Allenlyng2047

PURPOSE Different titanium bases for implant-supported prostheses can present different mechanical behavior. The goal of this study was to evaluate the torque before and after fatigue, the load to failure, and stress concentration of zirconia restorations cemented or notched to a titanium base. MATERIALS AND METHODS Forty implants were included in polyurethane cylinders and divided into two groups zirconia restoration cemented on a titanium base and zirconia restoration notched on a titanium base. The specimens had their torque loosening and vertical misfit evaluated before and after cyclic fatigue (200 N/2 Hz/2 × 106 cycles/37°C). Load to failure was evaluated in a universal testing machine (1 mm/min, 1,000 kgf). Failures were evaluated by scanning electron microscopy. Three-dimensional models were created, and the stress concentration was calculated using the finite element method. Data from the in vitro tests were submitted to two-way analysis of variance and Tukey test (α = .5). RESULTS The cemented restorations presented less torque loosening (19.79 to 15.95 Ncm), lower vertical misfit (3.7 to 10.5 μm), lower stress concentration in the restoration (88.2 to 99.8 MPa), and higher fracture load (451.3 to 390.8 N) than notched restorations. CONCLUSION The presence of a cement layer between the restoration and titanium base reduced the susceptibility to abutment screw loosening, improved the resistance to compressive load, and reduced the stress concentration in the restoration.PURPOSE To evaluate the dimensional variations after elevation of the maxillary sinus floor and the healing of the antrostomy left unprotected or protected by a collagen membrane. MATERIALS AND METHODS Twenty patients were included in the study. After the elevation of the sinus mucosa, natural bovine bone was grafted into the elevated space. In 10 randomly selected patients, a native collagen membrane made of porcine corium was placed on the antrostomy (membrane group). learn more In the other 10 patients, the antrostomy was left uncovered (no-membrane group). Cone beam computed tomography (CBCT) images were taken for all patients before surgery (T0), 1 week after sinus floor augmentation (T1), and after 9 months of healing (T2), and evaluations of dimensional variations over time of soft and hard tissues were performed. RESULTS At T1, the elevation of the sinus floor in the middle aspect was 12.5 ± 3.8 mm and 11.9 ± 3.6 mm in the membrane and no-membrane groups, respectively. At T2, the reduction in height of the elevated space was 0.6 ± 0.9 mm and 0.8 ± 0.8 mm in the membrane and no-membrane groups, respectively. The elevated area decreased between ~10% and 11% in the membrane group and between ~15% to 20% in the no-membrane group. However, no statistically significant differences were found. CONCLUSION The use of a collagen membrane to cover the antrostomy after sinus floor elevation did not produce significant clinical effects on dimensional variations over time.PURPOSE To evaluate the effect of continuous tooth eruption on the outcomes of single-implant-supported restorations in the anterior maxilla of adults. MATERIALS AND METHODS Seventy-six patients (age 21 to 78 years) treated with single-implant-supported restorations in the esthetic zone were included. Radiographs obtained at crown placement and follow-up examinations from 1 to 15 years postloading were analyzed with regard to vertical incisal plane changes of the implant-supported crown relative to adjacent teeth. RESULTS Infraocclusion increased over time by 0.08 ± 0.02 mm/year. Infraocclusion was more pronounced (P = .04) for delayed (0.09 mm/year) versus immediate implant placement (0.06 mm/year) and for younger versus older adults (0.0013 mm/year per additional year of age; P = .014). No statistically significant association between infraocclusion and sex, ethnicity, implant site, timing of implant temporization, surgical protocol, and type of restoration was found. CONCLUSION Infraocclusion of single-implant-supported maxillary anterior restorations may result in esthetic concerns over time. Greater infraocclusion occurs in delayed implant placement and in younger individuals.PURPOSE To evaluate the factors affecting peri-implant marginal bone level of single platform-switched implants with a smooth neck placed at gingival level (tissue level) using a flapless technique. MATERIALS AND METHODS Consecutive healthy patients requiring dental implant rehabilitations were enrolled in this study. Titanium implants with a zirconium-oxide-blasted surface and a platform-switch neck tulip configuration were used. Loading was performed 3 months after insertion with a provisional resin crown and after approximately 15 days with a definitive ceramic crown. Peri-implant marginal bone level (MBL) was measured on periapical radiographs at 1, 3, 6, 12, 24, 36, and 48 months by a blinded assessor. The following parameters were evaluated location (maxillary/mandibular), position (anterior/posterior), sex (male/female), smoke (yes/no), implant placement timing (immediate, early, delayed), gingival thickness (thin/thick), endodontically treated adjacent teeth (yes/no), and diameter (3.8/4.25/5.0 mm). Multilevel analyses exploring factors associated with MBL at 36 and 48 months were performed. RESULTS A total of 76 patients (42 women, 34 men; mean age 55.6 ± 10.7 years) received 128 implant rehabilitations. The survival rate was 98.4%. MBL displayed an initial increase during the first months from insertion (preload period). Cumulative mean MBL at T48 was 0.99 ± 0.68, which was not statistically significant from the values at T24 to T36 (P > .05). Mandibular location, delayed implants, and presence of adjacent endodontically treated teeth showed higher bone loss at 36 months (P .05). CONCLUSION Platform-switched implants placed nonsubmerged with a flapless approach showed a reduced bone loss progression in the first 4 years, as MBL remained stable at longer times (36 and 48 months). Implants placed with early and immediate timing showed reduced bone loss compared with delayed implants.PURPOSE The aim of this study was to compare how two innovative laser titanium surfaces and sandblasted and acid-etched surfaces influence human osteoblast behavior during osteogenesis and the initial phases of bone deposition. MATERIALS AND METHODS Human osteoblasts from human adipose stem cells were sorted by flow cytometric analysis and induced to differentiate. After 40 days, the osteogenic differentiation was detected by alizarin red staining, and the alkaline phosphatase (ALP) was evaluated with western blot (WB) and real-time reverse transcriptase-polymerase chain reaction (RT-PcR) analysis. After confluence, human osteoblasts were cultured onto two different innovative laser-obtained titanium surfaces (L1 and L2) and compared with one sandblasted and acid-etched (SBAE) surface as the control. At different times, human osteoblast behavior was evaluated with cell proliferation viability assay (MTT), scanning electron microscopy (SEM), energy-dispersive x-rays (EDAX), osteogenic markers with RT-PcR, and WB analysis of matrix extracellular phosphoglycoprotein (MEPE), ALP, and osteocalcin (OCN).