Relationship between cavity form, restorative technology and strength of restored teeth
Morin, D. L.
mesheuropmc: stomatognathic diseases | stomatognathic system
The results of an experimental and theoretical stress analysis of an invitro human tooth are presented. The experimental work involved developing a technique utilizing strain gauge technology to evaluate the surface strains of a tooth which are produced under a variety of cavity and restorative conditions. The results indicated that a tooth with a cavity preparation is significantly less stiff than a intact, sound tooth. When the tooth was restored with a traditional, non-bonding, restorative material the overall stiffness showed no difference from that of the tooth with the cavity preparation. Bonding the restorative material to enamel and dentin resulted in a significant recovery of stiffness approaching that of the sound tooth. Also, the bonded restorations displayed much less hysteresis as compared to the non-bonded restorations.\ud \ud The theoretical work consisted of formulating and validating a mathematical model to simulate the strain generation and distribution in a tooth under a variety of cavity and restorative conditions. The model used the plane strain assumption and was based on the finite element method. Results demonstrated that when the restorative material is bonded to both the enamel and the dentin the strain distribution approximantes that of a sound tooth. When bonding to just enamel is utilized in the restoration, the overall strain distribution approximates the sound tooth but localized areas of strain concentration still exist in the region bounded by the pulpal floor of the cavity and the pulp chamber. The modelling of a non-bonding restoration demonstrated no reduction in the strain magnitude or concentration.