Testing rate and cementation seating load effects on resin-strengthening of a dental porcelain analogue

ObjectivesTo determine the resin-strengthening dependence of a soda-lime-glass analogue for dental porcelain as a function of biaxial flexure strength (BFS), test crosshead rate and cementation seating load.MethodsDisc-shaped soda-lime glass specimens were divided into twelve groups (n = 24), alumina particle air abraded and hydrofluoric acid-etched. Specimens (Groups A–D) were stored in a desiccator prior to testing at crosshead rates of 0.01, 0.1, 1 and 10 mm/min, respectively. The remaining specimens were silane treated, Rely-X Veneer resin-coated with a seating load of 5 N (Groups E–H) and 30 N (Groups I–L) prior to light irradiation at 480 ± 20 mW/cm2, 24 h dry storage and BFS testing at 0.01, 0.1, 1 and 10 mm/min, respectively. A linear logarithmic regression curve was fit to the raw data to elucidate static fatigue effects of the soda-lime-glass. Analysis of group means was performed utilising a general linear model univariate analysis and post hoc all paired Tukey tests (P < 0.05).ResultsThe linear logarithmic regression curve demonstrated the static fatigue effects of the soda-lime-glass analogue. Rely-X Veneer resin-coating (Groups E–L) resulted in significant increases in the mean BFS data for all crosshead rates examined (all P < 0.001). However, the pattern of rate dependence effects on resin-cementation deviated from the log relationship observed with the uncoated controls.ConclusionThis study further highlights that when slow crack growth is simulated during testing, valuable insights into the significant modification of a hereto well described phenomenon such as resin-strengthening mediated by the resin–ceramic hybrid layer is provided.