Surface alterations on dental restorative materials subjected to an air-powder abrasive instrument.

This study assessed the effect of an air-powder abrasive instrument (Prophy Jet) on the surface integrity of a series of restorative materials. Four types of amalgam alloys (Amalcap, Dispersalloy, Tytin, Ana 2000), three types of composite resins (Silux, Brilliant Lux, Adaptic II), a heat-cured resin (SR Vivadent), and porcelain (Vita VMK) fused to a Gr-Ni alloy at 1 mm and 2.5 mm thickness were subjected from 5 mm distance to the abrasive stream at 100 psi for 5 seconds. The resulting surface topography was studied under an electron probe microanalyzer. All of the amalgams presented increased surface roughness and alterations in the surface composition assigned to the destruction of the soluble gamma-2 and n phases. Composite resins showed excessive matrix disruption, exposure of the filler particles and pitting on the prepolymer surfaces. The crown and fixed partial denture resin was the most affected material. Porcelain at 2.5 mm thickness exhibited moderate stain pitting, whereas in 1 mm thickness severe glaze cracking was identified.

31P-NMR study of P-based dental adhesives and electron probe microanalysis of simulated interfaces with dentin.

The structure and function of P in P-based dental adhesives have not been defined properly. The purpose of this study was to evaluate these parameters in some currently available materials. Five dental adhesives were selected: Bondlite, Clearfil New Bond, J&J Dental Adhesive, Prisma Universal Bond, and Scotchbond. High-resolution 31P-NMR spectroscopy was used to identify the phases of the incorporated P and the kinetics of monomer-bonded P in an aqueous environment. Areas of 5 mm diameter located on polished sound dentin were subjected to the corresponding adhesive treatments and covered with translucent molds of the same diameter, which were filled up to 1 mm length with a visible-light-cured hybrid composite. Following 60 sec of light exposure from lateral directions, the specimens were embedded in fast-setting resin, cross-sectioned, and analyzed in an electron probe microanalyzer. The elemental profiles of Ca, P, and Cl were determined from area and line scans. Great differences in the 31P resonance shifts were obtained from the tested adhesives, indicating the presence of monomer-bonded and free P. A rapid hydrolysis of the resin-bonded P in the presence of water was identified. The x-ray images revealed dentin demineralization, with distinct differences in the P distribution pattern and the P/Cl ratio.