The International Journal of Oral & Maxillofacial Implants, 02/2018

Purpose: To evaluate the effect of different degrees of mesial implant inclinations on the retention and stability of two-implant mandibular overdentures retained with stud attachments. Materials and Methods: Four experimental mandibular acrylic models were constructed. Two laboratory implants were inserted in the canine areas of each model with the following degrees of mesial inclinations: 0, 5, 10, and 20 degrees. Experimental overdentures were connected to the implants with Locator extra-light retention (Le), Locator light retention (Ll), and Locator medium retention (Lm). Vertical (retention) and oblique (stability) dislodging forces (anterior, posterior, and lateral) were measured at the beginning of the study (initial retention) and after 540 cycles of denture insertion and removal (final retention). Results: The final retention was not significantly affected by small (5 degrees) and large (20 degrees) implant inclinations, but decreased with a moderate (10 degrees) inclination. For a small implant inclination (5 degrees), Lm showed the highest final retention/stability and Le showed the lowest, while for moderate and large inclinations (10 and 20 degrees), Le showed the highest final retention/stability and Lm showed the lowest. Vertical dislodging recorded the highest final stability, and lateral dislodgment recorded the lowest stability. Conclusion: Within the limitations of this in vitro study, only moderate implant angulation (10 degrees) negatively affects the final retention and stability of Locator-retained overdentures. Locator medium retention for small angulation (5 degrees) and Locator extra-light retention for moderate (10 degrees) and large (20 degrees) angulations are recommended to maintain high retention and stability after 540 cycles of denture insertion and removal. Keywords: implant inclinations, Locator, overdenture, retention, stability

Purpose: This study evaluated the expression pattern of micro RNAs (miRNAs) on a surface with nanotopography compared with a smooth surface (control). Materials and Methods: Human mesenchymal stem cells (hMSCs) were plated on different surfaces and compared at 3, 7, and 14 days for alkaline phosphatase (ALP) activity, expression of genes (osterix [OSX], runt-related transcription factor 2 [RUNX2], bone morphogenetic protein 2 [BMP2], and ALP), and expression of miRNAs. Western blot was also used to detect osteogenic proteins (BMP2, OSX, and osteocalcin [OCN]). Scanning electron microscopy of cells plated onto the surfaces was obtained. Results: ALP activity on different surfaces was significantly greater in the nanotopography surface. At day 14, there was a 3.5-fold and a 9-fold increase for the RUNX2 and OSX genes, respectively. BMP2 and ALP also increased by fourfold and sevenfold compared with the control. Protein levels for OSX and BMP2 were also upregulated compared with the control group. Using RNA sequencing technology (RNA-Seq), a total of 117 miRNAs were found to be differentially expressed comparing the control (day 7) with the nanosurface (day 14). Forty-five miRNAs were upregulated, and 72 were downregulated. Several of the miRNAs that were differently expressed regulate osteogenic genes. For example, hsa-miR-135b-5p targets OCN, BSP, RUNX2, COL15A1, and OSX; hsa-miR-122-5p targets OPN; hsa-miR-196a-5p targets BMP4; hsa-miR-26b-5p targets BMP2; and hsa-miR-148b-3p targets OPN. Conclusion: Surfaces with nanotopography have the potential to improve the osseointegration response in order to reduce the osseointegration time and also increase bone formation around the implants, improving areas with low bone quality. Within the limitation of this study, nanotopography surfaces affected MSC differentiation to osteoblasts. Several miRNAs were differentially regulated by surface topography. These miRNAs could be related to the differentiation response to help control the osseointegration process. Keywords: dental implants, human mesenchymal stem cells, micro RNAs, nanotopography, osteoblasts, surface properties

Purpose: The reliability of combining natural teeth and implants in one removable prosthesis is controversial. This systematic review was conducted to evaluate the prognosis of combined tooth/implant-supported double-crown-retained removable dental prostheses (DCR-RDPs) and to compare them with solely implant-supported prostheses with a minimum observation period of 3 years. Materials and Methods: Electronic database (PubMed, Embase, Central, and SCI) and manual searches up to August 2016 were conducted to identify human clinical studies on tooth/implant-supported DCR-RDPs. Literature selection and data extraction were accomplished by two independent reviewers. Meta-analyses of survival and complication rates were performed separately for combined tooth/implant-supported and solely implant-supported DCRRDPs. Results: Among the initially identified 366 articles, 17 were included in a quantitative analysis. The estimated overall cumulative survival rate (CSR) for implants in combined tooth/implant-supported DCRRDPs was 98.72% (95% confidence interval [95% CI]: 96.98% to 99.82%), and that for implants in solely implant-supported DCR-RDPs was 98.83% (95% CI: 97.45% to 99.75%). The summary CSR for abutment teeth was 92.96% (95% CI: 85.38% to 98.12%). Double-crown-retained dentures with both abutment types showed high CSRs, most of which were approximately 100%. Regarding prosthetic maintenance treatment, the estimated incidence for patients treated with combined tooth/implant-supported RDPs was 0.164 (95% CI: 0.089 to 0.305) per patient per year (T/P/Y) and that for patients restored with solely implant-supported RDPs was 0.260 (95% CI: 0.149 to 0.454) T/P/Y. Based on four studies with combined tooth/implant-supported DCR-RDPs, no intrusion phenomena were encountered. Conclusion: Subject to the limitations of the present review, combining remaining teeth and implants in DCR-RDPs is a reliable and predictable treatment modality for partially edentulous patients. Comparable high survival rates and minor biologic or technical complications are observed for combined tooth/implant-supported and solely implant-supported DCR-RDPs. Due to the heterogeneity of the included studies, the results must be interpreted with caution. Keywords: combined tooth/implant-supported removable prostheses, complications, dental implant, double crown, meta-analysis, survival

Purpose: The aim of this study was to confirm the in vivo effect of surface-modified titanium (Ti) implants with zinc (Zn) prepared by a plasma electrolytic oxidation (PEO) method on the process of osseointegration. Materials and Methods: Forty-five New Zealand white rabbits were used. Implants were divided into three groups due to different surface treatments (the PEO-Zn group, the PEO-calcium phosphorus [Ca/P] group, and the sandblasted [control] group) and were randomly inserted into rabbits' mandibles. The implant surface morphology and chemical state of the relevant elements were observed. The maximum push-out force, the bone-to-implant contact (BIC), and the mineral apposition ratio (MAR) were detected at 4, 8, and 12 weeks after implantation. Results: A two-layer structure, with a dense inner layer and a porous outer layer, was found in the PEO samples. In the PEO-Zn group, CaHPO4·2H2O (dicalcium phosphate dihydrate) was the main calcium compound, and ZnO was identified as the predominant form of Zn. More bone deposition was found on the top of the PEO-Zn implant, which was also confirmed by scanning electron microscope (SEM) afterward, and the shear strength reached a maximum value of 1.57 ± 0.26 MPa at 12 weeks compared with the sandblasted group and the PEO-Ca/P group. The BIC values and the MARs of the PEO-Zn group were significantly higher than the control group, especially at the early weeks (P .05), and first reached maximum values of 73.91% ± 9.01% and 4.89 ± 0.60 μm/d at 12 weeks, respectively. Conclusion: Implants with Zn coating by the PEO method could accelerate bone formation and bone remodeling, shorten the osseointegration period, and enhance bone-implant bonding force. Keywords: bone-to-implant contact, dental implant, mineral apposition ratio, osseointegration, plasma electrolyte oxidation, zinc

Purpose: This animal study investigated vertical bone formation (VBF) around implants and used histomorphometric analysis to compare different bone-filling materials associated with a massive titanium dome as a tissue barrier. Materials and Methods: Seven dogs were submitted to surgical procedures with extraoral access to the lower edge of the mandible, and four implants were semi-inserted in each animal. Each implant received one treatment: autogenous bone with clot (AB), control clot (C), synthetic graft (Biogran [BG]), or xenograft (Bio-Oss [BO]). Massive titanium domes were stabilized over the implants. Histologic analysis was performed after 3 months, and quantitative aspects were evaluated in extraosseous and intraosseous threads on Image Pro-Plus software. Results: VBF around implants exhibited significant values in AB compared with other groups. BG and BO presented statistical equivalency to AB and C in the apposition and filling of extraosseous threads. There was no difference between groups for parameters evaluated in intraosseous threads. Conclusion: The experimental model was valid for evaluation of VBF around implants placed in atrophic mandibles. Considering the limitations of this study, histomorphometric analysis evidenced better outcomes for group AB. Even though groups BG and BO presented worse outcomes than AB, they were slightly better compared with the control group. Keywords: animal experiments, biomaterials, bone-implant interactions, bone regeneration, guided tissue regeneration

Purpose: To investigate the stress distribution in an implant-abutment complex with a preloaded abutment screw by comparing implant-abutment engagement features using three-dimensional finite element analysis (FEA). Materials and Methods: For FEA modeling, two implants-one with a single (S) engagement system and the other with a double (D) engagement system-were placed in the human mandibular molar region. Two types of abutments (hexagonal, conical) were connected to the implants. Different implant models (a single implant, two parallel implants, and mesial and tilted distal implants with 1-mm bone loss) were assumed. A static axial force and a 45-degree oblique force of 200 N were applied as the sum of vectors to the top of the prosthetic occlusal surface with a preload of 30 Ncm in the abutment screw. The von Mises stresses at the implant-abutment and abutment-screw interfaces were measured. Results: In the single implant model, the S-conical abutment type exhibited broader stress distribution than the S-hexagonal abutment. In the double engagement system, the stress concentration was high in the lower contact area of the implant-abutment engagement. In the tilted implant model, the stress concentration point was different from that in the parallel implant model because of the difference in the bone level. Conclusion: The double engagement system demonstrated a high stress concentration at the lower contact area of the implant-abutment interface. To decrease the stress concentration, the type of engagement features of the implant-abutment connection should be carefully considered. Keywords: double engagement system, finite element analysis, implant-abutment interface, nonlinear analysis, preload, single engagement system

Purpose: The aim of this in vitro study was to evaluate the accuracy of template-guided implantation planned with implant-planning software (Implant Studio), comparing computer-aided design/computer-assisted manufacture (CAD/CAM)-based measurements with measurements via cone beam computed tomography (CBCT). Materials and Methods: Thirty template-guided implantations were planned and performed on acrylic-resin models. The implant positions were detected with an intraoral scanner, evaluated with CAD quality-control software, and compared with the planned positions in the test group. Preliminary deviations were measured via CBCT in the control group of the first 10 samples and compared with the first 10 samples of the test group. Results: When directly compared, measurements obtained using CBCT (control group) showed a trend toward greater deviations. In the CAD/CAM-based evaluation of the 30 samples, the mean ± SD deviation of the insertion axis from the planned implant axis was 2.011 ± 0.855 degrees. The mean deviations of the implant shoulders in the horizontal direction and at the implant apices were 0.725 ± 0.142 mm and 0.990 ± 0.244 mm, respectively. In the vertical direction, the mean deviation was 0.541 ± 0.129 mm. Conclusion: CAD/CAM-based measurements are more accurate than CBCT measurements. Therefore, this radiation-free measurement method is a viable diagnostic alternative. Implant planning with planning software and subsequent placement using surgical templates appears to be a reliable and precise therapeutic option in vitro. However, these findings will still have to be supported by in vivo studies. Keywords: dental implant, guided surgery, implant planning accuracy, intraoral scanner, navigated surgery, surgical template

Purpose: The purpose of this study was to evaluate mouthguard shock absorption ability, strain, and stress generation during impact on dental implants placed in the anterior maxilla. The mouthguard material was also characterized. Materials and Methods: Sixty experimental models were created and divided into six groups (n = 10): implant type, external hexagon (EH) and Morse taper (MT); without and with two mouthguards (MTG), EVA custom-fitted (Ct-MTG) and standard self-adapted (St-MTG). The Shore A hardness, EVA sheet and mouthguard thickness, and elastic modulus were measured to characterize the mouthguard material. A strain gauge was attached to the palatal surface of the implant abutment, which was subjected to an impact test. Distortion of the abutment and implant was determined after impact from centroid displacements in standardized radiographic images. Two-dimensional finite element models were created to represent the six groups and were submitted to nonlinear dynamic impact analysis. The data were statistically analyzed using analysis of variance (ANOVA) and Tukey test (α = .05). Results: Ct-MTG resulted in higher Shore A hardness (P .001). After the heat-forming process, the St-MTG maintained the original thickness, but the Ct-MTG thickness had decreased. The elastic modulus of EVA was 18.1 ± 0.5 MPa. The mouthguard presence reduced strain values significantly (P .001), particularly for Ct-MTG. There was no significant difference between implant connection types EH and MT (P = .547). Conclusion: The external hexagon abutment resulted in higher stress and micro-displacement values. The mouthguard was able to absorb 40% to 46% of the energy caused by the impact on the dental implant. Keywords: abutment design, dental implant, dental implant-abutment connection, ethylene vinyl acetate copolymer, finite element analysis, mouthguards, single-tooth dental implant, strain, stress

Purpose: The search for optimizing rehabilitation results with the use of osseointegrated implants has led oral surgeons to look for other technologies that can provide better predictability for treatments; however, effectiveness must be considered as well. This study aimed to compare temperature variation during preparation of implant surgical beds using conventional rotary implant burs versus ultrasonic tips and to study perforation effectiveness by analyzing the functional wear of both systems and the influence of such wear on the overheating of cortical bone. Materials and Methods: This evaluation was made using thermocouples placed in fresh bovine cortical bone (femur) and connected to a data collector so that the recorded temperatures could provide the thermal behavior of both systems after repeated use of the burs and piezoelectric tips, to compare the wear and the loss of cutting efficiency. Scanning electron microscopy (SEM) was used to compare the topography of both systems' perforations. Biostatistics assays were performed comparing both techniques as well. Results: The collected data and images showed that the wear of the burs and tips did not significantly influence the temperature variation, and the greatest variation occurred in the piezoelectric system for preparations of 13-mm depth. The SEM images show a different surface topography between both systems. While the burs cut the bone, showing a smooth surface, the piezoelectric tips condense the bone and present a rough surface. Conclusion: The use of either rotatory burs or piezoelectric tips generates a temperature that does not affect the tissue healing. Burs create a smooth surface, and piezoelectric tips show a more rough and condensed bone surface. The wear of both systems does not have a relevant increase in temperature after the preparation of 30 surgical beds. Keywords: dental implants, efficiency, heating, piezoelectric

Purpose: To investigate the influence of dishevelled-2 (Dvl2) protein and the phosphorylation and ubiquitination of Dvl2 on dental implant osseointegration in hyperlipidemic rats. Materials and Methods: Thirty-six Wistar rats were divided equally into two groups: an experimental group fed with a high-fat diet for 8 weeks and a control group fed with a normal diet for 8 weeks. Serum lipids were detected, and titanium implants were placed into bilateral proximal metaphysis of rats' femurs. At 1, 3, and 5 days after implantation, rats were sacrificed, and 1 mm of bone around each implant was obtained. Real-time polymerase chain reaction of runt-related transcription factor 2 (Runx2), Cathepsin K, and Dvl2 was performed. Western blot of Dvl2, phosphorylation, and ubiquitination of Dvl2 was also performed. Results: In the experimental group, the expressions of Runx2, Dvl2, and phosphorylation of Dvl2 were lower (P .05), while that of Cathepsin K and ubiquitination of Dvl2 were higher than those in the control group (P .05). Conclusion: Hyperlipidemia suppressed the dental implant osseointegration. This inhibition may be modulated by downregulated Dvl2, phosphorylation of Dvl2, and upregulated ubiquitination of Dvl2. Keywords: dishevelled-2, hyperlipidemia, implant osseointegration, rats, Wnt signaling pathway

Purpose: Palateless maxillary implant overdentures are often used for patients experiencing problems with a full-palate denture. However, palateless overdentures are reported to be a risk factor for implant complications. The purpose of this study was to examine the strain on implants beneath palateless overdentures with unsplinted attachments under various implant distributions. Materials and Methods: A maxillary edentulous model with implants and an experimental palateless overdenture were fabricated. Four strain gauges were attached to each implant, positioned in the anterior, premolar, and molar areas. Three types of unsplinted attachments (ball, locator, and magnet) were set on the implants under various implant distributions. A vertical occlusal load of 98 N was applied through the mandibular complete denture, and the bending strain on the implants was compared using the Kruskal-Wallis test (P = .05). Results: When comparing the strain among different attachments, those using a magnet attachment were the smallest and those using a ball attachment were the greatest, and this difference was significant in most situations (P .05). When comparing the strain among different implant distributions, the strain on a four-implant distribution was significantly smaller than that on a two-implant distribution in most situations (P .05), and those using premolar and molar implants recorded the smallest strain. The strain on implants using a locator attachment tended to be midway between those using ball and magnet attachments, regardless of the implant distribution. Conclusion: In most implant distributions, magnet attachments decrease the strain on implants more than ball and locator attachments. The most favorable unsplinted attachments for use beneath palateless overdentures to decrease the implant strain are magnet attachments and four implants placed in the premolar and molar areas. Keywords: ball attachment, locator attachment, magnet attachment, maxillary implant overdenture, palateless overdenture, strain

Purpose: The aim of this randomized prospective split-mouth clinical trial was to evaluate the outcome of bone block harvesting from the retromolar region using the MicroSaw and Piezosurgery. Materials and Methods: Fifty-three patients for extensive bilateral bone grafting procedures with or without concomitant implant placement in the maxilla and/or mandible were scheduled. In each patient, bone blocks were harvested in the retromolar area within the external oblique ridge of the mandible. Using a randomized protocol, bone blocks were harvested with the MicroSaw and Piezosurgery either from the right or the left side. Clinical outcome parameters were the comparison of osteotomy time; volume of block graft; and clinical determination of intraoperative complications such as hemorrhage, nerve injury, pain, swelling, and healing of the donor site. Results: The mean osteotomy time for harvesting including luxating a bone block was 5.63 (± 1.37) minutes using the MicroSaw and 16.47 (± 2.74) minutes using Piezosurgery (P .05). A mean graft volume of 1.62 (± 0.27) cm3 was measured with the MicroSaw and 1.26 (± 0.27) cm3 with the piezoelectric surgical device (P .05). No heavy bleeding at the donor site occurred in any of the cases. Complications due to injury of adjacent teeth or nerve lesion of the mandibular nerve were not observed in any cases. According to a scale, there was little postoperative pain with both instruments, and it decreased within 14 days postoperatively (P > .05). Swelling did not appear significantly different either (P > .05), and none of the donor sites showed primary healing complications. Conclusion: The data described in this randomized prospective split-mouth clinical trial indicate that the MicroSaw and Piezosurgery allowed efficient and safe bone block harvesting from the external oblique ridge. Clinically, concerning harvesting time and volume of the grafts, the MicroSaw performed significantly better, whereas pain, swelling, and healing did not appear to be considerably different. Given the improved visibility, precise cut geometries, and the margin of safety afforded by the MicroSaw and Piezosurgery, they are both instruments of choice when harvesting bone from the retromolar area. Keywords: autogenous bone graft, bone block graft, bone harvesting, external oblique ridge bone graft, mandibular bone graft, MicroSaw, piezoelectric surgical device, Piezosurgery, ramus bone graft, retromolar bone graft

Purpose: The primary aim of the study was to describe a novel technique to evaluate volumetric hard tissue dimensional changes after ridge augmentation procedures. The secondary aim was to apply this newly developed measuring method to compromised alveolar sockets grafted with a slowly resorbing biomaterial covered with a collagen membrane. Materials and Methods: Eleven patients (6 men and 5 women, mean age 52.7 ± 8.3 years) requiring extraction of one hopeless tooth for severe periodontitis in the maxillary anterior area were consecutively treated with a ridge augmentation procedure. All experimental sockets showed advanced buccal bone plate deficiency and were grafted with deproteinized bovine bone mineral with 10% collagen covered with a collagen membrane. Sockets healed by secondary intention. Three-dimensional volumetric alveolar bone changes were calculated by superimposing cone beam computed tomography scans obtained before and 12 months after the augmentation procedure. Results: After 12 months, the alveolar mineralized tissue filled 91.20% ± 7.96% of the maximum volume for regeneration. The augmentation procedure appeared not only to compensate for bone remodeling in most alveolar regions but also to repair a significant portion of the buccal wall. The most significant ridge width changes occurred 1 mm apical to the bone crest (2.33 ± 1.46 mm, P .001). Conclusion: Within present limitations, this radiographic measuring methodology can be a useful tool to evaluate changes in socket volume. A ridge preservation technique performed with collagenated bovine bone and a collagen membrane was able to improve ridge shape and dimensions in compromised alveolar sockets. Keywords: alveolar process, bone substitutes, cone beam computed tomography, periodontitis, regenerative medicine

Purpose: Preoperative planning of the implant position as part of a coordinated prosthetic and surgical concept is becoming increasingly important regarding function and esthetics. The aim of this study was to investigate the transmission accuracy of template fixation during surgery in edentulous arches with hand fixation in comparison to intermediary screw fixation. Materials and Methods: Preoperatively, 10 implant positions were planned using computed tomography (CT) with the system med3D for implant placement in four mandible models of the Goettingen study model, using a prosthetic diagnostic template. A total of 40 implant insertions were created. For every 20 insertions, the template was temporarily fixed with three screws and compared with the insertion using a hand-fixed template. The precision of the transmission was evaluated with and without screw fixation by re-evaluating the preimplant planning with additional CT scanning of the respective models. Results: Compared with the hand-fixed procedure (HFG) in the model situation, there were no significant differences between the deviations of planned and final implant position in the screw-fixed group (FG). According to the study results, the fixed procedure leads to less depth deviation and lateral error of the implant base in relation to the HFG. Within both groups, there were significant differences between the radial deviation tendencies from the implant base to the implant apex (P = .033 for FG and P = .001 for HFG). Conclusion: The use of CT-based implant planning succeeds in fixed and handfixed surgical procedures with high precision in the atrophic, edentulous mandible model. According to the results of this study, in cases demanding high depth precision, screw-fixation of the template can be helpful. Keywords: dental implants, navigation-guided dental implant, template fixation

Purpose: The objective of this study was to assess whether long-term implant survival rates and bone loss in patients with moderately controlled type 2 diabetes is similar to the rates reported in the nondiabetic population. Materials and Methods: This retrospective observational study utilized patient medical records from a general practitioner's dental office. The records of patients who had moderately controlled type 2 diabetes with hemoglobin A1C (HbA1c) up to 8% and glucose level below 150 mg/dL were reviewed, as patients with HbA1c up to 7% are considered to be well-controlled type 2 diabetes. Follow-up data were recorded and analyzed. Inclusion criteria were as follows: partially edentulous patients with missing teeth who were subsequently treated with implant-supported prosthetic restorations; patients were at least 18 years of age and demonstrated the ability to maintain oral hygiene. Exclusion criteria were as follows: patients did not present for annual follow-up visits; patients presented with a neglected periodontal status; patient records had incomplete surgical or restorative data or nondiagnostic radiographs; implants with external hexagonal and machined surfaces. All the restorations were cement-retained. Three different implant insertion/placement methods were used: (1) implants immediately inserted following tooth extraction; (2) implants inserted 6 to 8 weeks after tooth extraction to allow for primary healing; and (3) implants inserted 4 to 6 months after tooth extraction. Results: After review of more than 3,256 medical records, 169 patients were identified (with 1,112 implants) who met the inclusion criteria. The mean follow-up time was 8.7 years, with a minimum of 4.9 years. Sixty-seven implants failed, yielding a 94% overall implant survival rate. The overall mean bone loss around the implants was 1.98 (± 1.81) mm. Comparable to data published earlier, no statistical significance in survival rate was found between the nondiabetic and diabetic population. The delayed insertion protocol presented the least bone loss, compared with immediate insertion (P = .06), and compared with early insertion (P = .046). Conclusion: The results show that implant survival and bone loss levels were comparable to reported outcomes in the nondiabetic population. The delayed insertion protocol presented less bone loss compared with other insertion methods. Likewise, less bone loss was found in implants placed in the posterior region. Keywords: bone loss, delayed implant placement, type 2 diabetes mellitus

Purpose: The primary prevention of peri-implantitis onset is a key factor in long-term implant success, and the evaluation of the antibacterial efficacy of different implant surfaces is fundamental in this way. The aim of this study was to assess if implants with collars coated with anatase were less subjected to bacterial colonization than implants with noncoated collars, and to investigate how implant bacterial colonization varies over time. Materials and Methods: Eighteen patients in need of implant-supported rehabilitation were selected to have two adjacent implants placed, one with an anatase-coated collar and one with the collar uncoated. Biofilm samples were collected at four sites around each implant at four different time points. Samples were analyzed through polymerase chain reaction (PCR) to detect and calculate the colonization rate of Aggregactibacter actinomycetemcomitans, Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia, and Prevotella intermedia. Results: Due to one patient dropout and two nonosseointegrated implants, 32 out of 36 placed implants were followed up for 12 months, and 128 samples for each time point were collected: in total, 512 biofilm samples were analyzed. The type and rate of bacterial colonization were not significantly different between the two groups at all the intervals. However, the anatase-coated collar showed no proliferation of T forsythia. A significant difference in marginal bone level could be observed at the 12-month follow-up only. No significant difference in the other clinical and radiographic indexes was observed. Conclusion: In this study, anatase-coated collar implants did not seem to provide significantly different microbiologic outcomes than uncoated collar implants. However, the absence of colonization of the species T forsythia and the slightly smaller peri-implant bone loss at the 12-month follow-up suggest that further investigations on anatase coating are needed. Nevertheless, data on bacterial colonization and crestal bone levels need further investigations to draw meaningful conclusions, due to the statistical power of this pilot study. Keywords: anatase, coated materials, dental implants, osseointegration, peri-implantitis, polymerase chain reaction

Purpose: This retrospective study quantitatively analyzed the minimum prosthetic abutment height to eliminate bone loss after 4.7-mm-diameter implant placement in maxillary bone and how grafting techniques can affect the marginal bone loss in implants placed in maxillary areas. Materials and Methods: Two different implant types with a similar neck design were singularly placed in two groups of patients: the test group, with platformswitched implants, and the control group, with conventional (non-platform-switched) implants. Patients requiring bone augmentation underwent unilateral sinus augmentation using a transcrestal technique with mineralized xenograft. Radiographs were taken immediately after implant placement, after delivery of the prosthetic restoration, and after 12 months of loading. Results: The average mesial and distal marginal bone loss of the control group (25 patients) was significantly more than twice that of the test group (26 patients), while their average abutment height was similar. Linear regression analysis highlighted a statistically significant inverse relationship between marginal bone loss and abutment height in both groups; however, the intercept of the regression line, both mesially and distally, was 50% lower for the test group than for the control group. The marginal bone loss was annulled with an abutment height of 2.5 mm for the test group and 3.0 mm for the control group. No statistically significant differences were found regarding marginal bone loss of implants placed in native maxillary bone compared with those placed in the grafted areas. Conclusion: The results suggest that the shorter the abutment height, the greater the marginal bone loss in cement-retained prostheses. Abutment height showed a greater influence in platform-switched than in non-platform-switched implants on the limitation of marginal bone loss. Keywords: abutment height, crestal sinus floor augmentation, dental implants, marginal bone loss, platform switching

Purpose: To present a technique to rehabilitate atrophied alveolar ridges in the posterior maxilla and mandible using bone lateral to the maxillary sinus and to the inferior alveolar nerve and to present a retrospective study of the technique. Materials and Methods: Severe resorption of the posterior region of the maxilla and mandible was treated following a conservative approach. Patients who presented this bone crest condition that impeded the placement of implants and had an anatomy that allowed the inferior alveolar nerve or the maxillary sinus to be approached laterally were treated. The bone ridge thickness lateral to the maxillary sinus and the inferior alveolar nerve was measured by computed tomography, and implants with a wedge-shaped design were placed in the available bone. A retrospective review of clinical records of these patients, treated between 1998 and 2012 at the Clinest - Clinical Center of Research in Stomatology, was conducted. The studied variables were surgical and prosthetic complications, the implant survival rate, and the difference between the remaining bone ridge measurement in the ridge center and the implant length placed laterally. Results: Fifty-six patients met the inclusion criteria. These patients received 208 implants according to the aforementioned technique. The mean implant length gain was 6.9 mm, varying from 0.5 to 12 mm. The cumulative survival rate was high for both maxillaries. For the implants placed beside the inferior alveolar nerve, none were lost at 2 years, two were lost at 5 years, and four were lost at 10 years. For the implants placed beside the maxillary sinus, only four implants were lost at 10 years. Nerve injuries and surgical/prosthetic complications occurred but were not significant. Conclusion: The use of available bone alongside the maxillary sinus and inferior alveolar nerve to place implants is a surgical possibility, and a predictable, safe approach, albeit delicate and experience-dependent. Keywords: bone atrophy, inferior alveolar nerve, maxillary sinus, wedge-shaped implants

Purpose: The use of antibiotic prophylaxis in dental implant surgery is a routine dental practice to prevent implant failure. Current systematic reviews have yet to confirm the effectiveness of antibiotic treatment at reducing postoperative infection rates in implant procedures. The aim of this study was to quantify amoxicillin plasma levels at the peripheral venous blood and at the surgical implant site in patients undergoing dental treatment. Materials and Methods: A prospective study was conducted. Patients undergoing dental implant surgery were selected, and preoperative doses of 1 g of amoxicillin, in the form of an oral tablet, were administered 1 hour prior to implant surgery. The blood samples (1.5 mL) were collected from both the venous and implant sites. Data on the antibiotics were measured using high-pressure liquid chromatography. The quantification method was validated for linearity, selectivity, and detection limits. Statistical analysis of plasma antibiotic was performed, comparing both samples and the age, height, weight, and body mass index (BMI) (Wilcoxon test, P .05; STATA v.10.0). Results: Thirty-two patients (mean age: 56.28 ± 12.2 years; range: 31 to 79 years; 20 men) were selected. Both blood samples were taken at a mean 1.16 ± 0.37 hours after antibiotic intake. The mean amoxicillin concentration at the implant site reached 5 ± 2.63 μg/mL (range: 2.04 to 11.18 μg/mL), while the venous blood level was 4.21 ± 2.12 μg/mL (range: 1.6 to 9.98 μg/mL) (P = .33). No correlations were observed between age, height, weight, and BMI with antibiotic plasma levels. Conclusion: These findings demonstrate that plasma concentrations of a prophylactic dose of amoxicillin are higher than the minimum inhibitory concentration needed to prevent the common dental bacteria involved in peri-implantitis and periodontal diseases. Keywords: antibiotic prophylaxis, chromatography, dental implants, oral surgery, plasma concentration

Purpose: The aim of this study was to clinically and radiographically compare the trephine core procedure and the bone-added osteotome sinus floor elevation technique in the augmentation of the sinus floor. Materials and Methods: A single site in each subject requiring sinus augmentation where the residual bone height was ~4 mm was randomly allocated to either the trephine core procedure or the bone-added osteotome sinus floor elevation technique. Measures of bone fill and bone height were also acquired through scans from cone beam computed tomography obtained before the sinus augmentation procedure (baseline) and before implant placement at approximately 6 months postoperatively. Clinical parameters for healing (early wound healing index), swelling (measurement of preset facial landmarks), and pain (through visual analog scale) were assessed at 1 week and 2 weeks after surgery. The evaluation of bone fill was performed using the digital subtraction technique and morphometric area analysis on the baseline and postoperative scans using two kinds of image processing software. Implants were placed after a healing period of 4 to 6 months, and implant stability quotient values (using SmartPeg Type 49) were recorded immediately after implant placement. Results: While both of the procedures resulted in an increase in bone fill and bone height, there were no significant differences between the techniques. No significant differences were observed between the two groups for implant stability quotient values after implant placement. No significant differences were observed between the two groups for measures of healing, swelling, and pain. Conclusion: Based upon this study that compared the trephine core procedure with the bone-added osteotome sinus elevation technique, comparing bone height, bone fill, and primary implant stability, the two procedures appeared to perform in an equivalent fashion. Keywords: dental implant, maxillary sinus, sinus floor augmentation, trephining

Purpose: The purpose of this study was to retrospectively compare long-term outcomes for immediately loaded tilted and axial implants placed in the posterior region of the edentulous maxillary arch. Materials and Methods: Data obtained from a 5-year prospective study designed to assess clinical outcomes following immediate loading of implants with screw-retained fixed restorations in the edentulous maxillary arch were retrospectively reviewed. Where insufficient alveolar bone was available for axial placement of the posteriormost implant on each side of the arch, tilted placement was employed. Implant survival and marginal bone level changes for these tilted and axial posterior implants were compared. Results: Fifty-one subjects received 64 tilted and 38 axial posterior implants. Forty subjects with 53 tilted and 34 axial posterior implants returned for follow-up after 5 years. Five tilted and seven axial implants failed, representing an 89% and 86% survival proportion, respectively. The mean marginal bone loss was 0.79 (SD: 1.42) mm for tilted implants and 0.14 (SD: 0.34) mm for axial implants. The differences in survival proportions and marginal bone loss between axial and tilted implants were not statistically significant. Conclusion: Predictable long-term implant rehabilitation may be achieved in the edentulous maxillary arch using posterior tilted implants in combination with immediate loading. Keywords: dental arch, dental implants, immediate dental implant loading, maxilla

Purpose: The aim of this study was to evaluate the buccopalatal volumetric tissue change that occurs following flapless single-tooth immediate extraction placement in the esthetic area and to analyze the role of four different variables. Materials and Methods: Patients in need of a single-tooth replacement in the anterior maxillary or mandibular area (premolar to premolar) were recruited for the study. Patients were treated using four different therapeutic modalities: group 1 (healing abutment), group 2 (healing abutment + bone graft), group 3 (provisional restoration), and group 4 (provisional + bone graft). Alginate impressions were taken the day of implant insertion before tooth extraction (T0), at 1 month (T1), at 3 months (T2), and at 6 months (T3). Buccopalatal dimension (BPD) was measured on the study casts at 1, 3, and 5 mm apical to the free gingival margin and compared between T0 and T1 and T2 and T3. Results: Seventy-seven patients were included in the study, 29 men and 48 women with a mean age of 54 years (range: 24 to 76 years), and 80 implants were inserted. Thirteen implants were inserted in group 1, 13 in group 2, 20 in group 3, and 34 in group 4. The BPD contraction was more evident for group 1, smaller in group 2 and group 3, and minimal in group 4. Repeated measures analysis of variance (ANOVA) and post hoc tests were used. The data analyzed were considered statistically significant with a level of α = .05. The interaction effect P value was numerically zero. Conclusion: The results of this study seem to indicate that volumetric tissue changes after immediate extraction placement in the esthetic area can be minimized if a provisional is immediately connected and a bone graft is inserted simultaneously. Keywords: flapless, immediate implant placement, single tooth, tissue dimensional changes

Purpose: The aim of this randomized clinical trial with a 5-year follow-up was to assess the differences in radiographic levels of peri-implant bone crest between tissue-level implants restored with platform matching (control group) and bone-level implants restored with platform switching (test group) in the posterior region. Materials and Methods: To assess marginal bone level changes, periapical radiographs were taken at the moment of prosthesis delivery (baseline), at 1 year, and at 5 years after the definitive restoration. Results: One hundred subjects, partially edentulous in the posterior region, were selected for this study. There were 54 men and 46 women between the ages of 25 and 70 years (mean = 50.5 years). A total of 202 implants were assigned to both groups using a randomized procedure (100 implants in the control group and 102 in the test group). The mean marginal bone level (MBL) changes for tissue-level implants restored with platform matching were 0.26 ± 0.55 mm at baseline to 1 year, 0.34 ± 0.54 mm at 1 year to 5 years, and 0.61 ± 0.73 mm at baseline to 5 years. The mean MBL changes for bone-level implants restored with platform switching were −0.03 ± 0.74 mm at baseline to 1 year, −0.17 ± 0.67 mm at 1 year to 5 years, and −0.20 ± 0.75 mm at baseline to 5 years. The mean difference between the two groups was 0.31 mm at baseline to 1 year, 0.53 mm at 1 year to 5 years, and 0.85 mm at baseline to 5 years. There was a statistically significant difference in MBL (P .001). Both implant systems showed good and similar survival rates (98% for tissue-level implants restored with platform matching and 96.1% for bone-level implants restored with platform switching). Conclusion: In this randomized controlled trial, the following observations were made. Radiographic levels of peri-implant bone crest in tissue-level implants restored by platform matching were statistically significant in the three interval times. Meanwhile, MBL changes for bone-level implants restored with platform switching were not statistically significant in the different times studied. Nevertheless, the mean difference between the two groups was statistically significant. Keywords: bone-level implant, marginal bone loss, platform matched, platform switching, posterior healed site, tissue-level implant

Purpose: To retrospectively evaluate the incidence of peri-implant mucositis and peri-implantitis around dental implants with the same body design and surface but different collar surface (laser-microgrooved vs not laser-microgrooved) after 5 years of loading in private practice patients. Materials and Methods: The study was carried out on patients at a private dental clinic enrolled in a periodontal maintenance program, who received at least one implant with a laser-microgrooved collar surface and one implant without a laser-microgrooved collar surface. Clinical variables such as plaque, pocket depth, bleeding on probing, suppuration, and radiographic marginal bone loss at > 5 years around implants were investigated. The correlation between the prevalence of peri-implant mucositis/peri-implantitis and biotype, keratinized tissue width, prosthetic connection type, and prosthetic design type was also analyzed. Results: A total of 166 implants in 74 patients were investigated. At the end of the 5-year follow-up period, 38 implants presented peri-implant mucositis, accounting for 22.8% of the total, affecting a total of 24 patients (32.4%), while 13 implants (7.8%) in 10 patients (13.5%) were diagnosed with peri-implantitis. Sixteen of 82 laser-microgrooved implants (19.5%) and 24 of 84 implants (28.5%) without a laser-microgrooved collar presented peri-implant mucositis, while 3 of 82 (3.6%) of laser-microgrooved implants and 10 of 84 (11.9%) implants without a laser-microgrooved collar demonstrated peri-implantitis. Differences in implantbased incidence of peri-implant diseases between implants with and without a laser-microgrooved collar were statistically significant (P .05). Conclusion: In private practice patients enrolled in a professional, controlled oral hygiene regimen, implants with a laser-microgrooved collar, compared with implants without a laser-microgrooved collar, presented a statistically significantly lower incidence of peri-implant diseases. Keywords: dental implants, laser-microgrooved collar surface, peri-implantitis, peri-implant mucositis, prevalence

Purpose: The aim of this study was to investigate the effects of tightening torque, screw head angle, and thread number on the preload force of abutment screws. Materials and Methods: The test specimens consisted of three self-manufactured components (ie, a thread sleeve serving as an implant analog, an abutment analog, and an abutment screw). The abutment screws were fabricated with metric M1.6 external threads. The thread number varied between one and seven threads. The screw head angles were produced in eight varying angles (30 to 180 degrees). A sensor unit simultaneously measured the preload force of the screw and the torsion moment inside the screw shank. The tightening of the screw with the torque wrench was performed in five steps (15 to 35 Ncm). The torque wrench was calibrated before each step. Results: Only the tightening torque and screw head angle affected the resulting preload force of the implant-abutment connection. The thread number had no effect. There was an approximately linear correlation between tightening torque and preload force. Conclusion: The tightening torque and screw head angle were the only study parameters that affected the resulting preload force of the abutment screw. The results obtained from this experiment are valid only for a single torque condition. Further investigations are needed that analyze other parameters that affect preload force. Once these parameters are known, it will add value for a strong, but detachable connection between the implant and abutment. Short implants and flat-to-flat connections especially will benefit significantly from this knowledge. Keywords: abutment, abutment screw, abutment screw configuration, dental implant, preload force, thread pitch

Oroantral fistulae (OAF) are surgical sequelae that require complete resection and often leave large defects for the surgeon to repair. Closing these lesions is often technique sensitive and requires a detailed protocol, which, if not adhered to, can lead to recurrence. This case report presents a combined approach to closing an OAF by first excising the fistula and then resecting to retrieve the buccal fat pad to form a pedicle graft over the wound site. Next, a platelet-rich fibrin membrane is sandwiched over the buccal fat pad and completely covered by a buccal advancement flap. This triple-layered technique is a novel method to close a chronic OAF. Keywords: buccal advancement flap, buccal fat pad, maxillary sinus, oroantral fistula, platelet-rich-fibrin

Purpose: To evaluate the feasibility of a commercially available immediate root analog implant system Replicate (Natural Dental Implants). Materials and Methods: Five consecutive patients in need of an implant in the premolar region were recruited for this pilot study. Following clinical examination, a cone beam computed tomography scan was made and the dental impressions digitized. On the basis of the superimposition of these datasets, a three-dimensional (3D) envelope was created for the selected tooth. Subsequently, the tooth root at the prospective implant site was segmented to create a 3D surface, and the obtained mesh data were used as the basis for designing a single-piece root analog implant within the 3D envelope. The designed root analog implant was fabricated using a five-axis computer-aided manufacturing machine. The root analog implants were inserted following flapless minimally invasive root extraction. Following 3 months of uninterrupted healing, definitive restorations were fabricated. Peri-implant clinical and radiographic measurements were obtained up to 12 months follow-up. Results: All patients functioned well following 12 months of functional loading. Within one patient, one of the two root analog implants failed early. Peri-implant clinical and radiographic measurements demonstrated a stable situation after 12 months of functional loading. Conclusion: A novel digital approach for immediately restoring single teeth using root analog implants was introduced. In the future, long-term evaluation of the root analog implant technique is necessary to evaluate the success and survival of implants that were inserted using this technique. Keywords: CAD/CAM, CBCT, custom implants, digital dentistry, 3D planning