Objective assessment of mandibular motor control using a 'reach-and-hold' task

Mandibular motor function is well known to be impaired in the presence of temporomandibular disorders. However, while a vast literature is available concerning accuracy of motor control in limbs, quantitative and objective assessment of mandibular motor control has been seldom performed, also because of the lack of adequate investigative tools. Aim of this work is to present a technique for reliable evaluation of the motor performance of the mandible based on a kinesiography-monitored reach-and-hold task. Nineteen healthy subjects were engaged in a task in which they had to drive a cursor on a screen by corresponding movements of the mandible in the frontal plane and reach 30 random targets sequentially displayed on the screen. The whole task was repeated three times per session in two different days. The individual performance was assessed by different indices evaluating precision and steadiness of target matching. The performance progressively improved in the three trials of the first session, further improved and stabilised in the second session, with an average positioning error of 0·59 ± 038 mm and was slightly correlated with the horizontal dimension of the mandible border movement (r = 0·55). Intraclass correlation coefficient ranged between 0·76 and 0·94 for the different indices indicating good repeatability. The kinesiographic technique allowed for objective and reliable assessment of the voluntary control of the mandible position. Its potential applications include support to the characterisation of temporomandibular disorders and to motor training and progress monitoring in rehabilitation treatments.