In vitro analysis of the fracture resistance of CAD-CAM monolithic lithium disilicate molar crowns with different occlusal thickness
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.
Aim: To compare the fracture resistance and mode of failure of CAD-CAM monolithic lithium disilicate crowns with different occlusal thickness.
Materials and methods: Thirty CAD-CAM monolithic lithium disilicate crowns with different occlusal thickness were randomly distributed into 3 experimental groups: 0.5 mm (group 1), 1.0 mm (group 2) and 1.5 mm (group 3). The restorations were cemented onto human molars with a self-adhesive resin cement. The specimens were loaded until fracture; the fracture resistance and mode of failure were recorded. The data were statistically analyzed with the one-way ANOVA followed by the Fisher€™s Exact test with Bonferroni€™s correction (p=0.05).
Results: The fracture resistance values of all the specimens exceeded the maximum physiological occlusal loads in molar regions. The highest fracture resistance was noticed in 1.0 mm-thick crowns. Ultrathin restorations (group 1) proved to be statistically less resistant to fracture than those of the other experimental groups (p<0.05). The crowns were mainly interested by unrestorable fractures.
Conclusions: The occlusal thickness of CAD-CAM monolithic lithium disilicate crowns influences either the fracture resistance and the mode of failure of the restorations; the occlusal thickness of such restorations can be reduced up to a lower bound of 1.0 mm in order to keep sufficient strength to withstand occlusal loads; CAD-CAM monolithic lithium disilicate crowns showed sufficient fracture resistance to be used in molar regions but not in an ultrathin configuration (0.5 mm).
The Journal of Osseointegration has chosen to apply the Creative Commons Attribution NonCommercial 4.0 International License (CC BY-NC 4.0) to all manuscripts to be published.