Pages 404-412, Language: EnglishProos, Kaarel A. / Swain, Michael V. / Ironside, Jim / Steven, Grant P.Purpose: This study examined the effects of using four different core-ceramic materials on the stresses that developed in a single all-ceramic first premolar crown.
Materials and Methods: This was done by analyzing models constructed in an axisymmetric fashion with finite element analyses. The model had a 600-N vertical load applied uniformly over a circular area on top of the crown. Particular emphasis was placed on the tensile stresses that developed.
Results: For this particular type of model and loading configuration, radial tensile stresses were predominant in magnitude. Peak hoop and axial tensile stresses were approximately 80% and 2% of this value, respectively. The peak radial and hoop tensile stresses were located on the inside of the coping and scaled with the elastic modulus of the coping. For the axial component, the peak was located in the veneer ceramic on its outermost perimeter.
Conclusion: Under normal loading, a near-uniform tensile stress field developed within the coping, directly beneath the contact area. The magnitude of this stress for realistic bite forces using current design recommendations was significantly lower than the fracture strength of the four ceramic materials investigated. The stresses developed within the porcelain were in all instances well below typical strength values.
