MARGINAL DITCHING AND STAINING AS A PREDICTOR OF SECONDARY CARIES AROUND AMALGAM RESTORATIONS - A CLINICAL AND MICROBIOLOGICAL STUDY

Caries at the margins of restorations is difficult to diagnose. In par ticular, the relevance of both marginal ditching and staining around a malgam restorations is unclear. This clinical study questions the rele vance of marginal ditching and color change to the level of infection of the dentin beneath the margins of amalgam restorations. Clinically visible sites (330) on the tooth/restoration margin were selected on 1 75 teeth. The enamel adjacent to each site was noted as stained (a gre y discoloration) or stain-free. One hundred and seventy-eight sites we re clinically intact, 83 sites had narrow ditches (< 0.4 mm), and at 4 9 sites, wide ditches were present (> 0.4 mm). Twenty sites with frank ly carious lesions were also included. Plaque was sampled at the tooth -restoration margin, and the dentin was sampled at the enamel-dentin j unction below each site. Samples were vortexed, diluted, and cultured for total anaerobic counts, mutans streptococci, lactobacilli, and yea sts. Plaque samples showed that margins with wide ditches (> 0.4 mm) h arbored significantly more bacteria, mutans streptococci, and lactobac illi than did clinically intact margins and margins with narrow ditche s. There were no significant differences in the degree of infection of the dentin beneath clinically intact restorations and those with narr ow ditches, but samples associated with wide ditches and carious lesio ns yielded significantly more bacteria, mutans streptococci, and lacto bacilli. The color of the enamel adjacent to the sample site was irrel evant to the level of infection of the dentin beneath the filling marg in, provided a frankly carious lesion was not present. The results sug gest that amalgam fillings where margins show wide ditches or carious lesions should be replaced. Narrow ditches and color change alone shou ld not trigger the replacement of a filling.