Mechanical performance of polymer-infiltrated zirconia ceramics.

OBJECTIVE: The aim of this study was to evaluate the microstructure and mechanical behavior of polymer-infiltrated zirconia ceramics as a function of pre-sintering temperature (1000-1150°C). METHODS: Polymer-infiltrated zirconia ceramics were prepared by combining the porous zirconia networks and polymer through infiltration and polymerization. XRD was employed to determine phase structure. The microstructure and fracture mechanism were observed by SEM. Flexural strength and fracture toughness were measured by three-point bending method and single-edge-notched beam method, respectively. A nanoindentation system was employed to determine elastic modulus and hardness. RESULTS: Different porosities and polymer contents can be obtained by tuning the pre-sintered temperature of zirconia ceramic precursors. Zirconia network porosity varies from 46.3% to 34.7% and the relevant polymer content ranges from 18.4wt.% to 12.3wt.% when the pre-sintered temperature is set from 1000°C to 1150°C. The flexural strength, fracture toughness, hardness, and elastic modulus values of the specimen pre-sintered at 1150°C are 240.9MPa, 3.69MPam1/2, 3.1GPa, and 58.8GPa, respectively. CONCLUSION: The pre-sintering temperature has a significant effect on the microstructure and mechanical properties of polymer-infiltrated zirconia ceramics and the optimal pre-sintering temperature is 1150°C. CLINICAL SIGNIFICANCE: Specimen pre-sintered at 1150°C shows tooth-like mechanical properties, suggesting a promising restorative material in dental clinic. Moreover, the synthesis process is simple and can be easily performed in a prosthesis laboratory.

High strength and toughness in chromatic polymer-infiltrated zirconia ceramics.

OBJECTIVE: To evaluate the microstructure and mechanical behavior of polymer-infiltrated zirconia ceramics as a function of Fe2O3 concentration (0-0.3mol%). METHODS: Polymer-infiltrated zirconia ceramics with different concentrations of Fe2O3 were prepared by infiltration and polymerization. XRD was employed to determine phase structure. The microstructure and fracture mechanism was observed by SEM. Flexural strength and fracture toughness were measured by three-point bending method and single-edge-notched beam method, respectively. Data were analyzed by Weibull distribution. A nanoindentation system was employed to determine elastic modulus and hardness. RESULTS: With increasing content of Fe2O3, the flexural strength, fracture toughness, elastic modulus and hardness are all greatly enhanced and the chromatic behavior also improves significantly. As a tradeoff made between strength and elastic modulus, specimen containing 0.2mol% Fe2O3 is found to be the better one, with flexural strength and fracture toughness values being 336.8MPa and 3.91MPam1/2, respectively. Moreover, it maintains a relatively low elastic modulus of 88.2GPa and a moderate hardness of 4.8GPa, close to those of natural enamel. SIGNIFICANCE: This polymer-infiltrated zirconia ceramic material is a dental material of biomimetic chromatic and mechanical properties.