Enamel deproteinization and its effect on acid etching: an in vitro study

The goal of this in vitro study was to identify the topographical features of the enamel surface deproteinized and etched with phosphoric acid (H3PO4) compared to phosphoric acid alone.

Ten extracted lower first and second permanent molars were polished with pumice and water, and then divided into 4 equal buccal sections having similar physical and chemical properties. The enamel surfaces of each group were subjected to the following treatments: Group A: Acid Etching with H3PO4 37% for 15 seconds. Group AH1: Sodium Hypochlorite (NaOCl) 5.25% for 30 seconds followed by Acid Etching with H3PO4 37% for 15 seconds. Group AH2; Sodium Hypochlorite (NaOCl) 5.25% for 60 seconds followed by Acid Etching with H3PO4 37% for 15 seconds. Results showed that group AH2 etching technique reached an area of 76.6 mm2 of the total surface, with a 71.8 mm2 (94.47%), type 1 and 2 etching pattern, followed by group AH1 with 55.9 mm2 out of 75.12 mm2 (74.1%), and finally group A with only 36.8 mm2 (48.83%) out of an area of 72.7 mm2. A significant statistical difference (P < 0.05) existed between all groups, leading to the conclusion that enamel deproteinization with 5.25% NaOCl for 1 minute before H3PO4, etching increases the enamel conditioning surface as well as the quality of the etching pattern.