Fatigue Resistance of 2 Different CAD/CAM Glass-Ceramic Materials Used for Single-Tooth Implant Crowns

Purpose: To evaluate the fatigue resistance of 2 different CAD/CAM in-office monoceramic materials with single-tooth implant-supported crowns in functional area

A Pilot Study of Joint Stability at the Zirconium or Titanium Abutment/Titanium Implant Interface

Purpose: To compare the interfaces of loaded and unloaded zirconium and titanium abutments with titanium implants using scanning electron microscopy (SEM). Materials and Methods: Zirconium and titanium abutments (n = 5 per group; four test and one control) were torque-tightened into titanium implants secured into metal blocks, and computer-aided design/computer-assisted manufacture-based zirconium oxide copings were fabricated and cemented to the abutments with temporary resin-based cement. Specimens of each restoration were subjected to cyclic axial and lateral loading of 30 N at 2 Hz for 500,000 cycles using a servohydraulic test system; control specimens were left unloaded. Then, the abutment/implant assemblies were embedded in acrylic resin, sectioned longitudinally along the midline, and inspected under SEM with x-ray microanalysis. Results: Loosening or fracture of the copings and implant components was not observed after dynamic loading in both groups. SEM and x-ray microanalysis revealed unexpected microleakage of acrylic resin at the interface. Acrylic resin in the implants tightened to the titanium abutments was limited to the cervical part, and the components displayed scratched and smashed regions, suggesting slight deformation of the implant neck. Micro leakage and pooling of acrylic resin were observed approaching the screw joint in loaded implants tightened to zirconia abutments, and the amount of microleakage was greater than in the unloaded control specimens, which had a larger microgap than the titanium abutment/titanium implant interface. Loaded zirconia abutments were associated with wear, scratches, and, in one sample, chipping. Conclusions: Zirconium abutment/titanium implant interface may be susceptible to wear of the abutment coupled with deformation of the implant neck greater than that associated with the conventional titanium abutment/titanium implant interface under dynamic loading

Immediate Versus Conventional Loading Of Implant-Supported Maxillary Overdentures: A Finite Element Stress Analysis

Purpose: To compare biomechanical outcomes of immediately and conventionally loaded bar-retained implant-supported maxillary overdentures using finite element stress analysis. Materials and Methods: Finite element models were created to replicate the spatial positioning of four 4.1- x 12-mm implants in the completely edentulous maxillae of four cadavers to support bar-retained overdentures with 7-mm distal-extension cantilevers. To simulate the bone-implant interface of immediately loaded implants, a contact situation was defined at the interface; conventional loading was simulated by "bonding" the implants to the surrounding bone. The prostheses were loaded with 100 N in the projected molar regions bilaterally, and strain magnitudes were measured at the buccal aspect of bone. Results: The amplitude of axial and lateral strains, the overall strain magnitudes, and the strain magnitudes around anterior and posterior implants in the immediate loading group were comparable to those seen in the conventional loading group, suggesting that the loading regimens created similar stress/strain fields (P > .05). Conclusions: Conventional and immediate loading of maxillary implants supporting bar-retained overdentures resulted in similar bone strains.Wo

Low-level laser therapy vs. pulsed electromagnetic field on neonatal rat calvarial osteoblast-like cells

To compare the effects of pulsed electromagnetic field (PEMF) and low-level laser therapy (LLLT) on osteoblast cells in a cell culture model. Fifty thousand neonatal rat calvarial osteoblast-like cells per milliliter were seeded and 0.06 mT PEMF, 0.2 mT PEMF, and LLLT at 808 nm were applied for 24 and 96 h on the cells. To evaluate cellular proliferation and differentiation, specimens were examined for DNA synthesis, alkaline phosphatase (ALP) activity, cell numbers, and viability of the cells. Morphological appearances of the cells were observed using scanning electron microcopy after 24 and 96 h of incubation. At 24 and 96 h, the control group had a higher cell proliferation than 0.06 and 0.2 mT PEMF groups (p = 0.001). At 96 h, 0.2 mT PEMF group had higher cell proliferation rate than 0.06 mT PEMF and LLLT groups (p = 0.001). The cell count and cell viability in 0.2 mT PEMF group were higher than the 0.06-mT PEMF and LLLT groups, although these differences were not statistically significant at 96 h (p > 0.05). At 24 and 96 h, cell viability in the control group was higher than the test groups. Alkaline phosphatase levels of the groups were comparable in both time intervals (p > 0.05). 0.2 mT PEMF application on osteoblast-like cells led to cell proliferation and differentiation better than 0.06 mT PEMF and LLLT at 808 nm, although a remarkable effect of both PEMF and LLLT could not be detected. The ALP activity of 0.2 and 0.06 mT PEMF and LLLT were comparable

Comparative in vitro activity of plazomicin and older aminoglyosides against Enterobacterales isolates; prevalence of aminoglycoside modifying enzymes and 16S rRNA methyltransferases

Comparative in vitro activity of plazomicin and 4 older aminoglycosides was evaluated with broth microdilution in 714 blood isolates from 14 hospitals in Turkey