Strength of tunnel-restored teeth with different materials and marginal ridge height

ObjectiveThe aim of the study was to investigate the strength of the marginal ridge of tunnel preparations with different marginal ridge heights, using different restorative materials.Materials and methods120 sound premolars were randomly divided into three groups of standardized tunnel preparations with a remaining marginal ridge height of 1.5 mm, 2.5 mm and 3.5 mm, respectively. In each tunnel group, 10 teeth were filled with all four newly developed adhesive materials that had not previously been used in tunnel preparation: Ketac Aplicap, Fuji IX, Fuji II LC and Beautifil Flow F02. The control group comprised 10 sound teeth. All teeth were subjected to incremental dynamic force testing. Remaining marginal ridge height and restoration material were the independent variables. The mean maximum energy (MEI) score was the dependent variable. Data were analyzed, using one- and two-way analysis of variance. Scheffe's test and Student's t-test were used for comparison between groups.ResultsBoth restorative material (P < 0.0001) and remaining marginal ridge height (P < 0.0001) had a statistically significant effect on the mean MEI score of tunnel-prepared teeth. At the 2.5 mm of remaining marginal ridge height, no statistically significant difference in mean MEI score existed between Beautifil Flow F02-filled tunnel-prepared teeth and sound teeth.SignificancePremolars tunnel-restored with Beautifil Flow F02 at 2.5 mm distance from the marginal ridge were as strong as sound teeth.