Li Chunfang, Risnes Steinar
Department of Oral Biology, Faculty of Dentistry, University of Oslo, P.O. Box 1052, Blindern, 0316, Oslo, Norway.
Arch Oral Biol. 2004 Jan;49(1):45-52. doi: 10.1016/s0003-9969(03)00195-x.
Sectioned and ground enamel surfaces need to be etched with acid in order for the enamel structure to be exposed for study in the SEM. In the present study Retzius lines and prism cross-striations were observed in variably ground specimens after etching with nitric acid of different concentrations (0.1, 1, 2.5 and 5%) and for different time periods (15, 30, 45, 90 and 180s). The aims were to improve our interpretation of these structures and to find the best etching regime.
Retzius lines in the superficial enamel were more readily exposed than Retzius lines in deeper parts of the enamel. The former showed discontinuity defects that facilitated their identification, while the latter lacked such defects. Few deep Retzius lines were exposed and could first be identified with certainty after etching for 30s in 1% acid. The structural and compositional basis for the visibility of deep Retzius lines may be subtle and difficult to identify. Scratches from the sectioning/grinding procedures may disturb their identification, but in general the grinding procedure was of minor importance for interpretation of enamel structure. Prism cross-striations were more readily exposed with the three stronger acid concentrations than with the weakest. They appeared as alternate light and dark bands, with a lower crystal concentration in the dark bands. No clear association with the prism varicosities/undulations was found. Etching with 1% nitric acid for 30s seems to be a good compromise for the study of Retzius lines and prism cross-striations.
为了在扫描电子显微镜（SEM）下对釉质结构进行研究，需要对切片和研磨后的釉质表面进行酸蚀，以使釉质结构暴露出来。在本研究中，观察了用不同浓度（0.1%、1%、2.5%和5%）的硝酸蚀刻不同时间段（15秒、30秒、45秒、90秒和180秒）的不同研磨程度标本中的芮氏线和棱柱横纹。目的是改善我们对这些结构的解释，并找到最佳的蚀刻方案。
表层釉质中的芮氏线比釉质深层的芮氏线更容易暴露。前者显示出有助于识别的间断性缺陷，而后者没有此类缺陷。很少有深层芮氏线暴露出来，在1%的酸中蚀刻30秒后才能首次确定识别它们。深层芮氏线可见性的结构和成分基础可能很微妙且难以识别。切片/研磨过程产生的划痕可能会干扰对它们的识别，但总体而言，研磨过程对釉质结构的解释影响较小。与最弱的酸浓度相比，三种较强的酸浓度更容易暴露棱柱横纹。它们表现为交替的明暗带，暗带中的晶体浓度较低。未发现与棱柱静脉曲张/波动有明显关联。用1%的硝酸蚀刻30秒似乎是研究芮氏线和棱柱横纹的一个很好的折衷方案。
