Mechanical behavior of all-ceramic composite beams
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Over the last 10 years, the increasing demand for metal-free restorative alternatives has resulted in the proliferation of all-ceramic systems. While these materials can predictably achieve good esthetic results in the anterior and high success rates for single restorations; they have traditionally been contraindicated for posterior applications and for multi-unit bridges due to the greater stresses present in the region and to the lack of adequate mechanical properties of the materials available today. This study examines the mechanical behavior of three all-ceramic systems, layered with low-strength conventional porcelains, with a different core/veneer ratio and subjected to bending stresses. The study included three all-ceramic composite beams groups: - A glass-infiltrated alumina (Vita In-Ceram) veneered with a feldspathic porcelain (Vitadur Alpha) with a constant (K) total thickness; - A glass-infiltrated alumina (Vita In-Ceram) veneered with a feldspathic porcelain (Vitadur Alpha) with a variable (V) total thickness; - A leucite reinforced porcelain (Ivoclar Empress 1) veneered with a conventional feldspathic porcelain (Ivoclar Classic) with a variable (V) total thickness; A three-point flexural test was conducted and formulae specifically derived from composite beams engineering were applied. A single-Anova test was used to evaluate the effect of different factors on the modulus of rupture. The results indicated that the low-strength porcelain, when placed on the tensile side, weakens the strong all-ceramic core to about 50-70% its intrinsic strength. Moreover, increasing the thickness of the core and reducing the feldspathic layer resulted in a stronger system. From the results we concluded that layered prostheses made of strong cores veneered with weaker feldspathic porcelains, may be prone to faillure especially when the feldspathic porcelain is subjected to bending stresses and when its thickness is increased versus the core's.
PLEASE NOTE: This work is protected by copyright. Downloading is restricted to the BU community: please click Download and log in with a valid BU account to access. If you are the author of this work and would like to make it publicly available, please contact firstname.lastname@example.org.Thesis (MSD) --Boston University, Goldman School of Dental Medicine, 2011 (Department of Restorative Sciences and Biomaterials).Includes bibliographic references: leaves 75-79.
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