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Effect of head position on vertical mandibular opening.
E J Higbie1, D Seidel-Cobb, L F Taylor
1Department of Physical Therapy, Georgia State University, Atlanta, USA. bhigbie@gsu.edu
Summary
Forward head posture significantly increases mandibular opening compared to neutral or retracted positions. This finding highlights the importance of head position in assessing vertical mandibular opening in healthy adults.
Area of Science:
- Biomechanics of the craniofacial complex.
- Temporomandibular joint (TMJ) function and kinematics.
Background:
- Head and neck position can influence temporomandibular joint function.
- Lack of standardized head positioning for mandibular opening measurements.
Purpose of the Study:
- To investigate differences in mandibular vertical opening across three head positions.
- To establish the impact of head posture on a key measure of jaw mobility.
Main Methods:
- Within-subjects repeated measures design with 40 healthy adults (20 male, 20 female).
- Measurements of vertical mandibular opening (VMO) using a millimeter ruler in forward, neutral, and retracted head positions.
- Reliability assessed via interclass correlation coefficients (ICCs).
Main Results:
- VMO was significantly greater in the forward head position (44 ± 5.3 mm) compared to neutral (41.5 ± 4.8 mm) and retracted (36.2 ± 4.5 mm) positions.
- VMO in the neutral position was significantly greater than in the retracted position.
- High reliability (ICCs 0.90–0.97) for measurements across all head positions.
Conclusions:
- Head position is a critical determinant of vertical mandibular opening in healthy adults.
- Standardized head positioning is essential for accurate and reproducible VMO assessments.