HYPEREXTENSION OF THE HEAD VERSUS CERVICAL VERTEBRAE MORPHOLOGY IN MOUTH AND NASAL BREATHERS: A PRELIMINARY STUDY

Abstract

Objective: This study aimed to compare through cone-beam computed tomography (CBCT) the morphology of the cervical vertebrae atlas (C1) and axis (C2) in mouth breathers (MB) and nose breathers (NB), correlating them with the head and neck postures of the two groups. Materials and Methods: CBCT images
of 36 subjects aged 11 to 22 years were evaluated using the InVivo Dental 5.1 (Anatomage, San Jose, California) software. The following measurements were used to assess C1 and C2 morphology: posterior height, anterior height, length, and volume. The craniocervical angle (NSL/OPT) was used to evaluate head
posture concerning the neck. Results: The posterior height, length, and volume of C1 and C2 were lower in the MB group, but only the posterior size was significantly shorter than the NB group (C1, p=0.01 / C2,  =0.05). Mouth breathers also showed a considerably higher craniocervical angle (p=0.04). Spearman test showed a
significant positive correlation between C1 and C2 length and craniocervical angle (C1, =0.629, p=0.005 / C2, =0.665, p=0.003). Conclusion: The mouth breathers showed an increased craniocervical angle and decreased posterior height of the C1 vertebra concerning nasal breathers. The hyperextension of the head present is positively correlated with the length of the vertebra.