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

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.