Effect of the additive dentine conditioning in all-in-one adhesives on the bonding strength at simulated intrapulpal pressure

The aim of the study was to investigate the infl uence of additive etching of dentine with phosphoric acid on the shear bond strength of two different, self-conditioning, all-in-one adhesives [Adect (ADE), and One-Up-Bond F (OUP)]. Dentine discs from 90 human molars (n = 15 per group) were exposed to penetration by Ringer's solution (60 cm height, 22 °C) by means of a perfusion device. A two-step, self-conditioning adhesive system [Clearfi l SE (CSE)] was used as the control group. The dentine was either treated (+) after preliminary additive etching wssith 36% phosphoric acid for 20 seconds or left untreated (-). Subsequently, the samples were provided with a composite cylinder (Herculite XRV). After thermocycling (5/55 °C, 5000 cycles, 20 s holding time, 4 s transportation time), the shear bond strength (MPa) was determined with a Zwick universal testing machine (feed rate 5 mm/min). Furthermore, parametric Weibull regression models were applied to evaluate whether there was a signifi cant association between shear bond strength and the method of surface conditioning. Weibull analysis was performed using R software (version 2.11.1, R Foundation for Statistical Computing, Vienna, Austria). Differences between groups were tested using Wald tests, and p-values below 0.05 were considered signifi cant.