Effect of Cubic Leucite Stabilization on the Flexural Strength of Feldspathic Dental Porcelain

作者：Isabelle L. Denry, J.R. Mackert, Julie A. Holloway, Stephen Rosenstiel · 发表于：Journal of Dental Research · 年份：1996 · DOI：10.1177/00220345960750120301 · 被引用次数：105 · 研究领域：Building materials and conservation、Dental materials and restorations、Dental Erosion and Treatment

Previous studies (Mackert and Evans, 1993) have shown that, when feldspathic dental porcelain is cooled, leucite undergoes a transformation from cubic to tetragonal, associated with a 1.2% volume contraction. This contraction leads to the formation of microcracks in and around the crystals and the development of tangential compressive stresses around the crystals. Our aim was to stabilize increasing amounts of the cubic form of leucite in a leucitereinforced dental porcelain, evaluate its effect on the flexural strength, and characterize its microstructure. The hypothesis was that in the absence of crystallographic transformation, the contraction of the leucite crystals would be lower, thereby limiting the formation of microcracks and minimizing the development of tangential compressive stresses around the leucite particles. We prepared 8 porcelain compositions by mixing increasing amounts of either leucite (KAlSi2O6) or pollucite (CsAlSi2O6) with Optec HSP porcelain (Jeneric/Pentron Inc., Wallingford, CT). Porcelain disks were made from each composition (n = 10 per group). X-ray diffraction analyses showed that the amount of stabilized leucite increased with the amount of pollucite added. The microstructure of the specimens containing tetragonal leucite was characterized by twinned leucite crystals, whereas no twinning was observed in the specimens containing cubic leucite. The evaluation of crack deflection showed that significantly less deflection occurred in the specimens...