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The effect of cuspal flexure on a buccal Class V restoration: a finite element study
1Department of Restorative Dentistry, Dental School, University of Wales College of Medicine, Heath Park, Cardiff, UK.
Objectives:
Failure of Class V restorations is a clinical occurrence which is often blamed on inadequate moisture control. However, the effects of occlusal forces and cuspal movement may also have an effect. The aim of this study was to examine the effects that cuspal movement had on the shear forces around a buccal Class V restoration in a lower first premolar.
Method:
A lower first premolar restored with a buccal Class V composite restoration and a Class I composite or amalgam restoration were modelled using the finite element method. The width of the occlusal restoration was varied from 2.1 to 3.7 mm and the depth varied from 1.7 to 3.7 mm.
Results:
Compared to the unrestored premolar, the presence of an occlusal preparation restored with composite increased the interfacial forces around the buccal Class V restoration by 1-67%. Similarly, the presence of an amalgam occlusal restoration increased the interfacial forces by 9-228%.
Conclusions:
It was found that the presence of an occlusal restoration increased cuspal movement, which in turn increased the shear forces around the buccal Class V cavity. This effect was more pronounced with increases in cavity depth compared to cavity width, and when amalgam was the occlusal restorative material.