Edge Toughness and Material Properties of Dental Ceramics
Janet Quinn, Isabel K. Lloyd
Objectives: In the edge chipping test, an increasing load is applied near the edge of a material until a chip is formed. Higher loads are required to form chips at greater distances from the specimen edge. The chip loads are plotted against the edge distances, and the resulting linear slope is the edge toughness parameter. The magnitude of this parameter is indicative of a material's propensity to chip. The purpose of the current research was to determine the edge toughness parameters for a variety of dental ceramics. Also under consideration was the possible usefulness of this parameter in predicting clinical performance.Methods: A machine was built to apply a load via a conical diamond indenter near the edges of ceramic specimens. The measured loads and edge chip distances were used to determine the edge toughness parameters of eleven dental materials. The parameters are compared with material properties of the ceramics, including fracture toughness, strain energy release rate, elastic modulus and hardness.Results: For some of the materials chipped at very low loads, the load vs. edge chip distance plots were not linear as expected. At higher loads, however, the slopes were linear and the edge toughness parameters could be obtained. The parameter values varied from 92.7 N/mm for a fine-grained glass-ceramic to 534 N/mm for a tranformation-toughened zirconia. The edge toughness parameters roughly scaled with fracture toughness and strain energy release rate, with low fracture toughness materials more easily chipped.
Dental Materials Congress
chipping, dental ceramics, edge toughness, material properties
and Lloyd, I.
Edge Toughness and Material Properties of Dental Ceramics, Dental Materials Congress
(Accessed June 10, 2023)