Dentin bonding agents and composite retrograde root filling.

The purpose of this in vitro study was to evaluate the applicability of five different commercial dentin bonding agents to the composite retrograde root filling technique. The evaluation was performed by bond strength measurements and by the tendency of retrograde composite fillings to develop gaps during exposure to thermal stress. Bond strength was measured in shear and the interface between retrograde filling and dentin was examined microscopically. In adaptation tests the apical cavity design was performed as a slightly concave dissection of the root area. Gaps were found between retrograde filling and resected root as a consequence of thermocycling when using Scotchbond 2, Prisma Universal Bond 3 and XR-Bonding System, while Tenure Solution and Gluma maintained gap-free interfaces in all test specimens. A directly proportional relationship was found between the percentage of thermocycled specimens exhibiting no gaps and the mean bond strength. Based upon these results, it is advisable to apply the dentin bonding systems Tenure Solution or Gluma for retrograde composite root filling.