Histochemical Studies of the Periodontium

¹ National Institute of Dental Research, National Institutes of Health, Bethesda, Maryland

A variety of histochemical and other methods has been applied to the study of the structure and enzymatic activities of cells of the periodontium.

1. A collagenase has been identified from cultures of gingivae removed for the treatment of periodontal diseases of man. The enzyme is active under physiologic conditions, requires living tissue for production, and is not the result of contamination with microorganisms, although the particular cell from which it originates is still unknown.

2. Slices of fresh periodontal tissues, 2 to 3 mm. thick, rapidly demineralized in the cold with a neutral 10 per cent solution of EDTA in 10 per cent polyvinylpyrrolidone in tris buffer retain considerable activity of many enzymes. The method is useful for possible correlation of enzymatic activity to the status of the intercellular substances.

3. Electron microscopic studies of oxytalan fibers reveal them to be composed of many fine fibrils approximately 100 to 150 Å in diameter with an interfibrillar amorphous material of approximately the same diameter. The electron microscopic observations support the thesis that oxytalan fibers are a distinct connective tissue fiber; however, the electron microscopic and chemical data secured from studies of developing elastic fibers of fetal ligamentum nuchae of cattle provide substance to the view that oxytalan fibers may be related to elastic fibers. The use of Oxone instead of peracetic acid as an oxidant in the staining procedure to identify oxytalan fibers as suggested is recommended. The substitution permits good oxidation and staining without concomitant tissue destruction.

4. Recent sulfation and acetylation experiments suggest that OH groups of collagen are active with the van Gieson staining procedure, and mordant experiments tend to indicate that NH₂ groups may be utilized with the trichrome staining methods for collagen. These latter data may be helpful in the analysis of changes of collagen associated with conditions such as disease and aging.