Fatigue behaviour of dental composite materials

The intent of the project was to evaluate the fatigue behavior of particle and fiber filled dental composites that are fabricated either directly or indirectly using a notched specimen with respect to the number of cycles until failure.

The materials were five dental composites, three normally cured in the oral cavity (Restolux, Renew and Filtek Supreme), direct processing, and two laboratory produced (BelleGlass, and Tescera), indirect processing. The specimens were 3mmx3mmx25mm bars with a 0.75 or 1.0mm notch in the mid-span of the bars, polished with 320 grit SiC paper and aged for 6 months in air, distilled water, artificial saliva, and a 50/50 mixture of ethanol and distilled water. Testing was performed with a stress mean range of 5-49MPa, the maximum number of cycles was 100,000, and the number of cycles to failure was recorded.

For the specimens that failed, BelleGlass, Restolux, and Tescera were able to withstand a higher cyclic loaded stress than Renew and Filtek. The 50/50 by volume mixture of water and ethanol resulted in the lowest resistance to fatigue for all materials.

Of the dental composite materials investigated, the indirect processed and those with large particle fillers (higher weight percent filler) had better cyclic fatigue resistance than micro- and nano-particle fillers (lower weight percent filler).