Durability of tunnel restorations in general practice: a three-year multicenter study.

Twelve dentists, clinically experienced and familiar with the tunnel technique, placed 374 tunnel restorations in permanent teeth. Mean age of the patients was 19.1 years (range 10-74). The filling material used was a glass cermet cement, Ketac Silver. After 1, 2 and 3 years the teeth were controlled by the dentists. The bitewing radiographs from baseline, 1, 2 and 3 years were also analyzed by 2 of the authors, independently. The baseline radiographs showed technical defects in 6% and indicated remaining dentin caries in 8% of the restorations. After 3 years, 305 restorations were accessible for examination. The cumulative replacement rate was 20%. The main reasons for replacement were marginal ridge fracture (14%) and dentin caries (3%). The number of restorations showing untreated progressive caries increased during the study. After 3 years, untreated dentin caries was seen in 28 cases (11%) and almost half of the left enamel lesions showed progression.