092-642-6346

092-642-6348

Doctor of Philosophy (Dental Science)

Dental materials, Biomaterials

"Surface modification of titanium implant with quick osteointegration"
As it has outstanding corrosion resistance and biocompatibility, Ti is widely applied in orthopedics and dentistry as a replacement material for hard tissue. When Ti for mouth implants is embedded in the jawbone, bone is formed at the perimeter and bonding to bone occurs, but it usually takes 1-2 months for bone to form and the implant to become fixed. Therefore, during this period, it is important not to apply unnecessary force to the implant and to beware of infection. Even after osteointegration, if a strong force acts on the implant, separation may occur in the part bonded to bone and worsen the prognosis. In order to improve this, it is necessary that the implant bonds with the bone quickly, and that the bond is firm. In this study, in order to generate a quick bone-like apatite, the surface modification method of titanium is developed.

"Development of high corrosion resistance titanium alloys in fluoride-containing environment"
The effects of dissolved-oxygen concentration and fluoride concentration on the corrosion behaviors of commercial pure titanium, Ti-6Al-4V and Ti-6Al-7Nb alloys and experimentally produced Ti-0.2Pd and Ti-0.5Pt alloys were examined using the corrosion potential measurements. The amount of dissolved Ti was analyzed by inductively coupled plasma mass spectroscopy. A decrease in the dissolved-oxygen concentration tended to reduce the corrosion resistance of Ti and Ti alloys. If there was no fluoride, however, corrosion did not occur. Under low dissolved-oxygen conditions, the corrosion of pure Ti and Ti-6Al-4V and Ti-6Al-7Nb alloys might easily take place in the presence of small amounts of fluoride. They were corroded by half or less of the fluoride concentrations in commercial dentifrices. The Ti-0.2Pd and Ti-0.5Pt alloys did not corrode more, even under the low dissolved-oxygen conditions and a fluoride-containing environment, than pure Ti and Ti-6Al-4V and Ti-6Al-7Nb alloys. These alloys are expected to be useful as new Ti alloys with high corrosion resistance in dental use.

"Effect of Fluoride Concentration and pH on Corrosion Behavior of Titanium for Dental Use"
Titanium is used as a metal for biocompatible materials such as the dental implant or restorations because of an excellent chemical stability. However, the corrosion of Ti in prophylactic fluoride-containing environment comes into a problem. To clarify the effect of fluoride concentration and pH on the corrosion behavior of Ti, anodic polarization tests and immersion tests were carried out in NaF solution of various concentrations and pH values. The concentrations of dissolved Ti in the test solutions were analyzed by inductively coupled plasma mass spectroscopy. There were obvious limits of fluoride concentration and the pH value at which the corrosion behavior of Ti changed. The corrosion of Ti in the solution containing fluoride depended on the concentration of hydrofluoric acid (HF). When the HF concentration in the solution was higher than about 30 ppm, the passivation film of the Ti was destroyed. The results of this study revealed a relation between fluoride concentrations and pH values at which corrosion of Ti took place and provided information whether Ti is corroded or not, if the fluoride concentration and pH value are known in the concerned environment.


"Development of the carbonate apatite as a hard tissue substitution materials and a porosity ceramic bone filler"
The carbonate apatite attracts attention as a biomechanical material which is excellent in bone absorption property. Generally, although sintering gives strength and form, there is evil of a part of carbonate leaves during sintering. Then, in this study, the method of creating a hardening product, without sintering is developed. Moreover, a porosity sintering product is created from calcium phosphate powder (hydroxyapatite, alpha-TCP, etc.), and the porosity ceramic bone filler with osteoconductivity is developed.

Research Interests

• Development of osteoconductive titanium and titanium alloys implants with high bone bonding strength.
  keyword : Titanium, implant, apatite, osteocondictive, surface modification
  2004.04.
• "Development of high corrosion resistance titanium alloys in fluoride-containing environment"
  The effects of dissolved-oxygen concentration and fluoride concentration on the corrosion behaviors of commercial pure titanium, Ti-6Al-4V and Ti-6Al-7Nb alloys and experimentally produced Ti-0.2Pd and Ti-0.5Pt alloys were examined using the corrosion potential measurements. The amount of dissolved Ti was analyzed by inductively coupled plasma mass spectroscopy. A decrease in the dissolved-oxygen concentration tended to reduce the corrosion resistance of Ti and Ti alloys. If there was no fluoride, however, corrosion did not occur. Under low dissolved-oxygen conditions, the corrosion of pure Ti and Ti-6Al-4V and Ti-6Al-7Nb alloys might easily take place in the presence of small amounts of fluoride. They were corroded by half or less of the fluoride concentrations in commercial dentifrices. The Ti-0.2Pd and Ti-0.5Pt alloys did not corrode more, even under the low dissolved-oxygen conditions and a fluoride-containing environment, than pure Ti and Ti-6Al-4V and Ti-6Al-7Nb alloys. These alloys are expected to be useful as new Ti alloys with high corrosion resistance in dental use.
• "Effect of Fluoride Concentration and pH on Corrosion Behavior of Titanium for Dental Use"
  Titanium is used as a metal for biocompatible materials such as the dental implant or restorations because of an excellent chemical stability. However, the corrosion of Ti in prophylactic fluoride-containing environment comes into a problem. To clarify the effect of fluoride concentration and pH on the corrosion behavior of Ti, anodic polarization tests and immersion tests were carried out in NaF solution of various concentrations and pH values. The concentrations of dissolved Ti in the test solutions were analyzed by inductively coupled plasma mass spectroscopy. There were obvious limits of fluoride concentration and the pH value at which the corrosion behavior of Ti changed. The corrosion of Ti in the solution containing fluoride depended on the concentration of hydrofluoric acid (HF). When the HF concentration in the solution was higher than about 30 ppm, the passivation film of the Ti was destroyed. The results of this study revealed a relation between fluoride concentrations and pH values at which corrosion of Ti took place and provided information whether Ti is corroded or not, if the fluoride concentration and pH value are known in the concerned environment.
• "Development of the carbonate apatite as a hard tissue substitution materials and a porosity ceramic bone filler"
  The carbonate apatite attracts attention as a biomechanical material which is excellent in bone absorption property. Generally, although sintering gives strength and form, there is evil of a part of carbonate leaves during sintering. Then, in this study, the method of creating a hardening product, without sintering is developed. Moreover, a porosity sintering product is created from calcium phosphate powder (hydroxyapatite, alpha-TCP, etc.), and the porosity ceramic bone filler with osteoconductivity is developed.

Academic Activities

Awards

• Preperation of carbonate apatite monolith from bardened vaterite-gypsum by hydrothermal treatment in sodium phosphate.
• Corrosion behavior of titanium and titanium alloys in simulated oral environment.
• Fabrication of carbonated apatite monolith by treatment of calcium carbonate in phosphate solutions.
• Effect of Fluoride and Dissolved Oxygen Concentrations on the Corrosion Behavior of Pure Titanium and Titanium Alloys.

Educational Activities

Professional and Outreach Activities