Objective: Improvements in the bioactivity of zirconia implants for accelerated healing and reduced morbidity have been of continuing interest in the fields of dentistry and orthopedic surgery. The aim of the present study was to examine whether UV treatment increases the osteoconductivity of zirconia-based materials. Materials and Methods: Smooth and rough zirconia-based disks and cylindrical implants were treated with UV light for 15 min and subsequently placed in rat femurs. Surface characterization was performed using scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and contact angle measurements. Results: In vivo histomorphometry revealed that the percentage of bone-implant contact and the amount of bone volume, formed around UV-treated implants, increased by 3–7-fold for smooth surfaces and by 1.4–1.7-fold for rough surfaces compared to non-treated specimens at Weeks 2 and 4 of healing, respectively. A biomechanical test showed that UV treatment accelerated the establishment of bone-zirconia integration and enhanced the strength of the bone-implant interface by two-fold. Additionally, surface characterization of the zirconia disks revealed that UV treatment decreased the amount of surface carbon and converted the hydrophilic status from hydrophobic to superhydrophilic. Conclusions: This study indicates that UV light pretreatment enhances the osteoconductive capacity of zirconia-based materials.

No abstract

No abstract

No abstract

No abstract

No abstract

The kinetics of oxidation of methyl cellulose polysaccharide by acidic permanganate at a constant ionic strength of 2.0 mol dm −3 has been investigated, spectrophotometrically. Pseudo-first-order plots showed two distinct stages. The first stage was found to be relatively slow which corresponded to the formation of the substrate radical and Mn 3+ or Mn 4+ species as initial oxidation products, followed by an increase in the reaction rate at longer time periods. The reaction kinetics showed first-order dependence in permanganate and fractional second-order kinetics with respect to methyl cellulose concentration. The hydrogen ion dependence of the reaction rates indicated that the oxidation process is acid catalyzed. The induced polymerization of acrylonitrile indicated the intervention of free-radical mechanism. A kinetic evidence for the formation of 1:2 intermediate complex between the oxidant and the reductant, respectively, was revealed. The activation parameters have been evaluated, and a tentative reaction mechanism consistent with the kinetic results obtained is discussed.

No abstract