Wear Resistance of Magnetic Fe-Pt Alloy Teeth

Abstract

Purpose: Fe-Pt alloys have magnetic properties and can be cast using a dental casting machine. However, no studies have ever been conducted to examine the wear of Fe-Pt alloys. This study evaluated the in vitro wear resistance of magnetic Fe-Pt alloy teeth.Materials and Methods: Maxillary and mandibular tooth patterns were duplicated from artificial first molars (Livdent FB30, GC, Japan) and cast from a custom-made Fe-Pt ingots (Fe-39.5 at % Pt-0.75 at % Nb) using a high-frequency centrifugal casting machine (Jelenko Eagle, Jelenko, NY, USA). The cast teeth were vacuum-enclosed in quartz-glass tubes, solution-treated at 1,325°C for 45 min., and then quenched in ice water. Subsequently, the teeth were aged at 600°C for 5 hours to acquire hard magnetic properties. As controls, Au-Ag-Pd alloy (Castwell MC, GC), Au-Pt alloy (PGA-3, Ishifuku, Japan) and Co-Cr alloy (Wisil, Austenal, Germany) were also prepared by conventional casting. The wear of the teeth (both maxillary and mandibular) was measured using an in vitro two-body wear testing apparatus that simulated chewing function (60 strokes/min., grinding distance: 2 mm under flowing water). Wear resistance was assessed as volume loss (mm3) at 49 N (grinding force) after 50,000 strokes. The results (n=5) were analyzed by ANOVA/Fisher's test (α=0.05).Results: The wear resistance [Mean (SD)] of each alloy was: Au-Pt [0.55 (0.14)], Au-Ag-Pd [0.40 (0.05)], Fe-Pt [0.02 (0.03)], and Co-Cr [0.04 (0.01)]. Fe-Pt alloy had the least wear although there were no significant differences compared to Co-Cr alloy (p>0.05). The Au-Pt alloy had the worst wear resistance of all the metals tested (p<0.05).Conclusion: Based on the results of this study, Fe-Pt alloy should wear very little when used for both maxillary and mandibular teeth.