Functional Tongue Posture Variations between Norm-Occlusion and Angle Class II and III Malocclusion Subjects

Objectives: To assess the relationship of tongue posture and malocclusion by comparing intraoral pressures at the subpalatal compartment and vestibular space in subjects with either norm-occlusion, or Angle Class II and III malocclusion.

Methods: Intra-oral pressures of sixty consecutive undergraduate students (mean age: 21.6 ± 1.6 years; min/max: 18/25 years; groups size: n=20 Norm-Occlusion, n=20 Angle Class II and n=20 Angle Class III) were measured by a digital pressure gauge connected to the subpalatal space and vestibular space by a canula. Five biofunctional phases with different tongue positions were performed by each subject. Descriptive statistics and Mann-Whitney U-Test for independent samples were applied to assess malocclusion-related variations in intraoral pressures, adopting a significance level of p<0.05.

Results: During Swallowing, norm-occlusion subjects reached peaks of up to -99.1mbar negative pressure (median -53.1 ± 23.57) for, compared to -102.9mbar (median -50.89 ± 20.9) in Angle Class II subjects, or -78mbar (median -53.49 ± 17.26) in Angle Class III subjects. During inspiration, variation in sub-palatal pressure ranged from -20.20mbar in Angle-Class II to -40.40mbar in Angle-Class III subjects. During phases of tongue-palate contact, no significant variation in subpalatal pressures were detected between the normocclusion and malocclusion groups. No group-specific variations were recorded for intraoral pressures under open and semi-open mouth conditions.

Conclusions: Generation of negative sub-palatal pressure seems to be an essential part of the initiation of the act of deglutition, regardless of the quality of occlusion.