Abstract
Ultrastructural and immunohistochemical investigations were performed on 2 cases of acute necrotizing ulcerative gingivitis (ANUG). Results obtained were as follows:
1. Lesions of necrosis were composed of large numbers of spirochetes and neutrophils in addition to small numbers of fusiform, rod-like and coccal shaped organisms.
2. Spirochetes that contained protoplasmic cylinder, cell envelope and axial filament had a width of 0.3-0.4μ and invaded in rarely intercellular spaces and within epithelial cells that appeared to have relatively normal structures of epithelial arrangement.
3. Spirochetes were often phagocytized by neutrophils and macrophages.
4. Immunoglobulin positive cells in lamina propria of ANUG were predominantly of IgG, followed by IgA and IgM.
5. Increased numbers of IgA positive cells were found in ANUG compared to periodontitis. Nature of IgA was a monomeric form suggestive of hematogenious origin.
