OBJECTIVES: This cross-sectional study is nested in a randomized clinical trial. It was designed to evaluate the influence of using two different clinical criteria to assess caries lesion around restorations on the decision to replace restorations in primary posterior teeth. Variables that might influence this decision were also considered.

METHODS: One trained and calibrated examiner assessed 550 restorations of 160 children (3-10 years old). Children were randomized to have their restorations evaluated and subsequently treated according to World Dental Federation (FDI) or Caries Associated with Restorations and Sealants (CARS) criteria. After reaching the treatment decision, the same examiner performed another evaluation using the other criteria. Spearman's correlation coefficients and 95 % confidence intervals (95 %CI) between the scores obtained with both criteria and respective treatment decisions were calculated. Poisson multilevel regression analysis were performed between the exploratory variables related to children, restored tooth and restoration assessment; the outcome variables were decisions related to restoration replacement, any operative intervention and presence of secondary caries.

RESULTS: The strongest correlation observed between the methods was for recurrence of caries. A total of 94 restorations (17.1 %) were indicated for replacement with FDI criteria and 30 (5.5 %) were indicated for replacement with CARS. Besides the diagnostic method used, number of decayed teeth and restorations with two and three restored surfaces were associated with the decision of replacement and presence of recurrent caries lesions.

CONCLUSIONS: The decision to replace posterior restorations in primary teeth is influenced by the criteria used for the restorations assessment and also by the children's caries experience and multisurface restorations. The restoration material did not influence the decision of restorations replacement.

CLINICAL SIGNIFICANCE: The decision to replace posterior restoration in primary teeth is strongly related to the evaluation method and not only by patients' risk factors.