A 3-YEAR CLINICAL-STUDY OF TUNNEL RESTORATIONS

Tunnel restorations (n = 161) performed by 4 dentists were evaluated a fter a mean of 35 months in situ. Demineralized enamel was to be spare d during preparation. The preparations were filled with a cermet glass ionomer (polyalkenoate) cement. Evaluation was carried out using clin ical and radiographical criteria. During the observation period, appro ximately 16% of the restorations were replaced due to caries in dentin and 14% due to marginal ridge fracture. Cavitation in the approximal surface and/or increased radiolucency of the approximal enamel were ob served in 34% of the remaining tunnel-restored teeth. A significantly higher frequency of failures were registered when treating patients wi th a high caries activity, where the initial lesion was large, and whe re the restoration did not reach the approximal surface.