| EFFECT OF HYDROGEN PEROXIDE CONCENTRATION ON THE WHITENING AND PHYSICAL PROPERTIES OF HYDROXYAPATITE DISCS |
| 전북대학교 치과대학 소아치과학교실 및 구강생체과학연구소 |
| Hydrogen Peroxide 농도와 적용시간이 Hydroxyapatite Discs의 미백과 물리적 성질에 미치는 영향 |
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양연미, 이두철, 백병주, 김재곤, 신정근 |
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전북대학교 치과대학 소아치과학교실 및 구강생체과학연구소 |
Correspondence:
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| Abstract |
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The purpose of this study was to evaluate the effect that various concentration and application time of hydrogen peroxide had on tooth whitening and physical properties. The hydroxyapatite (HA) discs of 12mm(φ) ×1.2mm(t) in dimensions were made by compression (100kg/cm2) and sintering (at 1350℃ for 2 hours) All specimens were polished sequentially with '240 through '2000 emery paper and one side of each specimen was polished finally with 0.3㎛ alumina paste. The discs were placed in sterile whole stimulated saliva overnight at 37℃ in order to form an in vitro pellicle layer. Then the discs were rinsed with distilled water and soaked into staining broth at 37℃ for 7 days. These stained specimens were bleached with hydrogen peroxide according to the change of concentration (3~30%) and application time (3~10days). The specimens were analyzed with a spectrophotometer, X-ray diffractometer (XRD), scanning electron microscope (SEM), surface roughness tester, microhardness tester and biaxial flexural strength. The results of present study can be summarized as follows : 1. The bleaching effect was increased with the increased concentration and the extended application time of hydrogen peroxide. 2. The surface roughness was significantly increased from the specimen bleached with 15% hydrogen peroxide for 10 days and with 30% for 7 and 10 days respectively (p<0.05). 3. The changes of crystal phase observed by XRD between before and after bleaching weren't shown of any difference, but microporous structure of surface observed by SEM was shown of increase with the increased concentration and the extended application. 4. The biaxial flexural strength was significantly decreased from bleaching of specimen with 30% hydrogen peroxide for 7 and 10 days respectively (p<0.05) 5. Microhardness was significantly decreased from bleaching with 15% hydrogen peroxide for 10 days and with 30% for 3, 7 and 10 days respectively (p<0.05). Although the tooth bleaching effect was greater when the high concentration was applied, further in vivo experiment will be needed to prove it's safety. |
| Key Words:
Hydroxyapatite discs, Hydrogen peroxide, Whitening |
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