Efeito da colonização de streptococcus Mutans nas propriedades físicas de Diferentes cimentos odontológicos

Abstract

Dental materials must withstand the exposure to the several substances in the oral cavity, which is an important requirement for their clinical performance. This study evaluated, in vitro, the effect of Streptococcus mutans bacterial colonization, for thirty days, on physical properties of dental cements. Cylindrical specimens (4 mmx 2 mm) were prepared from five different cements: glass ionomer cement (Ketac Cem – 3M/ ESPE), zinc phosphate (Cimento de Zinco – SS White), resinous with dual cure polymerization (RelyX ARC – 3M/ESPE), resinous with light cure (RelyX Veneer – 3M/ESPE) and self-adhesive resinous with dual cure (RelyX U200 – 3M/ESPE). Samples were divided into experimental groups according to experimental design: G1 – Control (n=10): 100% of relative humidity for 24h; G2 – BHI (n=10): immersion in BHI + 1% sucrose for 30 days; G3 – BHI + S. mutans (n=30): immersion in BHI + 1% sucrose, for 30 days, after S. mutans biofilm adherence on the surfaces of the disks. Samples were analyzed using surface roughness, Vickers microhardness, diametral tensile strength and optical microscopy. Data collected were analyzed using ANOVA and Tukey-Krammer tests (α = 0.05). Glass ionomer cement presented a significant increase in surface roughness values after storage in BHI and BHI + S. mutans. Resin cements showed no significant difference. Regarding microhardness, it was observed statistically significant difference between samples of BHI + S. mutans group and the other groups of all tested materials. It was not possible to determine roughness and microhardness of zinc phosphate cement specimens of BHI and BHI + S. mutans. With respect to the diametral tensile test, glass ionomer and zinc phosphate cements showed a significant change in the results of groups BHI and BHI + S. mutans, while the same was not observed for the other materials. Optical microscopy images showed alterations in the surface of the non-resinous materials, while resinous materials did not show any change. Based on the results, it can be concluded that none of the materials tested remained unaffected by Streptococcus mutans biofilm, and that the effects were material-dependent.