Influência de diferentes métodos de preparo e sistema adesivo na resistência máxima de adesão à dentina bovina e humana

Abstract

The aim of this study was: determine the microtensile bond strength (&#956;TBS) of two adhesives, one total-etch and one self-etching primer, to bovine dentin prepared with a carbide bur, a diamond rotary instrument and CVD bur; and evaluated the microtensile bond strength (&#956;TBS) of two adhesives, one etch-and-rinse and one self-etching, to bovine and human dentin prepared with a carbide bur and diamond rotary instrument. For the first evaluation, forty-two bovine incisors with similar age were randomly divided into three groups according to surface preparation: carbide bur CB, diamond rotary instrument PD and CVD bur. For the second evaluation, twenty-eight bovine incisors and twenty-eight human molars were randomly divided into two groups according to surface preparation: carbide bur CB and diamond rotary instrument PD. Each group (n=7) was bonded using a total-etch adhesive (Scotch Bond Multi Purpose) - SBMP and one self-etching primer (Clearfil SE Bond) - CfSE. The cavities were incrementally restored with composite resin. The teeth were sectioned into 0.8 mm2 beam, and loaded to failure at a crosshead speed of 0.5 mm/min using mechanical machine. Microtensile bond strength data were analyzed using analysis of variance and Tukey test (p<0.05). The results of first evaluation showed that &#956;TBS values of PD and CVD were similar and higher than CB. And &#956;TBS values of CfSE were always higher than SBMP. For the second evaluation, the dates do not show statistically difference between substrate, adhesive and rotary instrument (p=0,495). But have difference between substrate and adhesive (p=0,000), and substrate and rotary instrument (p=0,000). A &#956;TBS value of SBMP in human dentin was similar to CfSE, and in bovine dentin, the &#956;TBS values was smaller invariable of rotary instrument used. And human teeth show higher &#956;TBS values than bovine teeth. Hence, for bovine dentin, &#956;TBS values of PD were significantly than CB, and show difference only to bovine dentin, not been influence for human dentin. The bovine dentin show &#956;TBS values significantly higher when to CfSE, while in human dentin, both adhesive system show similar &#956;TBS values. Ten, the type of rotary instrument and adhesive system influence the &#956;TBS values differently between bovine and human substrate.