Dentin bonding degradation of permanent and primary endodontically treated teeth

Objectives: To evaluate, by microtensile bonding strength (µTBS) and the resin/dentin interface micromorphology, the 90-day-bonding degradation of primary and permanent dentin after simulating the irrigation procedure during endodontics, using different adhesive systems. Methods: Ninety sound third molars and primary molars were divided into eighteen permanent and primary dentin groups, according to: adhesive systems (Single Bond 2-SB, Clearfil Protect Bond-CP, Adper Prompt-Lpop-APL); dentin treatment (with or no 0.5% NaOCl irrigation) and storage time (24h, 45 days, 90 days). The middle dentin was exposed; NaOCl irrigation was accomplished according to the group, and restored with composite (Charisma-Shade-A3.5). Sticks with 1mm2 section area were obtained and submitted to µTBS test and obtained data were submitted to ANOVA and Tukey tests(P<0.05). The failure mode, tags presence and the resin/dentin interface were evaluated by SEM and obtained data were submitted to Chi-square test(P<0.05). Results: For primary dentin, APL showed the lowest µTBS values, regardless irrigation and storage time. For permanent dentin, µTBS values of APL decreased when NaOCl was used, and CP and SB showed similar values. There was significant decrease in µTBS at 90-day storage when primary and permanent dentin was not irrigated with NaOCl, however until 45-day storage did not affect µTBS values. The often failure mode was the mixed for both permanent and primary dentin. At 90-day storage, the tags presence generally decreased, except for SB in primary dentin that it remains almost 100%. Conclusions: concerning permanent and primary teeth, NaOCl irrigation did not affect the bonding strength after 90-day storage, preventing the bonding degradation, except when APL was used in permanent dentin; in addition, for primary teeth the most important factor in adhesion is the adhesive system used, while for permanent teeth the interaction between adhesive system and NaOCl irrigation is significant. (supported by FAPESP #05/58808-7)