Effect of surface roughness on flexural strength of veneer ceramics.
The strength of ceramic restorations depends on the occlusal surface roughness of the veneering porcelain, which is influenced by the final preparation. The hypothesis of the study was that roughnesses below a critical microscopic defect size--based only on fracture mechanics considerations--also affect flexural strength. The bending failure stress was evaluated on standard specimens of 4 veneer ceramics with 4 different surfaces of defined roughnesses, respectively. A linear correlation was found between roughness and failure stress. A "roughness-free" failure stress value was predicted for each tested material. This theoretical value can represent the "true" strength of the respective ceramic material. We conclude from our results that the final preparation of a ceramic restoration is critical to the strength of the material, and that ceramic veneering materials can be compared more objectively with respect to their strength by means of roughness-free strength values.
Fischer
H
H
Department of Dental Prosthetics, Section of Dental Materials, University RWTH Aachen, Germany. h.fischer@rwth-aachen.de
Schäfer
M
M
Marx
R
R
D020906:Air Abrasion, Dental; D000538:Aluminum Silicates / Q000737:chemistry; D002516:Ceramics / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry*; D003799:Dental Stress Analysis; D003801:Dental Veneers; D006358:Hot Temperature; D006801:Humans; D016014:Linear Models; D018020:Lithium Compounds / Q000737:chemistry; D008422:Materials Testing; D018583:Pliability; D017655:Silicon Compounds / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties
D000538:Aluminum Silicates; C118557:Empress 2; C075815:IPS-Empress ceramic; D018020:Lithium Compounds; D017655:Silicon Compounds; D003776:Dental Porcelain; C032734:silicon nitride