RESUMO
Specimens of human dental enamel and dentin were topically etched with two acid etching solutions including 37% phosphoric acid and 10% maleic acid. While another group of specimens were exposed to laser irradiation for etching at different exposure times. All the specimens were studied using SEM for evaluation and comparison. The results showed that 10% maleic acid produce mild etching to both enamel and dentin and it can be used as a universal etchant. Application of Nd: YAG laser to enamel caused etching with some cracking and voids to the depth comparable to that achieved with phosphoric acid etching. Lasing dentine causes melting of dentine and closure of exposed dentinal tubules while three minutes laser etching exposed dentinal tubules again