Craniocervical posture and trigeminal nerve mechanosensitivity in subjects with a history of orthodontic use: a cross-sectional study.

The purpose of the study was to evaluate whether, in asymptomatic subjects, there are differences in: (i) head posture while sitting and standing still and (ii) trigeminal nerve mechanosensitivity, between those who have a history of using orthodontics and those who do not. The sample consisted of 72 subjects (21 +/- 2.14 years): one group who had used orthodontics in the past (n = 37), and another group who had not had previous orthodontic treatment (n = 35). The authors measured the CranioVertebral Angle (CVA) while the subject was sitting and standing still by means of lateral photographs, and the pressure pain threshold (PPT) of the trigeminal nerve. The orthodontics group showed a more upright position of the head when sitting compared to the non-orthodontics group, with the difference being statistically significant (ANOVA test; p < 0.001; F1,70 = 16.705; R2 = 0.19), but not for the standing position (p = 0.538). The values of the PPT in the trigeminal nerve (supraorbital-V1, infraorbital-V2 and mandibular-V3) were lower on both sides (dominant and nondominant) in the non-orthodontics group. The between-group comparison (ANOVA test) showed statistically significant differences for the trigeminal nerve PPT in its different branches (V1 p = 0.001; F1,70 = 13.012; R2 = 0.15) (V2 p = 0.004; F1,70 = 9.103; R2 = 0.11) (V3 p = 0.005; F1,70 = 8.228; R2 = 0.10). Based on these observations, it was concluded that subjects with a history of orthodontic use show a better sitting craniocervical posture and mechano-sensitivity of the trigeminal nerve branches compared to the group that had not used orthodontics in the past.