Radiation-induced changes in the microstructure of epithelial cells of the oral mucosa: A comparative light and electron microscopic study

Objectives: The microplicae is a typical structure of the epithelial cell surface of the oral mucosa. The cell surface is potentially of great significance, as it provides the underlying basis for the protective function of the salivary pellicle. The aim of this study was to investigate whether radiation therapy affects the surface morphology of the superficial cells of the human oral mucosa in patients who have received radiotherapy for oral cancer.
Material and methods: Oral mucosal tissue samples from 91 patients were collected during dental implant surgery or ablative surgery. Study group 1 consisted of 28 patients who underwent dental implant surgery after radiotherapy. Group 2 consisted of five patients who developed osteoradionecrosis. Group 3 consisted of eight oral cancer patients without radiotherapy. Group 4 consisted of 50 clinically healthy subjects as controls. The samples were studied with scanning electron microscopy and compared with both light and transmission electron micrographs.
Results: Radiation therapy (RT) induces breakage and destruction in the microplicae morphology and declines the density of the microplicae surface structures. In some of the irradiated cells, the microplicae were completely vanished, especially in patients who developed osteoradionecrosis. In non-irradiated tissue, the microplicae of the superficial epithelial cells were intact in all cases.
Conclusion: Scanning electron microscopy, in contrast to light microscopy, appears to be a useful tool to reveal the condition of superficial oral mucosal cells. In respect of the possible pathogenesis of osteoradionecrosis, the radiation-induced damage of the microplicae and its influence on the mucosal salivary pellicle is discussed.