The International Journal of Oral & Maxillofacial Implants, 06/2014

Purpose: Because of the immediate loading implant process, clinicians must consider implant primary stability issues before initiating surgery. The aim of this study was to assess the correlation between the bone density assessed by computed tomography (CT) images and the primary stability of two implant designs, as determined by resonance frequency analysis (RFA). Materials and Methods: Sixty implants (30 NobelActive, 30 NobelSpeedy [Nobel Biocare]) were placed in five totally edentulous fresh cadaver maxillae. Before surgery, CT images were analyzed and bone densities measured. Implant primary stabilities (measured in implant stability quotient [ISQ] units) were determined along the buccolingual and mesiodistal axes by RFA. Correlations were assessed using the Pearson correlation test. Results: Bone densities were similar near NobelActive and NobelSpeedy implants: 434.67 (± 220.53) versus 479.87 (± 209.05) Hounsfield Units (HU). Bone densities and NobelActive primary stabilities were highly correlated with ρ = 0.74 (P = .000) and ρ = 0.78 (P = .000) for the buccolingual and mesiodistal axes, respectively. An association was found between the 350 HU and 50 ISQ values, confirming good primary stabilities. For NobelSpeedy implants, no correlation was found regardless of the axis, with ρ = -0.07 (P = .72) (buccolingual) and ρ = -0.10 (P = .59) (mesiodistal). However, poor and good stabilities were observed in the anterior and posterior areas, respectively. Conclusion: This study revealed variations in primary stabilities depending on the implant design. The primary stability of conical implants with a double-lead thread design (NobelActive) seemed bone density-dependent regardless of the area of the maxilla, whereas the primary stability of nearly parallel-wall implants with a classical thread design (NobelSpeedy) seemed dependent on anatomical morphology. These results raise questions about the specific roles of the implant shape and thread design depending on the bone density and alveolar morphology. Keywords: bone density, implant design, implant primary stability, resonance frequency analysis

Purpose: The authors conducted a meta-analysis to determine the effect of a history of periodontitis on the long-term survival of dental implants. Materials and Methods: An electronic search of PubMed and a supplemental manual search were conducted. Studies published in English through March 2013 were included in the meta-analysis. Survival rates, success rates, periodontal status, types of periodontitis, most recent follow-up time, and other information were extracted and analyzed. Results: Thirteen studies involving 2,011 patients and 6,802 implants were included in the meta-analysis. The results revealed that a history of periodontitis, especially aggressive periodontitis, is associated with significantly higher risks of long-term implant failure versus a healthy periodontium (risk ratio [RR] = 1.03, 95% confidence interval [CI] = 1.02 to 1.04). Based on the limited number of included articles, a subgroup analysis showed that a history of periodontitis had no statistically significant effect on implant survival up to 100 months of follow-up (RR = 1.03, 95% CI = 0.99 to 1.06); however, it did significantly affect implant survival within a period of 101 to 200 months (RR = 1.03, 95% CI = 1.02 to 1.04). Some implant systems also significantly influenced the correlation between a history of periodontitis and implant survival. Conclusion: Within the limitations of this meta-analysis, a history of periodontitis is estimated to be a statistical risk factor for the long-term survival of dental implants. This negative effect would be most evident in patients with aggressive periodontitis, severe periodontitis, or after a longer follow-up. Keywords: implant survival, implants, meta-analysis, periodontitis, risk factors

Purpose: To compare the accuracy and reproducibility of digital versus conventional dental impressions and fabrication techniques for single units and full-arch implant frameworks. Materials and Methods: A total of 24 samples, divided into four groups, were created using conventional and digital implant impression/fabrication techniques: group 1 (conventional single implant), group 2 (digital single implant), group 3 (conventional complete arch), and group 4 (digital complete arch). All impressions were made at the abutment level. Marginal fit measurements were made using an optical microscope at two points (buccal and lingual) for each sample. Statistical analysis was performed using F and t tests (α = .05). Results: For single implants, the conventional impression/fabrication pathway resulted in a mean marginal discrepancy of 24.1 µm compared to 61.43 µm for the digital impression/fabrication pathway. For full-arch frameworks, the conventional impression/fabrication pathway resulted in a mean marginal discrepancy of 135.1 µm compared to 63.14 µm for the digital technique. Conclusion: The conventional pathway resulted in a smaller marginal discrepancy for single-implant frameworks. In contrast, the digital pathway resulted in a smaller marginal discrepancy for full-arch implant frameworks. Keywords: CAD/CAM, digital impression, framework, implant, iTero, marginal accuracy

Purpose: Variable abutment displacement could potentially affect proximal contacts, incisal edge position, or occlusion of implant-supported prostheses. This study aimed to measure and compare displacements of splinted and nonsplinted restorations into implants featuring internal conical connections as screws were tightened by hand or by torque driver. Materials and Methods: A stereolithic resin model was printed using computed tomography data from a patient missing mandibular left first and second molars. Two 5.0 × 11-mm implants were placed in the edentulous site using a surgical guide. Two sets (splinted and nonsplinted) of gold screw-retained prostheses were made indirectly to fit the implants in the stereolithic model representing the patient. The axial position of the crowns relative to a fixed location on the model was recorded following hand tightening using the three-dimensional image correlation technique and image correlation software. A pair of high-resolution digital cameras provided a synchronized view of the model during the experiment. Relative crown positions were again recorded after tightening with a torque driver to 25 Ncm. Testing was repeated randomly three times for each set of crowns. Displacement data after torque tightening were compared using a factorial analysis of variance with JMP 9.0 software (SAS) followed by a Tukey-Kramer post hoc test (α = .05). Interproximal contacts were evaluated using an 8-μm tin foil shim after tightening by hand and torque driver. Results: Displacements for splinted and nonsplinted restorations differed only in a buccal direction. The nonsplinted crowns displaced significantly more than splinted crowns. Discernible differences were observed for the tin foil shim when dragged through proximal contacts following hand versus torque tightening. Conclusion: Differences between screw tightening by hand or torque driver should be taken into consideration during laboratory and clinical adjustments to prevent esthetic and functional complications. Keywords: displacement, implant, internal connection, screw-retained

Purpose: Peri-implant osteogenesis is reported to be impaired in patients with diabetes. The current study tested the hypothesis that ultraviolet (UV) treatment of titanium, or photofunctionalization, is able to mitigate the impaired osseointegration associated with type 2 diabetes. Materials and Methods: Untreated and photofunctionalized titanium implants were placed into the femurs of genetically modified rats with a close phenotypic resemblance to human type 2 diabetes, as characterized by late-onset hyperglycemia and obesity. Implants were photofunctionalized with UV light for 15 minutes immediately before placement. The strength of osseointegration was evaluated using a biomechanical push-in test, and the tissue-implant interface was examined using scanning electron microscopy and energy-dispersive spectroscopy. Results: Photofunctionalization converted implants from hydrophobic to superhydrophilic. Photofunctionalizationinduced hemophilicity was also confirmed during surgery. The strength of osseointegration of photofunctionalized implants was significantly greater than that of untreated implants, by 1.8 and 3 times, at weeks 2 and 4 of healing, respectively. Osseointegration of photofunctionalized implants in diabetic animals was even stronger than that of untreated implants placed in normal animals throughout the healing period. Photofunctionalized implants placed in diabetic rats were extensively covered with calcium- and phosphorusrich tissue that masked the titanium signal. Conclusion: Photofunctionalization accelerated and enhanced levels of osseointegration and overcame impaired osseointegration in a rat model of type 2 diabetes. Further prospective studies are warranted to establish the clinical efficacy of photofunctionalization in patients with diabetes. Keywords: bone-titanium integration, dental and orthopedic implants, hydrophilicity, photofunctionalized implants, ultraviolet radiation

Purpose: To analyze available evidence on the incidence of anatomical variations or disease of the maxillary sinuses as identified by cone beam computed tomography (CBCT) in dentistry. Materials and Methods: A focused question was developed to search the electronic databases MEDLINE, EMBASE, the Cochrane Oral Health Group Trials Register, and CENTRAL and identify all relevant papers published between 1980 and January 19, 2013. Unpublished literature at ClinicalTrials.gov, in the National Research Register, and in the Pro-Quest Dissertation Abstracts and Thesis database was also included. Studies were included irrespective of language. These results were supplemented by hand and gray literature searches. Results: Twenty-two studies were identified. Twenty were retrospective cohort studies, one was a prospective cohort study, and one was a case control study. The main indication for CBCT was dental implant treatment planning, and the majority of studies used a small field of view for imaging. The most common anatomical variations included increased thickness of the sinus membrane, the presence of sinus septa, and pneumatization. Reported sinus disease frequency varied widely, ranging from 14.3% to 82%. There was a wide range in the reported prevalence of mucosal thickening related to apical pathology, the degree of lumenal opacification, features of sinusitis, and the presence of retention cysts and polyps. More pathologic findings in the maxillary sinus were reported in men than in women, and the medial wall and sinus floor were most frequently affected. Conclusion: CBCT is used primarily to evaluate bony anatomy and to screen for overt pathology of the maxillary sinuses prior to dental implant treatment. Differences in the classification of mucosal findings are problematic in the consistent and valid assessment of health and disease of the maxillary sinus. Keywords: cone beam computed tomography, dental implants, maxillary sinus, mucosal thickness, sinus floor elevation, sinus membrane

Purpose: The aim of this study was to conduct a systematic review and meta-analysis to evaluate the influence of cantilevers upon implant-supported fixed partial dentures on marginal bone loss (MBL) and prosthetic-related complications. Materials and Methods: An electronic literature search was conducted in the PubMed database by two reviewers (LTM and AM) for articles written in English from June 2003 to January 2013 that were prospective human clinical trials with the clear purpose of appraising the effect of implant-supported fixed partial prostheses on peri-implant bone level and prosthetic complications. Data from the selected studies were extracted to carry out the statistical analysis. Results: Following the method described earlier, from initial research of 643 studies, 4 human clinical studies met the inclusion criteria and provided enough data to include them in the present meta-analysis. For the overall data, the pooled weighted mean (WM) of the MBL was 0.72 mm (range, 0.49 to 1.10 mm), with a 95% confidence interval (CI) of 0.36 to 1.08 mm. For the chi-square test, P = .60, representing a low heterogeneity among studies. MBL around implant-supported restorations with and without cantilevers was not found to be significant between both groups. The weighted mean difference (WMD) was 0.10 mm (favoring the noncantilever group), with a 95% CI = −0.18 to 0.39 mm (P = .47). For the chi-square test, P = .97, also indicating a low degree of heterogeneity between the studies. Conclusion: The dearth of scientific evidence in this matter does not permit clear conclusions to be drawn. However, within the limitations, marginal bone loss does not seem to be influenced by the presence of cantilever extensions. Moreover, minor technical complications were found when a cantilever was present when compared to the control groups. Keywords: cantilever, dental implant, endosseous implant, fixed prosthesis, implant-supported prosthesis, partial fixed prosthesis

Purpose: The primary objective of this pilot study was to evaluate the effectiveness of biphasic calcium phosphate (BCP) covered with a polyethylene glycol (PEG) membrane in the regeneration of 5-mm-diameter defects created in the calvaria of Wistar rats and compare this with the regeneration of defects covered only with the PEG membrane. Materials and Methods: Two 5-mm-diameter parietal defects were created in seven Wistar rats. The control defect in the left parietal bone was covered with an experimental PEG membrane (Straumann MembraGel); the test defect in the right parietal bone was filled with BCP (Straumann BoneCeramic) and covered with the same membrane. After a healing period of 2 months, the animals were sacrificed, and the samples were processed for histologic and histomorphometric analysis. Results: The test defects regenerated with BCP and covered with the PEG membrane had a percentage of new bone formation area of 61.7% ± 14.6%, and the control defects obtained mean new bone area of 57.3% ± 21.8%. The difference between groups was not statistically significant. The BCP did not reveal osteoconductive properties, and few particles were fully incorporated into the newly formed bone. The BCP maintained the space, and there was extremely low particle resorption during the healing period. The PEG membrane remained intact. Conclusion: There were no statistically significant differences between the test and control groups. BCP did not exhibit osteoconductive properties. Keywords: animal studies, biphasic calcium phosphate, guided bone regeneration, guided tissue regeneration, polyethylene glycol, Wistar rat

Purpose: The aim of this study was to identify the different techniques of cementation (half filling, practice abutment, and venting) that will reduce the amount of retained cement and the effect of these techniques on retention of implant-supported prostheses. Materials and Methods: Thirty implant-abutment assemblies were prepared and were subdivided further into three groups: half filling, practice abutment, and venting techniques. Crowns were prepared for each sample and cemented according to the respective techniques. The retention values were then determined using a universal testing machine, and the net weight of the retained cement was determined using a digital scale. Results: Analysis of variance (ANOVA) tests revealed that there was not a significant difference in the retention values of the three cementation techniques, but a significant difference was observed in the amount of retained excess cement. Tukey honestly significant difference tests further showed that there was a significant difference in retained excess cement between the half-filling technique vs the venting and practice abutment techniques. Conclusion: The venting and practice abutment techniques are suitable methods for reducing retained excess cement with optimal retention values. Keywords: dental implant, cementation, venting, practice abutment, retention, residual cement

Purpose: Micromotion at the implant-abutment level has been reported to be a major determinant of longterm implant success, as technical problems ranging from screw loosening to screw fracture may occur as a consequence of excessive micromotion. Materials and Methods: Following published standards, implant-abutment assemblies were fixed in a universal testing machine at a 30-degree angle. A cyclic load of 200 N was applied to the specimens 10 times at a crosshead speed of 100 N/s while relative displacement between the implant and the abutment was quantified using extensometers. For five consecutive loading cycles per specimen, micromotion was recorded as a basis for statistical analysis, with two-sample t tests (Welch test) applied. Results: Micromotion at the implant-abutment interface ranged from 1.52 to 94.00 μm. While a significant effect of tightening torque was found, implant shoulder design did not reveal a significant effect in all cases. Lack of engagement of antirotational features of the implants resulted in increased micromotion. Casting onto prefabricated gold cylinders resulted in abutments with significantly less micromotion as compared to copy-milled and stock abutments. Computer-aided design/computer-assisted manufacture (CAD/CAM) zirconia abutments showed less micromotion than CAD/CAM titanium abutments. Inconsistent levels of micromotion were recorded for CAD/CAM abutments coupled to proprietary and competing implant systems. Great variations in micromotion were found with clone abutments and clone implant systems. Conclusion: A broad range of micromotion values was observed with the implantabutment combinations investigated. There seems to be no perfect implant shoulder geometry or perfect fabrication technique that would result in no detectable micromotion. Keywords: biomechanics, clone abutments, implant-abutment connection, micromotion

Purpose: The pink esthetic score (PES) and white esthetic score (WES) are tools utilized to objectively evaluate single-tooth implant restorations (STIR) in the esthetic zone.1 A questionnaire study was developed to address two objectives: (1) establish a total PES/WES score that is clinically acceptable based on layperson perception and (2) report outcomes in laypeople's perceptions of pink and white deficiencies. Materials and Methods: A presentation book of 27 color-calibrated photographs of a STIR in the esthetic zone (canine to canine) surrounded by virgin teeth and one photograph without a STIR (control) was presented to three prosthodontists (evaluators) to conduct a PES/WES evaluation. The same 27 photographs were presented to 101 laypeople. The laypeople were instructed to identify which tooth was the STIR. The laypeople were also instructed to record, based on pink or white esthetics, what factors influenced their decision on the selection of the STIR. Results: For the evaluator's scores of the 27 cases, the mean PES score was 5.7 (range, 3 to 10). The mean WES score was 6.2 (range, 3 to 10). The mean total PES/WES score was 11.9 (range, 6 to 20). The mean percentage of laypeople unable to correctly identify the STIR was 59.1% (range, 13.9% to 89.2%). When the evaluator's PES/WES score was greater than 12, 79% of the layperson population was not able to identify a STIR (ρ = −0.86). In addition, when the PES score was 6, 90% of the laypeople were not able to perceive a pink deficiency (ρ = −0.65), and when the WES score was 6, 83% of the laypeople were not able to perceive a white deficiency (ρ = −0.57). Conclusion: Within the limitations of this study, in single-tooth implant restorations, a total PES/WES score greater than 12 would provide a STIR that would be clinically acceptable in the majority of situations. This study also concluded that laypeople identify white esthetic deficiencies more easily than pink esthetic deficiencies. Keywords: implant esthetics, pink esthetic score, white esthetic score

Purpose: To evaluate the three-dimensional (3D) reconstruction of atrophic alveolar ridges using titanium mesh (Ti-mesh) and its correlation with the extent and timing of mesh exposure and amount of reconstruction planned. Materials and Methods: This study retrospectively evaluated 12 patients (mean age, 49.1 years) with 15 alveolar defects treated with Ti-mesh and particulate grafts (70/30 autogenous bone/anorganic bovine bone) followed by implant placement 8 to 9 months later. For each site, computed tomography images were analyzed using software designed to measure 3D volumes. The lacking bone volume (LBV) was calculated by subtracting the reconstructed bone volume at reentry from the planned bone volume (PBV). In all cases, the meshes were modeled preoperatively on a stereolithographic model. LBV was correlated with the extent and time of mesh exposure and PBV. Results: The mean LBV (0.45 cm3) was 30.2% (range, 6% to 74%) of the mean PBV (1.49 cm3). The mean extent and timing of mesh exposure, which occurred at 80% of augmented sites (12/15), were 0.73 cm2 (range, 0.09 to 3.45 cm2) and 2.17 months (range, 1 to 8 months), respectively. LBV was significantly positively correlated with the area of mesh exposed, with 16.3% LBV for every cm2 of mesh exposed; there were positive correlations between LBV and early exposure and PBV. Conclusion: On average, there was 30.2% less bone than planned preoperatively; there was a significant negative correlation between the amount of reconstructed bone and area of mesh exposed. Keywords: alveolar ridge reconstruction, bone volume, computed tomography, titanium mesh exposure

Purpose: To evaluate the influence of the milliamperage settings on cone beam computed tomography (CBCT) images for qualitative and quantitative preoperative implant planning. Materials and Methods: Eight dry mandibles were scanned under different milliamperage values (2, 4, 6.3, 8, 10, 12, and 15 mA) available for selection on the Kodak 9000 CBCT unit. Cross-sectional slices of incisor, canine, premolar, first molar, and second molar regions were analyzed by three oral radiologists. A subjective image quality evaluation of the anatomical structures and an objective evaluation using bone height measurements compared with the real measurements obtained in the mandible were performed. After 30 days, 25% of the sample was reevaluated to obtain the reproducibility of the results. Results: The weighted-kappa coefficient and intraclass correlation coefficient for intra- and interobserver agreement varied between moderate and substantial agreement for the image quality evaluation, and excellent agreement was found for the bone measurements. For the image quality evaluation, the Friedman test showed a negative influence of the milliamperage setting only when the lowest values (2 and 4 mA) were used; for the measurements, one-way analysis of variance with the post hoc Tukey test showed that milliamperage settings did not influence their accuracy. However, images obtained with 6.3 mA were closest to the real measurements. Conclusion: On the basis of this study of dried skulls using CBCT, it was determined that image quality degradation was not significantly improved when the milliamperage setting was increased above 6.3 mA, whereas a milliamperage level below 6.3 mA resulted in degradation of the image quality. Therefore, significant dose reduction can be achieved with diagnostically satisfactory image quality on CBCT exams for implant planning by reducing the milliamperage setting. Keywords: cone beam computed tomography, image quality enhancement, implant planning, radiation dosage

Purpose: The aim of this study was to evaluate the clinical and radiographic outcomes of early loaded platform-switched implants in the anterior maxilla. Materials and Methods: In this study, patients were treated with implants that supported all-ceramic single-tooth crowns and were followed for 2 to 4 years. Implants were evaluated on the basis of clinical and radiographic parameters, including Plaque Index, Sulcus Bleeding Index, peri-implant probing depths (PDs), Papilla Index, soft tissue recession, and marginal bone levels. Statistical analyses were performed. Results: Fifty-five implants were placed in 47 patients. At the recall examinations, all implants had successfully integrated, demonstrating healthy peri-implant soft tissues as documented by standard clinical parameters. At the time of recall, 7 implants had been followed for 4 years, 30 implants for 3 years, and 18 implants for 2 years. Plaque accumulation scores of 2 and 3 were not noted at any point during the study. At baseline, the mean PD was 2.1 ± 0.6 mm, at 2 years it was 2.2 ± 0.6 mm, at 3 years it was 2.2 ± 0.6 mm, and at 4 years (7 implants), the mean PD was 1.9 ± 0.4 mm. There were no statistically significant differences between time intervals. Complete papilla fill was seen for 49 implants. All implants showed less than 0.5 mm of marginal bone loss; mean bone loss at the time of final recall was 0.12 ± 0.22 mm. Seven implants showed an increase in the level of bone contact. There were no statistically significant differences over time. Conclusion: Bone-level implants with a platform-switched design are a successful treatment modality for anterior single-tooth implants. Keywords: anterior implant, bone-level implant, clinical study, dental implants, radiographic outcome

Purpose: The purpose of this trial was to evaluate crestal bone level changes radiographically in a standardized fashion over a period of 12 months in humans for implants with a 0.7-mm machined collar (implant type A) versus type B implants with a 1.5-mm machined collar. Materials and Methods: Twenty-five patients with multiple missing teeth in posterior sectors were randomly assigned to one of the two groups: A (0.7-mm machined-collar implants) or B (1.5-mm machined-collar implants). Changes at crestal bone level were assessed by measuring the shoulder-crest distance (SCD) on the mesial and distal aspects of each implant on customized periapical radiographs, which were taken on the day of surgery and 3, 6, and 12 months after surgery. Results: Eighty-one implants were included in the study. Mean SCD was 0.54 ± 0.53 mm at baseline and 1.49 ± 0.40 mm after 12 months. For 0.7-mm-collar implants, mean SCD was 1.40 ± 0.39 mm, while it was 1.56 ± 0.40 mm for 1.5-mm-collar implants. Statistically significant differences were found only between the two types of implants for distal measurements at 3 and 12 months after placement. Conclusion: Both 0.7- and 1.5-mm machined-collar implants can be used with predictable results, as changes in peri-implant crestal bone levels are similar for both implant types and do not seem to be significant from a clinical point of view. The SCD may well depend more on the location of the abutment-implant interface than on machined-collar height. Keywords: bone resorption, dental implants, implant stability, marginal bone levels, surface properties

Purpose: To compare long-term survival and clinical outcomes of endosseous implants with different surface characteristics in patients with sinus elevation procedures, autologous bone grafting, and delayed implant placement. Materials and Methods: Implant survival, peri-implant soft tissue conditions, marginal bone level, intrasinus apical bone level, and sinus health were studied in patients subjected to autologous bone graft and delayed placement of implants with turned or oxidized surfaces. After a minimum of 5 years of functional loading, all patients were clinically examined regarding gingival pocket depth (PD) and bleeding on probing (BoP). The marginal bone level (MBL) was measured in intraoral radiographs. Cone beam computed tomography was used to evaluate the apical bone level (ABL) of the implants and intrasinus conditions. Results: Twenty-eight patients received sinus elevation and a total of 92 dental implants. Thirteen patients received 47 implants with a turned surface, and 15 patients received 45 implants with an oxidized surface. Mean follow-up was 10 years (range, 5 to 19 years). No significant difference was found between the two implant surfaces in terms of PD, BoP, MBL, or ABL. Four patients (14%) exhibited radiographic signs of sinus pathology, with opacification, polyplike structures, and thickening of the sinus membrane. Radiographic signs of sinus pathology were not correlated to implant survival or to the investigated parameters. Conclusion: Grafting of the maxillary sinus floor with intraorally harvested bone and delayed placement of either turned or oxidized implants results in equally high long-term survival rates, stable marginal and apical bone levels, and good peri-implant soft tissue health. Keywords: bone graft, dental implants, maxillary sinus, surface properties

Purpose: This prospective study was undertaken to evaluate the 10-year implant survival rate as well as bone remodeling for immediately loaded anterior mandibular implants. Materials and Methods: Patients with nonrestorable anterior mandibular teeth were enrolled. All mandibular teeth were extracted, and five rough-surfaced (titanium plasma spray) one-piece implants were placed, evenly spread between the mental foramina. All implants were immediately loaded with a provisional prosthesis. A definitive prosthesis was . Results: Eight patients received 40 implants, 30 in extraction sockets and 10 in healed sites. All but two implants that did not achieve primary stability (35 Ncm) were immediately loaded. The progress of seven patients was evaluated after 10 years. The mean age at implant placement was 60 years, and the length of follow-up varied between 10.3 and 11.47 years. The results showed a 100% implant retention rate; however, clinically observed bone loss around two central implants led to consideration for future surgical intervention or removal. Average bone loss was 1 mm, and little difference was noted between implants placed in healed sites and those placed in extraction sockets. Technical problems with the prostheses were confined to two patients; one patient had seven fractures and the other had one. Conclusion: Rough-surfaced implants placed in extraction sockets between the mental foramina and immediately loaded can be successful in the long term. Because only is recommended that this site be avoided when immediately loaded implants are to be used in the anterior mandible. Keywords: anterior mandible, dental implants, extraction sockets, implant prosthesis, immediate implants

Purpose: To clinically evaluate immediate implant placement with simultaneous intentional retention of the buccal aspect of the root and to report longitudinal data on survival of implants placed with the use of this novel technique. Materials and Methods: A retrospective case series of implants placed with the root-membrane technique in the maxillary anterior region of adult patients was conducted. Clinical and radiographic analysis was performed to assess implant success and to evaluate the survival of the retained root fragment based on predetermined criteria. A Kaplan-Meier method analysis was used to estimate the 5-year success rate of implants placed with this technique. Results: Data from 46 patients (median follow-up time, 40 months; range, 24 to 60 months) were evaluated. Each patient contributed one implant site in this study. All implants successfully maintained osseointegration at the end of the follow-up period for a 100% cumulative survival rate, based on clinical and radiographic criteria. Radiographic examination revealed good crestal bone stability with mean crestal bone loss on the mesial and distal aspects of the implants estimated to be 0.18 ± 0.09 mm and 0.21 ± 0.09 mm, respectively. The only complication noted in this patient cohort was apical root resorption of a single retained root fragment that did not interfere with the osseointegration of the implant. Conclusion: The intentional retention of the buccal aspect of the root with its periodontal apparatus during immediate implant placement can lead to predictable and sustainable osseointegration of implants placed in the maxillary anterior region of healthy adults. Keywords: alveolar bone preservation, dental implant, dentin fragment, esthetics, immediate implant placement, root retention

Purpose: The aim of this study was to evaluate the survival and success of screw-retained versus cement-retained implant restorations in immediately loaded implants at 8-year follow-up. Materials and Methods: Patients who were scheduled for full-arch ceramic prosthetic restorations were divided into two groups by randomization: in one group, prosthetic frameworks were screwed onto implants (screw-retained group, SRG), and in the second group, the frameworks were cemented on abutments (cement-retained group, CRG). Dental implants were placed both in postextraction and in healed sites. A temporary full-arch prosthesis was placed immediately after implant placement. Intraoral digital radiographic examinations (evaluating marginal bone levels) were made at baseline, 6 months, and each year after implant placement. Results: In 28 patients, 24 full arches and 192 implants were placed in the maxilla and 10 full arches and 80 implants in the mandible (17 rehabilitations in each group). After an 8-year follow-up period, a survival rate of 99.27% was reported for all implants. Within the first year after implant placement, bone loss was recorded as follows: the CRG showed mean bone levels of −1.23 ± 0.45 mm, while the SRG showed mean bone levels of −1.01 ± 0.33 mm. After a 3-year follow-up, a slight increase was found (0.30 ± 0.25 mm in CRG and 0.45 ± 0.29 mm in SRG). After that point, marginal bone levels remained stable over time, up to the 8-year follow-up. No statistically significant differences were found between groups (P > .05). Conclusion: Definitive cement- and screw-retained ceramic restorations are highly predictable, biocompatible, and esthetically pleasing, and the two groups presented no statistically significant differences in bone loss. Keywords: fresh socket implants, immediate loading, prosthetic restoration

Purpose: The aim of this study was to evaluate the effect of tooth-implant proximity using an implant system with a double platform shift that was designed to load bone coronal to the implant-abutment interface. Materials and Methods: A retrospective cohort study was conducted between January 2008 and December 2009. The sample was composed of patients who had received at least one 5-mm-wide hydroxyapatite-coated single-tooth Bicon implant that had been placed adjacent to at least one natural tooth. Descriptive statistics and univariate and multivariate linear mixed-effects regression models, adjusted for multiple implants in the same patient, were utilized. The primary predictor variable was the horizontal distance between implant and adjacent tooth, and the primary outcome variable was the change in periimplant bone levels over time. Results: Two hundred six subjects who received 235 plateau root-form implants were followed for an average of 42 months. Tooth-implant distance ranged between 0 and 14.6 mm. Out of 235 implants, 43 implants were placed 1 mm to an adjacent natural tooth on mesial and/ or distal sides. The proximity of a plateau root-form implant was not associated with complications on the adjacent tooth such as bone loss, root resorption, endodontic treatment, pain, or extraction. The proximity of an adjacent tooth was not a risk factor for the failure of a plateau root-form implant. After adjusting for other covariates in a multivariate model, the proximity of a natural tooth did not have a statistically significant effect on peri-implant bone levels (P = .13). The extraction of an adjacent tooth was associated with a significant increase in peri-implant bone loss (P = .008). Conclusion: The placement of a plateau root-form implant with a sloping shoulder in close proximity to an adjacent tooth did not cause damage to that tooth or lead to bone loss or the failure of the implant. Keywords: adjacent structures, platform switching, retrospective cohort study, single-tooth implants, toothimplant distance

Purpose: This study aimed to evaluate (1) the association between implant diameter and marginal bone loss (MBL) of short (6 mm) implants and (2) the survival rates of short implants. Materials and Methods: Thirty-three 6-mm implants were placed in the mandibles of 16 qualified patients. The selected sites had > 5 mm ridge width and 9 mm bone height. None of the implant sites required bone augmentation procedures. All implants were uncovered 3 months after placement, and all patients were rehabilitated with 2- or 3-unit implant-supported fixed partial dentures. Standardized periapical films were taken after 24 months of function. Radiographs were digitalized, and MBL was assessed. Results: For all implants, the mean MBL was 0.17 mm at the point of uncovering. At the 2-year follow-up, all implants were immobile and functional. Implants with 4.2-mm diameters had significantly more MBL (1.95 mm) than wider implants (0.47 mm and 0.35 mm for 5.0-mm and 6.0-mm implants, respectively). Conclusion: This 2-year study illustrated that short implants are a viable option in selected clinical scenarios. Short implants with wider diameters are preferred because they have less marginal implant bone loss. Keywords: alveolar bone loss, dental implants, dental restorations failure, mandible

Purpose: To examine the relationships between three measures of body fat-body mass index (BMI), waist circumference (WC), and total body fat percent-and markers of inflammation around dental implants in stable periodontal maintenance patients. Materials and Methods: Seventy-three subjects were enrolled in this cross-sectional assessment. The study visit consisted of a physical examination that included anthropologic measurements of body composition (BMI, WC, body fat %); intraoral assessments were performed (full-mouth plaque index, periodontal and peri-implant comprehensive examinations) and peri-implant sulcular fluid (PISF) was collected on the study implants. Levels of interleukin (IL)-1α, IL-1β, IL-6, IL-8, IL-10, IL-12, IL-17, tumor necrosis factor-α, C-reactive protein, osteoprotegerin, leptin, and adiponectin in the PISF were measured using multiplex proteomic immunoassays. Correlation analysis with body fat measures was then performed using appropriate statistical methods. Results: After adjustments for covariates, regression analyses revealed statistically significant correlation between IL-1β in PISF and WC (R = 0.33; P = .0047). Conclusion: In this study in stable periodontal maintenance patients, a modest but statistically significant positive correlation was observed between the levels of IL-1β, a major proinflammatory cytokine in PISF, and WC, a reliable measure of central obesity. Keywords: body composition, cytokines, dental implants, interleukins, obesity, peri-implantitis

Purpose: Allografts, xenografts, and alloplasts are commonly used in craniofacial medicine as alternatives to autogenous bone grafts; however, these materials lack important bone-inducing proteins. A method for enhancing the osteoinductive potential of these commercially available materials would provide a major clinical advance. In this study, a calcium-binding domain, polyglutamate, was added to an osteoinductive peptide derived from collagen type I, Asp-Gly-Glu-Ala (DGEA), to anchor the peptide onto four different materials: freeze-dried bone allograft (FDBA); anorganic bovine bone (ABB); β-tricalcium phosphate (β-TCP); and a calcium sulfate bone cement (CaSO4). The authors also examined whether peptide binding and retention could be tuned by altering the number of glutamate residues within the polyglutamate domain. Materials and Methods: DGEA or DGEA modified with diglutamate (E2DGEA), tetraglutamate (E4DGEA), or heptaglutamate (E7DGEA) were evaluated for binding and release to the grafting materials. Peptides were conjugated with a fluorescein isothiocyanate (FITC) tag to allow monitoring by fluorescent microscopy or through measurements of solution fluorescence. In vivo retention was evaluated by implanting graft materials coated with FITC-peptides into rat subcutaneous pouches. Results: Significantly more peptide was loaded onto the four graft materials as the number of glutamates increased, with E7DGEA exhibiting the greatest binding. There was also significantly greater retention of peptides with longer glutamate domains following a 3-day incubation with agitation. Importantly, E7DGEA peptides remained on the grafts after a 2-month implantation into skin pouches, a sufficient interval to influence bony healing. Conclusion: Variable-length polyglutamate domains can be added to osteoinductive peptides to control the amount of peptide bound and rate of peptide released. The lack of methods for tunable coupling of biologics to commercial graft sources has been a major barrier toward developing materials that approach the clinical efficacy of autogenous bone. Modification of osteoinductive factors with polyglutamate domains constitutes a technically straightforward and cost-effective strategy for enhancing osteoinductivity of diverse graft products. Keywords: bone graft, bone regeneration, osteoinductive peptide, peptide coupling, polyglutamate domain

Purpose: Improving the peri-implant bone quality has notable clinical value in cases of osteoporosis following implant insertion. Materials and Methods: In this study, strontium ranelate-loaded chitosan film was produced on a titanium surface in different concentrations of strontium ranelate (SR) (0, 2, 20, 40, and 80 mmol/L of the strontium ion [Sr2+]) with the expectation of utilizing the bone healing-enhancement effect of Sr2+. The physicochemical properties of SR-loaded chitosan films were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The release/dissolution mechanism was tested by inductively coupled plasma optical emission spectrometry (ICP-OES), and in vitro cell responses were evaluated using primary osteoblasts (POBs) in terms of cell proliferation, alkaline phosphatase (ALP) activity, and quantitative analysis of key osteoblastic gene expression. Results: XRD and FTIR observation showed that only a few SRs reacted chemically with chitosan through hydrogen bonds or conjugate action. The initial burst release (70% to 85%) of Sr2+ occurred in the first 3 days and was followed by a slower release stage. At a low concentration (2 mmol/L or 20 mmol/L), SR-loaded chitosan film promoted cell responses of POBs with enhanced proliferation, ALP activity, and expression levels of bone morphogenetic protein 2 (BMP-2), runt-related transcription factor 2 (Runx-2), ALP, and osteocalcin, but at a high concentration (40 mmol/L or 80 mmol/L), it inhibited POB growth. Conclusion: These results indicated that SR-loaded chitosan film on a titanium surface promotes osteoblast proliferation and differentiation in a dose-dependent manner, which may represent a new approach in the treatment of a titanium implant. Keywords: chitosan, drug-releasing membrane, osteoblast, strontium ranelate, titanium surface coating

Purpose: Although the risks of using a cantilever to treat missing teeth have been described, the mechanisms remain unclear. This study aimed to reveal these mechanisms from a biomechanical perspective. The effects of various implant sites, number of implants, and superstructural connections on stress distribution in the marginal bone were analyzed with three-dimensional finite element models based on mandibular computed tomography data. Forces from the masseter, temporalis, and internal pterygoid were applied as vectors. Materials and Methods: Two three-dimensional finite element models were created with the edentulous mandible showing severe and relatively modest residual ridge resorption. Cantilevers of the premolar and molar were simulated in the superstructures in the models. The following conditions were also included as factors in the models to investigate changes: poor bone quality, shortened dental arch, posterior occlusion, lateral occlusion, double force of the masseter, and short implant. Multiple linear regression analysis with a forced-entry method was performed with stress values as the objective variable and the factors as the explanatory variable. Results: When bone mass was high, stress around the implant caused by differences in implantation sites was reduced. When bone mass was low, the presence of a cantilever was a possible risk factor. The stress around the implant increased significantly if bone quality was poor or if increased force (eg, bruxism) was applied. Conclusion: The addition of a cantilever to the superstructure increased stress around implants. When large muscle forces were applied to a superstructure with cantilevers or if bone quality was poor, stress around the implants increased. Keywords: biomechanical factors, cantilevers, dental implants, finite element analysis, implant-supported prostheses, multivariate analysis

A gunshot injury is one of the main trauma injuries that affect the head and neck region. Severe esthetic, functional, and psychologic deficiencies are consequences of gunshot injuries. The use of implants anchored in the zygomatic bone has been advocated as an approach to the prosthetic rehabilitation of a severely deficient maxilla. This approach provides the patient with an immediate, high-quality, esthetic, and functional complete fixed prosthesis and eliminates the need for bone grafting. In this case report, a patient with a severely deficient maxilla caused by a gunshot injury was rehabilitated by placement of four zygomatic and two pterygomaxillary implants, which were immediately loaded with a complete fixed all-acrylic resin interim prosthesis. The definitive CM Prosthesis (CM Prosthetics) was constructed using computer-aided design/computer-assisted manufacture (CAD/CAM) technology. Keywords: dental implant, extramaxillary, gunshot wound, immediate loading, osseointegration, pterygoid, pterygomaxillary, teeth in a day, zygoma