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Published on: December 20, 2024
Indirect restorations for severe tooth wear: fracture risk and layer thickness
J T Hamburger1, N J M Opdam2, E M Bronkhorst2
1Department of and Restorative Dentistry, Radboud University Nijmegen Medical Centre, Philips van Leydenlaan 25, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands.
Objectives:
This in vitro study investigated static failure risk related to restoration layer thickness for different indirect materials and compare them to direct composites.
Methods:
Two ceramics (IPS e-max CAD, EmpressCAD (Ivoclar Vivadent)), two indirect composites (Estenia (Kuraray), Sinfony (3M)) and two direct composites (Clearfil AP-X (Kuraray), Tetric EvoCeram (Ivoclar Vivadent)) were chosen. Of each material, 25 discs varying in thickness (0.5-3.0mm) were prepared and cemented to bovine dentine. For measuring compressive strength, samples were placed in a universal testing device. Each sample was uniaxially loaded until failure occurred. For each material a regression model based on the Weibull distribution was used to estimate the relation between restoration layer thickness and failure. Using these models, the chance of failure, standard error and 95% confidence interval for that chance is estimated. Groups of materials were compared as well.
Results:
Except for Tetric Evoceram, all materials show a significant positive association between layer-thickness and compressive strength, with an increased strength of increased thickness. ProCAD performed significantly worse than all other materials, especially when compared to the other ceramic material (IPS e-max CAD) (p=0.001).
Conclusion:
For most tested materials, a thicker layer offers more strength, however, this property seems to be material/brand specific.
Clinical Relevance:
As direct composites showed the best results within the limitations of this in vitro study, dentists should consider these materials as a good choice for restoring severe tooth wear, and may offer superior performance compared to indirect composites and ceramics. For some brands of materials thicker layers result in a stronger restoration.
