Effect of water exposure on the fracture toughness and flexure strength of a dental glass

Effect of water exposure on the fracture toughness and flexure strength of a dental glass Pages 367-371 Susanne S. Scherrer, Isabelle L. Denry, H. W. Anselm Wiskott, Urs C. Belser Close Preview Purchase PDF (128 K) | Related Articles AbstractAbstract | Figures/TablesFigures/Tables | ReferencesReferences Abstract Objectives: The low fusing dental glass (Duceram LFC) has been advertised as presenting a superior chemical resistance and augmented strength after 16 h exposure to water or 4% acetic acid. The purpose of this study was to evaluate the effect of prolonged exposure to water on two mechanical properties (fracture toughness and flexure strength) of LFC. Methods: Disks and bars were mirror polished and annealed prior to aging in: (1) air (control), (2) water for 24 h at 80°C and (3) water for 8 weeks at 80°C. Fracture toughness (KIc) was determined by indentation fracture (IF) and indentation strength (IS) using a 19.6 N Vickers indentation load. Flexure strength values were obtained from three-point bending at 0.1 mm/min. Statistical analysis was performed using the Weibull distribution, Tukey and Bartlett tests (P<0.05). Results: Both techniques (IS and IF) showed a significant improvement in the K of Duceram LFC after 8 weeks in water (0.88 and 1.14 MPa m0.5) as opposed to the 24-h values both in water and air (0.77–0.78 MPa m0.5). However, for flexure strength the Weibull characteristic (S0) and the m parameter did not change significantly with water storage (S0=90–100 MPa, Weibull m =7–8). Significance: The increase in toughness of Duceram LFC after aging in water is an interesting and favorable observation for a restorative material exposed to the oral environment. Nevertheless, in comparison with other contemporary ceramics, the toughness of this LFC remains in the range of soda-lime-glass or classic feldspar porcelains. Article Outline 1. Introduction 2. Materials and methods 2.1. Specimen preparation 2.2. Fracture toughness and flexure strength determination 2.3. Statistical analysis 3. Results 4. Discussion Acknowledgements References