Longevity of repaired restorations: a practice based study

The aim was to evaluate retrospectively the influence on restoration longevity of a repair and to evaluate longevity of repaired restorations.

In a practice, 1202 amalgam and 747 composite resin restorations were placed. 407 restorations failed (amalgam 293, composite 114), 246 restorations were repaired with composite resin using an etch-and-rinse technique. Of repaired restorations reason for failure and number of surfaces of original restoration, repair date, and date of patients' last visit were recorded. Whenever a new treatment was necessary, this was considered failure. Data were analysed by Kaplan-Meier statistics and log-rank tests (p<0.05). A multi-variate Cox-regression analysis was conducted on results for variables number of surfaces, repair reason, and repaired material.

133 amalgam restorations (57% due to fracture) and 113 composite restorations (62% due to caries) were repaired. 151 of 246 repaired restorations (61%) were still in service without further intervention after 4.8 years. The annual failure rates for repaired amalgam and composite restorations was 9.3% and 5.7% after 4 years (log-rank, p=0.001). Restorations that were repaired due to fracture had a lower survival than restorations that were repaired due to caries (log-rank, p=0.006). The Cox-regression showed influence of the gender but no significant influence of material or reason for repair, indicating that the findings are a consequence of joint negative influences of investigated variables.

The present study shows that repairs can enhance the longevity of dental restorations considerably. Moreover, repairs on restorations failing due to caries have a better prognosis compared to repairs on restorations failing due to fracture.