Jaw-neck movement integration in 6-year-old children differs from that of adults

Abstract

Background: A functional integration between the jaw and neck regions during purposive jaw movements is well described in adults, but there is a lack of knowledge of such integration during jaw function in children. Objectives: To determine the movement integration between the jaw and neck during jaw motor tasks in 6-year-olds, whether there is a difference between children and adults. Methods: Jaw and neck movements were recorded with an optoelectronic 3D system in 25 healthy 6-year-olds (12 girls, 13 boys) and 24 healthy adults (12 women, 12 men) during paced jaw opening-closing and self-paced gum chewing. Jaw and neck movement amplitudes, intra-individual variation in movement amplitude, ratio between neck-jaw movement amplitudes and movement cycle time were analysed. Differences between children and adults were evaluated with Mann-Whitney U test for independent samples. Results: Compared to adults, 6-year-old children showed larger neck movement amplitudes (P =.008) during chewing, higher intra-individual variability in amplitudes of jaw (P =.008) and neck (P =.001) movements, higher ratio between neck-jaw movement amplitudes for jaw opening-closing (P =.026) and chewing (P =.003), and longer jaw movement cycle time (P ≤.0001) during the jaw opening-closing task. Conclusion: Despite integrated jaw-neck movements in 6-year-old children, the movement pattern differs from that of adults and may be interpreted as an immature programming of jaw-neck motor behaviour. The well-integrated movements observed in adults most likely develop over years, perhaps into adolescence, and needs further research including well-controlled longitudinal studies to map this development in order to provide appropriate age-related clinical treatment for functional disorders.