Initial enamel wear of glazed and polished leucite-based porcelains with different fusing temperatures.

This study used the radiotracer method to measure the initial enamel wear caused by low- and high-fusing porcelains after glazing or polishing. It also tested the correlation between enamel wear and porcelain surface roughness (Ra). Surface morphology was assessed by optical microscopy. Cylindrical specimens of three porcelains (two high-fusing, one low-fusing) were either autoglazed or polished. Flattened enamel specimens were irradiated with neutrons and submitted to the wear assay for 2,500 cycles in distilled water using a 285 g load; the released beta 32P particles were measured for 10 minutes. For all samples, Ra was recorded with a profilometer before and after testing. Enamel wear was not significantly different for porcelain or finishing method but there was a trend of interaction between the two variables (p = 0.08). A positive correlation was found between enamel wear and the initial Ra of porcelain (r = 0.71). The glazed surfaces of high-fusing porcelains were wavy and had a greater Ra, while the polished surfaces had grooves and pores prior to wear testing. The low-fusing porcelain demonstrated lower Ra and a more homogeneous surface. All abraded surfaces had similar morphology after the wear assay.