Influence of Dentin Deproteinization on Bonding Degradation: 1-year Results

The decalcification protocol of dentin surface with sodium hypochlorite removes the exposed collagen fibrils and could improve the longevity of the bonding interface. This study evaluated the influence of collagen removal with 10% sodium hypochlorite (10% NaOCl) on the longitudinal shear bond strength (SBS) of adhesives to dentin.

Seventy-two extracted human molars were sectioned and the buccal and lingual surfaces were flattened and acid etched with 37% phosphoric acid for 15 seconds. The specimens were divided into six groups (n = 12 teeth - 24 sections), according to adhesive and collagen removal protocol: group 1: UNO Dentastic; group 2: Prime and Bond NT; group 3: Single Bond; group 4: 10% NaOCl + UNO Dentastic; group 5: 10% NaOCl + Prime and Bond NT; group 6: 10% NaOCl + Single Bond. Composite Z100 buildup was prepared, and the SBS test was assessed after 24 hours and 1 year. Data were submitted to three-way analysis of variance (ANOVA) and Tukey tests (p < 0.05).

The mean values (MPa) were for 24 hours: G1: 22.45^B; G2: 7.90^DE; G3: 12.56^CD; G4: 19.85^BC; G5: 33.73^A; G6: 20.77^B; and for 1 year: G1: 2.43^E; G2: 2.26^E; G3: 4.3^DE; G4: 18.79^BC; G5: 26.49^AB; G6: 22.73^B.

Dentin deproteinization treatment with 10% NaOCI influenced the SBS compared with conventional treatment. The negative influence on SBS detected for conventional groups at 1-year interval was not detected for deproteinized groups.

The longevity of hybrid layer is critical due to the hydrolysis process at the adhesive interface over time. The use of 10% NaOCl deproteinization protocol might improve the longevity of bonding in adhesive restorations.