The International Journal of Oral & Maxillofacial Implants, 01/2019

Purpose: To investigate the optimal degree of convergence of the abutment with which the bond strength achieved by the pre-bonding method is comparable with that in direct bonding with a conventional degree of convergence. Materials and Methods: Abutments with 5.5-mm diameter, 5-mm height, 0.5-mm shoulder width, and three kinds of degrees of convergence (2, 4, and 6 degrees) were first designed by digital modeling. Their corresponding inner crowns were also modeled, and a gap of 40 μm was kept between the abutment and the inner crown. Thirty abutments and 30 inner crowns were then lathed out from a titanium plate (10 sets per degree of convergence). Six groups were defined in this study, according to the different degrees of convergence and bonding methods (direct bonding, pre-bonding) (n = 10 sets). The samples handled with direct bonding would be cleaned for reuse in tests with pre-bonding. Temporary cement was used as an adhesive, and the bond strength was tested in each set of samples. The comparison among the results was performed by the Kruskal-Wallis test. Results: The mean values of bond strength with direct bonding methods were 349.39 ± 65.75 N, 316.49 ± 54.22 N, and 277.49 ± 56.96 N, and with pre-bonding methods were 279.35 ± 48.58 N, 227.97 ± 26.72 N, and 154.6 ± 23.03 N, respectively (2, 4, and 6 degrees). No statistical difference was found among the values in direct bonding groups and, in pre-bonding groups, only the comparison between 2 and 6 degrees of convergence showed statistical significance (P = .000). Between different bonding methods, statistical differences were shown in abutments with 4 and 6 degrees of convergence (P = .006, P = .000), respectively. The bond strength with pre-bonding methods and 2 degrees of convergence showed no significant difference from that with direct bonding and 6 degrees of convergence. Conclusion: The bond strength was inversely proportional to the degree of convergence, and the bond strength of pre-bonding was lower than that of direct bonding with the same degree of convergence. When using the pre-bonding method, the bond strength between the abutment and inner crown with 2 degrees of convergence could be comparable with using the direct bonding method and abutments with conventional degrees of convergence. Keywords: bond strength, degrees of convergence, pre-bonding

Purpose: This in vitro study aimed to evaluate and compare the effect of different bar designs on the retention forces of implant-retained maxillary overdentures. Materials and Methods: A maxillary edentulous acrylic resin model without alveolar undercut was fabricated. Four implant analogs were placed in the canine and second premolar regions. Overdentures were made and attached to the analogs with Dolder bar, Hader bar, and milled bar attachments. A universal testing machine was used to measure axial (resistance to vertical displacement) and nonaxial (resistance to anterior, posterior, and lateral displacement) retention forces (in Newtons). Measurements were made at the start of the experiment (initial retention) and after 540 cycles of denture insertion and removal to simulate 6 months of clinical function (final retention). Results: Hader bar had the highest retention after insertions and removals, and Dolder bar had the lowest retention. Vertical displacement showed the highest retention for Dolder and milled bars, and posterior displacement showed the highest retention for Hader bar. Lateral displacement recorded the lowest retention for all bar designs. No significant difference in axial retention loss was observed between different bar designs. Dolder bar showed the highest nonaxial retention loss, and milled bar showed the lowest retention loss. Conclusion: Hader bar is recommended to retain maxillary implant overdentures, as it was associated with higher axial and nonaxial retention compared with Dolder and milled bars after 6 months of simulated denture wear. Keywords: Hader bar, implant, maxillary, milled bar, overdenture, retention

Purpose: The aim of this study was to characterize and compare the behavior of human osteoblasts and human gingival fibroblasts in contact with polyetheretherketone (PEEK), zirconia, and titanium implant surface materials. Materials and Methods: PEEK, yttria-stabilized zirconia (YTZP), and titanium disks were produced under appropriate and similar conditions to achieve controlled surface features. Human osteoblasts and human gingival fibroblasts were cultured on disks for 14 days. Cell viability and proliferation were evaluated using a resazurin-based method. Morphology and cellular adhesion were observed using field emission gun-scanning electron microscopy (FEG-SEM). Alkaline phosphatase (ALP) activity and bone cell mineralization was evaluated on osteoblasts. Confocal laser scanning microscopy (CLSM) images of fluorescent-stained fibroblasts were obtained at 7 and 14 days of the culture. Results were presented as mean and standard deviation (SD). Group comparisons were tested using analysis of variance (ANOVA) (Tukey's post hoc) with appropriate statistical software, and significance was set at P .05. Results: Cell viability and proliferation were higher in PEEK and YTZP groups compared with titanium on osteoblast cells (P .05, all time points) and on fibroblasts (P .05, 7 and 14 days). All groups showed an increase in ALP activity over time, which was not significant. Mineralization patterns demonstrated an increase in mineral content over time, which was more apparent in the YTZP group. Cell spreading was more evident on PEEK and YTZP specimens. Conclusion: The results suggest increased adhesion, viability, and proliferation of osteoblasts and gingival fibroblasts on zirconia and PEEK surfaces compared with titanium. These results are correlated with the increased wettability of these materials. Keywords: dental implants, fibroblasts, osteoblasts, polyetheretherketone, titanium, zirconium oxide

Purpose: The purpose of this systematic review was to evaluate the outcome of dental implant treatment in fully edentulous patients who underwent Le Fort I osteotomy as a preprosthetic surgical technique. Materials and Methods: A search was conducted of the PubMed (MEDLINE), EMBASE, Scopus, and Cochrane databases to identify records published from 1995 to 2017 dealing with Le Fort I osteotomy procedures for implant placement purposes. The primary outcomes of interest were the survival and success rates. The secondary outcomes consisted of the analysis of intrasurgical and postsurgical complications and the surgical and prosthetic loading protocols. Results: Overall, 20 articles were selected for data analysis. A total of 483 patients accounting for 3,596 implants were analyzed. The cumulative survival rate was 90.22% ± 0.8% at 10 years (mean: 59.20 ± 32.31 months). The cumulative success rate was 89.07% ± 1.3% at 10 years (mean: 62.82 ± 25 months). Higher survival rates were found for implants with a rough surface (P .001) and for implants loaded with a delayed protocol (P .001). The fracture of the palatine bone during the downfracture procedure was the main intrasurgical drawback, while sinus pathology and graft resorption were commonly observed during the postoperative healing. Surgical and prosthetic loading protocols were heterogenous. Conclusion: Based on this review, Le Fort I osteotomy might be considered a viable technique to recreate favorable conditions for implant-supported rehabilitations. Caution has to be taken when using machined implants, particularly in the case of a simultaneous approach. Keywords: bone augmentation, dental implants, Le Fort I osteotomy

Purpose: The design and surface features of dental implants substantially affect the healing and remodeling of adjacent bones. This study aimed to investigate the impact of design and surface on bone regeneration using implants of two different pitches, each with three different surface features. Materials and Methods: Custom-manufactured titanium implants (length, 10 mm; diameter, 3.5 mm) were divided along the major axis into two sections: one with 0.6-mm pitch and the other with 0.4-mm pitch. They were processed by turned, blasting and etching, and anodic oxidation surface treatments and implanted into rabbit tibia. The upper 4 mm of the inserted implants was exposed, and bone regeneration was induced around the exposed area using a titanium chamber (height: 4 mm) containing particulate autogenous and bovine bone. After a 12-week healing period, the quantity and quality of bone regeneration around the implants were evaluated. Thirty specimens-10 specimens each from the turned, blasting and etching, and anodic oxidation surface groups with 0.6- and 0.4-mm-pitch sizes-were evaluated by histomorphometric analysis. Results: The vertical height and width of regenerated bone around blasting and etching and anodic oxidation surfaces were significantly greater than those around turned implants (P .05); the vertical heights of regenerated bone around the 0.4-mm-pitch sections of blasting and etching and anodic oxidation surfaces were significantly greater than those around the 0.6-mm-pitch sections (P .05). Both blasting and etching and anodic oxidation surfaces exhibited significantly greater bone-to-implant contact and bone volume at the implant thread than turned implants (P .05). However, there was no significant difference between the 0.6- and 0.4-mm-pitch sections. Conclusion: The findings of this study indicate that blasting and etching and anodic oxidation surfaces with a 0.4-mm-pitch design result in greater vertical ingrowth of regenerated bone than those with a 0.6-mm-pitch design. Keywords: anodic oxidation, blasting and etching, bone regeneration, exposed implant, implant pitch, surface features

Purpose: This systematic review evaluated the mean survival rate and marginal bone loss (MBL) of dental implants with ≤ 6 mm in length, across a time frame of 5 years. The overall prosthetic and biologic complications were evaluated, and their survival rates obtained. In addition, the complication rates of the splinted vs nonsplinted implants were assessed. Materials and Methods: An electronic literature search in PubMed (MEDLINE) and EMBASE (OVID) and Cochrane were performed, in addition to a manual search through all periodontics and implantology-related journals, up to October 2017, to identify relevant articles. Results: Out of 515 potentially eligible articles, 19 investigations assessing a total of 910 extra-short (≤ 6 mm) implants were included and further evaluated. After 5 years of follow-up, a mean survival rate of 94.1% (90% in the maxilla and 96% in the mandible) and a maximum bone loss of 0.53 mm were demonstrated. Additionally, a statistically significant difference in terms of bone loss was observed between tissue-level (0.12 mm) and bone-level implants (0.36 mm) at 12 months (P .01), but not between internal and external abutment connections (P = .17). The most commonly reported prosthetic complication was screw loosening. Finally, splinted implants showed less overall prosthetic complications (RR = 3.32; 95% CI: 1.9 to 5.7), screw loosening (RR = 15.2; 95% CI: 5.92 to 39.31), and implant failure (RR = 1.96; 95% CI: 0.8 to 4.8) than nonsplinted implants. Conclusion: Extra-short implants are a viable treatment alternative in ridges exhibiting atrophy, demonstrating a satisfactory survival rate, as well as a low rate of prosthetic and biologic complications across a 5-year follow-up. Additionally, splinting extra-short implants is associated with fewer prosthetic complications and lower implant failure rate compared with nonsplinted implants. Keywords: dental implants, screw loosening, short implants, single crown, splinted

Purpose: Real-time surgical navigation has been increasingly applied in implant placement. The initial registration procedures were found to substantially affect the overall accuracy, but the number and distribution of fiducial markers are yet undetermined. This study aimed to determine the minimal number and optimal distribution of fiducial markers to achieve clinically acceptable accuracy in surgical navigation for zygomatic implant placement by systematically analyzing the effects of different setups of fiducial markers on target registration error (TRE). Materials and Methods: A maxillary phantom with bone-anchored fiducial markers was scanned using cone beam computed tomography, followed by data processing on Brainlab, a commercially available navigation system. A total of 10 miniscrews were inserted in the edentulous maxilla for the configuration of the fiducial markers, with another two miniscrews as implant targets to assess the TRE in zygomatic bone. Data were then collected in nine configurations with distinct fiducial numbers and positions. Statistical analyses were performed with SPSS. Results: The accuracy of the surgical navigation system was found to depend on both the number and the position of fiducial markers. No significant difference was observed in accuracy among groups with eight fiducials and with a polygon span distribution (P > .05). When the fiducial number decreased to less than six, the markers inserted in a regular triangle were more precise than those in an inverse triangle configuration. When the number of fiducials was five with a polygonal distribution, a low TRE value of 0.59 mm was detected, which was comparable to the accuracy with more than eight fiducials in this study. Conclusion: A scattered distribution with a polygon span with at least five fiducial markers in the edentulous maxilla for registration seems to achieve acceptable TRE values with high accuracy for navigation in zygomatic implant placement. Keywords: accuracy, edentulous, navigation system, registration, zygomatic implant

Purpose: The possibility that the sympathetic nervous system (SNS) controls bone remodeling has been raised; however, the actual function of the SNS in osseointegration is still unknown. This study aimed to investigate the effect of chemical sympathectomy on peri-implant osseointegration in adult mice. Materials and Methods: Forty C57BL/6J mice (8-week-old) were divided into two groups: a sympathectomy group and a control group, which were administered 6-hydroxydopamine and saline, respectively, by intraperitoneal injection for 5 days. Then, the mice were exposed to implant surgery. Analyses of serum chemistry, microcomputed tomography, biomechanical test, and bone histomorphometry were employed at 2 and 4 weeks. Results: Compared with the control, the chemical sympathectomy group had a higher serum level of C-terminal collagen I cross-links but lower serum osteocalcin. After 4 weeks, peri-implant trabecular microstructure, including trabecular volume, trabecular thickness, the percentage of osseointegration, and bone-to-implant contact, was lower; however, the trabecular separation was higher in the sympathectomy group mice in comparison with the control group. In addition, the strength of bone-titanium integration measured by the biomechanical resistance test was lower. Furthermore, histomorphologic evidence revealed that the osteoclast counts were higher in the sympathectomy group, while the mineral apposition rate and the bone formation rate per bone surface were significantly lower. Conclusion: Within the limitations of this experimental study, the data showed that chemical sympathectomy has a negative effect in peri-implant osseointegration, suggesting that the SNS may need to be taken into consideration in terms of peri-implant bone healing. Keywords: chemical sympathectomy, implant, osseointegration, sympathetic nervous system

Purpose: The aim of this systematic review and meta-analyses was to evaluate fits of zirconia custom abutments and frameworks on implants and to identify the factors that influence their fits. Materials and Methods: An electronic search was conducted through PubMed (MEDLINE), Google Scholar, and Cochrane Central Registrar of Controlled Trials. The search was completed in August 2017. Series of meta-analyses were conducted to compare fits of zirconia custom abutments and frameworks on implants with metal abutments and frameworks. The interest variables were the interface gap and the rotational misfit of abutments and the vertical fit of frameworks. Results: Initially, a total of 672 articles were identified from the electronic search. After applying the inclusion criteria, 17 suitable articles were selected, including 9 studies on the fit of zirconia custom abutments and 8 studies on the fit of zirconia frameworks. There is a tendency for zirconia abutments to exhibit greater interface gaps and rotational misfits than metal abutments. Abutments produced by manual-aided designs/manual-aided manufacturing (MAD/MAM) exhibited inferior fits compared with those produced by computer-aided design/computer-aided manufacturing (CAD/CAM). Proprietary abutments had superior fits compared with nonproprietary abutments. Milled zirconia frameworks had insignificantly inferior fits compared with milled metal frameworks. Conclusion: Within the limitations of this study, custom zirconia abutments and nonproprietary abutments appeared to exhibit slightly inferior fits compared with metal abutments or abutments produced by the same implant company. However, the clinical significance of this difference is yet to be determined. The fit of milled zirconia frameworks is generally comparable to milled metal frameworks. Keywords: accuracy, CAD/CAM, interface gap, MAD/MAM, passive fit

Purpose: The purpose of this study was to survey clinicians' choice of peri-implant instrument selection and the application used to probe dental implants as well as to evaluate peri-implant probing force and pressure applied compared with that reported in current literature. Materials and Methods: Forty-eight clinicians (16 periodontists/periodontal residents, 16 restorative dentists, and 16 hygienists) participated in the study. A questionnaire to determine the frequency and method of probing dental implants was provided and subject to the chi-square test. Each participant was given a choice of three periodontal probes (Marquis, UNC-15, plastic) to use on the typodont, and the probing force was recorded blindly. The probing force and pressure data were analyzed with analysis of variance (ANOVA) among subject groups as well as probe types per site; where statistical differences (P .05) were detected, Tukey's post hoc test was applied. Results: The questionnaire resulted in a variety of answers, although the majority demonstrated an agreement on probing implants in everyday practice. There was no significant difference among provider groups in regard to instrument selection, probing forces, and pressure in both the maxilla and mandible, although the mean probing forces and pressures in all provider groups were higher than the suggested value reported in the literature. Conclusion: This study indicated that there are variations among clinical provider groups with regard to peri-implant probe instrument type used and forces applied, though these are not statistically significant. Probe tip diameter should be considered to avoid bleeding on probing false positives when probing dental implants, especially as the forces generally used by the clinicians may be higher than advised. Keywords: bleeding on probing, implant health, implant probing, probing pressure

Purpose: The aim of this study was to investigate a guided implant surgery procedure performed without any manual processes, by assessing the in vivo results following a digital planning and placement of dental implants using surgical templates. Materials and Methods: Eligible patients were screened and enrolled in this prospective clinical study. A cone beam computed tomography (CBCT) scan was acquired, and the remaining dentition and soft tissues were recorded by an intraoral scanner after enrollment. The CBCT data and intraoral scan were fused in the planning software. The prosthetic reconstructions were digitally designed by a prosthodontist, and the ideal position of the dental implants was determined. The surgical template was digitally designed based on this plan, and a guide design was exported and manufactured in a stereolithographic process. The entire surgical procedure was performed with the aid of the template. An intraoral scan was performed 10 days after stage-two surgery using scan bodies placed on the implants. Digital preoperative and postoperative models were compared, and the metric difference between the planned and achieved implant positions was calculated. Results: Twenty-seven implants were placed in 20 patients using tooth-supported surgical templates after a digital planning procedure. No implants were lost during the study period. The mean lateral deviation measured at the coronal point was 1.05 mm (SD: 0.59; range: 2.74 to 0.36). The mean lateral deviation measured at the apical point was 1.63 mm (SD: 1.05; range: 5.16 to 0.56). The mean depth displacement was + 0.48 mm (SD: 0.50; range: 1.33 to -0.52). The mean angle deviation was 3.85 degrees (SD: 1.83; range: 8.6 to 1.25). Conclusion: A simplified full digital planning procedure yields results comparable to conventional guided implant surgery. The main deviation between the planned and achieved implant positions in this prospective clinical study was angular. More clinical studies are needed to verify the procedure further. Keywords: clinical study, dental implant surgery, dental implants, digital treatment planning, guided implant surgery

Purpose: This study aimed to evaluate whether different surface modifications affect the dynamics of bone remodeling at the implant and the adjacent local bone. Materials and Methods: Seventy-two dental implants with different surfaces (smooth and rough control [smCtrl; rCtrl], smooth and rough + O₂-plasma spray [smPlas; rPlas], smooth and rough + nanocrystalline SiO₂-hydroxyapatite coating [ncSiO₂HA] + O₂-plasma spray [smNB-C; rNB-C]; each n = 12) were bilaterally inserted into the femora of 36 New Zealand white rabbits. Intravital fluorochrome labeling was performed to visualize the dynamics of bone formation. The objectives were quantification of bone-to-implant contact (BIC [%]) at 2 and 4 weeks and the dynamic bone formation (dbf [%]) at the implants' adjacent local bone within 1, 2, and 3 weeks. Results: After 2 weeks, BIC was significantly higher for both smNB-C (BIC: 59% ± 2% SEM) and rNB-C (BIC: 66% ± 3% SEM) compared with controls (BIC: 42% ± 1% SEM; P .005). After 4 weeks, BIC for rNB-C (65% ± 2%) was superior to all test groups (BIC: 39% ± 2% SEM; P = .012). Regarding dbf (%), neither within 1 (P = .88), 2 (P = .48), nor after 3 weeks (P = .36) did any differences occur among the groups, even in accordance to the implant level. Conclusion: Although distance osteogenesis seems crucial for the development of secondary stability, and thus, of osseointegration, it apparently is not affected by a bioactive ncSiO2HA surface coating. Changing the surfaces' release kinetics and composition may increase distance osteogenesis. Keywords: adjacent bone formation, distance osteogenesis, intravital labeling, ncSiO2HA-coating, secondary stability, surface modification

Purpose: Immediate dental implant loading has been investigated with favorable results. However, short implants have not been investigated in this treatment option. This study compared the clinical outcomes and survival rates of immediately loaded short and conventional-length dental implants in replacing mandibular molar teeth. Materials and Methods: Forty-six implants (23 short dental implants and 23 conventional dental implants) in 46 patients were included in the study. Provisional computer-aided design/computeraided manufacturing (CAD/CAM) ceramic crowns were cemented to the abutments and immediately loaded. Several clinical parameters were recorded and statistically analyzed at 4-month and 1-year follow-up. Results: Two short implants lost integration, and one conventional implant failed. No statistically significant difference between the two implant types was found (P = 1.00). Minor complications were recorded; three provisional crown fractures were found in the short implant group and two provisional crown fractures in the conventional implant group. There was no significant difference in implant stability quotient values for short or conventional implants between baseline (short: 73.86 ± 2.38, conventional: 75.05 ± 3.26, P = .088), 4 months after loading (short: 72.37 ± 1.35, conventional: 72.89 ± 1.87, P = .165), and 1 year after loading (short: 74.60 ± 2.03, conventional: 75.35 ± 2.66, P = .296). The mean marginal bone level loss 4 months postloading was 0.28 ± 0.29 mm for short implants and 0.25 ± 0.25 mm for conventional implants (P = .73), and at 1 year postloading was 0.33 ± 0.47 mm for short implants and 0.26 ± 0.27 mm for conventional implants (P = .554); there was no statistical difference between the two implant types. Conclusion: The immediate loading of short implants is comparable to conventional-length implants in terms of implant survival, marginal bone level change, and implant stability quotient value. Keywords: CAD/CAM, immediate loading, short implant, standard implant

Purpose: The goal of this investigation was to define time-dependent peri-implant tissue changes at implants with different abutment interface designs. Materials and Methods: Participants requiring replacement of single maxillary anterior and first premolar teeth were recruited and treated under an institutional review board (IRB)-approved protocol. Implants, titanium abutments, and provisional crowns were placed in healed ridges 5 months following preservation after tooth extraction with recombinant human bone morphogenetic protein-2 (rhBMP-2). Twelve weeks later, permanent crowns were placed on patient-specific abutments and evaluated at 6, 12, and 36 months following implant placement. Clinical and radiographic assessments of abutments and crowns, peri-implant mucosa, and marginal bone levels were recorded. Results: The 3-year assessment included 45 conical interface (CI), 34 flat-to-flat interface (FI), and 32 platform-switched interface (PS) implants in 111 participants. At 3 years, the mean marginal bone level (MBL) change at CI, FI, and PS implants was -0.12, -1.02, and -1.04 mm, respectively (P = .014). "Zero" MBL loss or gain was measured over the 3-year period at 72.1% CI, 3.0% FI, and 16.6% PS implants. There was a minor change (0.0 to 0.3 mm) in peri-implant mucosal zenith positions over time and between groups. Eighty percent of CI implants, 61% of FI implants, and 84% of PS implants were observed to have a clinically stable periimplant mucosal zenith position with less than 0.5 mm of measured recession. Over the 36-month period, there were no significant changes in the location of mesial or distal papilla in any group. Conclusion: Significant differences in MBLs were observed at different implant interfaces. Conical implant interfaces, but not flat-to-flat or platform-switched implant interfaces, were associated with no MBL changes over 3 years. Peri-implant mucosal stability was generally observed. The relationship of marginal bone responses and peri-implant mucosal stability requires further evaluation. Keywords: esthetics, immediate provisionalization, marginal bone levels, peri-implant mucosa

Purpose: The aim of this retrospective cohort study was to assess the effects of annual maintenance over a 7-year period on the peri-implant health of patients rehabilitated with overdentures using clinical and radiographic parameters. Materials and Methods: In order to be considered for inclusion in the study, patients had to have been rehabilitated with overdentures that had at least two implants placed in the mandible and four implants in the maxilla. Patients were divided into two groups: group 1 comprised individuals who had undergone annual maintenance over the previous 7 years, and group 2 comprised those who had not attended any dental appointment over the previous 7 years. All patients were submitted to clinical peri-implant examinations and radiographic assessments. Results: Sixty-six patients received 396 implants of the external hexagon type, 132 in the mandible and 264 in the maxilla. Group 1 (44 patients with 264 implants) had a mean probing depth of 2.72 mm, while group 2 (22 patients with 132 implants) had a mean probing depth of 3.10 mm. It can be concluded that the mean of the variable probing depth is influenced by the presence of bleeding (P = .0005) and the implementation of maintenance (P = .0188), whereas plaque and local variables were not otherwise significant (P = .0605 and .0796, respectively). Conclusion: In this study, it was possible to observe better clinical conditions in individuals who had attended annual appointments for maintenance purposes. Keywords: alveolar bone loss, dental implantation, periodontal index

Purpose: The aim of this study was to evaluate the proximal contact alterations between implant-supported restorations and adjacent natural teeth with the passage of time. In addition, potential factors influencing proximal contact loss were also evaluated. Materials and Methods: Patients in need of implant-supported restorations in the posterior region were included. Proximal contact was divided into the following three groups: tight (group T), appropriate (group A), and open (group O). It was judged by dental floss (OralB, Essentialfloss) at restoration insertion and 1-year follow-up. In addition, patients' age, sex, implant sites, restoration type, retention type, and parafunction were recorded. Results: At 1-year follow-up, 74 patients with 144 proximal contacts were included. After 1-year follow-up, the proximal contact loss rate was 24.3%, and 45.1% of proximal contacts did not show any alterations. The proximal contact loss rates in group T at baseline were significantly lower than those in group A at baseline (12.9% and 32.9%, respectively; P = .03). The proximal contact loss rates in the mandible were significantly higher than those in the maxilla (37.2% and 9.1%, respectively; P .01). Other variables did not show a significant effect on proximal contact loss. Conclusion: Based on the current evidence, the proximal contact loss between implant-supported restorations and the adjacent teeth was frequent in the short term. It is helpful to reduce the proximal contact loss rate in the short term by making the proximal contact slightly tense at restoration insertion. Evaluation of proximal contact should be monitored carefully, especially in the mandible. Keywords: adjacent teeth, dental implants, proximal contact loss

Purpose: This 10-year retrospective study aimed to report implant bone changes in completely edentulous patients after a mandibular immediate loading protocol using two ball attachments. Materials and Methods: This study was initially designed as a prospective 1-year cohort study, then extended with a 10-year retrospective evaluation of implant bone change. In the first part of the study, 43 edentulous patients wearing satisfactory maxillary and mandibular dentures for at least 3 months were included. Two interforaminal implants (Brånemark system, Nobel Biocare) were placed symmetrically in the anterior mandible using a surgical template and a torque greater than 40 Ncm. Immediately following surgery, 2.25-mm-diameter ball abutments were screwed to the implants, and their matrices (Dalbo Plus, Cendres et Métaux) were incorporated in the denture base. In an initial 1-year study, clinical recalls were scheduled 3, 6, and 12 months after implant placement with a team of two investigators. The follow-up consisted of a clinical examination and a standardized radiographic assessment of the vertical bone change. Implant stability was then monitored. The patient satisfaction was evaluated with a questionnaire before and 3 months after loading. The second part of the study occurred 10 years after the inclusion, as patients were recalled for an implant bone change monitoring. Results: The included patients were 28 to 80 years of age (mean: 61 ± 11.4 years). Three out of 86 implants failed during the healing phase (survival rate of 96.5% [90.1%, 99.2%]). Implant stability was maintained all along the 1-year follow-up (Δ = 73.33, 95% CI [72.39 to 74.26], P = .032). The mean radiographic bone loss was 0.27 ± 0.35 mm at 3 months after surgery, 0.47 ± 0.42 mm after 1 year, and 0.95 ± 0.98 mm after 10 years. General visual analog scale satisfaction was increased by 25 units with the treatment. No patients were lost to follow-up at 1 year, but five were lost at 10 years. Conclusion: This protocol of immediate loading of two unsplinted mandibular implants in overdenture patients using ball attachments is a clinically viable treatment with a high implant success rate and improved satisfaction. Keywords: ball abutment, immediate loading, implant overdenture, implant success, unsplinted implants

Purpose: This randomized, controlled, split-mouth trial with a 3-year follow-up was carried out to compare radiologic changes of crestal bone level (CBL) between splinted tissue-level implants restored by platform matching and bone-level implants restored by platform switching. Materials and Methods: Periapical radiographs were taken to evaluate the peri-implant crestal bone changes at baseline (implant restoration), at 1 year, and at 3 years after the definitive restoration. Results: Thirty-five patients requiring a partial fixed dental prosthesis supported by two implants had their sites randomized according to receiving both implant types. Fifty tissue-level implants restored by platform matching, as control implants, and 50 bone-level implants restored by platform switching, as test implants, were placed. For baseline to 3 years, crestal bone changes were 0.18 ± 0.46 mm (P = .043) in the control group and 0.14 ± 0.35 mm (P = .514) in the test group. The mean differences between groups were as follows: baseline to 1 year, 0.07 ± 0.23 mm (95% CI: -0.034, 0.185); 1 to 3 years, 0.01 ± 0.01 mm (95% CI: -0.055, 0.074); baseline to 3 years, 0.04 ± 0.11 mm (95% CI: -0.080, 0.150). No statistically significant differences in CBL at baseline to 1 year (P = .269), 1 year to 3 years (P = .811), and baseline to 3 years (P = .513) were observed. Conclusion: In this trial, CBL changes in the tissue-level control group were statistically significant only between the baseline and 3-year follow-up. Meanwhile, CBL changes in the bone-level test group were not statistically significant in the different times studied. No statistically significant difference in CBL between two implant types was observed. Keywords: bone-level implant, marginal bone loss, platform switching, split-mouth, tissue-level implant

Purpose: This cross-sectional study aimed to analyze the relation between peri-implant soft tissue biotype (STB) and different levels of peri-implantitis severity, and to identify the possible risk indicators that affect the severity of peri-implantitis with regard to STB around dental implants. Materials and Methods: Eightyseven patients with 229 implants were diagnosed with peri-implantitis and recruited to the study. Clinical and radiographic parameters including Plaque Index (PI), probing depth (PD), bleeding on probing (BOP), gingival/ mucosal recession (GR/MR), clinical attachment level (CAL), and marginal bone loss (BL) were analyzed. The periodontal status was assessed, and the levels of peri-implantitis severity were defined. These parameters were compared among the peri-implant STB groups (thick and thin biotype). To evaluate the effect of possible risk indicators on the levels of severity of peri-implantitis, univariate and multivariate logistic regression analyses were conducted for thick and thin biotype groups. Results: The mean values of BOP, MR, CAL, and marginal BL were significantly lower for the thick group compared with the thin group (P .05). For PI and PD values, no significant differences were found between the groups (P > .05). Moreover, multivariate analysis revealed statistically significant associations between peri-implantitis severity and the risk indicators of maintenance therapy compliance and current periodontitis for the thin group (P .05). Conclusion: The thin biotype could be more prone to an increase in the severity of peri-implantitis. Maintenance therapy compliance and current periodontitis could be important risk indicators that affect the progression of the severity of peri-implantitis for implants where keratinized mucosa is thin or absent. Keywords: keratinized mucosa thickness, maintenance, peri-implantitis, periodontitis, risk factors

Purpose: This case series illustrates a simplified soft tissue management, namely, the subperiosteal periimplant augmented layer (SPAL), to increase hard and soft tissue dimensions at the most coronal portion of an implant. Materials and Methods: Twenty-seven implants in 16 patients presenting either a buccal bone dehiscence or a thin ( 1 mm) buccal cortical bone plate (BCBP) were consecutively treated. Briefly, a split-thickness flap (namely, the mucosal layer) was raised on the buccal aspect. Then, the periosteal layer was elevated from the bone crest. A full-thickness flap was elevated on the oral aspect. After implant site preparation, a xenograft was used to fill the space between the periosteal layer and the BCBP and/or exposed implant surface and, if present, to completely correct the bone dehiscence. The periosteal layer was sutured to the oral flap. The mucosal layer was coronally advanced and sutured to submerge both the graft and the implants. At 3 to 6 months, a re-entry procedure for implant exposure was performed. Results: Healing was uneventful, with no signs of infection in all cases. A wound dehiscence was observed in three implants in two patients at 2 weeks postsurgery. Out of 15 implants showing an initial bone dehiscence, 12 implants (80%) showed a complete resolution, with a subperiosteal tissue thickness (SPTT) at the time of re-entry of 3.1 ± 1.0 mm. Three implants presented a residual dehiscence of 1 mm (two implants) or 2 mm (one implant), with a SPTT of at least 2 mm. Out of 12 implants showing a thin BCBP at implant placement, 10 implants (90%) revealed a SPTT ≥ 2 at the time of re-entry. Two implants revealed a SPTT of 1 mm. Conclusion: The SPAL technique represents a valuable simplified surgical approach associated with a low rate of complications in the treatment of peri-implant bone dehiscence and in the horizontal augmentation of peri-implant tissue thickness. Keywords: alveolar bone loss, bone dehiscence, implant dentistry, reconstructive surgical procedures, surgical flaps, wound healing

Purpose: To evaluate the in vivo accuracy of dental implants placed using a dynamic computer-aided dental implant (CAI) navigation system. The impact of various factors on accuracy was also analyzed. Materials and Methods: A retrospective in vivo study was performed during the period of October 2015 to December 2017. Data were obtained on all implants placed during this time frame. A chart review was conducted to identify the type of flap, number of implants placed, number of patients treated, and factors related to the description of edentulism (partial or complete). To evaluate accuracy outcomes, the preoperative cone beam computed tomography (CBCT) plan was volumetrically registered to a post-implant placement CBCT scan. Deviations between the planned and placed implant positions were analyzed. Data were statistically analyzed for factors that may affect the accuracy during usage. Results: Data were obtained on 231 implants placed in healed ridges using a flapless or minimal flap approach under dynamic guidance by a single surgeon. In the 89 arches operated on, 28 (125 implants) were fully edentulous. For all implants, the mean (SD) discrepancies were: 0.71 (0.40) mm for entry point (lateral) and 1.00 (0.49) mm at the apex (3D). The mean angle discrepancy was 2.26 degrees (1.62 degrees) from actual vs planned implant positions. The accuracy measurements for partially edentulous patients using a thermoplastic stent attachment and for fully edentulous patients using a mini-implant-based attachment were nearly identical. No significant accuracy differences were found between implant positions within the different sextants. Guided insertion of the implant itself reduced angular and apex location deviations. The accuracy of implant placement improved during the study period, with the mean entry point and apex deviation as well as overall angle discrepancy measured for the last 50 implants being better (0.59 mm, 0.85 mm, and 1.98 degrees, respectively) compared with the first 50 implants (0.94 mm, 1.19 mm, and 3.48 degrees, respectively). Conclusion: Dynamic surgical navigation is an accurate method for executing CBCT-based computer-aided implant surgery. In addition, an increased experience level of the surgeon with dynamic navigation appears to improve accuracy outcomes. Keywords: computer-aided implantology, dental implant placement accuracy, dental navigation, dynamic guided implantology, dynamic navigation, static guided implantology

Purpose: The purpose of this study was to analyze the implant stability quotient (ISQ) values recorded by three commercially available resonance frequency analysis (RFA) instruments from a large cohort of implants in order to determine their accuracy and agreement with one another both for static measurements of ISQ at a given time and for change in ISQ over time. Materials and Methods: A cohort of n = 210 implants had their primary stability, secondary stability, or both evaluated in both the mesiodistal (MD) and buccolingual (BL) directions by means of ISQ using three different RFA instruments: Osstell ISQ (O_ISQ), Osstell IDx (O_IDX), and the Penguin (PG). ISQ values were recorded both at the time of implant placement and at 3 months postinsertion prior to definitive restoration. All values were tabulated for a blinded statistical analysis using Bland-Altman plots to determine if the outcome values were in agreement both for primary and secondary stability. In addition, a subgroup was evaluated to determine if change in ISQ was also in agreement. An intraclass correlation (ICC) was used to measure the reliability of the measurements for each instrument. Results: Bland-Altman plots confirmed that there was a high agreement for MD values between O_ISQ and O_IDX, with 72.7% of readings being within one ISQ unit and 94.7% within four units. Comparing PG to OISQ, the respective values at one and four units were 15.3% and 82.3%, and comparing PG to O_IDX, the respective values were 16.3% and 85.2%. In general, there was a greater uncertainty in the BL values having wider variability and demonstrating less agreement between instruments, with the percentage of readings falling within four units reducing to 85.9% (O_ISQ vs O_IDX), 72.3% (PG vs O_ISQ), and 74.3% (PG vs O_IDX). For change in ISQ over time, 92.3% of values were in agreement to within four units between instruments O_ISQ and O_IDX in the MD direction and 73% in the BL direction. The respective percentage changes of values in agreement within four units for PG vs O_ISQ were 76.9% and 60.3% and for PG vs O_IDX were 80% and 53.8%. The paired t test from mixed effects revealed that there was a significant difference for mean MD values between PG vs O_ISQ; P = .015 with a mean 0.823 units higher was recorded for PG. Similarly for PG vs O_IDX, P = .008 with a mean 0.871 units higher was recorded for PG. For mean BL values between PG vs O_IDX, P = .000 with a mean 1.161 units higher was recorded for PG, and finally, for O_ISQ vs O_IDX, P = .005 with a mean 0.597 units higher was recorded for O_ISQ. However, the maximum upper and lower bound estimated bias between any two instruments was only 1.86 units and 0.46 units both for PG vs O_IDX in the BL direction, and it is doubtful that this is of clinical relevance even if statistically significant. ICC revealed that for static MD measurements, there was an 85% reliability between all three instruments (range: 79% to 97%). For BL measurements, the reliability value was 66% (range: 69% to 71%). When considering ICC for changes in ISQ values over time in the MD direction, there was a 70% reliability between all three instruments (range: 58% to 94%). For BL measurements, the reliability value was 58% (range: 46% to 91%). Conclusion: Differences exist between instruments to some extent, most notably between the Penguin and the two instruments from Osstell, which showed good agreement to each other. While differences in evaluating ISQ with the PG were statistically significant, they were less than 1.86 units at the upper bound limit, and it is doubtful that this is of clinical relevance. Increased variability and reduced reliability for BL values render these less clinically sound when trying to assess primary stability. Keywords: dental implants, implant stability quotient, ISQ, primary stability, resonance frequency analysis

Purpose: To evaluate the influence of the height of the antrostomy on dimensional variations of the elevated space after sinus floor elevation. Materials and Methods: Twenty-four healthy volunteers planned for sinus floor elevation were included in the study. An antrostomy of either 4 mm (group A) or 8 mm (group B) in height was prepared in the lateral wall of the sinus. Cone beam computed tomography scans (CBCTs) were taken before surgery (T0) and after 1 week (T1) and 9 months (T2). Dimensional variation analyses were performed. Results: The CBCTs of 10 patients per group were evaluated. After 1 week (T1), the sinus floor was found elevated in the middle region by 12.0 ± 2.3 mm in group A, while in group B, the height was 11.8 ± 2.1 mm. After 9 months (T2), the respective heights were 9.9 ± 2.4 mm and 8.9 ± 2.7 mm, with a reduction of -2.1 ± 2.2 mm in group A and -3.0 ± 2.6 mm in group B. The area in a central position was reduced by 25.5% to 34.2%, showing a slightly higher shrinkage in group B compared with group A. However, no statistically significant differences were found between the two groups. Conclusion: In maxillary sinus floor elevations performed by the lateral approach, the size of the antrostomy did not affect the clinical and radiographic outcomes. Keywords: antrostomy size, biomaterial, cone beam tomography, maxillary sinus, sinus augmentation, sinus dimension, sinus height

Purpose: The purpose of this study was to evaluate the new graft material biphasic calcium phosphate, composed of 60% hydroxyapatite and 40% β-tricalcium phosphate, and deproteinized bovine bone mineral, which is established as a predictable graft material for maxillary sinus augmentation. Materials and Methods: Maxillary sinus augmentation was performed with different bone materials. Bone biopsies were performed on tissue harvested from the future implant bed using a trephine bur at 6 months after maxillary sinus augmentation. Resonance frequency analysis was performed immediately and at 6 months after the implant placement. Microcomputed tomography and histomorphometric analysis were performed in all patients. Results: Fifty-six patients (60 sinuses) were included in the study. At 6 months postoperative, 31 biopsies were performed on tissues harvested from the calcium phosphate, and 29 biopsies on tissues from the bovine bone grafts. There were no implant failures during the 21-month mean follow-up period. The overall implant stability quotient values were higher than 60, and gradually increased for 6 months. Higher new bone volume fraction and new bone surface density were observed in the calcium phosphate group compared with the bovine bone group. In contrast, residual bone graft volume in the bovine bone group was higher than that in the calcium phosphate group. Nevertheless, there were no significant differences between groups in the microcomputed tomography and histomorphometric parameters. Conclusion: Within the limitations of the study, both graft materials demonstrated similar biocompatibility and osteoconductivity in the maxillary sinus augmentation. Keywords: bone grafting, bone regeneration, bone substitutes, clinical trial, dental implants

A common site to harvest autogenous bone is the posterior mandible (ramus). Bone from this area may be cortical or cancellous in nature with different levels of osteogenic potential. Management of deficient alveolar ridges must be based upon anatomical and biologic characteristics of the donor bone from the ramus. This technical report provides all aspects of the presurgical planning, topographic features of autogenous ramus blocks, and loading concepts according to the biologic characteristics and resorption properties of these blocks. Long-term data from clinical cases are presented improving the clinical outcomes with high predictability. Keywords: bone block, bone formation, osseoconduction, osteoinduction

The purpose of this case report was to assess whether patient-specific implants (PSI, Xillocs) and soft tissue flaps contribute in reconstructing large mandibular defects. Five patients whose medical situation and history were not suitable for free microvascular bone flaps received PSI implants and were subsequently evaluated. The mean follow-up time was 12 months. The excellent fit, convenient surgery, and esthetic outcome were seen as the major advantages. PSIs can, in the authors' experience, be considered as a useful alternative provided they are well embedded by viable tissue and attached to vital resection margins of the recipient bone. Keywords: 3D printed titanium implant, jaw prostheses, mandibular reconstruction, osteoradionecrosis, patient-specific implant