بحث رقم 25 _ Evaluation of Bone-Implant Interface Of Commercially Pure Titanium And Ti-6Al-7Nb Alloy Dental Implants
- انشأ بتاريخ: السبت، 27 حزيران/يونيو 2015 14:47
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Evaluation of Bone-Implant Interface
Of Commercially Pure Titanium
And Ti-6Al-7Nb Alloy
(Experimental Study in Rabbits)
A thesis submitted to the council of the College of Dentistry at the University of Baghdad, in partial fulfillment of the requirements for the Degree of Doctor of Philosophy in Prosthetic Dentistry
Sabah Sahib Al-Habib
Dr. Salem A.L. Salem Dr. Thair L.Al-Zubaydi
Professor, Scientific Researcher
B.D.S, H.D.D., Ph.D M.Sc, Ph.D
Osseointegrated dental implants are currently recognized as a standard treatment method in dentistry.
Titanium and its alloys are the metals of choice for endosseous parts of currently available dental implants. Ti-6Al-4V is the most used titanium alloy, however, an improved version, Ti-6Al-7Nb, has been recently developed.
The new research on titanium biomaterial is focused on the generation of the new alloys by the addition of non-toxic elements like Niobium , Zirconium and Tantalium , to increase corrosion resistance and improve favorable tissue responses.
In this study, Ti-6Al-7Nb alloy reactions in bone and simulated body fluid were evaluated and compared with cpTi. A total of 180 screw-shaped implants (90 screws cpTi and 90 screws Ti-6Al-7Nb alloy) of 3 mm diameter and 8 mm length (threaded part 5 mm, smooth part 3 mm) implants were passivated in 28% nitric acid, then rinsed for five minutes in each of five separate washes of distilled water . Four implants (two from each material) were kept in an air tight glass container and sterilized by gamma irradiation.
The tibias of 45 white New Zealand rabbits (both sexes) weighed 2-3 kg were chosen as implantation sites. Animal population was divided into three groups (15 animals each) each of which received four implants (2 cpTi in left tibia and 2 Ti-6Al-7Nb alloy in the right tibia).
After 2, 6 and 18 weeks healing periods, one implant from each tibia was tested for the torque required to remove the implant and the other one was prepared for histological examination.
The corrosion rate for both materials was also calculated after immersion of 20 cylinders (10 cpTi cylinders and 10 Ti-6Al-7Nb alloy cylinders) in both artificial saliva and synthetic blood plasma, immersion periods were four and six months.
The results indicated that both materials were well-tolerated by the bone and there was matured bone around implant after six weeks implantation period.
After six months immersion period, Ti-6Al-7Nb alloy shows less rate of corrosion in blood plasma than cpTi. Moreover, there was a deposition of Ca and P on the surface of the alloy.
In conclusion both materials seem to be well-tolerated since no adverse tissue reaction was evident. However, there was a faster reaction of bone towards Ti-6Al-7Nb alloy implants and increased mechanical strength of bone-implant interface with time.
Regarding the removal torque values, it was found that the strength was increased with the maturation of bone with no significant difference between the two materials in all of the three implantation periods for both sexes.