Method: A total of 149 defective restorations in 48 patients were repaired in Nagasaki University Hospital between 1995 and 2013. All patients were under the charge of the principal investigator (SK) and all of them had been regularly checked up for up to 18 years. The repaired restorations were examined by SK from March 2013 to September 2013. The restorations were rated clinically acceptable, clinically unacceptable or already replaced according to FDI criteria. If the repaired restorations were not examined, they were dealt with censored cases. Survival time was defined as the age when the restoration was replaced, re-repaired, tooth extracted, or censored. In this study, data obtained from crowns were excluded from statistical analyses. Survival analysis was performed by the Kaplan-Meier method. The Cox proportional hazards (PH) model was used to study the dependence of survival time on potential explanatory variables (age, risk, tooth type, restoration type, materials, etc.).
Result: Data of ninety-one repaired restorations in 37 patients were obtained. Five restorations were not examined and 16 restorations were dealt with censored cases. Seventy-four restorations were repaired with resin composites and 15 restorations with glass ionomer cements. Survival rate at 10 years of all repaired restorations was estimated 61.9%. Cox proportional hazards model revealed that reasons for repair and retreatment risk had significant influence on the longevity of the repaired restorations. Age at repair and gender might have some effect on the clinical performance. There were no significant differences in survival rates between restoration type, between tooth type and between restorative materials.
Conclusion: Repair may help to preserve tooth structure and extend the longevity of restored teeth. This study was supported by JSPS KAKENHI, Grant Number 23592802.