Bevenius J, Lindskog S, Hultenby K
Department of Cariology, Karolinska Institutet, Stockholm, Sweden.
Acta Odontol Scand. 1993 Jun;51(3):135-42. doi: 10.3109/00016359309041159.
To investigate the validity of traditional data on the frequency of various relationships of root cementum to coronal enamel at the amelocemental junction, the relationship in 50 young premolar teeth extracted on orthodontic indications was documented, using replica techniques for scanning electron microscopy (SEM), combined with polarization microscopy of thin ground sections (< 40 microns). Of 200 surfaces, 30 were excluded because of damage during specimen preparation. Replicas of the other 170 surfaces were photographed at 20x and 80x in SEM and classified as having an edge-to-edge relationship of enamel to cementum in 76% and an overlap of cementum onto the cervical enamel in 14%. What appeared to be a gap between enamel and cementum at low magnification (10%) was seen at high magnification to be a ditch or trough in the cementum: no gaps with exposed dentin were observed in SEM. Polarization microscopy of ground sections of the original specimens confirmed the SEM classification. In this material, the edge-to-edge relationship of enamel to cementum predominated: overlapping of cementum onto the enamel was less prevalent than previously reported. The methods applied in this study circumvented some major sources of artefact formation due to shrinkage during specimen preparation, which may previously have caused misinterpretation of 'gap' relationships.
为了研究关于釉牙骨质界处牙根牙骨质与冠部釉质各种关系发生率的传统数据的有效性，我们记录了50颗因正畸原因拔除的年轻前磨牙的这种关系，采用复制技术进行扫描电子显微镜（SEM）观察，并结合厚度小于40微米的磨片的偏光显微镜观察。在200个表面中，30个因标本制备过程中的损伤而被排除。对其余170个表面的复制品在扫描电子显微镜下分别以20倍和80倍进行拍照，并分类为釉质与牙骨质呈边缘对边缘关系的占76%，牙骨质覆盖到颈部釉质上的占14%。在低倍镜下看似釉质与牙骨质之间的间隙（10%），在高倍镜下观察到是牙骨质中的一条沟或槽：在扫描电子显微镜下未观察到有暴露牙本质的间隙。对原始标本磨片的偏光显微镜观察证实了扫描电子显微镜的分类结果。在这种材料中，釉质与牙骨质的边缘对边缘关系占主导：牙骨质覆盖到釉质上的情况比以前报道的要少。本研究中应用的方法避免了标本制备过程中因收缩导致的一些主要伪像来源，而这些伪像以前可能导致对“间隙”关系的错误解读。
