Abstract: Objective To study the effect of artificial saliva and lactic acid solution on the fatigue strength of Vitallium 2000 Co-Cr-Mo alloy clasps. Methods 15 clasp specimens of Vitallium 2000 Co-Cr-Mo alloy clasps were made from prefabricated clasp wax, and were divided into 3 groups. Specimens were tested in air, artificial saliva and lactic acid solution. Initial loading force and loading cycle numbers before fracture were registered automatically, and fracture flaws were examined with a scanning electron microscope (SEM). Results Initial loading force of Vitallium 2000 Co-Cr-Mo alloy clasps didn’t differ significantly in three test conditions (P>0.05).The tested clasps had the highest loading number cycles in air and the lowest ones in lactic acid solution. Fatigue strength analysis of SPSS software showed a significant difference among three groups (P<0.01). Conclusion The results suggest that both artificial saliva and lactic acid solution reduce the fatigue strength of Vitallium 2000 Co-Cr-Mo alloy clasps.

Key words: Vitallium 2000 Co-Cr-Mo alloy, Fatigue strength, Clasp