No abstract available.
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

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* ; Forehead*

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

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

No abstract available.
Durapatite* ; Dust* ; Rabbits* ; Transplants*

The purpose of this study was to evaluated the method for quantitative assessment of bone mass from aluminum-equiv alent value of hydroxyapatite by using digital imaging system consisted of Power Macitosh 7200/120, 15-inch color monitor, and GT-9000 scanner with transparency unit. After aluminum-equivalent image made from correlation between aluminum thickness and grey scale, the accuracy of conversion to mass from aluminum-equivalent value was evaluated. Measured bone mass was compared with converted bone mass fr om aluminum-equivalent value of hydroxyapatite block by correlation formula between aluminum-equivalent value of hydroxy apatite block and hydroxyapatite mass. The results of this study were as follows: 1. Correlation between aluminum thickness and grey level for obtaining aluminum-equivalent imge was high positively ass ociated(r2=0.99). Converted masses from aluminum-equivalent value were very similar to measured masses. There was, statistically, no significnat difference(P<0.05) between them. 2. Correlation between hydroxyapatitie aluminum-equivalent and hydroxyapatite mass was shown to linear relation(r2 =0.95). 3. Converted masses from aluminum-equivalent value of 3 dry mandible segments were similar to measured masses. the diff erence between the exposure directions was not significantly different(P<0.05).
Aluminum ; Durapatite ; Equidae ; Mandible

No abstract available.
Durapatite* ; Radionuclide Imaging*