A comparative evaluation of metallurgical properties of stainless steel and TMA archwires with timolium and titanium niobium archwires - An in vitro study.

Objectives: This study aims to evaluate and compare the mechanical and metallurgical properties of stainless steel and titanium molybdenum alloy (TMA) archwires, with recently introduced timolium and titanium niobium arch wires. Materials and Methods: Archwires were categorized into four groups (group I to IV) with 10 samples in each group. They were evaluated for tensile strength, yield strength, modulus of elasticity, load deflection, frictional properties and weld characteristics. Results: The results were statistically analyzed using ANOVA test and it indicated that stainless steel has high strength, high stiffness and low friction compared to other arch wires, thereby proving that it is the best choice for both sliding as well as frictionless retraction mechanics. TMA with its high formability, low stiffness and low load deflection property is suited to apply consistent force in malaligned teeth but, high friction limits its use in retraction only with loop mechanics. Conclusion: Timolium possesses comparatively low stiffness, better strength and behaves as an intermediate between stainless steel and TMA and hence can be tried for almost all clinical situations. Low springback and high formability of titanium-niobium archwire allows creation of finishing bends and thus it can be used as finishing archwire.

In vivo biocompatibility of beta titanium alloys for internal fixation instruments / 中国矫形外科杂志

[Objective]To develop new beta titanium alloys made of titanium, niobium and zirconium (Ti-Nb-Zr) which have higher strength, lower moduli of elasticity. Its biocompatibility in vivo is evaluated in this paper. [Method](1) 24 SD rats were used in the modified air pouch model experiments. Air was injected subcutaneously on the back of rats to form the pouches and the Ti-Nb-Zr particles were introduced into them. The liquid in the pouches was harvested 48 hours later for IL-6 and TNF-?ELISA procedure and the capsules for histology examination. All the results were compared with Ti-6Al-4V. (2) Ti-Nb-Zr bone plates were fixed onto tibias of rabbits. The capsules around the plates and the bone under them were observed at 4, 8, 12, 24 and 36 weeks respectively. Ti-Nb-Zr-bone interfaces were emphasized in this procedure. This time the control material was stainless steel. [Result](1)Ti-Nb-Zr and Ti-6Al-4V particles made the air pouches secret more TNF-? than that of the control (P

An in vitro study of the biocompatibility of Ti-Nb-Zr Bate titanium alloy / 中国矫形外科杂志

[Objective]To evaluate the biocompatibility of a new bate titanium alloys made of titanium, niobium and zirconium (Ti-Nb-Zr) which have higher strength and lower elastic modulus by in vitro study.[Method](1)the cell toxicity of Ti-Nb-Zr was evaluated using L-929 cell line's relative growth rate (RGR) which was transformed into 6 toxicity ranks in according with the national standard;(2)the J774A.1macrophages cultured with Ti-Nb-Zr particles whose diameter was about 1 ?m for 24-48 hours were observed using inverted phase contrast microscopy and transmission electron microscopy. Expression of IL-6 and TNF-? mRNA in these cells were measured using RT-PCR technique. The TNF-? in the supernatant was also measured using ELISA method. All the results were compared with the traditional orthopedic implants metal materials such as Ti-6Al-4V and Co-Gr-Mo.[Result]The cell toxicity of Ti-Nb-Zr was ranked zero degree. The particles could be seen in the macrophages under the light microscopy. Ti-Nb-Zr particles made the J774.A1 macrophages less configurative changes than Ti-6Al-4V and Co-Gr-Mo did.Expressions of IL-6 and TNF-? mRNA in J774.A1 cell were increased after stimulation for 48 hours by all kinds of metallic materials. The TNF-? in the supernatants of Ti-Nb-Zr group were less than that of the Ti-6Al-4V and Co-Gr-Mo groups (P

Bate titanium alloys for orthopedic implants:fabrication,X-ray diffraction analysis,and biomechanics / 中国矫形外科杂志

[Objective] To develop new bate titanium alloys made of titanium,niobium and zirconium(Ti-Nb-Zr)which have higher strength,lower moduli of elasticity and better biocompatibility for orthopedic implants.[Methods]Alloy elements including titanium,niobium and zirconium were melted together and forged into forging Ti-Nb-Zr.Four kinds of alloys were developed because of the different proportion of alloy elements.All alloys were studied using X-ray diffraction analysis,biomechanical measurements,and scanning and transmission electron microscopy.[Results]X-ray diffraction analyses showed that all the candidates were beta alloys.The as-cast alloys had the strength values in 584~718 Mpa,elastic modulus values in 59~68 Gpa.The peak-aged alloys had the strength values in 706~874 Mpa,elastic modulus values in 59~66 Gpa,elongation rates in 5.4%~20%.The forging procedure could increase the strength significantly but almost have no influence in elastic modulus of Ti-Nb-Zr.[Conclusion]The Ti-Nb-Zr beta titanium alloys developed in our lab have lower modulus and high strength both.It is a promising material for orthopedic implants.

Influence on Ni seperation from TiNi alloy by coating its surface with Ti or TiNb alloy / 中国矫形外科杂志

[Objective]To investigate the influence of Nitinol modified on its surfaces by the coating of titanium or titanium-niobium alloy on separat ion of Ni~(2+).[Method]The specimens from 1 to 7 days after the experiments were collected and the concentration of Ni~(2+) were cletermined by physiologic saline immersing test,low temperature ashing furnace,Mg(NO_3)_2 as matrix modifier and graphite furnace atomic absorption spectrometry(GFAAS).[Result]Specimens of Nitinol were devided into 3 groups:alloy coated with Ti(Ti group);alloy with Titanium-Niobium(TiNi group);only Nitanol without coating group.Obvious separation of Ni~(2+) was detected in the groups of Nitinol that were not modified and were put in baking oven(37℃),the separating procedure was mainly within 4 days,the separation rate(10~(-7)??g? cm~(-2)?s~(-1)) from the first to the forth days was 18.2,3.45,1.75 and 0.45 respectively,the Ni~(2+)was no more separated from the fifth day.Whereas,Ni~(2+) was not separated in the groups of Nitinol that were modified by the coating of metallic Ti and TiNb alloy.The recovery rate of the experiments was between 94.6%～108.6%.[Conclusion]The coating of Ti or TiNb on the surfaces of Nitinol stopped Nitinol from separating Ni~(2+).