THE EFFECT OF RATE OF ERUPTION ON PERIODONTAL-LIGAMENT GLYCOSYLAMINOGLYCAN CONTENT AND ENAMEL FORMATION IN THE RAT INCISOR

The rate of eruption of rat mandibular incisors was either increased by cutting one tooth out of occlusion or eliminated by means of pinning. The effects of such changes in eruption rate on the sulphated glycosylaminoglycan content of the periodontal ligaments was analysed. The length of the enamel secretory zone and the composition of the developing enamel matrix protein was also compared. Sulphated glycosylaminoglycan content of the periodontal ligament increased fourfold (P < 0.001) during accelerated eruption but decreased to a corresponding extent (P < 0.001) in the absence of eruption, when compared with controls. The length of the enamel secretory zone was also significantly reduced in the immobilised teeth, although the protein content was similar compared with controls. The results demonstrate the differential response to varied eruption rates of the periodontal ligament and enamel, particularly in respect of the extracellular matrix. The data are consistent with the view that the ground substance of the periodontal ligament plays a role in the generation of the eruptive force.