Studies Of Casting Properties And Clinical Research Of Ti-6Al-7Nb Alloy For Dental Application

Much attention has been focused on titanium application in dental fields owing to its superior properties. In order to enlarge the application of titanium and titanium alloys in prosthodontics areas and to make up the deficiency of CP titanium in its strength, hardness and corrosion resistance, Ti-6Al-7Nb alloy was studied, which possesses similar microstructure and properties with Ti-6Al-4V alloy. Ti-6Al-4V alloy has been used widely in clinic as a high-strength biomedical alloy for its good mechanical properties and desirable microstructure. Ti-6Al-7Nb alloy is a novel medical titanium alloy, which consists ofαandβphases similarly as Ti-6Al-4V alloy. Niobium was used as a alloying element to replace the toxic-reacting element vanadium in Ti-6Al-4V alloy, at same time, niobium has high-hardness, corrosion resistance, good ductility, high-temperature and chemical stability. All those properties make Ti-6Al-7Nb alloy to be a high-strength biomedical alloy with excellent properties. In order to evaluate the possibility of applying Ti-6Al-7Nb alloy to clinical use, the article estimated the transverse deflection of the Ti-6Al-7Nb alloy after casting, the effect to precision after chemi- polishing and fatigue resistance of cast clasp. And we use it in clinic to get some clinical verifications of the Ti-6Al-7Nb alloy. The results of studies were as follows:1. According to the standard of ISO, the transverse deflection tests of Ti-6Al-7Nb alloy after casting were performed. Pure titanium, Ti-6Al-4V alloy and Co-Cr alloy were examined as the control. These groups of wax patterns with different thickness were designed. We found that when the thickness is 0.65 mm for Ti-6Al-7Nb alloy, pure titanium and Ti-6Al-4V alloy, and 0.57 mm for Co-Cr alloy, the transverse deflections could satisfy the requirement .This tells us that The reasonable thickness of Ti-6Al-7Nb alloy used as denture base material is above 0.65 mm.2. The research on the deflection fatigue resistance of titanium & titanium alloy cast clasp. The fatigue resistances of different domestic commercial types of metals including pure titanium, two titanium alloy(Ti-6Al-4V, Ti-6Al-7Nb alloy), Co-Cr alloy were measured in the present study. The results showed that the resistance of fatigue Co-Cr alloy was the highest, while that of the pure titanium was the lowest. The fatigue resistance of Ti-6Al-7Nb alloy was greater than Ti-6Al-4V alloy. Fatigue resistance increased of Ti-6Al-7Nb alloy and Co-Cr alloy clasps that are bended to reinforce retentions, while that of the pure titanium and Ti-6Al-4V alloy clasps decreased. Ti-6Al-7Nb alloy, a new type titanium alloy, doesn't include Vanadium, which is safer for human being. When Ti-6Al-7Nb alloy was first used to manufacture cast clasp, it possessed good fatigue resistance, and thus it was a suitable alloy to manufacture casting denture clasp.3. Studying the change of weight loss in different polishing methods of the Ti-6Al-7Nb alloy .Co-Cr alloy were examined as the control. We found that chemi-polishing does little difference to the precision of Ti-6Al-7Nb alloy. According to the government standard, we do some mechanical function tests, and we found that there were no statistically difference in 0.2% proof stress ,Ultimate Tensile Stress and Percentage Elongation between the control group and the test group. This tells us that chemi-polishing does little difference to the precision of Ti-6Al-7Nb alloy, and chemi-polishing can be popular used in Ti-6Al-7Nb alloy.4. According to the questionnaire investigation of 42 patients, we do some investigations of the clinical effect of Ti-6Al-7Nb alloy. We found that there were no statistical difference between the Ti-6Al-7Nb alloy group and the pure titanium group in the following 6 months. The Ti-6Al-7Nb alloy can be popular used in clinic.All the results sbove suggest if we use Ti-6Al-7Nb alloy as denture base material, we must make sure that the thickness come to 0.65mm or above; The Ti-6Al-7Nb alloy is better than pure titanium and Ti-6Al-4V alloy in fatigue resistance; Chemi-polishing does little difference to the precision of Ti-6Al-7Nb alloy, and chemi-polishing can be popular used in Ti-6Al-7Nb alloy; The Ti-6Al-7Nb alloy can be popular used in clinic.