Effect of hypophysectomy on dentin production in maxillary incisors in the rat

Abstract

abstract— The effect of hypophysectomy on the dentin production and on the longitudinal growth of the maxillary incisors of female rats 60–105 d of age was determined In‐ the tetracycltne technique. In normal rats, the highest rate of dentin apposition amounted to about 23μm per clay in the middle part of the tooth with lower values in apical and incisal directions. Because of incisal attrition, the tooth was exchanged in about 55 d, corresponding to a longitudinal growth rate of'about 400μm per day. After hypophysectomy, the rate of dentin production was reduced to about 60%, with a considerable variation depending on the position of the odontoblasts along the tooth. The longitudinal growth rate was reduced to about 50% of normal. As the length of the tooth was the same within the period studied, this resulted in a slower transfer of the odontoblasts along the tooth and a time delay of about 55 d before they reached the incisal part of the tooth. The total dentin production of the odontoblasts in the hypophysectomized animals was the same as in normals. Compared with the effect of hypophysectomy on the rate of longitudinal bone growth and cortical bone remodeling, the effect on the dentin production and longitudinal growth of the incisors is less pronounced, indicating differences in sensitivity to hormones between the different cell systems.