SEM evaluation of a non-rinse conditioner and a self-etching adhesive regarding enamel penetration

This study evaluated the effect of a non-rinse conditioner (NRC) associated with two adhesive systems, Prime & Bond NT and Prime & Bond 2.1. The study also evaluated a self-etching adhesive, comparing it with the 37% phosphoric acid effects related to the regularity and infiltration depth of adhesives in human tooth enamel via observation using Scanning Electronic Microscopy (SEM). Fifteen third molars were longitudinally sectioned into four parts by means of a mesio-distal cut and facio-lingual cut. All pieces were flattened with silicon carbide paper, randomly separated and divided into five groups where the enamel surfaces were treated with different materials according to the manufacturers' instructions as follows: Group 1-Prime & Bond NT (Dentsply); Group 2-37% phosphoric acid + Prime & Bond NT; Group 3-Non-Rinse Conditioner (Dentsply) + Prime & Bond NT; Group 4-NRC + Prime & Bond 2.1 (Dentsply); Group 5-Prompt L-Pop (3M ESPE). All teeth were covered with Dyract AP (Dentsply). Specimens were decalcified, metalized and the inner portions of Dyract were observed in SEM and evaluated by calibrated examiners to evaluate resin penetration on enamel. Resin penetration was ranked from 0 = no penetration, to 3 = maximum penetration. The Kruskal-Wallis and Mann-Whitney U tests (p<0.05) showed only three statistically homogeneous groups: {1}, {2,3} and {4,5}. The authors concluded that Prime & Bond NT showed the lowest penetration, NRC showed similar effects compared to phosphoric acid when associated with Prime & Bond NT, and concluded that Prompt L-Pop showed similar effects to NRC, which was associated with Prime & Bond 2.1.