The crystallographic properties of the mineral phases of enamel and dentin in normal deciduous and permanent teeth / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the crystallographic properties of the mineral phases of normal enamel and dentin (dental apatite) in deciduous and permanent teeth.</p><p><b>METHODS</b>Three kinds of physical methods including X-ray diffraction (XRD), infrared absorption spectroscope (IR) and electron probe micro-analysis (EPMA) were utilized in this study.</p><p><b>RESULTS</b>Dental apatite was not uniphase, but multiphase, which could be described as carbonate-substituted hydroxyapatite. Compared to dentin apatite, the higher crystallinity and expanded a-axis lattice parameters were found in enamel. Chemical analyses demonstrated that higher concentrations of Mg and CO(3)(2-) were found in dentin than those of enamel. But enamel had higher Cl content.</p><p><b>CONCLUSIONS</b>The differences among enamel and dentin, in terms of lattice parameter and crystallinity may be partially attributed to the incorporation of Mg, CO(3)(2-) and Cl minor elements.</p>

A histological and ultrastructural study of the tidemark in human condylar cartilage / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To study the histology and ultrastructure of the tidemark in the adult condylar cartilage and their significance.</p><p><b>METHODS</b>After embedded in paraffin, 50 adult condyles were stained with HE, partly with Van-Gieson and histochemical methods, then observed by light microscope. 3 cases of the tidemark region were observed by transmission electron microscope, another 5 cases were studied by scanning electron microscope.</p><p><b>RESULTS</b>In the tidemark region, there had shown the presence of the AKP and calcium, absence of the proteoglycan, abundance of the membrane-bound matrix vesicles, crystals of hydroxyapatite and lipid nodule-like substances, which were often observed in the load-bearing areas. The collagen fibrils of the noncalcified cartilage crossed the tidemark gradiently and were continuous with those of the calcified cartilage; a band of horizontal fibrils surrounded the whole tidemark region, which was wider in the load-bearing areas than that in the nonload-bearing areas and which interweaved with the gradient fibrils so as to form a net. Digested with papain, the surface of the tidemark was highly undulating, and a lot of chondrocyte lacunae were seen on the surface, which were surrounded by calcified tissues.</p><p><b>CONCLUSIONS</b>In the region of the tidemark, physiological calcification takes place and is more active in the load-bearing areas; gradient and horizontal fibrils interweave with each other, which is correlated with the force on the articulation.</p>

A quantitatively pathological study on malignant ameloblastomas / 华西口腔医学杂志

<p><b>OBJECTIVE</b>The purpose of this study was to investigate the role of nuclear morphometric parameters, DNA content and Ag-NOR count in the differentiating malignant and benign ameloblastomas.</p><p><b>METHODS</b>Totally 17 cases of malignant ameloblastomas were examined by using HE, AgNOR and DNA stain methods. Morphometric parameters of cell nuclei, DNA content and AgNOR count were quantitatively studied by using an image analysis system.</p><p><b>RESULTS</b>Seven parameters (area, perimeter, equal diameter, minor diameter, mean diameter, round index, axis ratio) out of ten shape factors were significantly different between malignant and benign ameloblastoma (P < 0.01). AgNOR count and DNA index in malignant ameloblastoma were significantly higher than those in benign ameloblastoma (P < 0.01). Logistic regression equation was established, according to nuclear morphormetric parameters and DNA index.</p><p><b>CONCLUSION</b>Quantitative analysis of DAN content, nuclear morphmetric parameters and AgNOR count may be helpful in differentiating malignant and benign ameloblastomas.</p>

Proliferating activity and differentiation between peripheral cells and central cells in ameloblastoma / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the proliferating activities and differentiation between peripheral cells and central cells in ameloblastoma.</p><p><b>METHODS</b>Expressions of proliferating cell nuclear antigen (PCNA), Ki-67, CK10&13 and CK19 were detected in 43 ameloblastoma (15 follicular, 20 plexiform and 8 acanthomatous) by SP immunohistochemical methods.</p><p><b>RESULTS</b>The PCNA labelling indices were significantly higher in peripheral cells (5.12% +/- 2.76%) of tumour nests or strands than in central cells (1.36% +/- 1.02%, P < 0.001). The peripheral cells of tumour nests or strands exhibited a significantly higher Ki-67 labelling index (3.63% +/- 1.80%) than central cells (1.26% +/- 0.96%, P < 0.001). The labelling indices between PCNA and Ki-67 showed a significant correlation (P < 0.01). The positive expressions of CK10&13 and CK19 were significantly higher in central cells than in peripheral cells (P < 0.01).</p><p><b>CONCLUSIONS</b>The peripheral zones of tumour nests or strands are regarded as proliferating areas; there exists a significantly different differentiation between central cells and peripheral cells.</p>