Cross-sectional clinical study of quality of amalgam restorations, oral health and prevalence of recurrent caries.

The purpose of the present cross-sectional clinical study was to evaluate the relationship between recurrent caries prevalence, quality of class II amalgam restorations and various oral health parameters. One hundred and forty-four randomly selected 35-yr-old citizens of Oslo were included in the investigation. Caries was scored based on a combined clinical and radiographic examination according to the DMFS index system. Oral hygiene (OHI-S) and periodontal index (PI) were registered, and the quality of class II amalgam restorations was ranked according to a set of occlusal index pictures. A total of 1694 class II amalgam restorations were included and 93 (5.5%) of these were affected by recurrent caries. A statistically significant correlation was found between prevalence of recurrent caries and poor oral hygiene, high PI-scores and prevalence of primary caries. However, a severe deterioration of the quality of amalgam restorations had to be present before a concomitant increase in recurrent caries prevalence could be registered. The present results indicate that measures improving the oral health may be of major importance in preventing recurrent caries and thereby increase the durability of amalgam restorations.