Influence of organic acids present in the oral biofilm on the microtensile bond strength of adhesive systems to human dentin

This study evaluated the influence of organic acids present in the oral biofilm on the microtensile bond strength (μTBS) of adhesive systems to human dentin. Sixty occlusal dentin surfaces were wet ground with 600 grit SiC abrasive paper and divided into four groups according to the adhesive systems: Scotchbond Multipurpose (SMP), Adper Single Bond 2, Adper Scotchbond SE (ASE), and Clearfill SE Bond (CSE). After the adhesive systems were applied, a block of resin composite was built up on the dentin surfaces. After 24 h storage in distilled water at 37°C, the teeth were perpendicularly cut to obtain beams (1 mm(2)). For each adhesive system, the beams were divided into three groups according to storage media: artificial saliva (AS); propionic acid (PA), and lactic acid (LA). After 7 days storage at 37°C, the beams were submitted to μTBS testing. The μTBS ranged from 36.0 ± 1.6 (ASE-PA) to 52.5 ± 1.2 (CSE-AS). For all adhesive systems, the μTBS values after storage in PA were lower than those in AS. Except for the SMP, the values of μTBS after storage in LA were lower than those in AS. The adhesive ASE presented the lowest values of μTBs in the three media. The acids present in the oral biofilm may affect the bond strength of adhesive systems to human dentin.