Performance of tunnel restorations at 3–6 years

Objectives: the purpose of this study was to evaluate the success of the tunnel restoration method in the Norwegian public dental service. Methods: all patients from three age cohorts (born 1975–1977) who had received one or more tunnel restorations at least 3 years earlier, at the public dental clinic in Kongsberg and a neighboring clinic in Numedal, were examined clinically and radiographically by two calibrated dentists. Individuals with two or more filled surfaces per year were classified as “caries active”. The statistical analyses consisted of non-parametric Kaplan–Meyer estimates of the survival function, and rank tests for associations to the longevity data and the background variables. Results: a total of 182 restorations in 94 patients were studied. Sixty-five percent of the restorations were considered successful. A total of 118 restorations were censored within the 76-month observation period. The median survival time was estimated to be 55 months, with a 95% confidence interval of 51–61 months. About 90% survived 3 years, while only 35% survived 5 years. Both caries activity and operator had significant effects on the survival period. On the other hand, there was no difference between “wells” and “tunnels”, tooth type, tooth surface or jaw with regard to success rate. Conclusions: The tunnel preparation filled with currently available glass-ionomer cement is not a generally favorable alternative in primary approximal lesions. However, in the hands of a well-trained, careful operator it may be chosen as a semi-permanent solution for patients with modest caries activity.