The effect of applied force on two-point discrimination threshold in the trigeminal region

Aims: To determine the effect of alterations in applied force on the two-point discrimination (TPD) threshold and to evaluate whether these effects were gender- or site-dependent. Methods: A total of 62 healthy adults were enrolled in the study and divided into two groups based on gender (men and women, n = 31 each). The TPD test was performed using a modified compass on the forehead, upper labium, and lower labium, and each site was tested with Semmes-Weinstein monofilaments (SWMs) of sizes 4.56, 5.07, and 5.46 that exerted bending forces of 6, 10, and 26 g, respectively. The differences in thresholds according to alterations in the applied forces were evaluated for different genders and sites. Results: Both gender groups showed a significant decrease in TPD thresholds with the 5.46-size monofilament than with the 4.56- or 5.07-size monofilaments. This decrease was more apparent on the forehead regardless of gender. Conclusion: These findings suggest that increased intensity of mechanical stimuli could increase tactile acuity as measured by the TPD test.