Extrusive mobility of teeth in adult monkeys (Macaca fascicularis).
Extrusive mobility of 15 teeth in 4 adult macaques was compared with intrusive mobility of the same teeth. The character of the load displacement and recovery records was similar; the qualitative response to repeated 4 N thrusts, 4 N loads sustained for 30 s and residual loading with 50, 30 and 10 mN, was the same whether the force was applied in an intrusive or extrusive direction. Fast and slow loading rates (100 and 1 Ns-1) both caused greater intrusion than extrusion at 4 N (p less than 0.001). Thus the mechanisms of tooth support are similar for intrusive and extrusive force. The oblique orientation of the principal fibres of the ligament may allow a greater degree of initial intrusive movement, before tension is generated, than occurs in axially-aligned fibres under extrusive force. Extrusive loading may be a convenient method for studying tension in the periodontal ligament.
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D000818:Animals; D001641:Bicuspid; D001696:Biomechanical Phenomena; D007180:Incisor; D008252:Macaca fascicularis; D008297:Male; D008963:Molar; D013997:Time Factors; D014086:Tooth Mobility