Tunnel restorations: a long-term pilot study over a minimum of five years

Objectives: The purpose of this study was to investigate the long-term performance of tunnel restorations. Methods: Thirty-three glass polyalkenoate (ionomer) or cermet restorations were placed in the premolar or first molar teeth of 25 patients. Conservative amalgam control restorations were the means of treatment in 14 similar teeth of the same group. Review as to performance consisted of a regular clinical and radiographic examination and the criteria for failure were recurrent caries, fracture of the marginal ridge or gross loss of restorative material. Results: After 3 years all types of restoration were satisfactory. By approximately 5 years one-quarter of the glass ionomer and 10% of the cermet restorations had failed. All the failures after any period of service could be replaced by conservative amalgam fillings. None of the controls required replacement. Conclusion: While tunnel restorations employing glass ionomer material and the cermet variant do enjoy a degree of success, this preliminary work suggests that small restorations of dental amalgam are more successful in the long term.