Tunnel restorations in permanent teeth. A 7 year follow up study.

The aim of the study was to perform a long-time evaluation of tunnel restorations made in a general dental practice concerning survival time and type of failures. 267 Class I (87%) and II (13%) tunnel restorations in permanent teeth on 193 patients--mostly teenagers and young adults--were evaluated at annual recalls. The observation time-span was 1-7 years. The restoration material was a conventional glass ionomer cement in Class I tunnels and a silver cermet glass ionomer cement in Class II tunnels. The yearly failure rate was 7% and the 50% survival time was 6 years. The reasons for replacement were: marginal ridge fracture (41%), recurrent caries (40%) and cavitation in approximal enamel (19%). No differences in failure rate between Class I and II tunnels could be seen, but recurrent caries was more frequent in Class I tunnels. Restorations made during the second year of the study were more successful, indicating a learning effect. Class I tunnel restorations in general practice can be an alternative to conventional Class II restorations with narrow indications, i.e. patients with relatively low caries activity, small approximal lesions in combination with small demineralization zones in the enamel wall.