In vitro analysis of the fracture resistance of CAD-CAM monolithic lithium disilicate molar crowns with different occlusal thickness


Published: 29 May 2018
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Authors

  • R. Sorrentino Department of Neurosciences, Reproductive and Odontostomatological Sciences, School of Dental Medicine, Division of Prosthodontics and Digital Dentistry, University "Federico II" of Napoli, Italy.
  • Y. Nagasawa Department of Restorative and Biomaterials Sciences, School of Dentistry, Division of Dental Biomaterials Science, Meikai University, Sakado, Saitama, Japan.
  • M. Infelise Department of Medical Biotechnologies, School of Dental Medicine, Division of Prosthodontics and Dental Materials, University of Siena, Italy.
  • G. Bonadeo Department of Medical Biotechnologies, School of Dental Medicine, Division of Prosthodontics and Dental Materials, University of Siena, Italy.
  • M. Ferrari Department of Medical Biotechnologies, School of Dental Medicine, Division of Prosthodontics and Dental Materials, University of Siena, Italy.

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).


Sorrentino, R., Nagasawa, Y., Infelise, M., Bonadeo, G., & Ferrari, M. (2018). In vitro analysis of the fracture resistance of CAD-CAM monolithic lithium disilicate molar crowns with different occlusal thickness. Journal of Osseointegration, 10(2), 50–56. https://doi.org/10.23805/jo.2018.10.02.04

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