An evaluation of replacement rates for posterior resin-based composite and amalgam restorations in US Navy and Marine Corps recruits

Background. Restoration replacement is a clinical concern that has not been studied among military personnel. The authors determined the prevalence of placement of posterior amalgam and resin-based composite restorations and the incidence of replacement among U.S. Navy and Marine Corps personnel. Methods. The authors analyzed dental records from 2,780 personnel to determine the relative risk of replacement for initially sound restorations during subjects' first years of military service. Results. At the initial examination, 964 (15.2 percent) of amalgam restorations and 199 (17.4 percent) of resin-based composite restorations required re-treatment. Of those judged clinically acceptable, 14.2 percent of amalgam and 16.7 percent of resin-based composite restorations required replacement during the observation period. The authors found significant increases in replacement rates for resin-based composite restorations compared with amalgam restorations for replacement due to all causes (adjusted hazard ratio, 1.28; P <.05), as well as for replacement due to restoration failure (adjusted hazard ratio, 1.64; P <.01). Conclusions. About 30 percent of posterior restorations required replacement, either at the initial examination or during the subjects' first years of military service. In a young military population, significantly more resin-based composite restorations in place at the initial examination will require replacement than will amalgam restorations. Multi-surface restorations had higher rates of replacement than did one-surface restorations, and subjects at high caries risk experienced significantly higher replacement rates than did those at low caries risk. Clinical Implications. The number of surfaces restored and subjects' caries risk status may influence the longevity of resin-based composite and amalgam restorations.