Dental enamel submmitted to gamma radiation and ER,CR: YSGG laser associated to fluoride

Abstract

The in situ caries model can use bovine dental samples in human volunteers. Gamma radiation is a very efficient sterilization method that is not expected to alter the mineral content of the hard tissues, avoiding biases in the results. Samples (n=40) were irradiated through a source of 60Co multipurpose irradiator aiming complete sterilization (25 kGy/h) with the purpose of accumulating the native plaque on them at an in situ study. An Er,Cr:YSGG laser was used alone and in combination with the topical applications of: 1 dentifrice (1,100 μg F /g) or 2 APF (12,300 μg F--/g). Morphological and chemical analyses were performed by scanning electron microscopy (SEM), determination of alkali soluble fluoride concentration by specific ion electrode and surface microhardness determination. Then, the 15 volunteers used palatal devices containing previously treated samples and remained using F dentifrice. The effects of Fformation, on the reduction of demineralization were correlated. The biochemical analysis for quantification of alkaline soluble F determined the groups in which the laser was used after the topical application of the two types of fluoride products of different concentrations (dentifrice and APF) to be statistically different (p≤0.05), suggesting a prolonged effect of the synergy of the treatments in the reduction of the demineralization. Electronic Microscopy Scanning analysis has not shown thermal damage neither interprismatics changes from hydroxyapatite crystals, at dental enamel outside the buccal environment, after 25 kGy gamma irradiation, established that gamma radiation could be used aiming dental enamel sterilization.