The effect of thermal stress on bonding durability of resin composite adaptation to the cavity wall.

This study evaluated the effect of thermal stress on marginal sealing and cavity wall adaptation using two adhesive systems. Cylindrical cavities were prepared in superficial dentin of bovine incisors and bonded with Clearfil SE Bond or Single Bond adhesive. Cavities were bulk-filled with Photo Clearfil Bright or Filtek Flow resin composite and light-cured for 40 seconds. Specimens were thermocycled for 0, 500, or 5000 times. A dye penetration test was carried out to determine adaptation to the cavity wall. Dye penetration length was calculated as a percentage of the total cavity wall length. Clearfil SE Bond showed excellent marginal sealing and cavity wall adaptation regardless of composite type up to 500 cycles of thermal stress. As for the Single Bond groups, significantly greater marginal leakage occurred after 500 cycles. At 5000 cycles of thermal stress, both adhesive systems showed significantly decreased marginal integrity compared with the 0 cycle group.