Clinical behaviour of glass ionomer restorations in primary teeth

Objective: To compare a silver-reinforced glass ionomer material (cermet) with a resin-modified glass ionomer in minimal Class II preparations in primary teeth. Methods: Matched pairs of primary molars with approximal caries that required operative treatment were used. Each cavity was filled with either Vitremer or Ketac-Silver. The restorations were followed for at least 36 months and examined annually using bitewing radiographs and clinical inspections. Impressions were taken at each recall and models were examined microscopically. Results: After 36 months, one of the resin-modified glass ionomer (RMGI) restorations and 13 (26.5%) of the silver cermet restorations had failed. The RMGI failed because of secondary caries, while most of the failures of the silver cermet fillings were marginal defects alone or in combination with secondary caries. The median survival time (MST) for the silver cermet restorations was 37 months. The RMGI restorations had a MST exceeding 42 months, but MST could not be calculated exactly because of the low failure rate during the study period. Conclusions: The resin-modified glass ionomer had the overall best performance of the two materials under comparison. The silver cermet material cannot be recommended for Class II restorations in primary teeth.