Wear behavior of low Fe titanium alloys

Objective: This study investigated the wear behavior of industrial low Fe titanium alloys for consideration for dental applications. Methods: Two alloys, LN (1%Fe, 0.35% O, 0.005% N) and HN (1% Fe, 0.30% O, 0.04% N) (Nippon Steel Corp., Chiba, Japan), were tested. Maxillary and mandibular teeth duplicated from artificial first molars (Livdent FB30, GC Dental, Tokyo, Japan) were used as patterns for casting. Each alloy was cast into a mold made using a phosphate-bonded, Al₂O₃/LiAl SiO₆ investment material (GC Dental) using a gas-pressure casting unit (Autocast HC-III, GC Dental). After chemically treating the cast teeth specimens with a HNO3/HF solution (Chemipolish, Shofu), wear was tested using a two-body wear testing apparatus that simulated chewing function (Ohkubo et al., J Prosthodont 11:263-269, 2002). Wear was assessed as volume loss (mm³) after the test. The data for these alloys were compared to previously recorded data for CP Ti, Ti-6Al-4V (6-4), Ti-6Al-7Nb (6-7), and a dental gold casting alloy (PGA-3, Ishi-fuku, Tokyo, Japan) (Ohkubo et al.). The wear resistance (n=5) were analyzed by ANOVA/Duncan's test (a=0.05). Results: The results of testing [Mean (SD)] were: CP Ti: 1.89(0.37), 6-4: 1.2(0.2), 6-7: 0.9(0.2), LN: 1.14(0.47), HN: 1.28(0.57), Control: 0.55(0.14). Excluding the data for the CP Ti and the gold control alloy, there were no statistical differences among the metals tested (p>0.05). The wear was statistically the highest for CP Ti, whereas it was the lowest for the gold alloy (p<0.05). Conclusion: The wear behavior of the new low alloy titanium tested (LN and HN) was comparable to that of 6-4 and 6-7. This study was partially supported by NIH-NIDCR grant 11787.