Responses of tooth eruption and alveolar bone subject to somatic growth retardation in the rat.

The morphogenesis and regression of the osteodental fissure formed by alveolar bone in the maxillary and mandibular regions has been investigated in relation to eruption of the dentition during and following a period of somatic retardation stemming from nutritional suppression. Fissural formation occurred above the first and second molars of the maxilla and mandible, morphologically within normal limits but retarded by two days. During eruption a sequence of cuspal perforations of the alveolar bone took place behind the edge of the alveolar crest which later disintegrated as the bulk of the crown moved upwards. The appearance of the specific cusps of the experimental animals was two days behind that of the controls. Eruption through the oral mucosa was fairly rapid and the deficit noted in the bone emergence phase was reduced to one day. As in control animals, fissural formation did not occur over the third molars which were totally encapsulated by bone. Eruption of third molars in experimental animals was similar to control observations- no difference in timing and the removal of the encapsulating bone being achieved by the rapid enlarging of a wedge-shaped area at the mesio-occlusal aspect. Observation of eruption through alveolar bone is regarded as a more accurate assessment of changes in the early phases.