Thermal decomposition of developing enamel.
The decomposition of forming, maturing, and mature enamel was studied between room temperature and 1,000 degrees C by powder X-ray diffraction and infrared absorption methods. In mature dental enamel, carbonate decomposition proceeds relatively fast until 500 degrees C and at a slower rate beyond it. In forming and maturing enamel, decomposition is faster and is completed around 800 degrees C. The formation of beta-Ca3(PO4)2 is observed in dental enamel at 500 degrees C. At 1,000 degrees C, the apatite phase in forming and maturing enamel transforms almost completely to beta-Ca3(PO4)2, whereas in mature enamel, even at 1,000 degrees C, only partial decomposition occurs. Infrared results show the appearance in dental enamel of (1) A-type carbonate at room temperature and in the 500-900 degrees C range, in addition to the commonly observed B-type carbonate, and (2) intermediate CO2 molecules during carbonate decomposition (200-500 degrees C).
Mayer
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Department of Inorganic and Analytical Chemistry, Hadassah Faculty of Dental Medicine, Hebrew University, Jerusalem, Israel.
Schneider
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Sydney-Zax
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Deutsch
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D000818:Animals; D001031:Apatites / Q000032:analysis / Q000145:classification; D002417:Cattle; D003743:Dental Enamel / Q000032:analysis* / Q000254:growth & development; D006358:Hot Temperature; D006801:Humans; D066298:In Vitro Techniques; D013055:Spectrophotometry, Infrared; D014961:X-Ray Diffraction
D001031:Apatites; C030782:carboapatite