Whisker-Reinforced Heat-Cured Dental Resin Composites: Effects of Filler Level and Heat-Cure Temperature and Time

Published

June 1, 2000

Author(s)

Hockin D. Xu, Douglas T. Smith, Gary E. Schumacher, F Eichmiller

Abstract

Extensive studies have been undertaken to improve the mechanical properties of resin composites to extend their use to large stress-bearing crown and multiple-unit restorations. The aims of the present study were to investigate the ceramic whisker reinforcement of heat-cured resin composites, and to investigate the effects of whisker filler level, heat-cure temperature and heat-cure time. Silica particles were fused onto the whiskers at a high temperature to facilitate silanization and to roughen the whiskers for improved retention in the resin matrix. The whisker filler mass fraction was varied from 0 % to 79 %, the heat-cure temperature from 80 degrees C to 180 degrees C, and the heat-cure time from 10 min to 24 h. An inlay/onlay composite and a prosthetic composite were tested as controls. Flexural strength, work-of-fracture, and fracture toughness of the composites were measured, and specimen fracture surfaces were examined with scanning electron microscopy. Filler level and heat-cure time had significant effects on the composite properties. The whisker composite with 70 % filler level cured at 140 degrees C for 0.5 h had a flexural strength (mean {+ or -) SD; n = 6) of (248 ± 23) MPa, significantly higher than (120 ± 16) MPa of the inlay/onlay composite and (123 ± 21) MPa of the prosthetic composite (Tukey's multiple comparison test; family confidence coefficient = 0.95). Heat-cure time also played a significant role. At a heat-cure temperature of 120 degrees C, the strength at a cure time of 10 min was 178 ± 17) MPa, significantly lower than (236 ± 14) MPa at a cure time of 3 h. In conclusion, heat-cured dental resin composites were substantially reinforced via ceramic whiskers; filler level and heat-cure time played significant roles; the reinforcement mechanisms appeared to be whiskers bridging and resisting cracks; the strength and fracture toughness of the whisker composite were two times those of currently available inlay/onlay and prosthetic composites.

Citation

Journal of Dental Research

Volume

79

Issue

No. 6

Pub Type

Journals

Keywords

ceramic whisker, filler level, heat cure, reinforcement mechanisms, resin composite, strength, toughness

Citation

Xu, H. , Smith, D. , Schumacher, G. and Eichmiller, F. (2000), Whisker-Reinforced Heat-Cured Dental Resin Composites: Effects of Filler Level and Heat-Cure Temperature and Time, Journal of Dental Research (Accessed May 1, 2024)