Susceptibility of contemporary single-bottle self-etch dentine adhesives to intrinsic water permeation

Abstract

Objectives To evaluate the effect of intrinsic water permeation on the microtensile bond strengths of different adhesive systems to dentine and the quality of resin-dentine interfaces. Methods Ninety-six non-carious human third molars were divided into 4 groups: Clearfil S3 Bond Plus (CSBP; Kuraray); Clearfil S3 Bond (C3S; Kuraray); iBond Self-Etch (IB; Heraeus-Kulzer) and Prime&Bond NT (PB, control etch-and-rinse adhesive, Dentply-Sirona). For each adhesive, specimens from one subgroup (N = 10) were bonded using zero pulpal pressure, while specimens from the other subgroup (N = 10) were bonded using 15 cm water pressure (PP). Each bonded tooth was sectioned into 1 × 1 mm sticks and stressed to failure. Data were analysed using two-way ANOVA and Holm-Sidak pairwise comparisons to examine the effects of “adhesive”, “pulpal pressure” and their interaction on bond strength (α = 0.05). Representative fractured sticks were examined by SEM. The remaining tooth slabs in each subgroup were used for TEM and CLSM. Results Microtensile bond strengths (mean ± SD; in MPa) were: 33.4 ± 6.9 (CSBP), 33.2 ± 4.7 (CSBP-PP), 35.0 ± 8.6 (C3S), 25.5 ± 7.3 (C3S-PP), 18.4 ± 4.0 (IB), 16.5 ± 6.9 (IB-PP), 28.2 ± 5.5 (PB), 20.5 ± 7.2 (PB-PP). “Adhesive-type” (P < 0.001), “pulpal-pressure” (P < 0.001) and their interactions (P < 0.001) significantly affected bond strength results. No difference between no-PP and PP subgroups was found for CSBP and IB (P > 0.05). Water droplets were identified along the resin-dentine interface for IB, IB-PP and C3S-PP. Conclusion IB exhibits water sensitivity when bonding is performed with/without pulpal pressure. C3S exhibits water sensitivity when bonding is performed with pulpal pressure. CSBP does not exhibit water sensitivity when bonding is performed with/without pulpal pressure. Clinical significance: Intrinsic water permeation during bonding procedures significantly affects bond strength results and the resin-dentine interface of contemporary single-bottle self-etch dentine adhesive systems.