The mobility of the lathyritic rabbit mandibular incisor in response to axially-directed extrusive loads.

Axially-directed extrusive loads of 0.01-0.1 N were applied to the lathyritic mandibular incisors of 12 rabbits. Tooth position was monitored continuously with a variable capacitance displacement transducer. Compared with pair-fed controls, lathyritic teeth showed markedly reduced resistance to extrusive loading, indicating that the periodontal collagen has a role in supporting the tooth. The pattern of tooth mobility, however, was little affected. The results may have implications for the eruptive mechanism. That eruption rates can appear unchanged by lathyrogens might not preclude an effect of the drug upon the eruptive force, assuming that there is a concomitant decrease in the resistance of the periodontal tissues to eruption. The teeth of rabbits in the pair-fed control group showed increased resistance to extrusive loading compared with animals fed ad libitum, indicating that changes in food and water intake may also influence the mechanical properties of the periodontium.