All-Ceramic Restorations in Dental Work

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Superior aesthetics and biocompatibility of dental ceramics has driven the increasing use of all-ceramic restorations over the past decade (1). However, the brittleness and low fracture strength of ceramics can initiate crack propagation causing fracture of the restoration. Clinical studies have demonstrated that all-ceramic dental restorations have an increased resistance to fracture in service when adhesively cemented to the prepared tooth structure with resin-based composite cements (2). It is thought that the cement interacts and penetrates ceramic surface defects, preventing crack propagation. However, strengthening is dependent on sufficient resin cement polymerisation via free radical photo-polymerisation in response to blue light (450-500nm). Adequate polymerisation (DC) depends on appropriate light transmission (LT) to the resin cement, which is affected by the opacity and the thickness of the ceramic and the resin cement layer. Consequently, this will influence the mechanical properties of the resin cement together with the strength and longevity of the restoration (3, 4, 5). The aim of this current study is to analyse LT through ceramics of different shade and thicknesses; measure and map DC; and correlate the results to the degree of reinforcement achieved.
Specimen preparation
Twenty ceramics discs (4 ceramic shades (A1, A2, A3, A3.5)) were prepared by mixing 0.73g of Base Dentine VM7 powder (Vita, Bad Säckingen, Germany) powder with 0.29mL of Modelling Liquid
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