Morphological changes in oral mucosae and their connective tissue cores regarding oral submucous fibrosis

Oral submucous fibrosis (OSF) is a chronic disease of the oral cavity characterized by an inflammatory reaction followed by severe fibro-elastic changes. The aim of the present study was to investigate the three-dimensional morphological changes in the connective tissue cores (CTCs) of the oral mucosa in OSF. The sample consisted of buccal mucosal biopsies from ten human subjects ranging in age from 40-45 years; five of them were clinically diagnosed as having moderate to severe OSF, and the remaining five served as unaffected controls. Half of each biopsy was formalin-fixed and paraffin-embedded for light microscopy, while the other half was fixed in a Karnovsky's solution, treated with HCl to exfoliate the epithelium, and processed for examination under a scanning electron microscope (SEM). Oral submucous fibrosis biopsies exhibited heavily packed aldehyde fuchsin-positive fibers (i.e. elastic fibers) in the submucosa under the light microscope. Broad bundles of collagen fibers were seen in a concentrated manner in the deeper layers. Scanning electron microscopy of the buccal mucosa in OSF showed the finger-shaped CTCs to be attenuated beneath the epithelium at the initial stages of the disease. Patchy degenerative areas lacking the CTCs were observed in advanced cases. These degenerative areas increased gradually with the progression of the disease. Highly fibrosed cases showed severe degeneration of the CTCs, resulting in a smoothening of the connective tissue surface in the buccal mucosa.