Influência da técnica de manipulação na resistência à tração diametral em cimentos resinosos

Abstract

Intraradicular fiber posts have been a widely accepted alternative to reinforce teeth with destroyed crowns. Resin cementation procedure is very technical sensitive and the formation of voids or bubbles is an inherent limitation. The bubbles formed during mixing and insertion may lead to a reduction at the contact area between the bonding surfaces, generating stress concentration tensions, cracking, cement degradation at the interface and a reduction in adhesive strength. It is also expected that the presence of bubbles decreases cement cohesive strength leading to cementation failures under fiberglass posts and indirect restorative materials. The objective of this in vitro study is to evaluate the influence of the mixing technique on the cohesive strength of resin cements. Cylindrical specimens (n=8) of 4X2mm were produced and diametral tensile (DT) test was evaluated in a universal testing machine according to the groups: Group NA - Nexus 3 cement using automix system, Group NM - Nexus 3 cement with manual mixing, Group RA - cement RelyX ARC using a automix system and Group RM - RelyX ARC cement with manual mixing. The obtained data were examined using ANOVA and Tukey's test (=0.05). There was a significant difference in DT strength for Nexus 3 cement (p=0.002), being greater in the automixing group, whereas the RelyX ARC cement did not show statistical differences between groups auto and manual mixing. The null hypothesis was partially accepted and it is suggested that more tests to assess the influence of bubbles in resin cements during cementation procedure be carried out.