Hayashi Y
Department of Conservative Dentistry, Faculty of Dentistry, Kyushu University, Fukuoka, Japan.
Scanning Microsc. 1995 Mar;9(1):199-205; discussion 205-6.
Acids produced by various oral bacteria cause mineral loss and crystallite dissolution during the development of enamel caries. In order to demonstrate this phenomenon, the initial disappearance of lattice fringes and the formation of a central perforation in crystallites were examined by high resolution electron microscopy (HREM) in initial enamel caries without macroscopic tissue evidence of destruction. Ultrathin sections were also examined by selected area electron diffraction to reveal the mineral phase of the surface layer in carious enamel. A marked variation in the dissolution pattern was disclosed in the initial carious lesions. HREM revealed that disappearance of the lattice fringes from the lateral portion of the crystallites was predominant in the superficial layer covering the lesion, while central perforation of crystallites mainly occurred in the subsurface prismatic region. The beginning of the central dissolution occurred at the dislocated area where lattice striations appeared to be disordered. Selected area electron diffraction of the gradually demineralized enamel revealed a pattern consistent with hydroxyapatite (OH-AP) or fluorapatite (F-AP) mineral. These findings suggest that the susceptibility to caries of enamel crystallites is spatially and temporally different during the progression of the caries. Furthermore, the formation of central perforations and the consequent easy intracrystalline diffusion of acids might induce rapid crystallite dissolution.
在釉质龋发展过程中，各种口腔细菌产生的酸会导致矿物质流失和微晶溶解。为了证明这一现象，通过高分辨率电子显微镜（HREM）对无宏观组织破坏证据的早期釉质龋中晶格条纹的最初消失和微晶中心穿孔的形成进行了检查。还通过选区电子衍射对超薄切片进行了检查，以揭示龋损釉质表层的矿物相。在早期龋损中发现溶解模式存在显著差异。HREM显示，在覆盖病变的表层中，微晶侧面晶格条纹的消失占主导地位，而微晶中心穿孔主要发生在亚表层棱柱区域。中心溶解始于晶格条纹似乎无序的错位区域。对逐渐脱矿的釉质进行选区电子衍射显示出与羟基磷灰石（OH-AP）或氟磷灰石（F-AP）矿物一致的图案。这些发现表明，在龋病进展过程中，釉质微晶对龋病的易感性在空间和时间上是不同的。此外，中心穿孔的形成以及随之而来的酸在晶体内的容易扩散可能会导致微晶迅速溶解。
