Influence of pretreatments on microtensile bond strength to eroded dentin using a universal adhesive in self-etch mode

Purpose: To evaluate the influence of pretreatments on microtensile bond strength (mu TBS) to eroded dentin when using a universal adhesive in self-etch mode. Materials and methods: Forty-eight human molars were randomly assigned to six groups (G1-G6, n = 8) and ground down until dentin exposure. G2-G6 were eroded with citric acid (pH 2.6) for 10 x 2 min (within 12 h) on 5 consecutive days. G1 and G2 served as uneroded and eroded controls and were not pretreated. G3 and G4 were pretreated for 60 s with NaOCl (10% and 5%, respectively). G5 was airborne-particle abraded using Al2O3 for 15 s, and G6 was roughened with a diamond bur. The universal adhesive Scotchbond Universal was applied in selfetch mode. After composite build-up, mu TBS was determined. Results: Control group G1 (uneroded) showed higher mu TBS than G2 (eroded). The mu TBS (mean MPa +/- SD) of G5 (airborne-particle abrasion; 11.6 +/- 4.6) and G6 (bur-roughening; 11.0 +/- 3.3) did not differ significantly from the mu TBS of G1 (12.4 +/- 4.2). Significantly higher mu TBS compared to all other groups was observed in G3 (NaOCl 10%; 17.6 +/- 7.6). Pretreatment with NaOCl 5% (G4) achieved significantly lower mu TBS (3.5 +/- 2.6) than the other groups, except for G2 (8.8 +/- 2.0). Conclusions: Pretreatment with 10% NaOCl, diamond bur roughening or airborne-particle abrasion can increase bond strength of the tested adhesive to eroded dentine. Pre-treatment with 5% NaOCl is not recommended.