Open bite and cervical column: is there a relationship?

Abstract

Introduction: Cervical column is one of the elements of the craniofacial system, which contains three major structures: occipito-atlanto-axial joint, temporomandibular joint and hyoid bone. These structures communicate with vertebral column across muscles and ligaments. According to several studies, cranio-cervical morphology depends on many factors, including age [1], malocclusion, and gender [2]. Changes in cervical column morphology may be present in individuals with normal craniofacial morphology [3].

Materials and methods: This study evaluated 1162 profile radiographs of individuals that attended the orthodontist at the Clínica Dentária Egas Moniz, between November and December 2017. The following inclusion criteria were applied: individuals without prior orthodontic treatment, age between 8 and 18 years-old; profile radiographs with C1-C4 perceptible, overbite less than 3 mm (Group 1) and overbite between 3–5 mm (Group 2), selecting 335 individuals. After that, we proceeded to the cephalometric analysis, with Solow and Tallgren analysis [4]. A request was submitted to the Ethics Committee of Instituto Universitário Egas Moniz and the research was approved with procedure nº 593.

Results: In the correlation between age and postural variables, in open bite individuals, there was a significant correlation between age and the variables A-N-Pog, Overbite, Mx-VER, OPT-HOR, and CVT-HOR. When evaluated the influence of overbite on gender, it was verified that female was significative differences in the variables Mx-Md, SN-VER, Mx-VER, SN-OPT, Mx-OPT, SN-CVT, Mx-CVT, OPT-HOR. When evaluated the influence of gender on overbite, it was verified that group 1 had significant differences between male and female in the variables SN-Mx, SN-VER, SN-OPT, Mx-OPT, SN-CVT, Mx-CVT, OPT-HOR, CVT-HOR.

Discussion and conclusions: Analyzing the results, as age increase, mandible adopts a more posterior position and promotes a class II pattern, mandible rotation and more cervical vertebral inclination, leading to head extension and cervical lordosis less pronounced. These results suggest that when age increases C2 and C4 tend to be more inclined, not affecting the other values. Thus, cervical vertebral inclination may be consequence of growth and development of individuals, which adopts a more inclined position, and this accentuates cervical inclination may be due to the time that the individual presents the pathology. When evaluating the individuals without open bite, we verify that female present more inclination of C4, and C2 presents similar values in both genders. In this reasoning, C4 inclination may be due to lack of muscular tissue in the neck, and the C2 inclination maintained may be due to atlanto-occipital joint which has more broad movements and functions, and changes provoked by external factors affect C2. If we analyze open bite group, female persists with C4 and C2 more inclined, suggesting that overbite influence C2 too. Thus, in individuals of feminine gender, the presence of open bite causes more inclination of C2 and female present tendentially more C4 inclination, but when an open bite is present, it affects more C2 than C4.