The effect of excision of the root apex on the intrusive mobility of anterior teeth in adult monkeys (Macaca fascicularis).

Intrusive tooth mobility was recorded on anterior teeth in four adult male animals by linear variable-differential transformers. Reflection of the labial mucosa caused a significant increase in mobility at 4 N when the loading rate was slow (1 N s-1) but not when fast (100 N s-1). No significant additional increase in mobility was recorded after the apices were removed from eight incisors and canines. A further study on five incisors was made in which the displacement at 4 N load was noted half hourly during a control period of 5 or 6 h. Some weeks later, the sequence was repeated but the apices were resected after 3 or 4 h. As there was no increase in mobility for the majority of teeth following apicoectomy and, for two teeth studied in detail where there was an increase, that change was short lived; it seems that compression in the fundus of the socket is not a mechanism of importance in supporting the tooth against small intrusive loads.