The pattern of alveolar bone activity during development and eruption of the molar in the rat.

Abstract

The pattern of alveolar bone activity around the developing and erupting mandibular first molar of the rat was studied by autoradiography. The rats were hilled at 1 day and 1, 2, 3 and 4 weeks after birth. One hour prior to sacrifice, they were injected with 3H‐proline intraperitoneally. At one day after birth, the alveolar bone surfaces surrounding the tooth germ were unlabeled. At one week, the surface of the alveolar bone mesial to the developing tooth crown revealed heavy labeling, whereas the remaining surfaces surrounding the crown were unlabeled. The interdental septum between the first and second molars appeared at this stage. lts mesial surface was unlabeled troughout the four stages. Formation of the interradicular septum was ohserved at two weehs, and the future crestal area displayed very intense labeling. At three weeks, the crestal, mesial and distal surfaces of the interradicular septum showed heavy labeling. However, the apical one‐third of the mesial surface of the septum was unlabeled at four weeks. The surfaces of the fundic bone just beneath the primitive pulp chamber and beneath the open ends of the roots were unlabeled throughout the entire period. At three and four weeks, the interdental and interradicular crests exhibited very heavy labeling, more intense than that at the crest of the alveolar bone mesial to the first molar.