Long-term durability of dentin bonds made with a self-etching primer, in vivo

The long-term durability of bonds between adhesive resins and dentin is of significant importance for the longevity of bonded restorations. We carried out an in vivo one-year study to evaluate the durability of resin-dentin b ends in the oral cavity, as well as to test the hypothesis that the adhesiv e interface would show morphological changes in cine over time. Very shallo w saucer-shaped dentin cavities were prepared in 12 intact teeth of one Jap anese monkey (Macaca fuscata) under general anesthesia. The cavities were r estored with Clearfil Liner Bond II and Clearfil Photo Posterior resin comp osite. The teeth were extracted at three different times: immediately, and 180 and 360 days after placement of the restorations. One day after the mon key was killed, specimens of the three time periods were subjected to the m icro-tensile bond test at a crosshead speed of I mm/min. The surfaces of th e failed bonds were observed under a field emission scanning electron micro scope (FE-SEM). Bond strength measurements in this study were successfully performed and were stable at approximately 19 MPa Juring the one-year testi ng. Scanning electron microscopic observations of the failed surfaces revea led, at the top of the hybrid layer and within the adhesive resin, porosity which increased over time. Long-term bonds can be assessed in vivo by the combined evaluation of the microtensile bond strength and SEM morphological examination of the adhesive interface.