Effect of irrigation protocol during post space preparation on the dentin adhesive interface: An in vitro study

The post space must be prepared with techniques that do not interfere with the bond strength. These techniques are related to the availability of opened dentinal tubules and incidence of residue among the dentin, the adhesive, and the cement. Nevertheless, the effect of different irrigants during endodontic instrumentation is unclear.

The purpose of this in vitro study was to assess the incidence of residue, the number of opened dentinal tubules, and the bond strength of the cementation system to root dentin of post space after 3 different irrigation protocols.

The roots of bovine incisors were obturated, prepared to receive a fiber post, and divided into 3 groups as per the irrigation protocol: without irrigation, with alternating irrigation, and with continuous irrigation. Thirty roots (n=10) were evaluated by using scanning electron microscopy to assess the incidence of residue (×100 magnification) and the number of opened dentinal tubules (×2000 magnification). The fiber posts were cemented, and the remaining specimens (n=10) were subjected to pushout testing and failure mode evaluation.

All protocols presented a similar incidence of residue, regardless of the post space third (P>.05). The irrigation protocol without irrigation had the lowest number of opened dentinal tubules in the cervical and middle thirds (P<.05). The number of opened dentinal tubules was similar in all protocols in the apical third of the post space (P>.05). The irrigation protocol without irrigation had the lowest bond strength values in the cervical and middle thirds (P<.05). The irrigation protocol with continuous irrigation had the highest bond strength values in the apical third (P<.05).

Post space preparation without irrigation negatively affected the bond strength of the resin cementation system to root dentin.