Scanning electron microscope characterization of noncarious cervical lesions in human teeth.

AIMS: Abfraction is a theoretical process whereby occlusal forces create microfractures in enamel and dentin along the cervical area and predispose it to erosion and abrasion, forming noncarious cervical lesions. However, the theory is not yet proven. The aim of this study was to elucidate the role of abfraction as an etiology of these lesions. MATERIALS AND METHODS: Ten human premolars with these lesions from 10 patients requiring tooth extraction, one tooth from each patient, were used in this study. After extractions, all teeth were stored in 10% formalin until required, then prepared routinely for scanning electron microscopy. RESULTS: In all 10 teeth, at low magnification, noncarious cervical lesions appeared as crescent-shaped lesions. The upper edges of the lesions were on the enamel surfaces and their lower edges were on the cemental surfaces. In four teeth, the lesions showed evidence of microfractures characterized by the presence of fracture lines and fracture surfaces. In addition, in the first tooth of these teeth, the surface was also covered by a network of poorly fixed collagen fibers. In the third tooth, linear scratches, the openings of the dentinal tubules, a dentin matrix which consisted of a network of poorly fixed collagen fibers, and numerous dentinal tubules were also observed. In the remaining six teeth, they showed linear scratches, and the presence of the dentinal tubules or the exposed collagen fibers. CONCLUSIONS: It appears that abrasion and erosion are associated etiologic factors in forming noncarious cervical lesions and an ultrastructural finding that supports the abfraction theory of these lesions is observed.

A Scanning Electron Microscopic Study of Enamel Surfaces of Incipient Caries.

The surface changes of natural incipient caries in human teeth were examined by scanning electron microscopy. Numerous small round depressions due to dissolved prism ends are observed. The prism sheaths seem to be preferentially demineralized, followed by demineralization of prism cores. Perikymata are well-pronounced. Focal holes and relatively large dissolution areas can be present. A new prismatic pattern of destruction with an appearance of fish scales is found. Evidence of remineralization of the incipient carious lesions is seen on the surfaces of the lesions. This study disagrees with the concept of an intact enamel surface layer.

Scanning Electron Microscope Characterization of Erosive Enamel in Human Teeth.

This study aimed to examine the surface characteristics of erosive enamel in extracted human teeth by scanning electron microscopy. Morphologic changes in naturally eroded enamel depend on the stages of dental erosion. In its early stages, the enamel surfaces show a honeycomb appearance due to the dissolution of enamel rod ends. In its advanced stages, the erosive process involves the underlying dentin and the eroded dentin shows exposed dentinal tubules and the dentinal matrix may be exposed due to the dissolution of the peri- and intertubular dentin. Evidence of remineralization is seen at the early stage of natural dental erosion.

Fibro-osseous lesions of the jaws: an analysis of 122 cases in Thailand.

BACKGROUND: There are no previously published reports on fibro-osseous jaw lesions in Thailand. The aims of this study were to determine the relative frequencies and the clinicopathologic features of these lesions in Thailand, and to compare these data with information available in the literature. METHODS: A total of 122 cases of fibro-osseous lesions of the jaws, out of a total of 4808 biopsy specimens, were collected from the files of the Department of Oral Pathology, Faculty of Dentistry, Mahidol University, Bangkok, Thailand, during a 34-year period from 1973 to 2006. Clinical data and histopathologic diagnoses were reviewed and analyzed. RESULTS: The most common was ossifying fibroma (50.8%), followed by fibrous dysplasia (42.6%). Ossifying fibroma most frequently occurred in the third and fourth decades of life (61.3%) and mostly involved the posterior region of the mandible (41.9%). Fibrous dysplasia was mostly seen in the second decade of life (40.4%). The maxilla was involved far more often than the mandible (53.8% and 6.2%, respectively), most common in the posterior region of the maxilla (28.8%). Both lesions presented as painless swellings (62.9% and 90.4%, respectively). Radiographically, ossifying fibroma mostly was mixed radiolucent-radiopacity (45.2%). Fibrous dysplasia mostly appeared as a radiopaque lesion (34.6%). CONCLUSIONS: The relative frequency of osseous dysplasia is underestimated because most lesions are not treated and the patients are kept under long-term follow-up without biopsy. The clinicopathologic features of ossifying fibroma and fibrous dysplasia in Thailand are identical to those in the literature.

A scanning electron microscopic study of the dysplastic epithelia adjacent to oral squamous cell carcinoma.

By light microscopy, the dysplastic oral epithelia due to the neoplastic processes are similar to epithelial changes due to the inflammatory processes. Scanning electron microscopy may elucidate the different surface changes between the two. The aim of this study was to examine the surface appearances of the dysplastic oral epithelia adjacent to oral squamous cell carcinoma to see if there are any surface changes. A total of 2 specimens, one specimen from each patient with oral squamous cell carcinoma, were used for this study. Each specimen was divided in two. One half was prepared for light microscopy and the other half was prepared for scanning electron microscopy. Light microscopically, the epithelia showed mild dysplasia. By scanning electron microscopy, the keratinized cells showed irregular microridges surrounding pits, which were variable and irregular in size and shape, and the nonkeratinized cells showed parallel microridges with irregularly widened intervals between each microridge. Irregular, broad, and partly swollen microridges and irregular short, stubby surface projections were also seen. The oral epithelia adjacent to oral squamous cell carcinoma showed mild dysplasia light microscopically but appeared abnormal by scanning electron microscopy. The abnormal epithelial cells showed pleomorphism, irregular and disoriented microridges, and abnormal surface microstructures.

A comparative study of the surfaces of normal oral epithelia and inflammatory hyperplasias by scanning electron microscopy.

The oral epithelia may show epithelial changes induced by the inflammation of the underlying lamina propria. Light microscopically, the epithelial changes are similar to epithelial dysplasia seen in a premalignant lesion. A scanning electron microscope permits a resolution higher than that of a light microscope. Therefore, it may elucidate the changes observed light microscopically. The purpose of this study was to examine the surface changes of the epithelia of parulides (gum boils) compared with those of normal oral epithelia to see if there were any surface changes due to the underlying inflammatory processes. A total of 3 specimens (1 buccal mucosa, 1 gingiva, and 1 hard palate) taken from 3 patients, one specimen from each patient, were used as controls. A total of 2 parulides from 2 patients, 1 specimen from each patient, were used as experimentals. Each specimen was cut in two. One half was prepared for light microscopy and the other half was prepared for scanning electron microscopy. Light microscopically, it was confirmed that the buccal mucosa was nonkeratinized, the gingiva was parakeratinized, and the hard palate was orthokeratinized. The epithelium of the parulis was nonkeratinized to parakeratinized with increased intercellular spaces and distinct epithelial changes similar to epithelial dysplasia. By scanning electron microscopy, the nonkeratinized mucosa (buccal mucosa) showed that most of the ridges ran parallel to each other and the parakeratinized mucosa (gingiva) and the orthokeratinized mucosa (hard palate) exhibited ridges surrounding uniform pits. The surface of the parulis of the first patient showed relatively smooth areas with residual pits, reminiscent of that of keratinized mucosa, and the surface of the parulis of the second patient showed relatively smooth areas with residual parallel ridges, reminiscent of that of nonkeratinized mucosa. Light microscopically, the oral epithelia overlying the intensely inflamed lamina propria showed distinct epithelial changes similar to epithelial dysplasia seen in a precancerous lesion but appeared normal except for markedly decreased numbers of microridges by scanning electron microscopy.