Brendan J. J. Scott

Laser scanning of the ear identifying the shape and position in subjects with normal facial symmetry.

The objective of the present study was to discover if dimensional measurements of the ear could be determined with a laser scanning technique and whether or not the location of landmarks of the ear could be reliably measured with respect to those on the midline of the face. Computer-generated images were created from laser scans of 20 subjects. Dimensional measurements were made between landmarks on the ear and face. Differences between repeated dimensional measurements of the ear were very small, as were those measurements made between landmarks on the ear to the midline of the face. Differences between dimensions of the left and right ears were observed, but were of a small magnitude. The results suggest that the dimensions of the ear and its position with respect to landmarks in the midline of the face can be reliably measured on normal subjects and that laser scanning is a useful technique for planning and monitoring facial reconstruction of the ear.

Remote noxious stimuli modulate jaw reflexes evoked by activation of periodontal ligament mechanoreceptors in man

The purpose of the study was to investigate whether jaw reflexes evoked by selective stimulation of periodontal ligament mechanoreceptors are susceptible to modulation by remote noxious stimulation. Experiments were performed on 10 volunteer subjects. Skin surface recordings were made from the jaw‐closing masseter muscle. The subjects activated the muscle to approximately 10% of maximum by biting on a rubber impression of their molar teeth while they received visual feedback of the electromyogram (EMG) of the muscle. Reflexes were produced by the application of gentle mechanical stimuli to an upper central incisor tooth. The stimuli were in the form of ‘ramp and hold’ forces with a 5 ms rise‐time and a 1.5 N plateau which lasted 350 ms. The resulting reflexes were recorded both under control conditions and while the subjects received a remote noxious stimulus (immersion of a hand in water at 3 °C). In all 10 subjects, the stimuli produced a single period of inhibition of masseteric activity (latency, 12.8 ± 0.4 ms; duration, 18.1 ± 1.3 ms; means ± S.E.M.), which was usually followed by a period of increased masseteric activity. The period of inhibition constituted a downward wave in full‐wave rectified, averaged signals. The integrals of such waves were significantly smaller (by 17 ± 6.5%; P = 0.027; Students t test) when the reflex was evoked during remote noxious stimulation rather than under control conditions. As such reflexes are believed to play a modulatory role during normal oral function, this finding may be relevant to disorders of mastication associated with pain.