HISTOCHEMICAL AND IMMUNOHISTOCHEMICAL LOCALIZATION OF ELASTIC SYSTEM FIBERS IN FOCAL REACTIVE OVERGROWTHS OF ORAL-MUCOSA

Eight specimens each of the following groups were investigated: gingiv al pyogenic granuloma, fibrous epulis, calcifying fibrous epulis, peri pheral giant cell granuloma, giant cell fibroma (four gingival, four n on-gingival), denture-irritation hyperplasia and fibroepithelial polyp . These lesions have diverse histopathological appearances but the com position of their connective tissue is poorly defined. The elastic sys tem consists of a complex mixture of glycoproteins that in normal oral mucosa form three differentially distributed fibre types; oxytalan, e launin and elastic. The elastic system was investigated by Verhoeff's haematoxylin stain, aldehyde fuchsin staining and an anti-elastin mono clonal antibody. Elastin was identified in all fibroepithelial polyps and denture-irritation hyperplasias, but in none of the other lesions. In particular, this identified a distinct difference in the extracell ular matrix between the giant cell fibroma and fibroepithelial polyp. Many of the epulides included only oxytalan fibres, but the presence o f oxytalan fibres did not follow any pattern within either a single le sion group, or between different lesions. However, the presence of oxy talan fibres in the absence of elastin does not necessarily support a periodontal ligament origin for reactive epulides.