Effects of demineralization and parathyroid hormone on the availability of bone collagen to degradation by collagenase

Short-term effects of fluoride on biosynthesis of enamel-matrix proteins and dentine collagens and on mineralization during hamster tooth-germ development in organ culture

The effect of various concentrations of fluoride (F-) on cell proliferation, matrix formation and mineralization was examined in hamster molar tooth germs in premineralizing and mineralizing stages. The exposure lasted 16 h (mineralizing stages) and 24 h (premineralizing stages) and the F- levels ranged from 2.63 microM to 2.63 mM; [3H]-thymidine, [3H]-proline, 45Ca and 32PO4 were used as markers for cell proliferation, matrix formation and mineralization, respectively. The proline-labelled amelogenins were isolated by sequential extraction with water and formic acid and their nature examined by SDS-urea-polyacrylamide electrophoresis. Digestion by collagenase was used to assess the amount of proline incorporated into collagens. F- in concentrations up to 1.31 mM inhibited neither biosynthesis of DNA and amelogenins, nor synthesis of collagens and their hydroxylation. Amelogenins extracted from F- induced, non-mineralizing enamel matrix had the same electrophoretic mobility and the same degree of phosphorylation as amelogenins from normal, mineralizing enamel. However, F- increased the uptake of 45Ca and TCA-soluble 32P dose-dependently, starting with 52 microM. Thus, interference with secretion of enamel matrix by F- takes place at much lower concentrations than required to inhibit biosynthesis of enamel matrix.

Localization of collagenase in human middle ear cholesteatoma

The process of connective tissue breakdown in chronic otitis media is described in the context of recent advances in our understanding of collagen degradation and bone resorption. The significance of the initial step in collagen breakdown, brought about by the action of a specific collagen dissolving enzyme is emphasized in terms of recent studies in other chronic inflammatory diseases characterized by connective tissue breakdown. Bone resorption, a characteristic feature of chronic otitis media, requires the breakdown of collagen, which comprises over 90 percent of bone protein. Evidence in support of collagenase in bone resorption from adjacent tissue (in this case, inflammatory connective tissue) would require identification of the enzyme in cells involved in the inflammatory process adjacent to the resorbing bone. Collagenase was found localized in frozen sections of canal wall skin, middle ear granulation and in cholesteatoma by a specific binding of the enzyme with an antiserum produced against purified human skin collagenase. The antigen antibody complex was labelled with fluorescein. Collagenase appeared in the subepithelial connective tissue of cholesteatoma, granulation tissue from the middle ear and the dermis of canal skin; but was not seen in the keratin layer, epithelium or the epidermal appendages. The enzyme appeared within certain fibroblasts, macrophages and endothelial cells of capillary buds. Collagenase enhanced by chronic inflammation attacks the intact collagen molecule, making it susceptible to further digestion by other proteases that are also products of inflammation. This process brings about resorption of connective tissue and bone.

Oral manifestations of secondary hyperparathyroidism related to long-term hemodialysis therapy

Patients on long-term hemodialysis therapy may develop secondary hyperparathyroidism with oral symptoms. As the life expectancy of the dialysis patient increases, the dentist is seeing these manifestations with increasing frequency. A review of the subject is presented along with a case illustrating dramatic roentgenographic changes in a patient who was placed on hemodialysis when the technique was in its infancy.

The effect of thyrocalcitonin and growth hormones on bone metabolism

The use of the hormone, thyrocalcitonin, has been shown to change the bone metabolism so that resorption is decreased and calcium increased. The growth hormone seems to add to bone mass and indirectly prevents resorption. The combination of growth hormone and calcitonin seems to cause an unusual amount of resorption. This research has shown that metallic endosteal blade implants are not automatically successful even in short spans with additional support from two abutment teeth. It is true that the type of occlusion of the squirrel monkey is different from that of man, but the prosthetic devices that were placed in these animals can be validly compared to similar devices placed in man. While the hygiene cannot be practiced effectively by the animal, the psychogenic and emotional problems of man offset this disadvantage. Also, the diet of the monkey is not as traumatic to a prosthesis as is man's. Two of the most important criteria for implant success have not proved satisfactory: (1) no pocket depth beyond 3 mm. and (2) negative radiographic pathosis around the implant. While this study was not meant to be one of criticism or evaluation of metallic implants, it should be noted that thyrocalcitonin and the growth hormone, individually used, played an important part in retarding bone resorption around the blade. Autogenous bone grafts for residual alveolar ridge restoration often fail due to rapid osseous resorption and volume loss. The maintenance of osseous elements in the autogenous bone grafts when calcitonin had been administered was quite revealing. This might be the chemotherapeutic basis for the many conditions involving bone that dentists are called upon to treat.