A study on the survival of primary molars with intact and with defective restorations

Background. Failed restorations in primary teeth are not always re-restored. Is re-restoration not required anymore? Objective. To compare survival rates of primary molars with intact and defective amalgam and ART restorations. Methods. A total of 649 restored primary molars, of which 162 were assessed with defective restorations for mechanical reasons, from a cluster-randomised controlled clinical trial, were followed up over a period of 3.5 years. Restored primary molars, extracted because of dental sepsis or toothache, were considered a failure. Primary molars with defective restorations were followed up from the time they were assessed defective. Data were analysed using PHREG model with frailty correction, Wald test, t-test, and jackknife procedure. Results. The survival rate of primary molars with intact restorations (96.3%) was statistically significantly higher than that of primary molars with defective restorations (75.9%) over a 3-year period (P < 0.0001). Neither the effect of treatment protocol (amalgam or ART) (P = 0.05) nor the type of surface (single or multiple) (P = 0.73) was observed with respect to the survival rate of restored primary molars. Conclusions. Survival rates for primary molars with intact and defective amalgam and ART restorations were high. The 3-year survival rate of primary molars with intact restorations was significantly higher than that of primary molars with defective restorations.