Simulated pulpal pressure influences self-etch adhesives bonding to dentin

Objective: The study aimed to assess whether the application of simulated hydrostatic pulpal pressure (PP) may influence the bonding efficacy of self-etch adhesives to dentin. Methods: Flat coronal human dentin surfaces were bonded using four self-etch adhesives systems (1. Clearfil SE Bond; 2. Bond Force; 3. Adper Scotchbond SE; 4. G Bond). Adhesives were applied onto a deep dentin substrate with or without applying hydrostatic PP of 15cm H2O. A hybrid resin composite was selected for coronal build-up (AElite All Purposes). Bonded specimens were stored for 24 hours (at 37oC and 100% humidity) with zero pressure and under 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. The fracture pattern was evaluated under SEM. Data were statistically analysed with Kruskal-Wallis on ranks (p<0.05) and Mann-Whitney tests (p<0.001) including premature failures. Results: No significant differences for Clearfil SE Bond and Bond Force bonded specimens were recorded regardless the maintenance of simulated PP. Bond strength of Adper Scotchbond SE was significantly reduced under PP. (Table). All specimens failed prematurely when G Bond was applied under PP. Conclusions: Changes in dentin wetness may influence the bonding performance of self-etch adhesive systems. The application of a constant intra-pulpal perfusion should be considered when simulating bonding procedures in vitro.