Protective effects of resin impregnation on demineralization of enamel

Purpose: To determine if resin penetrated into the enamel etch pattern, in the absence of a polymerized outer surface film, could reduce the degree of demineralization of enamel subjected to a simulated caries challenge, and to evaluate whether the addition of fluoride to the resin would enhance red uctions in demineralization. Materials and Methods: Enamel surfaces of extr acted human incisors were acid-etched. One-half of the etched area was trea ted with an unfilled bonding resin, while the other one-half was left untre ated as a control. In another group, this same procedure was followed excep t the unfilled bonding resin contained fluoride. The applied resin was aggr essively air thinned to ensure oxygen inhibition throughout the external su rface film thickness. The thinned film was visible light-cured and the area was wiped with an ethanol swab to remove the inhibited layer. The specimen s were exposed to a buffer solution of pH=4.7 for 4 days, and were sectione d and examined by polarized light microscopy and microradiography. Results: In each of the two test groups, the demineralization of the resin-treated side was significantly lower than the control side (P < 0.015). Under the c onditions of this study, the experimental fluoride resin did not produce st atistically significant reductions in demineralization compared with the no n-fluoride resin.