May surface pre-treatments improve self-adhesive cements bonding to dentin?

Acid pre-treatment of dentin has been suggested as an alternative when bonding with self-adhesives resin cements. Objective: To evaluate the bonding effectiveness of self-adhesive resin cements applied on hydrated dentin after different surface pre-treatments. Methods: Three self-adhesive cements (Rely X Unicem, Bis-Cem and G-Cem) were used to lute twenty-seven composite overlays (Aelite All Purpose Body) to deep coronal dentin. Three groups were formed (n=9) according to the following surface pre-treatments: 1) 0.1 M EDTA demineralization; 2) 10% polyacrylic acid (PPA) etching; 3) No treatment of dentin. Luting procedures were performed under a simulated pulpal pressure (PP) of 15 cm H₂O. Bonded specimens were stored for 1 month (at 37^oC and 100% humidity) maintaining PP, then sectioned into microtensile beams (0.9x0.9 mm) and loaded in tension at a crosshead speed of 1.0 mm/min until failure. Data were statistically analysed with Kruskal-Wallis on ranks (p<0.05) and Mann-Whitney tests (p<0.001) including premature failures (PF). Representative fractured sticks were evaluated under SEM. Results: Mean bond strength (MPa) and standard deviations are presented in the table. Letters in each column and numbers in each row indicates significant differences. G-Cem performed better when luted to PAA conditioned dentin. Bond strength of Bis-Cem fell significantly after EDTA and PAA treatments. No significant differences were recorded for Rely X Unicem. Conclusions: Tested resin self-adhesive cements exhibit a differential behaviour after dentin pre-treatments. PPA conditioning of dentin may be beneficial when using G-Cem for cementation procedures. Acknowledgements:CICYT/FEDER-MAT2004-06872-C03-02.