Evaluation of Enamel After Microabrasion, Polishing and Storage in Saliva

Objective: To evaluate the effect of microabrasion on microhardness and roughness of bovine enamel and the action of polishing carried out with the appropriate pastes on abrasioned enamel, evaluate the effect of storage in artificial saliva, during different times of action, on the microhardness of bovine dental enamel. Method: 144 bovine enamel blocks, forming the groups: I-treatment with 37% phosphoric acid and pumice paste, II-treatment with Opalustre (Ultradent), III-treatment with Whiteness RM (FGM). The three groups were divided into three subgroups, according to the following treatments: a) diamond polishing paste, b) polishing with fluoride prophylactic paste and c) without polishing (control). Tests of hardness were carried out in the following set times: 1) initial (prior to the microabrasion and polishing), 2) after microabrasion with and without polishing (control), 3) after microabrasion with and without polishing and immersion in artificial saliva for 24 hours; 4) after microabrasion with and without polishing and immersion in artificial saliva for 7 days. Tests of surface roughness were performed in the following pre-set times: 1) initial (prior to the microabrasion and polishing) and final (after the completion of microabrasion with and without polishing) (control). Result: Microabrasion followed by polishing provided an increase of superficial microhardness; without the use of polishing, only the microabrasive systems with hydrochloric acid and silicon carbide showed increased superficial microhardness; different times of storage in artificial saliva did not result in increased microhardness; the products used for microabrasion did not provide surface roughness different from each other; all microabrasive systems followed by polishing showed a higher surface smoothness compared with the groups without polishing. Conclusion: Microabrasion followed by polishing provided higher hardness and better surface smoothness of the dental enamel. However, the immersion in artificial saliva for 24 hours and 7 days was not able to increase the enamel hardness.