Vickers micro-hardness of cross-linked artificial teeth after acid challenge

Objectives: This study evaluated the Vickers hardness of two layers (internal and external) of commercial cross-linked artificial teeth (Trilux and Postaris) after acid challenge. Methods: The occlusal surfaces of the denture posterior teeth (n=10), embedded in autopolymerizing acrylic resin, were ground flat with 1200-grit silicon carbide paper and polished with pumice. Specimens were stored in distilled water at 37°C for 48h and then hardness values (VHN) were obtained with a hardness tester (Shimadzu HMV-2000). Specimens were then placed in distilled water at 37°C for 28 days and submitted or not (control) to the acid challenge (immersion in acetic acid for 10 min, 3 times a day). Afterwards, micro-hardness tests were again performed. Data were analyzed using three-way repeated-measures analysis of variance (ANOVA) and Tukey's test (α=.05). Results: Postaris teeth exhibited an increase (P<.05) in hardness of external layer for up to 28 days of immersion in both conditions. For its internal layer, it was observed an increase (P<.05) in hardness values only after the acid challenge. For the external layer of Trilux teeth, no significant differences were observed despite of the immersion condition (P>.05). Whereas for its internal layer, 28-days' immersion in distilled water caused an increase in hardness values (P<.05). Postaris teeth showed the highest hardness values in all conditions (P<.05). Conclusions: The acid challenge increased the hardness of Postaris teeth, with no significant effect for Trilux teeth. Hardness of Postaris teeth was higher than that of Trilux teeth. (PIC/USP Grant No: 2009.1.1963.25.3)