Mechanical Analysis of Calcium Phosphate Crystalline Ceramic Crowns
1993 Volume 56 Issue 2 Pages 159-192
Details
1993 Volume 56 Issue 2 Pages 159-192
The mechanical behavior of crowns made of calcium phosphate crystalline ceramic (castable ceramic) was studied by the finite element method. Bond strength between the calcium phosphate crystalline ceramic and metal or composite resin core materials was established by cementation with adhesive resin cement.
The finite element model employed in this investigation was that of a mandibular second premolar restored with a calcium phosphate crystalline ceramic crown. Two-dimensional stress analysis of the crown was carried out under vertical and horizontal loading at the buccal cusp. We investigated the effects of the loading point, crown margin width, post core material and cement. Bond strength was evaluated by measuring the compressive shear strength between the calcium phosphate crystalline ceramic and the two core materials, with and without primer treatment.
1. Stresses induced in the crown under horizontal loading were higher than those induced under vertical loading. Tensile stresses were induced on the loading side of the inner surface of the crown.
2. As the width of crown margin increased, stresses induced in the crown decreased, and displacement of the abutment tooth increaced.
3. Stresses induced in the crown differed with the post core material. When the abutment was a natural tooth, stresses were likely to concentrate largely toward the buccal and lingual axial walls. When the abutment included a metal core, stresses were mainly concentrated in the crown under the loading point. However with a metal post and composite resin core abutment, stresses were mainly concentrated in the metal Post.
4. Tensile stresses generated in the crown cemented with temporary soft cement were mainly concentrated on the inner surface of the crown under the loading point, as well as on the buccal and lingual outer surfaces of the crown.
5. Compressive shear bond strength between the calcium phosphate crystalline ceramic and metal core material was significantly higher with primer treatment than without.
A rigid core and optimal bonding with the calcium phosphate crystalline ceramic are necessary for adequate long-term prognosis.
