The Caries Status of Occlusal Amalgam Restorations with Marginal Defects

Abstract

The purpose of this study was to examine histologically occlusal amalgam restorations with both defective and sound margins for comparison of their caries status. Thirty extracted teeth with occlusal amalgam restorations were sectioned so that a ditched and a clinically sound margin could be examined on the same tooth in the mouth. Histological examination showed a low prevalence of caries lesions in the outer enamel. However, lesions were present in the enamel of the cavity wall in 54% of specimens, whether the margin was defective or sound. If the results of this study are applicable to all occlusal amalgams with defective margins, it would appear that a defective margin alone is not an indication that a restoration needs to be replaced.

Isolated development of inner (wall) caries like lesions in a bacterial-based in vitro model

“…Both aspects deliver the rationale for the hypothesis that wider gaps allow the development of larger secondary wall lesions. However, the influence of the gap width is still a matter of debate, and conflicting results can be found in the literature [14,16,[21][22][23]. Also, recent investigations in vivo and on extracted teeth were often criticised because the diagnosed caries in the tooth restoration interface was not supposed to be a secondary caries lesion but either an inner part of the outer lesion or a residual caries [12,21,24,25].…”

Secondary caries, mind the gap!

“…Kidd and O'Hara (1990) found in sectioned, extracted teeth that 54% of the amalgam restorations had carious lesions in the enamel of the cavity wall, regardless of the margin being defective or sound. Pimenta et al (1995) carried out a similar study and found caries in 47% of margins without defects and found caries in 58% of ditched margins, which is not a statistically significant difference.…”

Inhibition of Secondary Caries Lesion Progression Using Fluoride Varnish

“…Wall lesions are very difficult to detect clinically, especially if they are incipient. The outer and wall lesions can occur together or separately [Kidd and O'Hara, 1990], so that the outer enamel could look sound clinically but have undermined dentin underneath [Kidd et al, 1992]. However, the development of wall lesions without an outer lesion is infrequent [Hals et al, 1974].…”