PURPOSE: To evaluate the effect of the slice thickness and the size of region of interest (ROI) on CT number using quantitative CT phantom MATERIALS AND METHODS: The phantom containing 150 mg/cc, 75 mg/cc and 0 mg/cc calcium hydroxyapatite was scanned with 1, 3, 5 and 10mm slice thicknesses by single energy quantitative computed tomography (QCT). CT numbers were measured on center position of the phantom. Shape of ROI was circular and sizes were 1, 3, 5, 11, 16, 21, 26 and 33mm2 . ANOVA and Tukey's multiple comparison method were performed for statistical compari-son of CT numbers according to different slice thicknesses. Coefficient of variation of CT number measured in each size of ROI was evaluated in same slice thickness. RESULTS: CT numbers had statistically significant difference according to slice thicknesses (p<0.05). As the slice thickness increased, CT number also increased. As the density of phantom became lower and the size of ROI became smaller, the coefficient of variation of CT number increased. When the size of ROI was more than 11mm2 in 1mm slice thickness, 5mm2 in 3mm slice thickness and 3mm2 in 5mm slice thickness, the coefficient of variation became consistent. In 10mm slice thickness, the size of ROI had little effect on the coefficient of variation. CONCLUSION: CT number had variation according to the slice thickness and the size of ROI although the object was homogeneous. The slice thickness and the size of ROI are critical factors in precision of the CT number measurements.
Durapatite

PURPOSE: To evaluate the effect of the slice thickness and the size of region of interest (ROI) on CT number using quantitative CT phantom MATERIALS AND METHODS: The phantom containing 150 mg/cc, 75 mg/cc and 0 mg/cc calcium hydroxyapatite was scanned with 1, 3, 5 and 10mm slice thicknesses by single energy quantitative computed tomography (QCT). CT numbers were measured on center position of the phantom. Shape of ROI was circular and sizes were 1, 3, 5, 11, 16, 21, 26 and 33mm2 . ANOVA and Tukey's multiple comparison method were performed for statistical compari-son of CT numbers according to different slice thicknesses. Coefficient of variation of CT number measured in each size of ROI was evaluated in same slice thickness. RESULTS: CT numbers had statistically significant difference according to slice thicknesses (p<0.05). As the slice thickness increased, CT number also increased. As the density of phantom became lower and the size of ROI became smaller, the coefficient of variation of CT number increased. When the size of ROI was more than 11mm2 in 1mm slice thickness, 5mm2 in 3mm slice thickness and 3mm2 in 5mm slice thickness, the coefficient of variation became consistent. In 10mm slice thickness, the size of ROI had little effect on the coefficient of variation. CONCLUSION: CT number had variation according to the slice thickness and the size of ROI although the object was homogeneous. The slice thickness and the size of ROI are critical factors in precision of the CT number measurements.
Durapatite

The present study was performed to evaluate the effect of Tetracycline-HCl on the change of implant surface microstructure according to application time. Implant with hydroxyapatite surface was were utilized. Implant surface was rubbed with 50mg/ml Tetracycline-HCl solution and sterilized saline for 1/2min., 1min., 1 1/2min., 2min., 2 1/2min. and 3min. respectively in the test group. Then, specimens were processed for scanning electron microscopic observation and measured surface roughness by optical interferometer. The results of this study were as follows. 1. Hydroxyapatite surface showed that round particles were deposited irregularly. 2. The roughness of surfaces conditioned with Tetracycline-HCl and saline was lessened and the cracks were increased relative to the application time. In conclusion, the detoxification with 50mg/ml Tetracycline-HCl must be applied respectively with appropriate time according to hydroxyapatite implant surfaces.
Durapatite*

No abstract available.
Durapatite*

No abstract available.
Durapatite* ; Forehead*

No abstract available.
Durapatite* ; Radionuclide Imaging*

No abstract available.
Animals ; Dogs* ; Durapatite* ; Transplants*

Root-form endosseous implants which are in use today have a variety of materials, designs and surface characteristics. Among them, pure titanium surface implants and titanium matrix coated with HA are popular as well as are available in many studies. Rate of clinical success is obviously lower in jaw with cancellous bone than dense bone., In order to increase the rate of success in poor bone quality. More advanced techniques of implant surgery and surface treatment of implant fixture body have been developed. As a successful result, the installation of HA coated implant in bone quality type III or IV became highly successful. Since most clinical studies were performed without knowing the characteristics of HA coated implants, it has been impossible to come up with proper clinical data. Therefore the characterization of HA coated implants is essential to understand long term clinical performance and the predictability of HA coated implant system. Our results showed that HA coated implants had the success rate at 93.7% in bone quality type III, IV for 3.8 years, and the fixture of Steri-Oss showed more stability with time.
Durapatite* ; Jaw ; Titanium

STATEMENT OF PROBLEM: Surface texture of the implant is one of the important factors of the implant success, especially in the immediate implant loading. Many methods of the surface treatment of implant have developed and introduced. PURPOSE: This study was to evaluate the effects of the Ca-P coating implant crystallized the hydroxyapatite on the surface by the removal torque test and the histomorphometric analysis in vivo. Material and methods: 135 screw type implants, 4.0mm in length and 3.75mm in diameter were used in this study. Implants were divided into 3 groups and treated in the different methods. Group I was not treated, Group II was treated in the SLA method, and Group III was treated in the Ca-P coating with the anodizing method and the hydroxyapatite was crystallized on the surface with the hydrothermal treatment. Firstly, the surface roughness of each group was measured. 45 rabbits were used in this experiment. Two implants were inserted on right tibial metaphysis and one implant was inserted on left side with the alternating order. After the healing periods of 3, 5, and 12 weeks, the rabbits were sacrificed to evaluate the osseointergration by the removal torque test and the histomorphometric analysis. RESULTS: 1. In the analysis for the surface roughness, Group II showed the highest roughness. And Group III showed higher secondly. There was a significant difference one another statistically. 2. In the removal torque test, Group III and II were significantly higher than Group I. There was no statistical difference between Group III and Group II. 3. For all Groups, the removal torque values at 12th week were significantly higher than at 3rd and 5th week. 4. In histomorphometric analysis, the bone implant contact rates of Group III and II were higher than that of Group I at 3rd and 5th week. There was a significant difference at 5th week. 5. In histomorphometric analysis, the bone implant contact rate of Group III and II increased from 3rd week to 5th week, but decreased at 12th week. In Group I, the contact rate at 12th week was significantly higher than at 3rd week and 5th week.
Durapatite ; Rabbits ; Tibia* ; Torque*

The hydroxyapatites were popularly been used as the ocular implant due to low incidence of post-operative exposure, infections, and excellent motility. For this purpose, it has been known that the drilling and peg implantations are performed after ingrowth of fibrovascularization tissue into the hydroxyapatites, so that ball and socket movement were occur. The authors reviewed 140 patients(140 eyes) who received enucleation or evisceration with the implantation of hydroxypapatite from Dec. 1991 to Jun. 1995. We performed that drilling after confirmation of the fiborvascularized hydroxyapatite by Technetium-99m-MDP bone scan, and investigated the method and complications. Among the 140 eyes(140 Patients), 39 eyes(28%) were found to have complications: 17 cases of peg extraction(44%), 10 cases of peg protrusion(26%), 4 cases of over-growth of granulation tissue(11%), 3 cases of poor motility(7%), 3 cases of hydroxyapatite exposure(7%) and 2 cases of malposition of peg(5%). Redrilling was performed in 20 eyes(51%) and exchanged by the screw peg due to re-extraction of peg in 4 eyes(20%). In a conclusion, overall the frequency of complications after drilling was about 28% and the most frequent complication was peg extraction.
Durapatite* ; Humans ; Hydroxyapatites ; Incidence