Performance of tunnel restorations at 3-6 years

Objectives: the purpose of this study was to evaluate the success of the tu nnel restoration method in the Norwegian public dental service. Methods: all patients from three age cohorts (born 1975-1977) who had recei ved one or more tunnel restorations at least 3 years earlier, at the public dental clinic in Kongsberg and a neighboring clinic in Numedal, were exami ned clinically and radiographically by two calibrated dentists. Individuals with two or more filled surfaces per year were classified as "caries activ e". The statistical analyses consisted of non-parametric Kaplan-Meyer estim ates of the survival function, and rank tests for associations to the longe vity data and the background variables. Results: a total of 182 restorations in 94 patients were studied. Sixty-fiv e percent of the restorations were considered successful. A total of 118 re storations were censored within the 76-month observation period. The median survival time was estimated to be 55 months, with a 95% confidence interva l of 51-61 months. About 90% survived 3 years, while only 35% survived 5 ye ars. Both caries activity and operator had significant effects on the survi val 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-i onomer cement is not a generally favorable alternative in primary approxima l 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 act ivity. (C) 2000 Elsevier Science Ltd. All rights reserved.