Sintering mechanism of the CaF2 on hydroxyapatite by a 10.6-l microm CO2 laser
| Autor: | Rong-Tai Roan, Cheng-Chei Wu, Jeng-Huey Chen |
|---|---|
| Rok vydání: | 2002 |
| Předmět: |
Thermogravimetric analysis
Materials science Differential Thermal Analysis Scanning electron microscope Lasers Fluorapatite Sintering Mineralogy Biocompatible Materials Dermatology In Vitro Techniques Thermogravimetry Calcium Fluoride Durapatite Chemical engineering X-Ray Diffraction Differential thermal analysis Spectroscopy Fourier Transform Infrared Microscopy Electron Scanning Humans Surgery Dental Enamel Eutectic system Diffractometer |
| Zdroj: | Lasers in surgery and medicine. 31(5) |
| ISSN: | 0196-8092 |
| Popis: | Background and Objectives Laser has been reported as a heat source for melting and re-crystallization. Occurring at about 1,100°C, the melting of surface dental enamel along with re-crystallization might have an assistant role in the therapy of hypersensitive tooth, apical sealing of endodontic surgery in dentistry, preventive dentistry for pit and fissure sealing, and fluoridation. For laser to be accepted in clinical applications, it is desired that, studies must show the incorporation of CaF2 into hydroxyapatite could reduce the sintering temperature for the sake of safety. Study Design/Materials and Methods In this study, the Sharplan 20XJ CO2 laser with 10.6-μm wavelength was set under the following parameters: power, 5 W; repetitive mode, 0.1 second; beam, focused. Fluorite was added to hydroxyapatite as a synthetic compound to lower the sintering temperature. Human dental enamel without caries was used for in vitro sintering test. Scanning electron microscopy (SEM), X-ray diffractometer (XRD), Fourier transforming infrared spectroscopy (FTIR), and differential thermal analysis/thermogravimetric analysis (DAT/TGA) were used for the investigation of sintering mechanism of CaF2. Results Fusion between hexagonal shape crystals and cubic shape crystals (CaF2) were observed under SEM study. Hexagonal shape crystals indicated the formation of fluorapatite under XRD analysis. Under FTIR study, we examined reductions of water (3,445 cm−1) and hydroxyl bands (3,567 and 627 cm−1) in irradiated compounds. From the DTA pattern of synthetic compound, it showed the endothermic reaction reaching its peak point around 1,180 ± 20°C. It was attributed to the phase transformation and/or initial melting. Conclusions In this study, we proposed the interrelationship of the eutectics between initiator (CaF2) and the reaction product (calcium hydroxide) that reduced the sintering temperature. It appeared that the co-eutectics interacted to reduce the sintering temperature of hydroxyapatite below 800°C and that the key eutectic was calcium hydroxide. The clinical feasibility of the melting and re-crystallization of hydroxyapatite under 10.6-μm CO2 laser would be therefore enhanced. Lasers Surg. Med. 31:333–338, 2002. © 2002 Wiley-Liss, Inc. |
| Databáze: | OpenAIRE |
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