Effects of glass ionomer's overlap on the cavosurface angle

Objectives: The objective of this study was to evaluate the effect of the glass ionomer in the dental enamel. Methods:40 fresh bovine teeth was selected. The apex of each tooth was cut off and the pulp was removed. The cervical portion of each specimen was prepared with 3053 drill and restored with glass ionomer. Two groups were obtained: group 1- the glass ionomer was accomodated until the cavosurface angle limit ;group 2 the glass ionomer was accomodated overshooting the cavosurface angle (1-2mm on the enamel). The specimens were submitted to a hight cariogenic level, using the Streptococcus mutans culture in a kiln (37 Celsius degrees) for a 7 and 15 days period. After cleaned, the specimens . The Labcut machine were to cut off, in a Labcut Machine, in slices which were placed in glass laminae for polishmentin Politriz Machine. Cover glasses were used to orient the samples thickness. The laminae were submitted to a polarized light microscopy analysis. Results: the group 1 specimens had different results varying from the absence of carious to enamel injuries in the interface cavosurface angle/restoration. The group 2 had absence of caries on the enamel subjacent to the ionomer glass. The lesions occurred after the restoration's limits with variations of intensity. Conclusions: the overlap of the ionomer glass protects the enamel when it is submitted to a cariogenic environment; therefore the ionomer glass can be used in cervical restorations. The gap formed between resin and enamel, on the cavosurface region can cause microleakage and alterations on the dental structures.