Effect of apical microsurgery on force regulation of incisor teeth during unpredictable force control task.

[BACKGROUND] Apical microsurgery (AMS) involves removal of the root-end which can affect the force regulation of teeth.

[OBJECTIVE] To investigate the force regulation of incisor teeth treated with AMS during the unpredictable force control task in comparison with their contralateral teeth with complete root apices, in humans.

[METHODS] Fifteen eligible participants (8 women and 7 men; mean age 52.9 ± SD 4.4 years) performed a standardised unpredictable force control task, which involved pulling and holding a force transducer with AMS-treated incisors and their contralateral control teeth (n = 30 teeth). A series of four load masses: 100, 200, 50 and 300 gm were attached to the force transducer through a string in an unpredictable manner. The obtained force profile was divided into initial and later time-segments. The peak force and peak force rate during the initial time-segment, and the holding force and coefficient of variability during the later time-segments were calculated and compared by the repeated measures analysis of variance.

[RESULTS] During the initial time-segment, the peak force and peak force rate were significantly lower in the AMS-treated teeth than in the controls (p = .001, p = .013, respectively). However, during the later time-segment, no significant differences in the holding force nor the coefficient of variability were observed between the AMS-treated teeth and their controls (p = .755, p = .213, respectively).

[CONCLUSION] In contrast to incisors with complete normal root apices, AMS-treated incisors do not show robust changes in force regulation.