IMPREGNATION BY DENTIN BONDING AGENTS INTO INSTRUMENTED ROOT-FACE DENTIN

Objectives: To examine the penetration of unfilled resin into instrume nted soot-face dentine, facilitated by five commercially available den tine bonding agents. Methods: Upper third molar teeth were decoronated , and a given dentine bonding agent and resin composite applied to the instrumented root face, according to the manufacturer's instructions. A control specimen was similarly prepared but no dentine primer was a pplied prior to resin composite. The teeth were sectioned longitudinal ly and the sectioned surface demineralized and deproteinated. Specimen s were examined by scanning electron microscopy (SEM) for resin tag le ngth and density in different areas of the root face. Results: Specime ns treated with dentine bonding agent systems exhibited minimum resin penetration of peripheral root-face dentine and much longer penetratio n of resin tags in dentine above the pulp chamber. A possible 'hybrid' layer of resin-impregnated dentine was observed in all specimens wher e a dentine bonding agent system had been used but was not observed in control specimens. Resin tags were also more sparsely observed in con trol specimens. Conclusion: Resin tag penetration is superior in both density and length of penetration in dentine overlying and adjacent to the pulp chamber, with shorter and sparser penetration exhibited in p eripheral root-face dentine. The possible clinical implications of the se observations are discussed.