Aim: The study investigated the effect of using surface protection agents in the adaptation of external and internal margins of restorations subjected to simulated erosion.Methods: Cavities with margins in dentin were prepared in bovine incisors (n=120).Adhesive restorations were placed using a three-step etch&rinse adhesive system and nanofilled composite resin.The specimens were divided into four groups, according to the surface protection: negative control, topical application of fluoride (TAF), resin sealant and resin-modified glass ionomer varnish (RMGI varnish).Afterwards, they were divided into three sub-groups, according to the exposure to a simulated solution of gastric acid (DES) (5% here HCl, pH=2,2) and subsequent remineralization (RE): negative control, 9 and 18 cycles of DES-RE.
The evaluation of the tooth-restoration interface was performed on the internal and frontal images with the aid of a stereoscopic microscope (15x), and the percentage of continuous margins without adhesive failures was quantified.Results: In the read more external margins, only those groups with surface protection using sealants (resin and glass-ionomer) did not exhibit a significant decrease in the percentage of continuous margins after the erosive challenges.After 18 cycles of DES-RE, the use of resin-modified glass ionomer varnish resulted in the highest percentage of continuous margins.Conclusion: It was concluded that physically covering the surfaces with a sealing agent preserved the marginal adaptation of composite resin restorations exposed to endogenous erosive challenges.