[Increased resistance to demineralization on enamel cavity walls by application of fluoride solution]

Dental enamel cavity walls of bovine extracted incisors were submitted to different treatments before to be "restored" with amalgam. The Group A non received treatment; the Group B received only a conventional cavity varnish and the Group C received a solution of sodium fluoride (2%) + conventional cavity varnish (2 applications). After 7 days of immersion in gel acid, the ground sections were studied in polarized microscope. The Group C that received sodium fluoride + conventional cavity varnish presented more resistance to demineralization. The Group B that received only cavity varnish presented a reduction in resistance to demineralization, and the Group A that non received treatment presented minor resistance to demineralization. Therefore, is emphasized the importance of application of sodium fluoride in cavity walls before lining with conventional cavity varnish and restoring with amalgam to obtain more resistance to demineralization.