Kodaka T, Kobori M, Hirayama A, Abe M
Department of Oral Anatomy, Showa University School of Dentistry, Tokyo, Japan.
J Electron Microsc (Tokyo). 1999;48(2):167-72. doi: 10.1093/oxfordjournals.jmicro.a023663.
Automatic toothbrushing with a commercial dentifrice containing hydroxyapatite (HAP) crystals was performed on the tangential polished surfaces of sound human enamel, mainly consisting of biological apatite similar to HAP, for 10 min in vitro. The X-ray diffraction peaks of HAP, brushite (DCPD), and monetite (DCP) crystals were detected from the dentifrice. After brushing, the enamel surfaces were observed with a scanning electron and a confocal scanning laser microscope. The brushing caused larger abrasive loss and more remarkable roughness of the enamel surfaces following the broad traces of brush bristles and the exposure of prism structures than brushing with a dentifrice containing only DCPD, which we previously reported. We claim that the fine granular-shaped HAP crystals of the dentifrice indicated as an active ingredient for preventing enamel caries possess stronger abrasivity of sound enamel than the DCPD and DCP as abrasives on account of their Mohs hardness values rather than sizes and shapes. The HAP crystals of dentifrices may not occlude the small defects of early caries enamel, but erode them more strongly as an abrasive than the other abrasives.
在体外，将含有羟基磷灰石（HAP）晶体的商用牙膏用于健康人牙釉质的切向抛光表面进行自动刷牙10分钟，该牙釉质主要由类似于HAP的生物磷灰石组成。从牙膏中检测到了HAP、磷酸二钙二水合物（DCPD）和磷酸一钙（DCP）晶体的X射线衍射峰。刷牙后，用扫描电子显微镜和共聚焦扫描激光显微镜观察牙釉质表面。与我们之前报道的仅含DCPD的牙膏刷牙相比，此次刷牙导致牙釉质表面出现更大的磨蚀损失以及更显著的粗糙度，沿着刷毛的宽痕迹以及棱柱结构暴露出来。我们认为，作为预防牙釉质龋的活性成分的牙膏中细颗粒状HAP晶体，由于其莫氏硬度值而非尺寸和形状，比作为磨料的DCPD和DCP对健康牙釉质具有更强的磨蚀性。牙膏中的HAP晶体可能不会封闭早期龋坏牙釉质的小缺陷，反而作为磨料比其他磨料更强烈地侵蚀它们。
