Silanes formulated with thio-urethanes for adhesive bonding of fiberglass posts to root canal

The aim of this study was to evaluate the push out test strength of conventional or anatomical fiberglass posts treated with experimental silanes formulated with thio-urethane oligomers. In the bovine teeth endodontic treatment were used conventional fiberglass posts or anatomical fiberglass posts customized with Filtek Z250 resin composite layer modeling the anatomy of the root canal. The roots were randomly divided into 8 groups (n = 10): CP-RX (Control); CP-HDDI; CP-HDMI; CP-BDI; AP-RX (Control); AP-HDDI; AP-HDMI; and AP-BDI⁽*⁾. Slices of each root third were subjected to the push out test and failure pattern evaluation (%). Marginal microleakage was observed in root slices submitted to 2% methylene blue solution (%). Push out test strength data were statistically evaluated using Core Team R Program (Language and environment for statistical computing - Foundation for Statistical Computing, Austria) at a significance level of 5%. Results showed that the bond strength varied for each root third as function of the fiberglass post types used ⁽**⁾. For the conventional posts, CP-HDMI and CP-BDI presented higher and significantly similar strengths at the cervical third. CP-HDDI, CP-HDMI and CP-BDI demonstrated higher and significantly similar strengths at the middle third, and CP-HDMI and CP-BDI presented higher and significantly similar strengths at the apical third. For the anatomical posts, AP-RX presented significantly higher strength at the cervical third; AP-RX, AP-HDDI, AP-HDMI and AP-BDI demonstrated greater and significantly similar strengths at the middle third, and AP-RX, AP-HDDI and AP-HDMI showed higher and significantly similar strengths at the apical third. For different post types as function of each silane, AP-RX, CP-HDMI, and CP-BDI had significantly higher strengths at the cervical third; AP-RX, CP-HDMI and CP-BDI displayed significantly higher strengths at the middle third, and CP-HDMI and CP-BDI had significantly higher strengths at the apical third. Mixed failures predominated and the microleakage scores varied between 3 (up to 2/3) and 4 (+2/3). The results showed positive effect of the experimental silanes composed by thio-urethane oligomers in all situations analyzed. Different values in the adhesion of fiberglass posts in relation to experimental silanes were observed, as well as its relation to adhesion in the root thirds. Mixed failures predominated and the microleakage showed similar values among root regions.