The Effects of Reducing Function and Stopping Eruption on the Periodontium of the Rat Incisor

¹ Department of Dentistry, The Queen's University, Belfast

The lower incisor teeth of rats were subjected to the following changes: (a) eruption was stopped and normal function maintained by fitting a metal crown over both incisors and (b) eruption was stopped and function reduced in one incisor by root filling it or by pinning it to the bone, the tooth being kept out of occlusion.

The normal periodontal membrane was described. The alveolar fibers were shown to be dependent on function for their maintenance, while the cemental fibers were not. The fibers of the intermediate plexus, when not required to connect alveolar and cemental fibers, adopted a longitudinal orientation.

After eruption stopped, the intermediate plexus fibers became grouped into bundles which were continuous with the alveolar and cemental bundles.

Complete root filling was found to prevent tooth eruption. This suggests that the periodontal membrane plays no part in eruption but that the pulp does.