In vitro wear assessment of titanium alloy teeth.
OBJECTIVE
Wear of commercially pure (CP) titanium prosthetic teeth has frequently been observed. The greatest wear has been found when the same grades of CP titanium are used for both maxillary and mandibular teeth. This study examined the wear behavior of teeth made with cast titanium alloy and compared these results with those for CP titanium and gold alloy teeth.


METHODS
All tooth specimens were cast with grade 3 alpha titanium, 3 metastable beta alloys [Ti-15Mo-2.8Nb-0.2Si (Timetal 21 SRx), Ti-13Nb-13Zr, and Ti-15V-3Cr-3Sn-3Al], and 2 alpha+beta alloys (Ti-6Al-7Nb and Ti-6Al-4V). As a control, Type IV gold alloy was also cast conventionally. All teeth (both maxillary and mandibular) were secured in an in vitro 2-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 (mm(3)) at 5 kgf (grinding force) after 50,000 strokes. The results (n = 5) were analyzed using analysis of variance or Fisher's exact test (alpha = 0.05).


RESULTS
Of the titanium teeth, the wear of 2 of the metastable beta alloys (Timetal 21 SRx and Ti-15V-3Cr-3Sn-3Al) was found to be significantly (p <0.05) higher than that of CP titanium and the 2 alpha+beta alloys. The Type IV gold alloy exhibited better wear resistance than all of the titanium teeth tested. No correlation was found between wear loss and hardness among all the metals tested.


CONCLUSIONS
Among the titanium teeth examined, the alpha+beta alloys exhibited significantly less wear than the other types of titanium. The dental casting gold alloy tested exhibited the best wear resistance among all of the metals tested.
Ohkubo
Chikahiro
C
Tsurumi University School of Dental Medicine, Yokohama, Japan. okubo-c@tsurumi-u.ac.jp
Shimura
Ichiro
I
Aoki
Takayuki
T
Hanatani
Shigeru
S
Hosoi
Toshio
T
Okabe
Toru
T
D000497:Alloys; D000704:Analysis of Variance; D001732:Bite Force; D003722:Dental Alloys / Q000737:chemistry*; D019554:Dental Restoration Wear / Q000145:classification*; D006047:Gold Alloys / Q000737:chemistry; D006244:Hardness; D006801:Humans; D008409:Mastication / Q000502:physiology; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D013223:Statistics as Topic; D013314:Stress, Mechanical; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*; D014093:Tooth, Artificial; D014961:X-Ray Diffraction
D000497:Alloys; D003722:Dental Alloys; D006047:Gold Alloys; C090153:titanium alloy (TiNb13Zr13); C070282:Ti-6Al-7Nb alloy; C031462:titanium alloy (TiAl6V4); D014025:Titanium