Device for in vitro Induction of Wear to Dental Materials

The rate of wear of the natural dentition and restorative materials is dependant on many factors. Wear-potential of materials itself and wear on the natural dentition is critical when selecting restorative materials. Improved materials are popularized by their ability to resist abrasion. Various methods, including clinical testing and wear machines have been used to investigate wear of teeth and dental materials. Because clinical trials are expensive, time consuming and requires resolution of problems of measurement, laboratory simulation of wear has been shown to be valuable. Objectives: An automated mechanical wear device for induction of in vitro wear of dental materials on natural tooth structure or different dental materials opposing each other was developed. Induction of wear must be in a well controlled environment with variable predetermined temperature, load, cycles, wear characteristics and reproducibility. Methods: A Labcon shake-incubator was converted by a stainless steel substructure that could fit into the incubator. The substructure supports one sample of dental material that is perpendicularly apposed by a second sample of dental material that can move freely in a vertical dimension. The top sample can be loaded with a predetermined force to enhance wear-potential. Accelerated wear results from circular cycles, the evaluation can be carried out under irrigation at set temperatures (0-100°C), predetermined loads, any amount of circular cycles and as a two or three body wear. Results: Wear measurement on a standardized acrylic tooth surface were: 6000 cycles = 0.1685mm (SD=0.025, CV=14.6%); 12000 cycles = 0.1975mm (SD=0.039, CV=19.8%); 18000 cycles = 0.2395mm (SD=0.019, CV=7.8%). Conclusions: The newly developed device can be used to induce in vitro abrasion and wear resistance of different materials and can be used for relative accurate and repeatable wear induction to compare materials, materials and natural tooth tissue, or evaluate newly released dental materials to similar materials.