Dentine Bonding Following Casein Phosphopeptide Amorphous Calcium Phosphate Paste Application

Aim: To evaluate microshear bond strength (MSBS) to dentine following application of a casein phosphopeptide amorphous calcium phosphate paste (Tooth Mousse TM, (GC Corp, Japan)).

Methods: Ninety human molars were sectioned approximately 2 mm from the buccal/lingual surfaces. The enamel was ground until dentine was exposed, then polished with wet silicon carbide papers up to 1,200-grit. The specimens were divided into two groups (1: the smear layer was retained; 2: the smear layer was removed by application of 15% EDTA for 90 s). In each group, half the specimens were left as untreated controls (1A, 2A) and half treated with TM for 60 min daily x 7 days (1B, 2B). Groups 1A, 1B, 2A and 2B specimens were further divided into three subgroups for conditioning (Primer, 35% phosphoric acid (PA) + primer and 20% polyacrylic acid (CC) + primer). Two self-etching/priming adhesives were used in bonding (Clearfil SE Bond, CSE, (Kuraray Medical, Japan) and G-Bond, GB, (GC Corp, Japan)). Resin composite-filled microtubes were bonded to superficial/deep dentine and 24 h afterwards, stressed in shear until failure. Maximum loads at failure were recorded, converted to MPa and taken as the MSBS. Group means were compared using one-way ANOVA and Tukey′s post-hoc test at a = 0.05. Bond failure modes were assessed.

Results: TM application did not significantly affect MSBS in group 1. In group 2, there was a statistically significant increase in MSBS for CSE on deep dentine (P = 0.002) and a reduction for GB (P = 0.013) on superficial dentine. PA application did not significantly affect MSBS for CSE and GB while CC significantly reduced MSBS for GB.

Conclusions: TM application did not reduce MSBS for CSE but significantly reduced MSBS for GB in group 2. Pre-conditioning did not improve dentine MSBS for CSE or GB with/without TM application.