IN-VITRO INHIBITION OF MARGINAL CARIES-LIKE LESIONS WITH FLUORIDE-CONTAINING AMALGAM

Carious lesions surrounding restorations represent one of the main cau ses of restoration failure. The addition of fluoride compounds to dent al restorative materials prevents or reduces recurrent caries. The pur pose of this study was to compare the capacity of three restorative ma terials to inhibit the development of recurrent caries in vitro. Thirt y unrestored, noncarious premolars that were being extracted for ortho dontic reasons were sectioned in half buccolingually and divided into three groups. One of the groups was restored with conventional amalgam . The second group was restored with a fluoride-containing amalgam, an d the third group was restored with a glass-ionomer cement. All the sa mples were submitted to a medium containing Streptococcus mutans (Ingb ritt strain) for 8 weeks. At the end of the 8-week incubation period,t he samples were cut into 100 mum sections, soaked in Quinoline (IR = 1 .62), and observed with light transmission and polarized light microsc opy. The development of artificial caries in the cavity walls was meas ured in microns. The results show that conventional amalgam had an ave rage caries penetration of 160 mum, fluoride-containing amalgam 46 mum , and glass-ionomer cement 11 mum. Glass-ionomer cement gave the best protection against recurrent caries.