PubMed Health⌕ Search

Biomedical subjects

Jai-Young Koak

Publications and source records attributed to Jai-Young Koak.

7 recordsLinked to original sources
PubMed2004

Improved biological performance of Ti implants due to surface modification by micro-arc oxidation.

The surface of a titanium (Ti) implant was modified by micro-arc oxidation (MAO) treatment. A porous layer was formed on the Ti surface after the oxidation treatment. The phase and morphology of the oxide layer were dependent on the voltage applied during the oxidation treatment. With increasing voltage, the roughness and thickness of the film increased and the TiO(2) phase changed from anatase to rutile. During the MAO treatment, Ca and P ions were incorporated into the oxide layer. The in vitro cell responses of the specimen were also dependant on the oxidation conditions. With increasing voltage, the ALP activity increased, while the cell proliferation rate decreased. Preliminary in vivo tests of the MAO-treated specimens on rabbits showed a considerable improvement in their osseointegration capability as compared to the pure titanium implant.

Animals↗
PubMed2004

Development and evaluation of digital subtraction radiography computer program.

OBJECTIVE: We developed a new program for digital subtraction radiography (DSR) having useful functions to get the DSR image more accurately and efficiently. The purpose of this study was to evaluate the accuracy of the DSR image acquired using the new program as compared with the ready-made program. STUDY DESIGN: Four observers performed the DSR process using our program and the ready-made program for digital intraoral radiographs taken from incisor, premolar, and molar regions. The statistical difference was evaluated between the programs, between the observers, and between the regions. RESULTS: The DSR image using our program was superior to that with the ready-made program in all the observers and all the radiographed regions. Also, there was the statistical difference among the observers, especially in our program. CONCLUSION: The DSR image using the new program was very accurate compared with ready-made program, so the program was useful to get an accurate DSR image.

Humans↗
PubMed2002

Hydroxyapatite-based composite for dental implants: an in vivo removal torque experiment.

Screw-shaped dental implants were fabricated from commercially pure Ti (c.p. Ti) and HA-based composites. The HA-based composites were fabricated by mixing HA with Al(2)O(3)-coated ZrO(2) powders. The mechanical properties of these composites were enhanced by a factor of 3. These were implanted into the rabbit tibiae and the removal torque to loosen the implants in vivo was measured in order to investigate the osteointegration. After a healing period of 6 weeks, the implants were retrieved with a torque gauge instrument. The HA-based composite implants showed an almost 2-times-higher removal torque when compared to the Ti implants (ANOVA, p < 0.05), indicating excellent biocompatibility to bone. Thus, HA-based composites had not only better mechanical properties but also similar bioactivity as HA itself. It is believed that a HA-based composite is suitable for artificial dental implants.

Aluminum Oxide↗
PubMed2002

Fractal analysis of mandibular bony healing after orthognathic surgery.

OBJECTIVES: We evaluated the radiographic changes to the operational sites after orthognathic surgery by using fractal analysis. STUDY DESIGN: Panoramic radiographs from 35 patients who underwent orthognathic surgery on the mandible without any complications during the osseous healing process were selected. The radiographs taken before the operation (stage 0) and 1 or 2 days (stage 1), 1 month (stage 2), 6 months (stage 3), and 12 months (stage 4) after the operation were digitized at 600 dpi with 256 gray levels. The fractal dimension was calculated by means of a tile-counting method in the region of interest centered on the operational site and was statistically analyzed according to its stages. RESULTS: The fractal dimension was decreased immediately after the operation and increased gradually according to the time lapse (P <.05). The fractal dimension in the region of interest 12 months postoperatively was similar to that preoperatively. CONCLUSION: This result suggests that fractal dimension can be used to evaluate the bony healing process after orthognathic surgery.

Adult↗
PubMedDate not supplied

A histomorphometric analysis of the effects of various surface treatment methods on osseointegration.

PURPOSE: One major factor in the success and biocompatibility of an implant is its surface properties. The purposes of this study were to analyze the surface characteristics of implants after blasting and thermal oxidation and to evaluate the bone response around these implants with histomorphometric analysis. MATERIALS AND METHODS: Threaded implants (3.75 mm in diameter, 8.0 mm in length) were manufactured by machining a commercially pure titanium (grade 2). A total of 48 implants were evaluated with histomorphometric methods and included in the statistical analyses. Two different groups of samples were prepared according to the following procedures: Group 1 samples were blasted with 50-microm aluminum oxide (Al2O3) particles, and group 2 samples were blasted with 50-microm Al2O3, then thermally oxidized at 800 degrees C for 2 hours in a pure oxygen atmosphere. A noncontacting optical profilometer was used to measure the surface topography. The surface composition of the implants used and the oxide thickness were investigated with Rutherford backscattering spectrometry. RESULTS: The different preparations produced implant surfaces with essentially similar chemical composition, but with different oxide thickness and roughness. The morphologic evaluation of the bone formation revealed that: (1) the percentage of bone-to-implant contact of the oxidized implants (33.3%) after 4 weeks was greater than that of the blasted group (23.1%); (2) the percentages of bone-to-implant contact after 12 weeks were not statistically significantly different between the groups; (3) the percentages of bone area inside the thread after 4 weeks and 12 weeks were not statistically significantly different between groups. DISCUSSION AND CONCLUSION: This investigation demonstrated the possibility that different surface treatments, such as blasting and oxidation, have an effect on the ingrowth of bone into the thread. However, the clinical implications of surface treatments on implants, and the exact mechanisms by which the surface properties of the implant affect the process of osseointegration, remain subjects for further study.

Aluminum Oxide↗
PubMedDate not supplied

Osseointegration of anodized titanium implants coated with fibroblast growth factor-fibronectin (FGF-FN) fusion protein.

PURPOSE: The synergistic effect of fibroblast growth factor (FGF) and human fibronectin fragment (hFNIII9-10) on osteoblast cell adhesion has been demonstrated in vitro. The purpose of this study was to evaluate the bone response around anodized titanium implants treated with FGF-FN fusion protein using the histomorphometric analysis and the removal torque test. MATERIALS AND METHODS: Threaded implants were manufactured by machining a commercially pure titanium (grade 4). Two different groups of samples were prepared: Group 1 samples were anodized under a constant voltage of 300 V, and group 2 samples were anodized under a constant voltage of 300 V and then soaked in a solution containing fusion protein (65 microg/mL) for 24 hours. Ten implants from each group were placed in rabbit tibiae (1 implant per group per rabbit; each rabbit served as its own control). After a 3-month healing period, the animals were sacrificed. Removal torque testing and histomorphometric analysis was then carried out. RESULTS: The mean removal torque value of group 2 (44.8 Ncm) was greater than that of group 1 (37.6 Ncm). The percentages of bone-implant contact of the best 3 consecutive threads were 76.37% for group 1 and 88.02% for group 2. The percentage of bone-implant contact for the total length of the implant was higher for group 2 (36.91%) than for group 1 (29.47%). However, the percentage of the area inside the threads that consisted of bone did not differ significantly for the 2 groups. DISCUSSION AND CONCLUSION: This study demonstrated that the FGF-FN fusion protein coating on anodized implants may enhance osseointegration. However, the influence of fibronectin- and FGF-treated rough surfaces on long-term prognosis and the propagation of inflammation are subjects for further study.

Animals↗