OBJECTIVEThe purpose of this study is to find some appropriate treatments on the dentin of root canal wall to obtain better bonding strength of fiber posts.

METHODS36 new extracted non-caries single root canal anterior teeth were collected and post spaces were prepared. The teeth were divided into six groups randomly and processed by different post-space treatments: Sodium chloride irrigation (group I , control group); irrigation with 2% chlorhexidine solution followed by 17% EDTA solution (group II ); irrigation with 3% hydrogen peroxide followed by 17% EDTA solution (group II); irrigation with 5.25% sodium hypochlorite (NaClO) followed by 17% EDTA solution (group IV); etching with 35% phosphoric acid-gel for 30 s (group V); 17% EDTA-gel for 1 min (group VI). After each post-space treatment, sodium chloride irrigation was applied in II-VI group. Fiber posts were then luted in the treated roots using 3M ESPE RelyX Unicem and the thin-slice push-out test was performed. The dentin surfaces and bonding interface were examined under scanning electron microscope. Fracture mode of fiber posts were observed by stereo microscope.

RESULTSGroup II-VI were effective in getting rid of smear layer. Resin rags of dentin bonding interface were observed in group II and group V. The majority fracture mode of specimens in each group were mixed mode which contained dentin destruction. Compared with control group, the bonding strength of group II, V increased obviously (P < 0.05).

CONCLUSIONIrrigation with 2% chlorhexidine solution followed by 17% EDTA solution and 35% phosphoric acid-gel etching improved the bonding strength of fiber posts. The depth of post space has no influence of bond strength.