrophy of the posterior maxilla, which provides satisfactory chewing ability, esthetics, and phonetics. Keywords: dental implants, extreme atrophic maxillae, hybrid zygoma, immediate loading, retrospective study, zygomatic implants

Purpose: To evaluate the diagnostic accuracy of bone loss/bone levels, as detected after 5 years of implant function, in identifying patients who suffered implant failures in the following 5 years. Materials and Methods: Data on radiographic measurements of marginal bone levels at prosthesis placement and after 5 years of function were retrospectively retrieved from 11 previous publications. Included patients were allocated into different subgroups with regard to bone loss/bone level during/after 5 years in function, respectively. A diagnostic test was used to estimate the accuracy of finding patients/jaws/implants at risk for a future implant failure by calculating sensitivity, specificity, positive predictive values (PPVs), and negative predictive values (NPVs) in different subgroups, respectively. Results: Altogether, 749 treated jaws (723 patients/3,363 implants) were included in the study group. Treated jaws in the high-level subgroups presented an overall higher risk of implant failures from 5 to 10 years in function (P < .05). Many treated jaws/implants were allocated into the high-level groups, but the proportions of implant failures were low in these groups. The diagnostic test comparing high- and low-level groups with and without implant failures showed low accuracy to predict implant failures; the PPV ranged from 4% to 33%. Lower PPVs were observed for diagnostic tests for individual implants (range: 4% to 6%). Conclusion: More severe bone loss was associated with higher risk of future implant failure. However, many patients/ implants with obvious bone loss in the study group and low prevalence of implant failures at the 10-year examination resulted in poor accuracy in identifying individual patients or implants at risk for failure. This suggests that it is difficult to predict future implant failures based only on radiographic measurements. Keywords: complication, dental implants, implant failure, prediction, radiology

Purpose: This study aimed to evaluate the deviations of implants with two different geometries placed with a bone-supported stereolithographic surgical template into the bone of Misch classification densities of D2, D3, and D4. Materials and Methods: Eight maxilla and eight mandible models were macrodesigned according to the jaw geometries. Bone densities of these models were created in parallel with the most frequently observed densities in the locations: D3 bone density in the anterior maxilla, D4 bone density in the posterior maxilla, D2 bone density in the anterior mandible, and D3 bone density in the posterior mandible. A bone-supported stereolithographic surgical template was prepared in accordance with the jaw models and planning and used to place 64 NobelParallel Conical Connection RP 4.3 × 13 mm and 64 NobelActive 4.3 × 13 mm implants on the models. Global deviation, lateral deviation, angular deviation, and depth deviation between planned and placed implants were calculated with Hypermesh. The Kruskal-Wallis test was used to analyze the differences between deviation data of the study groups, and the Mann-Whitney U test was used for pairwise comparisons of groups with significant differences. Significance was evaluated as P < .05. Results: The study groups showed statistical differences in terms of global, lateral, and depth deviation (P = .017, P = .044, and P = .012, respectively); no statistical difference was detected in terms of angular deviation (P > .05). When the data of all studies were evaluated, the deviation values for all maxillary and mandibular implants were examined regardless of bone and implant type; no statistical difference was found between the arches in terms of deviation type (P > .05). Conclusion: Regardless of the macrogeometry of the dental implants placed with the guide, no significant difference was observed between the deviation values of the different bone densities they were applied to. Keywords: accuracy, dental implants, implant-guided surgery, implant placement, stereolithography, surgical template

Purpose: To verify a novel method that improves the accuracy of static computer-aided implant surgery (sCAIS) through intraoperative measurement. Materials and methods: Forty-seven patients were selected for this study, each with a missing tooth or a tooth that required extraction from the anterior area. The patients were divided into the intraoperative measuring guide (MG) and conventional guide (CG) groups. Following the preoperative implant planning, the surgical guides were designed and fabricated. In the MG group, the drill was guided by double-armed zirconia sleeves, and the axial direction of the drill was assessed using the indicator components. The implant was guided using a resin guide tube. In the CG group, the drills were guided using a metal sleeve and handles, and the implants were placed with the guidance of the metal sleeve only. The angular and linear deviations at the entry and apex between the planned and actual implant positions were measured after matching the preoperative and postoperative CBCT data. The independent-samples t test was used to compare the deviation between the MG and CG groups. Results: The 3D deviations for the MG group at the entry and apex were 0.67 ± 0.44 mm and 0.93 ± 0.40 mm, respectively. The angular deviation was 2.27 ± 0.96 degrees. Statistical differences were found in the 3D deviation at the entry point and apical position between the MG and CG groups, yielding relatively smaller deviations in the MG group. Conclusion: The use of an intraoperative measuring guide could improve the accuracy of implant placement in sCAIS. Keywords: accuracy evaluation, angular deviation, implant placement, implant surgical guide, intraoperative measurement, linear deviation

Purpose: This preclinical comparison study assessed the diagnostic accuracy of low-dose CBCT protocols compared with standard-dose protocols in digital implant treatment planning and template-guided implant surgery. Materials and methods: Thirty mandibles of pig cadavers underwent both CBCT protocols on an Orthophos SL Unit (Dentsply-Sirona). Surface scans of the regions of interest were performed to create a digital diagnostic wax-up followed by 120 subsequent implant plannings (one implant per quadrant). Simple randomization (1:1) was assessed to assign each quadrant into one of the imaging protocols. Sixty implant surgical guides were manufactured using CAD/CAM technology, followed by the fully guided placement of 60 implants following the surgical protocol in randomized order. Geometric accuracy between the planned and definitive implant position was determined regarding apical distances between the central axes and angle deviation. Descriptive statistics and linear regressions were used for the statistical analysis of the data. Results: Regarding implant apex deviation using low-dose CBCT, the following differences were observed: apical deviation of 0.75 ± 0.63 mm and angular deviation of 2.5 ± 2.12 degrees, while the standard-dose CBCT showed the following results: apical deviation of 0.92 ± 0.55 mm and angular deviation of 3.06 ± 2.12 degrees. The regression analyses could not show evidence for a significant difference between the two CBCT protocols, neither with regard to the apical distance nor in view of the angular deviation. Conclusion: Low-dose CBCT imaging protocols providing accurate 3D anatomical information with an improved benefit-risk ratio according to the as low as diagnostically acceptable (ALADA) principle could become a promising option as a primary diagnostic modality as well as for radiologic follow-up. Keywords: computer-guided surgery, cone beam computed tomography, dental implant, diagnostic accuracy, low-dose protocol

Purpose: To assess the radiographic and histomorphometric outcomes of horizontally augmented maxillary alveolar ridges using solid nonperforated customized titanium barriers. Materials and methods: This case series study included patients who received guided bone regeneration treatment in the anterior maxillary esthetic zone (eight patients, 18 dental implants) using patient-specific solid titanium barriers loaded with a mix of autogenous and xenogenic particulate bone grafts. A radiographic comparison between three time periods (immediately postoperative, 4 months, and 10 months) included software-aided calibration of the linear changes in the horizontal dimensions on CBCT cross-sectional cuts after being standardized. Bone core specimens were retrieved for histomorphometric analysis by the time of implant insertion. Results: Wound healing was uneventful, except for two patients who showed soft tissue breakdown that did not affect the outcome. There was a statistically significant difference between the mean horizontal bone change at the different time intervals (P < .001), with a 79.6% ± 29.2% mean area of newly formed bone. Conclusion: GBR using customized solid titanium barriers appears to be efficient and promising concerning the final horizontal bone gain and the quality of the augmented sites. Keywords: alveolar ridge, anterior maxilla, CAD/CAM, computer guided, guided bone regeneration (GBR), horizontal bone gain, nonperforated meshes, patient-specific barrier

Purpose: To determine whether a less invasive window repositioning technique could provide a feasible, safe, and reliable lateral sinus augmentation. Materials and methods: The less-invasive window repositioning technique using a piezoelectric saw was performed on adult patient candidates for lateral sinus floor elevation. The augmented bone height (primary outcome variable), bone length, and posthealing outcome variables were evaluated to determine the augmentation adequacy, safety, and reliability of this technique overall and in one- and two-implant groups with different window dimensions. Data were analyzed using descriptive statistics, chi-square test, and Pearson correlation analysis. P < .05 was considered significant. Results: A total of 50 consecutive sinus floor elevations with simultaneous placement of 66 implants (one-implant: 34, two-implant: 16) were performed on 44 subjects (72% men) with a mean age of 46.7 ± 10.3 years and followed for a mean of 13.28 ± 3.5 months. The overall, one-implant, and two-implant group mean window sizes were 31.38 ± 6.78 mm2, 28.38 ± 4.2 mm2, and 37.75 ± 6.88 mm2, respectively. The mean overall augmented bone height and length were 12.3 ± 1.04 mm and 19.67 ± 2.01 mm, respectively. The mean window size was significantly smaller in the one-implant group versus the two-implant group (P < .001). However, there was no correlation between window size and augmented bone height (r = -0.9, P = .54) and length (r = 0.05, P = .68). The posthealing outcome variables showed perfect window integration without soft tissue ingrowth. Six sinus perforations (12%) during membrane elevation that were not related to window osteotomy were observed and were appropriately managed. Conclusion: The less-invasive window repositioning technique is feasible, safe, and reliable for appropriate sinus augmentation in height and length. The reduction of window dimension does not influence the feasibility, augmentation adequacy, and surgical safety and does not increase surgical risks or membrane perforation. The repositioned window showed proper integration. Also, sinus floor elevation through this technique is an experience-based surgery that requires delicate instruments. Keywords: dental implantation, dental implants, maxillofacial surgery, oral surgery, sinus floor augmentation

Purpose: The objective of this in vitro study was to evaluate the activity of local gel containing metronidazole (MN) in the leakage area, which was analyzed by the DNA-DNA checkerboard hybridization method. Materials and Methods: Thirty-six sets of Morse taper/mini-pillar implants were used in this study. These implants were equally divided into the following three groups: MN gel (test group), no MN gel (negative test group), and no gel (control). The gel was prepared with metronidazole (15%). Unstimulated saliva samples were collected, transferred to a Falcon tube, and stored at 37°C. The sets were partially immersed in microtubes containing 300 μL of saliva and were incubated at 37°C ± 1°C for 7 days. Microbial infiltration was evaluated (37 bacterial species and 5 species of Candida). The results were analyzed with Wald-Type, ANOVA, and multiple comparisons analysis between groups. Results: After comparing the quantity of microorganisms, both gel-treated groups (no MN gel and MN gel) had more significant microorganism presence than the control group (P < .001), and no significant result was found between the no MN gel and MN gel groups (P > .05). Regarding the bacteria found, the most common were Aggregatibacter actinomycetemcomitans, Prevotella melaninogenica, Bacteroides fragilis, and Candida tropicalis. Conclusion: Within the limitations of this study, it was concluded that the gel containing metronidazole used in this study was not effective in preventing the infiltration of microorganisms through the Morse taper implant-abutment interface. Keywords: bacteria, dental implant-abutment connection, dental implants, DNA sequencing, microbiology

Purpose: To compare subjects' sensory responses to horizontal and vertical forces on tooth- and implant-supported restorations. Materials and Methods: In this prospective study, three protocols simulating the horizontal or vertical forces that occur during mastication were used to obtain subjective responses from subjects. These protocols included the measurement of horizontal force intensity during excursive movements and the identification of initial contact during guided and free vertical closure. Responses were recorded using a 1- to 10-point visual analog scale (VAS) and/ or monitored with electromyography (EMG) and Tekscan. Results: The study included 30 patients with a single implant-supported restoration (ISR) with a contralateral tooth-supported restoration (TSR). For horizontal forces similar to those of mastication (0.6 N), subject VAS scores were similar for both ISRs and TSRs at 6.3 vs 6.1, respectively. At reduced forces (0.2 and 0.4 N), subject responses were greater for the TSR at 3.4 and 5.4, respectively, as opposed to 1.2 and 2.6 for ISR, respectively (P < .01). During vertical guided closure (Test 1) at 25% of maximum bite force (MBF), subjects were more successful at correctly identifying initial contact of TSRs at a rate of 12 out of 17, compared to ISRs, which achieved a rate of 4 out of 13 (P < .1). In vertical free closure (Test 2), subject responses for the correct identification of initial contact at 50% MBF were similar for both TSRs and ISRs at 13 out of 17 and 9 out of 13, respectively. However, comparing the correct responses for subjects whose initial contacts were ISR showed a significant improvement in correct answers from Test 1 to Test 2, from 4 out of 13 correct to 9 out of 13 correct (P < .05). Conclusion: While the mechanism is not clear, subjects' ability to discern the horizontal and vertical forces at levels comparable to mastication appear similar between TSRs and ISRs. Keywords: osseoperception, dental implant, proprioception, tooth proprioception, implant proprioception

Purpose: To evaluate the effect of chewing simulation and thermocyclic aging on the fracture resistance of CAD/CAM monolithic zirconia crowns supported by titanium and Ti-base abutments. Materials and Methods: Two implant abutment groups-titanium (Ti) and titanium base (Ti-base; Medentika)-were used. A total of 40 mandibular first molar CAD/CAM monolithic zirconia crowns (Vita YZ T) were fabricated, then cemented onto the abutments with Panavia V5. Each abutment group was divided into two subgroups (n = 10). The Ti and Ti-base groups were subjected to a single load until fracture, and the Ti/CT and Ti-base/CT groups (CT: chewing simulation and thermocyclic aging) underwent chewing simulation (1.2 × 106 cycles × 50 N load, 1.4 Hz) and thermocylic aging (3,911 cycles/5°C to 55°C). The fracture resistances of the crowns were tested with a universal testing machine (1 mm/minute). Shapiro-Wilk and one-way ANOVA test were used for statistical analysis (P = .05). Results: The survival rates after chewing simulation and thermocyclic aging were 100% for both CT groups. The fracture resistance values (mean ± SD) of the groups were as follows: Ti = 1,718.18 ± 331.06 N, Ti-base = 1,713.53 ± 233.24 N, Ti/CT = 1,664.82 ± 188.62 N, and Ti-base/CT = 1,551.28 ± 344.79 N. According to one-way ANOVA test results, there was no statistically significant difference between the four groups (P = .526). Conclusion: CAD/CAM monolithic zirconia crowns supported by Ti-base or titanium abutments were found to have sufficient fracture resistance in the treatment of an absent single posterior tooth. However, more in vitro and clinical studies are required to evaluate the long-term performance of Ti-base abutments and CAD/CAM zirconia crowns. Keywords: abutment design, CAD/CAM, monolithic, Ti-base, zirconia

Purpose: To evaluate primary stability of a new dental implant design in low-density bone sites, compare it with another implant design previously studied in the same bone density, and explore possible correlations between primary stability parameters. Materials and Methods: The study was carried out on fresh humid bovine bone classified as type III. The test group consisted of 30 DS Prime Taper implants (PT), and the control group consisted of 30 Astra Tech EV implants (EV). All the implants were inserted according to the protocol provided by the manufacturer. After placement, variable torque work (VTW), peak insertion torque (pIT), and resonance frequency analysis (RFA) were recorded. Results: Mann-Whitney test showed that the mean VTW and pIT were significantly higher in the test group PT compared to the control group EV; furthermore, statistical analysis showed that the mean RFA was slightly higher in the control group EV but without reaching statistical significance. Pearson correlation analysis showed a very strong positive correlation between pIT and VTW values in both groups; furthermore, it showed a positive correlation between pIT and RFA values and between VTW and RFA values again in both groups. Conclusion: The results showed that the novel tapered implants were able to reach good primary stability in low-density bone sites and that this was superior to parallel-walled implants when measured with VTW and pIT. Moreover, a statistically significant correlation was found between the three methods used to measure implant primary stability. Keywords: insertion torque, primary stability, resonance frequency analysis, tapered implants, variable torque work

Purpose: To evaluate the effect of maxillary sinus anatomy on sinus floor elevation (SFE) operations performed with the lateral window approach. Materials and Methods: CBCT and digital panoramic radiographs were evaluated before and at least 6 months after maxillary sinus floor elevation (SFE) operations performed in 33 maxillary sinus regions in 26 patients. Maxillary sinus volume, grafted volume (GV), sinus width (SW), residual bone height (RBH), and vertical graft resorption (VGR) were calculated. The effects of RBH and SW on GV and VGR were evaluated statistically. Results: The mean GV values in the maxillary sinuses classified as narrow, average, and wide were 2.60 ± 0.57, 3.44 ± 0.65, and 3.70 ± 0.64 cm3, respectively. The mean VGR was 2.12 ± 1.67 mm, and in the sites classified as narrow, average, and wide, the mean VGR values were 1.50 ± 0.79, 1.58 ± 1.28, and 3.46 ± 2.06 mm, respectively. A statistically significant difference in GV and VGR was found between the SW groups. The mean posterior maxillary RBH was 2.30 ± 1.05 mm, and 17 and 16 sinuses were classified as ≤ 2 and > 2 mm, respectively. There was no statistically significant difference in the effect of RBH on GV or VGR. Conclusion: Although posterior maxillary RBH did not affect new bone formation in the sinuses grafted only with hydroxyapatite-derived inorganic bovine bone, with increasing SW, the GV decreased and the VGR increased. Keywords: biomaterials, bone graft, bone substitute, case-control study, sinus elevation

Purpose: To compare the biomechanical behaviors of different surgical options that are preferred for implant-supported fixed prosthetic rehabilitation of the atrophic edentulous maxilla. Materials and Methods: A 3D finite element analysis (FEA) model was generated from the computed tomography data of a patient with an atrophic edentulous maxilla. Four scenarios were created in the atrophic maxilla. In model 1, the maxilla was reconstructed with an onlay bone graft harvested from the anterior iliac crest, and sinus augmentation procedures were performed. Standard dental implants were placed in the lateral incisor, first premolar, and first molar regions on each side. In model 2, the anterior part of the atrophic maxilla was reconstructed with an onlay bone graft harvested from the mandibular ramus, and zygomatic implants were placed in the posterior part of the maxilla. In models 3 and 4, two-piece subperiosteal implants made of titanium and polyether ether ketone (PEEK) materials, respectively, were placed in the atrophic maxilla. All implants were loaded with 150-N and 50-N forces in vertical and lateral directions, respectively. Stress accumulation on bones, implants, abutments, and prosthetic frameworks was investigated. Results: The tensile stress in both cortical and trabecular bone was highest in the iliac bone grafting group under vertical loading. The compressive stress in both cortical and trabecular bone was the highest in the PEEK subperiosteal implant model, and the compressive stress value on the trabecular bone exceeded the strength of the trabecular bone. The highest von Mises stress in the implants was obtained in the iliac bone grafting group under vertical loading. The highest stress value in the abutments was detected for the titanium subperiosteal implant. The highest von Mises stress in the prosthetic framework was detected in the titanium subperiosteal implant group, under both vertical and lateral loading. Conclusion: Based on the stress accumulation results of the four different scenarios, it can be seen that there is no ideal treatment modality for the fixed implant-supported prosthetic rehabilitation of the atrophic edentulous maxilla. Various intraoperative and prosthetic modifications are suggested to decrease the risk of biomechanical complications during long-term follow-up. Keywords: atrophic maxilla, finite element analysis, iliac bone graft, PEEK, subperiosteal implant, zygomatic implant

Purpose: To evaluate the 15-year survival rate of zirconia (Y-TZP) implants with a roughened acid-etched surface in a retrospective post-market clinical follow-up (PMCF) study. Materials and Methods: One-piece ceramic implants (CeraRoot) with a roughened acid-etched surface (ICE) were used. Six different implant shapes/sizes were used in this study. Either a standard or flapless surgical approach was used for implant placement. Simultaneous bone augmentation or sinus elevation was performed when bone height or width was deficient. Definitive zirconia restorations were placed after 2 months or later if the Periotest value was > -3. The implants were followed up for up to 15 years. Results: A total of 1,828 implants were placed in 771 patients with a mean age of 51.18 years. The overall implant survival rate after 15 years of follow-up was 98.69%. Conclusion: From this long-term investigation, it can be concluded that CeraRoot ceramic implants showed a 15-year long-term clinical performance with a survival rate of 98.69% under the described protocol, without significant differences between the six implant shapes/sizes. Keywords: ceramic implant, one-piece, PMCF, zirconia implant, Y-TZP

Purpose: Zygomatic implants (ZIs) have been considered a reliable alternative treatment for patients with maxillary atrophy and/or maxillary defects. The use of a navigation system for assisting ZI placement could be a reliable approach for enhancing accuracy and safety. The purpose of this in vitro study was to evaluate the accuracy of a new dynamic surgical navigation system with its minimally invasive registration guide for quad zygomatic implant placement in comparison with a gold standard navigation approach. Materials and Methods: A total of 40 zygomatic implants were placed in 10 3D-printed models based on the CBCT scans of edentulous patients. For registration, a surgical registration guide with a quick response plate was used for the test group, and five hemispheric cavities as registered miniscrews in the intraoral area were used for the control group. In each model, a split-mouth approach was employed (two ZIs in bilateral zygomata) to test both systems. After ZI placement, a CBCT scan was performed and merged with pre-interventional planning. The deviations between planned and placed implants were calculated as offset basis, offset apical, and angular deviation and compared between the systems. Results: The offset basis, offset apical, and angular deviation were 1.43 ± 0.55 mm, 1.81 ± 0.68 mm, and 2.32 ± 1.59 degrees in the test group, respectively. For the control group, values of 1.48 ± 0.57 mm, 1.76 ± 0.62 mm, and 2.57 ± 1.51 degrees were measured without significant differences between groups (all P < .05). The accuracy of ZI positions (anterior and posterior) were measured without significant differences between groups. Conclusion: Two navigation systems with different registration techniques seem to achieve comparable acceptable accuracy for dynamic navigation of zygomatic implant placement. With the test group system, additional pre-interventional radiologic imaging and invasive fiducial marker insertion could be avoided. Keywords: accuracy, minimally invasive, navigation system, surgical guide, zygomatic implant

Purpose: To evaluate the long-term functional and esthetic effects of immediate implantation combined with guided bone regeneration in patients with labial bone plate defects. Materials and Methods: A total of 46 implants were immediately placed into anterior maxillary fresh sockets with buccal bone defects. Jumping space and the outer side of buccal defects were densely filled with hydroxyapatite bioceramics and covered with biomembrane. CBCT was performed immediately after surgery (T1), 6 months later (T2), and after 5 years (T3). Radiographs were taken at 1 month after surgery (RT1), definitive crown delivery (RT2), and once a year after prosthetic loading (RT3 to RT7) for 5 years. Pink esthetic score (PES) was evaluated at the time of definitive crown delivery (PT1) and at follow-up visits 1, 3, and 5 years (PT2 to PT4) after crown fixation. Results: No implants were lost during the observational period. The labial bone was radiographically reconstructed to acceptable volumes, with an average 2.86-mm horizontal bone and 2.2-mm vertical bone. Significant marginal bone loss occurred within 1 year after delivery of the definitive prosthesis. PES scores did not reveal inferior results at the 5-year follow-up. Conclusion: When other conditions are met for immediate implant placement, small labial plate defects (≤ 5 mm) will not affect the long-term esthetic effect. Keywords: esthetic zone, facial bone defects, guided bone regeneration, immediate implant

Objective: To determine the median event-free survival and relative complication rates of monolithic and minimally layered full-arch zirconia prostheses, as well as to identify risk factors for prosthesis complications. Materials and Methods: In this retrospective cohort study, a total of 129 subjects (173 prostheses) were included in the chart review and 56 subjects (75 prostheses) participated in a clinical follow-up visit. All subjects had either single- or dual-arch monolithic or minimally layered zirconia implant-supported prostheses. Data related to patient, implant, and prosthesis factors were extracted from charts. The subgroup that presented for a clinical visit were asked to complete a satisfaction questionnaire. For this subgroup, the following clinical measures were assessed: routine intraoral examination, number of occluding units, cantilever length on each side of the prosthesis (right and left), prosthesis height, occlusal scheme, and oral hygiene methods. Periapical radiographs were obtained when the last radiographs of the patient were taken more than 12 months prior. Results: The follow-up period ranged from 12 months to 7.1 years (mean: 1.9 years). Observed complications included implant loss, peri-implantitis, mucositis, purulence, sinus tract formation, oroantral communication, implant fracture, titanium base debonding, ceramic chipping, prosthetic screw fracture or loosening, damage to opposing teeth, and clicking sounds. There was an insufficient number of complications to evaluate the effect of covariates on the risk of specific complications, such as titanium base debonding (eight events), ceramic chipping (nine events), and peri-implantitis (eight events). The unadjusted event-free median survival time was 5.8 years. The proportion of all prostheses with at least one complication was 30%. There were no observed prosthesis losses during the follow-up period. Conclusion: Monolithic and minimally layered zirconia full-arch implant-supported prostheses demonstrate an acceptable median event-free survival time. Event-free survival times were increased and the number of complications was reduced in prostheses with five to eight implants and conventional (as opposed to zygomatic) implants. There was a reduced hazard of complications with a regular recall regimen. Patient satisfaction with these prostheses was high. Int J Oral Maxillofac Implants 2023;38:381–390. doi: 10.11607/jomi.10022 Keywords: dental implant, monolithic zirconia, fixed, full-arch, complications, edentulous