Differences between sexes in maximum jaw opening when corrected to body size

Area of Science:

• Anatomy
• Biomechanics
• Physiology

Background:

• Linear measurements suggest men have greater maximum jaw opening than women.
• Epidemiological data indicate women generally possess increased joint mobility and laxity.
• Existing research presents conflicting findings on sex-based differences in jaw opening.

Purpose of the Study:

• To investigate sex differences in maximum jaw opening using both linear and geometric methods.
• To determine if body size adjustments influence the observed sex differences in jaw opening.
• To clarify the relationship between joint laxity and jaw opening range in different sexes.

Main Methods:

• Linear interincisal measurements were taken to assess maximum jaw opening.
• Covariate analysis adjusted for body size parameters to compare sex differences.
• Geometric estimation of the jaw opening angle was employed as a secondary method.
• Statistical analysis, including P-value calculation, was used to determine significance.

Main Results:

• Linear measurements indicated a 2.7% smaller maximum jaw opening in women compared to men.
• Covariate analysis adjusting for body size reduced the difference between sexes.
• Geometric estimation revealed a 5.4% wider jaw opening range in women (P < 0.057).
• The geometric method showed less correlation with body size factors.

Conclusions:

• Geometric assessment suggests women have a wider range of jaw opening than men.
• Adjusting for body size equalizes linear measurements of jaw opening between sexes.
• Increased jaw opening range reflects hyperextensibility, not necessarily joint laxity or instability.