Purpose. Bone atrophy after tooth loss may leave insufficient bone for implant placement. We compared volumetric changes after autogenous ramus block bone grafting (RBG) or guided bone regeneration (GBR) in horizontally deficient maxilla before implant placement. Materials and Methods. In this retrospective study, volumetric changes at RBG or GBR graft sites were evaluated using cone-beam computed tomography. The primary outcome variable was the volumetric resorption rate. Secondary outcomes were bone gain, graft success, and implant insertion torque. Results. Twenty-four patients (28 grafted sites) were included (GBR, 15; RBG, 13). One patient (RBG) suffered mucosal dehiscence at the recipient site 6 weeks after surgery, which healed spontaneously. Mean volume reduction in the GBR and RBG groups was 12.48 ± 2.67% and 7.20 ± 1.40%, respectively. GBR resulted in significantly more bone resorption than RBG (P<0.001). Mean horizontal bone gain and width after healing were significantly greater in the GBR than in the RBG group (P=0.002 and 0.005, resp.). Implant torque was similar between groups (P>0.05). Conclusions. Both RBG and GBR hard-tissue augmentation techniques provide adequate bone graft volume and stability for implant insertion. However, GBR causes greater resorption at maxillary augmented sites than RBG, which clinicians should consider during treatment planning.

Analyses of composition, distribution of cellular and extracellular matrix components, and molecular analysis of mitochondria related genes of bone loss in the presence of inflammatory environment in humans was the aim of the present project. As a human model we chose peri-implantitis. Morphological analyses were performed by means classical histological, immunohistochemical, and SEM (scanning electron miscroscopy) test. Gene expression analysis was performed to evaluate epithelium maturation, collagen fiber production, and genes related to mitochondrial activity. It was found that a well-defined keratinocyte epithelium was present on the top of all specimens; a distinct basal lamina was present, as well as desmosomes and autophagic processes related to the maturation of keratinocytes. Under this epithelium, a full inflammatory cell infiltrate was present for about 60% of the represented by plasma cells. Collagen type I fibers were present mainly in the form of fragmented cord tissue without cells. A different distribution of blood vessels was also present from the apical to the most coronal portion of the specimens. High levels of genes related to oxidative stress were present, as well as the activation of genes related to the loss of ability of osteogenic commitment of Mesenchymal stem cells into osteoblasts. Our study suggests that peri-implantitis lesions exhibit a well defined biological organization not only in terms of inflammatory cells but also on vessel and extracellular matrix components even if no difference in the epithelium is evident, and that the presence of reactive oxygen species (ROS) related to the inflammatory environment influences the correct commitment of Mesenchymal stem cells.

B. Alper Gultekin, DDS, PhD/Pinar Gultekin, DDS, PhD/Binnaz Leblebicioglu, DDS, PhD/Cansu Basegmez, DDS, PhD/Serdar Yalcin, DDS, PhD: Purpose: The aim of this prospective clinical trial was to compare the three-dimensional marginal bone level, implant stability, and peri-implant health of two types of submerged dental implants that were restored with matching or platform-switched abutments. Materials and Methods: Twenty-five subjects were recruited (test group: 43 implants with internal conical connection and back-tapered collar carrying a platformswitched abutment; control group: 50 implants carrying a matched-platform abutment). Implant uncovering and conventional loading were performed after 3 months of healing, and the total observation time was 15 months. Marginal bone levels, resonance frequency analysis, insertion torque, and peri-implant health indices were recorded and analyzed statistically. Results: The cumulative implant survival rate was 100%. At the second-stage surgery, bone levels were similar between groups. One year after loading, mean crestal bone loss was 0.35 ? 0.13 mm for test implants and 0.83 ? 0.16 mm for control implants, a significant difference. Primary stability was significantly higher in the test group than in the control group, but this difference disappeared after 3 months of healing prior to loading. Between-group differences for periimplant health indices were negligible. Conclusions: Both implant systems had the same survival rates. Implants with a built-in platform switch and conical connection with back-tapered collar design achieved higher primary stability at insertion and less bone resorption after 15 months. Int J Oral Maxillofac Implants 2013;28:815?823. doi: 10.11607/jomi.3087

Extensive alveolar bone resorption because of pneumatized maxillary sinus is a common problem that limits dental implant placement. Maxillary sinus floor augmentation (MSFA) is an accepted treatment protocol that provides sufficient bone volume. The aim of this study was to evaluate the percentage of graft volume reduction following MSFA using cone beam computed tomography. In this retrospective study, cone beam computed tomography scans of MSFA were measured to evaluate the volume of the grafted sinus with deproteinized bovine bone (DBB), mineralized allograft (MA), or a mixture of MA and demineralized allograft as a composite. The volumetric changes in sinus augmentation between 2 weeks (T-I) and 6 months (T-II) after operation were analyzed. Thirty-nine patients were included in this study. The average percent volume reduction was 8.14 ± 3.76%, 19.38 ± 9.22%, and 24.66 ± 4.68% for DBB, MA, and composite graft, respectively. A significant graft volume reduction was found between T-I and T-II for all groups (P < 0.01). The DBB group showed the least volume reduction (P < 0.01). Biomaterials can influence the bone graft volume change before implant placement. Deproteinized bovine bone may offer greater volume stability during healing than mineralized and composite allografts.

Purpose: This finite element analysis was conducted to determine changes in stress concentration in relation to different alveolar arch shapes of the maxilla. Materials and Methods: Five different maxillary alveolar arch shape measurements coded as shortest ellipsoid shape and medium width, longest ellipsoid shape and narrow, U-shaped long and narrow, U-shaped short and wide, and U-shaped medium length and medium width were obtained, and 5 different implant distribution strategies coded on the basis of a tooth number as 3,4,5; 2,3,4; 1,3,5; and 2,4,5 (total of 6 implants) and 2,3,4,5 (total of 8 implants) were plotted in each of the 5 maxillary arch models. The implants were assumed to support a 12-unit bridge with first molars region being the cantilever area. Combination of 5 different arch shapes, 5 different implant distributions, and 2 different loading points (anterior and posterior) led to 50 different simulated scenarios that are all solved and compared. Results: In case of either anterior or posterior loading, the most favorable implant distribution strategies for the arch models are as follows: 2,4,5 and 2,3,4,5 for longest ellipsoid shape and narrow; 2,4,5 and 2,3,4,5 for shortest ellipsoid shape and medium width; 1,3,5 and 2,3,4,5 for U-shaped long and narrow; 2,3,4,5 and 2,4,5 for U-shaped medium length and medium width; and 1,3,5 and 2,3,4,5 for U-shaped short and wide. Conclusions: Distribution of implants in 2,4,5 order seemed to be fairly favorable for ideal stress distribution in all simulated models.

Purpose: To assess the influence of different crown-implant (C/I) ratios and implant dimensions on periimplant stress in the partially edentulous posterior mandible by 3-dimensional finite element analysis (FEA). Materials and Methods: Two implants were placed in the second premolar and first molar regions of the mandibular model. The implants were then splinted with a 2-unit fixed bridge. The influence of 3 parameters (C/I ratio, implant length, and implant diameter) on periimplant bone stress was then analyzed by using FEA. Results: C/I ratios showed a direct relationship with periimplant bone stress, but the absolute height of the clinical crown had a much more significant influence. The implant length had less influence on the periimplant bone stress than the implant diameter. Lower stress values were detected in wide-diameter implants, even in scenarios involving long crowns. Conclusions: Crown height is a more important factor affecting the periimplant bone stress than the C/I ratio for splinted implant-supported crowns. Two-unit fixed restorations with high C/I ratios may be successfully used with wide-diameter implants in the posterior mandible.