response of dentin-pulp complex of the rat to thyroxin administrations for two different periods

ABSTRACT

The histological and carbohydrate histochemical studies of the response of the rat dental pulp to the subcutaneous administration of 50 mug/100 g body weight thyroxine for 5 or 10 consequent days were performed. Deeply seated alterations in the dentin-pulp complex were noted including changes in dentinogenesis evidenced by the most frequent localized increase in predentine formation in a regular or irregular pattern. Also, localized hyalinization of the accumulated collagen fibers and ground substance, proliferation of cellular and fibrillar elements and the development of osseous structures in the pulp stroma were noted. The vascular alterations were striking, as manifested by the proliferation of blood vessels and capillaries associated with the appearance of localized or diffused hyaline materials rich with neutral mucopolysaccharides intra- and extravascularity. Whereas, these alterations helped for the dentin-pulp complex after thyroxine injections for 5 days; however they became more dramatically accentuated after thyroxine injections for 10 days and in females than males. It was concluded that hormonization causes predominant stimulation of dentin matrix genesis, but dentin matrix mineralization is impaired. It also leads to alterations in the physical consistency of the ground substance, thus inducing stromal hyalinization and increased vascular permeability. However, the changes in the vessel walls and in the perivascular stroma may be reminiscent to those occurring in acute inflammation