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 b y cutting one tooth out of occlusion or eliminated by means of pinning . The effects of such changes in eruption rate on the sulphated glycos ylaminoglycan content of the periodontal ligaments was analysed. The l ength of the enamel secretory zone and the composition of the developi ng enamel matrix protein was also compared. Sulphated glycosylaminogly can 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. Th e length of the enamel secretory zone was also significantly reduced i n the immobilised teeth, although the protein content was similar comp ared with controls. The results demonstrate the differential response to varied eruption rates of the periodontal ligament and enamel, parti cularly in respect of the extracellular matrix. The data are consisten t with the view that the ground substance of the periodontal ligament plays a role in the generation of the eruptive force.