The International Journal of Oral & Maxillofacial Implants, 06/2021

Purpose: The keratinized tissue (KT) around dental implants may be useful to ease plaque control. This meta-analysis aimed to compare peri-implant health parameters based on KT width (≥ 2 mm vs < 2 mm). Materials and methods: A highly sensitive search of five databases was performed up to February 1, 2020. The quality of eligible studies was assessed using a modified version of the Newcastle-Ottawa checklist. A random-effects model was used to pool standardized mean differences with 95% confidence intervals. To discover sources of heterogeneity, subgroup analysis and meta-regression were used. Publication bias was evaluated by the Egger and Begg tests. Results: From 7,934 identified studies, 22 papers were included in the meta-analysis, representing 3,004 implants in the case group (KT ≥ 2 mm) and 1,829 implants in the control group (KT < 2 mm). The results indicated that most of the parameters, including gingival recession (GR), Gingival Index (GI), modified Gingival Index (mGI), Plaque Index (PI), modified Plaque Index (mPI), bleeding on probing (BOP), modified Bleeding Index (mBI), and bone loss (BL) revealed substantial differences between the control and case groups. On the contrary, no statistically significant association was detected for pocket depth (PD) between the two groups. Conclusion: The presence of at least 2 mm of KT around implants has a protective effect on the peri-implant tissue condition. Narrow KT was related to higher BL, BOP, mBI, GI, mGI, PI, mPI, and GR. In addition, with regard to PD, no significant difference was found. Keywords: dental implants, keratinized tissue, meta-analysis, peri-implant

Purpose: To assess the effect of different kinds of biomaterials placed with maxillary sinus floor augmentation (MSFA) on bone regeneration. Materials and methods: Thirty-six New Zealand rabbits were used in the study. A standardized method of surgical approach was used for MSFA under anesthesia in all groups. The procedure was performed for each animal. Six separate groups with 12 cases were created. In group 1, no graft was used in MSFA. Advanced platelet-rich fibrin (A-PRF), absorbable collagen cone (ACC), venous blood, the combination of ACC and platelet-rich plasma (PRP), and the combination of ACC and enamel matrix derivative (EMD) were used in groups 2, 3, 4, 5, and 6, respectively. At the end of 4 and 12 weeks, three rabbits from each group were sacrificed by applying high-dose anesthetic, and samples were examined histologically and immunohistochemically. Results: Groups 2 and 5 showed significantly increased new bone formation compared with groups 1 and 4, 4 weeks after MSFA (P < .05). Twelve weeks after sinus floor augmentation, groups 2, 3, 5, and 6 showed significantly higher new bone formation than group 1 (P < .05). Groups 2 and 5 showed significantly higher hard tissue response than groups 1 and 4 at the end of 4 weeks (P < .05). Groups 5 and 6 demonstrated significantly higher hard tissue response than group 1 at the end of 12 weeks (P < .05). Group 5 also showed significantly higher hard tissue response than group 4 at the end of 12 weeks (P < .05). Immunohistochemical analysis showed a significant difference between the osteocalcin scores of groups 2 and 4 and group 1 at the end of 4 and 12 weeks (P < .05). There was also a statistically significant difference between osteocalcin scores at 4 and 12 weeks for groups 1 and 5 (P < .05). When osteopontin scores were compared, there was no significant difference between groups at 4 and 12 weeks (P > .05). Groups 1, 2, and 5 showed significant changes in osteopontin scores between 4 and 12 weeks (P < .05). Conclusion: The combination of ACC and PRP and the combination of ACC and EMD showed increased new bone formation and hard tissue response. A-PRF also showed promising results in new bone formation at the end of both 4 and 12 weeks. The usage of ACC as a carrier for liquid-form biomaterials may be more beneficial than the usage of ACC alone. Keywords: absorbable collagen, enamel matrix derivative, platelet-rich fibrin, platelet-rich plasma, sinus augmentation

Purpose: The efficiency of bacterial removal using mechanical and chemical methods and recurrence rates was evaluated based on infected implant surface removal modalities. Materials and methods: The study comprises two main parts: in vitro bacterial removal (n = 49) and regrowth (n = 42) suppression tests on implant surfaces. Microorganisms were attached to each implant, and various methods were applied to clean the infected implants. The groups were allocated as follows: (1) no treatment, (2) cotton + saline, (3) brush, (4) scaler, (5) brush + scaler, (6) cotton + 3% H₂O₂, and (7) brush + 3% H₂O₂. All groups were further divided into two subgroups of mechanical treatment (3, 4, 5) vs mechanical + chemical treatment (2, 6, 7). After treatment for each group, immunofluorescence analysis and measurement using an ultraviolet-visible light spectrophotometer were performed. Results: In the mechanical treatment group, the brush, scaler, and brush + scaler groups, all of which had strong polishing abilities, exhibited superior removal efficiency compared with the other groups (P < .001). In the regrowth experiment, 3% H₂O₂ effectively restrained biofilm formation. In particular, the brush + 3% H₂O₂ group exhibited significant differences from the mechanical treatment group (vs brush: P < .001, vs scaler: P = .023, vs brush + scaler: P = .005). Conclusion: Mechanical methods, including brushes and scalers, effectively removed bacteria. Biofilm formation was effectively restrained by H₂O₂. In particular, the brush + H₂O₂ group exhibited a superior ability to suppress bacterial regrowth compared with the other groups. Keywords: antimicrobial, biomaterials, implantology, local antimicrobial therapy, pathogenesis of periodontal diseases

Purpose: To investigate retention and stability characteristics of soft-liner and clip attachments used for bar/implant-assisted mandibular overdentures. Materials and methods: Two implants were placed in an edentulous mandibular model. According to the type of bar, presence of cantilevers, and type of attachments, eight groups were tested: (1) Dolder bar with cantilevers and three titanium clips (DCC), (2) Dolder bar with cantilevers and resilient liner attachments (DLC), (3) Dolder bar without cantilevers and one titanium clip (DCWC), (4) Dolder bar without cantilevers and resilient liner attachments (DLWC), (5) Hader bar with cantilevers and three plastic clips (HCC), (6) Hader bar with cantilevers and resilient liner attachments (HLC), (7) Hader bar without cantilevers and one plastic clip (HCWC), and (8) Hader bar without cantilever and resilient liner (HLWC). Axial (retention) and nonaxial (stability during anterior, posterior, and lateral dislodging) forces were evaluated initially and after 540 times of prosthesis insertion and withdrawal. Results: The highest retention and stability forces were observed with HCC, and the lowest forces were recorded with DLWC. The lowest retention and stability after wear was noted with DCWC and HCWC. For the majority of groups, the highest forces were noted with posterior dislodgment, and the lowest forces were observed with lateral dislodgment. The largest retention loss was recorded with DCC and HCC, and the lowest retention loss was noted with HLWC. DLC and HLC showed retention gain. Conclusion: Hader bar with clips and cantilever extensions achieved the highest retention and stability forces after wear simulation, while bars without cantilevers and clips showed the lowest forces. For cantilevered Dolder and Hader bars, clip attachments showed increased retention loss, while soft-liner attachments showed retention gain. Keywords: attachment, clip, bar, implant, overdentures, retention, soft liner, stability

Purpose: This systematic review aimed to appraise the available evidence on the clinical characteristics produced by osseodensification drilling compared with the conventional drilling technique. Materials and methods: Five databases (PubMed, Google Scholar, LILACS, EMBASE, and CENTRAL) were searched up to July 2020. Randomized clinical trials (RCTs) and nonrandomized studies of interventions (NRSIs) that compared osseodensification drilling with conventional drilling in humans were included. Random-effects meta-analyses of standardized mean difference (MD) with 95% confidence intervals (CI) and risk ratio were performed. Results: Three NRSIs fulfilled the inclusion criteria, and all were scored as low risk of bias. Meta-analysis showed that the osseodensification drilling technique presented higher average implant stability quotient (ISQ) scores at baseline (MD: 13.1, 95% CI: 10.0 to 16.1, P < .0001) than conventional drilling, with complete homogeneity (I² = 0.0%). Furthermore, osseodensification drilling presented higher average ISQ scores at follow-up (MD: 5.99, 95% CI: 1.3 to 10.6, P < .0001) than conventional drilling, with high homogeneity (I² = 73.0%). Conclusion: This systematic review showed that osseodensification presented consistently higher ISQ at baseline and at 4 to 6 months after implant placement compared with conventional drilling. However, these results should be carefully interpreted since only three studies were selected in this meta-analysis. In the future, RCTs will be necessary to confirm the consistency of these results. Keywords: biomechanics, bone, conventional drilling techniques, implant site preparation, meta-analysis, osseodensification, systematic review

Purpose: The aim of this study was to investigate the effect of implant subgingival depth on the trueness and precision of the 3D implant position, and the effect of digital implant impression techniques on the 3D implant position. Materials and methods: Three resin master models were created with implant analogs submerged 3, 6, and 9 mm from the gingival margin. Four intraoral scanners (TRIOS, DWIO, Omnicam, and TruDef), one laboratory scanner (E3), and a conventional impression technique were used to take impressions of the master models, which resulted in six test models for each depth. These six impression techniques were performed six times for precision assessment. The master models were sent for high-powered micro-focused computed tomography as the gold standard control group. The scan body positions of the test models and their control models were superimposed using reverse-engineering software. The 3D distortion of the implant position in each comparison was measured by linear distortion (dx, dy, dz) and calculated as the global linear distortion (dR). Results: The trueness of the mean dR values at the 3-mm, 6-mm, and 9-mm implant depths was 99 μm, 60.6 μm, and 107 μm, respectively. The least significant difference test of the impression system showed that all the digital impression techniques except the DWIO scanner had better trueness than the conventional impression technique. The 6-mm implant depth exhibited a significantly lower 3D distortion of the implant position than those of the 3-mm and 9-mm implant depths. The E3 scanner had the highest precision, while the conventional impression technique had the lowest precision. All the intraoral scanners except the DWIO scanner showed better precision than the conventional impression technique. Conclusion: Most of the intraoral scanners had better trueness and precision than the conventional impression technique for up to 6 mm of implant subgingival depth. Keywords: accuracy, dental implant, implant depth, intraoral scanner, precision, trueness

Purpose: Previous studies assessing fibroblast interactions with implants have mainly relied on measurements such as cell migration, gene expression, and cell adhesion. For these studies, testing cellular behavior at the implant surface was done by imaging the cell-implant interface using standard microscopy techniques in 2D tissue culture dishes. The true behavior of cells relative to the implant can best be assessed in a more physiologic 3D microenvironment. Materials and methods: The embedding of the implant disks in 3D collagen gels was standardized with labeled fibroblasts to allow the imaging of fibroblast morphology and behavior when proximal to or binding to the implant disks. This allowed comparison of the behavior of laser-microgrooved and machined implant disk surfaces quantitatively in an in vitro 3D microenvironment. Results: This in vitro imaging assay revealed for the first time in a 3D microenvironment setting the statistically significant impact laser-microgrooved disk surfaces have on both cell adherence and recruitment of cells in proximity to the disk. It also allowed visualization of membrane protrusivity and cytoskeletal organization in cells adherent to the implant disk. Conclusion: This assay provides a simple and effective way of observing cell behavior on and around the implant disk surface in a more physiologic 3D setting. Within the limits of this study, it revealed that the laser-microgrooved implant surface demonstrates significant superiority in fibroblast recruitment and binding in a 3D microenvironment. Keywords: 3D, collagen, dental implants, fibroblasts

Purpose: To compare the clinical and radiographic outcomes of short implants (≤ 8 mm) vs standard implants (> 8 mm, < 10 mm) and to uncover risk factors influencing implant failure in short implants. Materials and methods: Short and standard implants were compared in the aspect of survival rates, biologic and mechanical complications, and marginal bone loss. To analyze risk factors of implant failure in short implants, several variables were taken into consideration, including sex, age, time interval, arch, implant brand, additional surgery, prosthesis material, restoration, smoking status, and crown-root ratio. Results: Three hundred twenty-one short implants and 136 standard implants were retrospectively followed up from 12 to 104 months with an average of 40 months (3.33 years) in short implants and 34 months (2.83 years) in standard implants. The survival rates of short implants were 95.6% at the implant-based analysis and 94.9% at the patient-based analysis, and rates of 96.3% and 94.0%, respectively, were calculated for standard implants. No statistically significant differences were observed between short and standard implants with respect to survival rate, complications, or marginal bone loss. The failure rates were 4.2% for implants and 5.4% for patients in total implants with an average of 38 months (3.17 years). In analyzing risk factors of short implants for survival rate, single short implants resulted in a higher failure rate compared with splinted short implants, while no significant variable was found in standard implants. Conclusion: Short implants tend to be a reliable alternative in atrophic posterior regions. Splinted prostheses were more ideal for short implant restorations. Keywords: complications, retrospective study, short implant, survival rate

Purpose: The occlusal force and occlusal contact area may be used to evaluate oral function following restoration of a missing tooth. This study aimed to monitor the initial changes in these factors after single molar implant restoration. Materials and methods: Patients who underwent single implant restoration between December 2018 and September 2019 were recruited for this study. Occlusal force was measured before, immediately after, and 1 month after prosthesis placement. The occlusal contact area was evaluated immediately and 1 month after the placement. Data were grouped by sex, restored tooth, and restored side for analysis. Results: In most groups, occlusal force was significantly increased 1 month after the placement compared with that before placement (P < .05), and the change was more significant in the first molar group than in the second molar group. There was a significant difference in the occlusal contact area of the implant prosthesis immediately and 1 month after placement when a thickness of 9 μm was used. The occlusal contact area of the natural tooth in the mesial side was significantly increased 1 month after placement (P < .05). Conclusion: Occlusal force was significantly increased 1 month after implant restoration, and restoration of the first molar had the most significant effect on the occlusal force. Occlusal contact areas may differ according to the occlusal indicator used in the clinical setting because the changes were significant with only 0 to 9 μm. Keywords: implant restoration, masticatory efficiency, occlusal contact area, occlusal force, oral function

Purpose: To evaluate the predictive value of microRNAs (miRNAs) found in peri-implant crevicular fluid (PICF) in the prognosis of peri-implant bone resorption. Materials and methods: Seven patients were rehabilitated with fixed partial dentures each supported by two dental implants (total of 14 implants). At 3 months post-implant insertion, a sample of peri-implant mucosa and a sample of PICF were taken at each implant site. MiRNAs were extracted from the samples and analyzed through microarray technology. MiRNAs extracted from PICF were compared with miRNAs extracted from soft peri-implant tissue and related with peri-implant bone resorption measured at the 5-year follow-up. Results: During the 5-year follow-up, no dropouts and no implant failures were recorded. The mean bone resorption was 1.98 mm (median: 2 mm). Extracellular miRNAs were recovered in well-detectable amounts in all PICF samples. Specific miRNA expression profiles were predictive of bone resorption. Fourteen miRNAs that were altered in PICF in case of bone resorption were also altered in the soft peri-implant tissue of the same implant sites. Conclusion: MiRNAs may be used as biomarkers of peri-implant bone resorption, and their presence in PICF lays the foundations for the development of a noninvasive and site-specific liquid biopsy. Keywords: bone resorption, dental implants, liquid biopsy, microarray, microRNA

Purpose: This study was conducted to compare the radiographic, esthetic, and patient-reported outcome measures (PROMs) between immediate and delayed restorations of immediately placed single implants in the maxillary esthetic zone. Materials and methods: Forty patients with immediate single dental implants in the anterior maxilla were included in this study. Afterward, they were allocated either for immediate restoration with a provisional restoration (IR: 20 patients) or for a delayed restoration (DR: 20 patients). The evaluations were performed after 1 year of follow-up. Results: No implant and prosthetic failures were observed during the 1-year follow-up. Two minor complications were found in two IR patients; however, no complication was reported in the DR group during the 1 year. Nevertheless, this difference was not statistically significant (P > .05). After 1 year, the mean marginal bone level changes (MBL) were 0.47 ± 0.29 mm and 0.54 ± 0.21 mm for IR and DR, respectively. There was no statistically significant difference between the two groups in terms of MBL (P = .3). Notably, the mean total pink esthetic score (PES) and white esthetic score (WES) after 1 year of follow-up were 11.2 ± 1.1 (PES) and 8 ± 1.02 (WES) for the immediate restoration, and 10.2 ± 0.97 (PES) and 7.65 ± 1.20 (WES) for the delayed restoration. Also, no statistically significant difference was found between IR and DR in terms of esthetic scores (P > .05). The patient satisfaction of these two groups had no statistically significant difference, except for the esthetic factor (P = .04). Conclusion: The immediate restoration and preferred esthetic satisfaction had similar outcomes compared with the delayed restoration. Keywords: dental implant, dental prosthesis, immediate dental implant loading, implant-supported, treatment outcome

Purpose: The main objective of this study was to assess the influence of bone remodeling on late marginal bone loss in immediately loaded, implant-supported, complete-arch restorations and, secondarily, to determine its relationship to peri-implant disease occurrence using a multilevel analysis. Materials and methods: A retrospective cohort study of patients treated consecutively in a private clinic with immediately loaded full-arch restorations with at least 12 months of follow-up was conducted. Bone remodeling and marginal bone loss were determined through measurements made on panoramic radiographs by two calibrated examiners. Peri-implant health status was diagnosed in a visit for peri-implant maintenance. Descriptive, bivariate, and multilevel analyses were performed with Stata/IC 15.1 software (StataCorp). Results: A total of 30 patients (11 men and 19 women, mean age: 63.3 ± 10.4 years), with a mean follow-up of 37.7 ± 19.6 months were included. Forty arches (20 maxillary and 20 mandibular) received 207 implants. Bone remodeling had an inversely proportional effect on marginal bone loss (P =.005) but was not related to peri-implantitis (P =.103; hazard rate [HR] = 2.1). Conclusion: Taking into account the limitations of this study, bone remodeling around immediately loaded dental implants supporting complete-arch restorations does not appear to increase marginal bone loss or peri-implantitis. Keywords: bone remodeling, dental prosthesis, immediate dental implant loading, implant-supported, peri-implantitis, private practice

Purpose: To compare the primary and secondary stability of conventional (≥ 8-mm) and extrashort (4-mm) implants in edentulous patients using different methods of assessment. Materials and Methods: Patients underwent implant surgery and were randomly allocated into two groups: test, with two conventional implants in the anterior region and two extrashort (4-mm) implants in the posterior region; and control, with two conventional (≥ 8-mm) implants in the anterior region only. Primary stability (S1–implant placement) was assessed by insertion torque, implant stability quotient (ISQ, Osstell), and damping capacity (PTV, Periotest), while secondary stability (S2²¹—21 days after S1; and S2^clip—at prosthetic loading, ± 3 months after S1) was evaluated by ISQ and PTV. The statistical significance level was set at P < .05. Results: Fifty conventional implants and 24 extrashort implants were placed in 25 patients. The overall survival rate was 97.3%. There was no statistically significant difference between the insertion torque of conventional and extrashort implants (P > .05). PTV values were significantly lower for conventional implants only at S2^clip (P = .041). ISQ values were significantly greater for conventional implants at S1 (P = .004), whereas at S2²¹ and S2^clip, no differences were found (P = .413 and P = .490, respectively). Damping capacity showed no significant differences between S1–S2²¹ and S1–S2^clip. ISQ values showed a significant increase of stability between S1–S2^clip, for conventional (P = .022) and extrashort (P = .005) implants, which was different from that observed between S1–S2²¹. There was a moderate negative correlation between the PTV and ISQ variables (r = 0.5) of extrashort implants, and between the PTV and insertion torque (r = –0.3) of conventional implants. For extrashort implants, there was a null correlation between ISQ and torque (r = 0.0). There was a moderately positive correlation between ISQ and torque (r = 0.3) in the conventional implant group. Conclusion: The results suggest that extrashort and conventional implants present similar primary and secondary stability values and may similarly influence restorative protocols. Keywords: bone-implant interface, bone remodeling, dental implants, dental implantation, osseointegration, resonance frequency analysis, torque

Purpose: The aim of this study was to analyze retrospectively the clinical reliability of complete-arch rehabilitations with screw-retained fixed prostheses supported by four dental implants inserted with a fully guided surgical protocol. Materials and methods: All the implants were placed between December 1, 2015, and April 30, 2019. Digital implant surgical planning was performed for all the complete-arch rehabilitations, and then, fully guided surgery was performed. The fixed provisional prostheses were delivered the day of the surgery and replaced by definitive prostheses after the healing period. Patients were followed up to determine survival of the implants and success of the overall treatment. Results: A total of 160 implants were positioned in 37 patients, with three patients receiving rehabilitations in both arches. A total of 40 complete-arch rehabilitations were performed, 26 in the maxilla and 14 in the mandible. Only five implants failed, resulting in an overall implant survival rate of 96.9%. No definitive prostheses failed, resulting in a 100% prosthetic success rate. The failed implants were successfully replaced before definitive prostheses were made, resulting in an overall treatment success of 100%. Conclusion: Within the limitations of this study, digital planning and guided surgery to perform complete-arch rehabilitations on four dental implants seems to be a valid treatment option. However, several prospective studies with longer follow-up are needed to achieve more predictable results. Keywords: complete-arch rehabilitation, computer-aided surgery, dental implant, immediate loading

Purpose: This study investigated the impact of 0.12% chlorhexidine gluconate mouthwash on dental implants with periimplant mucositis and contralateral teeth with gingivitis at 6 months of follow-up after nonsurgical treatment. Materials and methods: This was a secondary analysis of data from a previous controlled, randomized, double-blinded clinical trial of 30 patients diagnosed with peri-implant mucositis and gingivitis in contralateral teeth, at 6 months following treatment. Patients were randomly assigned into a test group (basic periodontal therapy + 0.12% chlorhexidine mouthwash) or a control group (basic periodontal therapy + placebo). Therapy consisted of an adaptation of the full-mouth scaling and root planing protocol. The clinical parameters of visible Plaque Index, Gingival Bleeding Index, probing depth, bleeding on probing, keratinized mucosa width, and gingival and peri-implant phenotype were evaluated at baseline and at 1, 3, and 6 months posttherapy. Data were analyzed using Poisson multilevel regression analysis with a significance level of .05. Results: The study analyzed 47 implants and contralateral teeth (376 sites) in the test group and 49 implants and contralateral teeth (392 sites) in the control group. No differences were found between the groups at the patient level. At the site level, the teeth and implants presented statistical differences in bleeding on probing, probing depth, and keratinized mucosa width at 3 months for both treatment groups. However, no difference was observed in bleeding on probing in the test group (P = .484) at 6 months, whereas the control group demonstrated increased bleeding on probing (indicating more inflammation) at implant sites than at teeth sites (P = .039). Additionally, implant sites with a thin peri-implant phenotype (P < .001) and located posteriorly (P = .002) presented greater inflammation. Conclusion: Use of a 0.12% chlorhexidine mouthwash for 14 days was beneficial for implant sites with peri-implant mucositis, compared to contralateral teeth sites with gingivitis, as indicated by the reduced percentage of teeth with bleeding on probing. Keywords: chlorhexidine, dental implant, full-mouth disinfection, gingivitis, peri-implant mucositis, treatment

Purpose: This study aimed to report changes in implant bone levels before and after peri-implantitis surgery (P-IS). Materials and methods: Patients were treated with P-IS from 2003 to 2010 and thereafter followed up until the last available radiographic examination (study termination: October 2018). Bone loss was measured before and after P-IS, and the numbers of clinical examinations post-P-IS were determined. The Student t test was used to compare the bone loss between examinations and reference populations, and correlations between different variables were calculated using the Pearson correlation coefficient (r). Results: One hundred thirty-four consecutive patients (137 arches) underwent P-IS during the inclusion period (2.3%). A total of 122 patients (125 arches) were followed up for a mean period of 6.9 (SD: 5.54) and 7.3 (SD: 3.39) years from the first annual examination to before P-IS, and from the time of P-IS to after P-IS, respectively. The mean bone loss during the aforementioned durations was 0.18 (SD: 0.23) and 0.26 (SD: 0.28) mm/year, respectively (P < .05). Bone loss per year was also greater for unaffected implants after (0.29 [0.34] mm/year) compared with before P-IS (0.06 [0.10] mm/year; P < .05). No difference in bone loss was observed between peri-implantitis affected and unaffected implants or between implants with a turned or moderately rough surface after P-IS. A greater amount of bone loss was associated with increasing numbers of clinical examinations and shorter follow-up times after P-IS (P < .05). Conclusion: Average bone levels decreased from the time of prosthesis placement to termination of the study. Bone loss increased after P-IS in the total and unaffected group, and edentulous patients compared unfavorably with partially and single implant conditions. Increased bone loss was associated with higher numbers of clinical examinations per year of followup after P-IS (P < .05). Keywords: bone loss, complication, dental implants, implant failure, peri-implantitis, peri-implantitis surgery

Purpose: Cone beam computed tomography (CBCT) is considered both reliable and safe and provides reproducible results in guided dental implant planning procedures. However, it has weaknesses in soft tissue contrast and is associated with radiation exposure. Recent studies showed promising results with magnetic resonance imaging (MRI) as a possible noninvasive, radiation-free, alternative imaging modality for dental indications. The purpose of this study was to evaluate the quality of 1.5 T MRI with a dedicated dental signal-amplification coil in comparison to CBCT for dental implant planning procedures. Materials and methods: Sixteen subjects undergoing preoperative MRI (3D HR T1w TSE and 3D HR T1w FFE) and CBCT were included in this prospective study. All imaging data were used for dental implant planning procedures using commercially available software. Two experts scored the planning as "ideal," "improvable," or "unacceptable." Furthermore, quantitative distances according to EuCC recommendations were collected. Finally, discrepancies between CBCT and 3D HR T1w TSE were analyzed. Statistical analysis was performed using the Mann-Whitney U test and analysis of variance (ANOVA). Results: The dental implant planning procedure was technically feasibly using all imaging data. CBCT allowed for "ideal" placement in all cases. Ratings for 3D HR T1w TSE and 3D HR T1w FFE were 81.9%, 18.1%, and 0% and 54.2%, 30.0%, and 15.3% for ideal, improvable, and unacceptable, respectively, identifying 3D HR T1w TSE as superior compared with 3D HR T1w FFE. Head-to-head comparison between CBCT and 3D HR T1w TSE revealed no significant differences regarding the apical position of the implant of 1.2 ± 0.7 mm and 1.3 ± 0.5 mm coronally, respectively (P = .287). The deviation of the planed angle was 3.0 ± 1.2 degrees. In these merged data sets, the distance to the mandibular canal was significantly higher with 1.3 ± 0.8 mm, indicating better utilization of the existing bone. Conclusion: Within the limits of this pilot study, it can be reported that the dental image planning procedure is feasible using 1.5 T MRI with a dedicated dental coil and specific MRI sequences. Keywords: cone beam computed tomography (CBCT), magnetic resonance imaging (MRI), dental signal amplification coil, surgical guide, dental implant surgery

Purpose: This study aimed to topographically examine the healing of mineralized human bone allograft in sinus augmentation. Materials and methods: Thirty-two patients with crestal bone height ≤ 2 mm who required sinus augmentation were recruited for the study. A mixture of 80/20 cortical/cancellous mineralized human bone allografts were used to augment the sinus floor using a crestal window approach. A bone core biopsy specimen was taken at the time of implant placement, 6 months after surgery. Microradiographs of methacrylate-embedded sections were split into five longitudinal sectors (crestal to sinusal) to topographically assess the bone, graft, and fibrous tissue amount. Results: All implants were osseointegrated 3 months later without any adverse effects. The polynomial (degree 2) of results (all with great correlation coefficient, P < .01) gave rise to a polynomial curve of graft percentage with a maximum at sector 4 (presinusal), a bone percentage with a minimum between sectors 3 and 4, and a fibrous tissue percentage with a maximum between sectors 3 and 4. Conclusion: Based upon topographic analysis, mineralized human bone allograft is capable of achieving adequate vertical bone height for implant placement. The need for a topographic analysis to assess the outcomes of sinus augmentation is emphasized. Keywords: bone allograft, bone regeneration, crestal access, maxillary sinus floor augmentation, microradiography, topographic histomorphometry

Purpose: Untreated severely damaged molar sockets often complicate implant placement. This study evaluated membrane degradation, soft tissue healing, and alveolar crest dimensional changes after alveolar ridge preservation (ARP) in severely damaged molar sockets using a polylactic acid membrane (PLA) and xenograft without primary wound closure. Materials and methods: A total of 14 damaged molar sockets in 12 patients were grafted with deproteinized bovine bone mineral, which was covered with a PLA membrane without primary wound closure. Wound healing was evaluated at set times. Three sets of CBCT data taken before surgery, at 1 to 2 weeks, and at 6 to 12 months after surgery were reconstructed and superimposed to analyze dimensional changes of the alveolar crest with volumetric imaging software. Results: Two weeks after ARP, no degradation of PLA membrane was present, and the xenograft had either no exfoliation (7 sites, 50%) or mild exfoliation (6 sites, 42.9%). One to 2 months following ARP, the membrane was partially degraded in 6 sites (42.9%) and completely degraded in 8 sites (57.1%). Nine sites (64.3%) presented with mild graft particle exfoliation, and four sites (28.6%) had granulation tissue covering the bone graft. All sites were fully covered by keratinized mucosa by 6 to 12 months. Compared with baseline measurements, the vertical bone graft height decreased by 2.2 ± 2.2 mm, and central alveolar ridge thickness measured at the level of the virtual implant platform decreased by 5.0 ± 5.1 mm after 6 to 12 months. Conclusion: The exposed PLA membrane maintains some barrier function for at least 3 to 4 weeks after ARP in severely damaged molar extraction sites. This technique allowed for implant placements without additional grafting. Future studies should include histologic assessment of the augmented bone and nongrafted control sockets. Keywords: alloplastic membrane, alveolar ridge preservation, osseous defects, wound healings

Purpose: Patients with maxillary defects after a maxillectomy live with a range of functional and social problems. As techniques for functional reconstruction of the maxilla have been applied in a number of these patients, some of them regained confidence in their lives again. Nevertheless, there was still no clear consensus on the connecting and loading patterns of zygomatic implant-supported prosthetics in bilateral maxillary defects. This study aimed to investigate the function of a novel technique using "three-dimensional ring"-supported prosthetics based on zygomatic implants and compared its effects with two other conventional approaches through assessing the quality of the patient's life. Materials and methods: Forty-five eligible patients who had different degrees of maxillectomy received treatment of conventional prostheses with a clasp (25 patients, group 1), a regular implant with obturator removal (10 patients, group 2), or a zygomatic implant combined with "three-dimensional ring"-supported prosthetics (10 patients, group 3). A questionnaire that included the indicators of the Obturator Functioning Scale (OFS) and EORTC Head and Neck 35 assessment was employed to evaluate the functional rehabilitation and quality of life (QOL) of patients in the study. The data were then summarized into a worksheet (Excel 2010), and the mean and standard deviation were calculated. The data were processed with SPSS 19.0 for Windows statistical software. Results: The questionnaire analysis showed a statistically significant difference in the OFS, EORTC H&N 35, and QOL scores between group 3 and group 1 or group 2. Importantly, in the assessment of EORTC H&N 35, the proportion of patients in group 3 who lost weight after the functional restoration of maxillary defection was lower than that of the other two groups. In this research, a new connection device mode, which provided a retentive force between the zygomatic implants and prosthetics through a 3D ring-shaped milling bar with golden galvanized frames, was conducted and proved to be a reliable and feasible functional reconstruction therapy through patients' questionnaire surveys. Conclusion: This research provided an effective reconstruction strategy for patients with maxillary resection that could remarkably improve the life quality of patients. Keywords: EORTC Head and Neck 35, maxillary defects, OFS, three-dimensional ring, zygomatic implants

In the March/April 2020 issue of JOMI, in the article, “Reliability of Interproximal Bone Height Measurements in Bone- and Tissue-Level Implants: A Methodological Study for Improved Calibration Purposes" (Int J Oral Maxillofac Implants 2020;35:289–296), on page 291, Figs 1 and 2 were in the incorrect order. The correct figures are as follows.

Purpose: Treatment alternatives based on implant-supported prostheses (ISPs) may be almost impossible in cases with extremely atrophic mandibles. Vertical bone augmentation is then the only possibility to achieve an ISP. Materials and methods: The consequences of vertical augmentation in extremely atrophic mandibles (≤ 10-mm bone height) of edentulous patients using allogeneic block grafts via a submental approach were assessed. The recorded parameters were sex, age, physical status, hospitalization duration, postoperative complications, implant characteristics (length, diameter), early and late implant failure (yes/no; primary outcome variable). Bone height was measured at three points using the pre-grafting and pre-implant placement CBCT imaging. The difference between the measurements was defined as bone gain (primary outcome variable). Results: Sixteen patients (2 men, 14 women) were included. The preoperative bone height ranged from 4 to 10 mm. A mean of 5.3 ± 1 months was allowed for graft consolidation. The average bone height gain was 11.2 ± 3.1 mm. Two to six dental implants were placed in the grafted bone. Early implant failure occurred in 4 out of 73 (5.5%). Follow-up ranged from 12 to 92 (mean: 48 ± 30) months. All patients were followed for more than a year, and two additional late implant failures were recorded, rendering a 92% cumulative survival rate. Conclusion: Bone grafting using allogeneic bone blocks via a submental approach seems to be a promising solution for reconstruction of the extremely atrophic mandible. Keywords: bone graft, bone substitute, full edentulism, overdenture, surgical procedure

Purpose: The purpose of this study was to examine whether the use of short dental implants with an expandable compressive design could be a proper alternative to the conventional sinus elevation procedure in cases of deficient alveolar ridge height in the posterior maxillary area. Materials and methods: Fifty patients with 73 short dental implants with an expandable compressive design who were treated for posterior maxillary alveolar ridges of 5 to 7 mm in the vertical dimension between 2012 and 2018 were included in a retrospective study. All patients had a minimum postrehabilitation period of 1 year. Patient demographics, implant properties, primary stability, and implant success and survival rates were analyzed. Results: The total success rate was 97.2%, with two failed implants at implant uncovering. The mean bone loss was 1.03 mm. No difference in bone loss was found between sexes or age groups. Conclusion: The results of this study suggest that short dental implants with an expandable apical compressive design could be an alternative to sinus elevation procedures in selected cases of vertically deficient maxillary alveolar ridges. Keywords: atrophic maxilla, edentulous maxilla, minimal invasive implant surgery, short dental implants

Purpose: Conscious sedation in oral surgical procedures provides comfort both for patients and practitioners. Midazolam is a sedative agent commonly used in this manner. Dexmedetomidine is also a decent sedative agent, with its analgesic and mild respiratory effects, which is usually preferred in intensive care units. Dexmedetomidine has been recently used in dental surgeries. This study aimed to investigate the analgesic and respiratory properties of midazolam and dexmedetomidine in conscious sedation during dental implant procedures and to compare these two drugs in terms of ease of use and comfort of dental implant operation. Materials and methods: This study was a prospective double-blind randomized controlled study. The patients who needed dental implant placement were divided into two randomized groups for either midazolam or dexmedetomidine. The amount of sedative agent used, duration of the procedure, onset of sedation, use of additional same sedative agent, and occurrence of desaturation were recorded. Hemodynamic and respiratory variables (mean blood pressure, heart rate, oxygen saturation, and respiratory rate) were recorded every 10 minutes, starting immediately before the loading dose until the end of the procedure. Patients completed a Likert scale for their satisfaction, and patient pain was scored using the numeric rating scale postoperatively. The amount of painkiller usage was recorded and reported. All surgical procedures were performed by the same surgeon, and all recordings were taken by an anesthesiology technician; both were blinded for the randomization. Descriptive and bivariate statistics were computed, and the P value was set at < .05. Results: This study included patients who were scheduled for two to five dental implant insertions to either arch under conscious sedation. A total of 163 dental implants were inserted into 43 patients. Patients receiving dexmedetomidine had lower pain, higher satisfaction with the procedure, and less desaturation (P = .002). The onset of sedation was more rapid with midazolam (P = .001). The number of implants according to drugs did not differ statistically. On the other hand, the mean operation time was 52.09 ± 20.12 minutes in the dexmedetomidine group and 87.14 ± 26.15 minutes in the midazolam group (P = .001). No significant difference was found for retrograde amnesia and preference of sedative between midazolam and dexmedetomidine. Conclusion: Dexmedetomidine is a good alternative to midazolam for conscious sedation during dental implant procedures, with its better analgesic property and minimal respiratory side effects. Keywords: analgesia, conscious sedation, dental implant, dexmedetomidine, midazolam

Purpose: The aim of this study was to evaluate suppuration on palpation, used as a diagnostic test, in the detection of peri-implantitis. Materials and methods: A total of 65 patients with 267 implants were examined. Clinical inspection was performed by two blinded examiners: The first measured suppuration on palpation, and the second conducted a complete clinical examination. A third examiner combined the previously collected information with radiographic data and diagnosed the patients according to the European Federation of Periodontology/American Academy of Periodontology (EFP/AAP) classification system. Calibration was conducted previously to the fourth examiner on a set of five patients not belonging to the study sample. Results: When suppuration on palpation was associated with diagnosis of peri-implantitis, the specificity and negative predictive value were high (88% and 84%, respectively), meaning that an implant that was negative to suppuration on palpation had a high chance of not being affected by peri-implantitis. Conversely, the sensitivity and positive predictive value were low (45% and 54%), demonstrating that a suppurating implant will be affected by peri-implantitis in only half of the cases. Area under the curve was calculated as 60.4 (P = .012), and accuracy was found to be 78%. Conclusion: Suppuration on palpation alone, as with any other clinical sign, does not allow a precise diagnosis of peri-implantitis. An implant without suppuration on palpation shows a high chance of being free of peri-implantitis, while an implant that suppurates upon palpation is not necessarily affected by peri-implantitis. Suppuration on palpation may be a valuable clinical sign, especially when evaluating implants that are difficult to examine via probing. Keywords: bacteria, biologic complications, cross-sectional study, diagnostic procedure, peri-implantitis, suppuration

Purpose: There is a substantial need to perform studies to evaluate crestal bone loss (CBL) and implant success when using a newly introduced low-speed drilling protocol. Therefore, this study aimed to evaluate the mean CBL and implant success rate by placing implants utilizing two drilling protocols, ie, standard and low-speed drilling protocols. Materials and methods: A randomized controlled clinical trial was carried out in patients who required dental implants to restore their esthetics and function. The patients were recruited from a university hospital (Academic Centre for Dentistry Amsterdam [ACTA], the Netherlands). Based on the inclusion criteria, patients were randomized to two study groups: (1) control group, standard drilling protocol; and (2) test group, low-speed drilling protocol without saline irrigation. The mean CBL and the implant success rate were evaluated after 12 months of implant placement. Results: Twenty-three patients (15 men and 8 women with a mean age of 57.5 ± 10.7 years) contributed to the study. Forty Camlog screw-line implants were placed (20 implants per study group). After 12 months of implant placement, the mean CBL of implants placed with the standard protocol and the low-speed protocol was 0.206 ± 0.251 mm and 0.196 ± 0.178 mm, respectively. No statistically significant difference could be recorded among both groups (P = .885). Concerning implants placed in the maxilla, the standard drilling group and low-speed drilling group showed a mean CBL of 0.252 ± 0.175 mm and 0.251 ± 0.175 mm, respectively, compared with 0.173 ± 0.210 mm and 0.141 ± 0.172 mm in the mandible, with no significant difference. The success rate of dental implants at 12 months was 95% in the control group and 90% in the test group. Conclusion: Within the limitations of this study, it can be concluded that implants placed with the low-speed drilling protocol without saline irrigation exhibited a similar CBL compared with implants placed with the standard drilling protocol. However, a higher success rate was recorded especially in type 1-quality bone for the control group compared with the test group. Further randomized clinical trials with greater sample sizes and extended follow-up times should be performed to obtain stronger evidence and a better understanding of the influence of drilling speed on mean CBL and long-term implant success. Keywords: crestal bone loss, dental implant, low-speed drilling, standard drilling