Investigation into Effect of Mold Temperature on the Fatigue Deflection of Clasps of Commercially PureTitanium

Abstract

Aim: The aim of the study was to evaluate the effect of mold temperature [room temperature (32°C), 450°C, and 790°C] on the fatigue deflection of clasps of commercially pure titanium. Materials and methods: Forty-five retentive wax profiles were cast in molds having three different mold temperature [room temperature (32°C), 450°C, and 790°C]. Specimens of grade 4 titanium, following the eligibility criteria, were selected. A 2-mm deflection test was done using an Instron machine and the flexibility of clasps of the respective groups was calculated. Deflection fatigue was tested using a cyclic-loaded custommade oscillating machine by calculating the number of loading cycles required to fracture the specimen. Results: The mean of flexibility of the clasp bars was observed and the difference was significant (between groups, F value was 38.49 at p = 0.0000 and within groups at p ≤ 0.01, respectively). The number of loading cycles applied to the clasp bars casted with 450°C and room temperature was more than that of 790°C, suggesting that the fatigue strength of clasps casted at 450°C and room temperature is more than that at 790°C. The mean of loading cycles of the clasp bars was observed and the difference was significant. Between groups, F value was 11.89 at p = 0.0001 and within groups at p ≤ 0.01. Conclusion: The number of loading cycles applied to the clasp bars casted with 450°C and room temperature was more than that of 790°C, and this suggests that the fatigue strength at 450°C and room temperature is more than that at 790°C. Temperature has an important role to play as the modulus of elasticity is higher at room temperature and 450°C than that at 790°C. Clinical implication: The ideal temperature for a titanium casting with relatively high fatigue strength would be 450°C mold temperature or room temperature. By investigating the fatigue deflection, it is clear that a desired undercut should be planned before clasp designing, considering the metal to be used.