Abstract
Objectives: The aims of this study were to investigate (1) the jaw-opening forces in different stages of jaw-opening, and determine the correlation among maximum jaw-opening force, maximum jaw-opening, and parameters such as age, height, weight, and gender, (2) the energy expenditure during jaw-opening, and (3) the jaw-opening patterns in adults.
Design: This was a cross-sectional study. The sample consisted of 87 participants were recruited from Dunedin, New Zealand. Jaw-opening forces were measured using an adjustable, rigid extra-oral device connected to a 1000 N load cell.
Main results: Outcomes were highly skewed. The median (IQR) value of maximum jaw-opening was 48 mm (8 mm). The median of maximum jaw-opening force (40.0 N) was higher than jaw-opening force at maximum jaw-opening (35.2 N) (P < 0.01). The median (IQR) of the work was 1.30 J (1.28 J), ranging from 0.38 J to 4.03 J. The median of maximum jaw-opening force and work was higher in males (54.8 N; 1.22 J) than females (33.5 N; 0.74 J) (P < 0.05). Four jaw-opening force patterns (Pattern 1, 2, 3 and 4) were fitted and generated using Origin Pro software.
Conclusion: A wide range of variation in jaw-opening force and work was observed, and they displayed a non-parametric, highly skewed distributions. The maximum jaw-opening force did not correspond to the maximum jaw-opening. Further studies could explore the potential association among the jaw-opening force pattern, the work of jaw-opening and TMJ diseases.