## 4 Discussion
However, it was statistically significant between the OPT-SN and ANB angles only. A possible explanation of this statistical relationship is as follows: in the presence of increased OPT-SN angle, SNA angle is increased and SNB angle is decreased, which leads to an increase in ANB angle. These changes summarise that Class II individuals have the highest value of the craniocerical angle [28]. Two studies evaluated the position of the mandible, forward head posture, and breathing pattern [26; 29]. Evaluating cervical spine inclination, [PERSON] et al. [26] measured OPT-SN, CVT-SN, VER-SN (angle between vertical and SN line), and VER-FH (angle between vertical and Frankfort Horizontal plane) angles for head position and CVT-HOR and OPT-HOR angles for cervical spine curvature evaluation. It was found that OPT-SN and CVT-SN angles were lower in mouth breathers, VER-SN angle was significantly higher in mouth-breathers than in nose-breathers, and VER-FH angle was significantly lower in mouth-breathers than in nose-breathers. The values of CVT-HOR and OPT-HOR angles were higher for mouth-breathers than for nose-breathers. The authors of this study concluded that hyperextension of the head and increased concavity of the cervical spine are bigger in mouth breathers. [PERSON] et al. [29] concluded that nose and mouth-breathers presented high percentages of craniofacial hyperextension. All in all, OPT-SN and CVT-SN angles were high in both study groups, showing a relationship between mandibular retrusion and forward head posture [26; 29]. This outcome supports previous findings by [PERSON] et al. [34]. Such craniocerical posture alteration, in other words, FHP, is a compensatory reaction to open up the airways that were blocked due to allergies, adenoid hypertrophy, or nose septum deviations. On the other hand, this cervical spine misalignment can be not a response, but a cause of respiratory function impairment [35; 36; 37]. In general, poor muscle tone at any part of the body can cause postural alterations in the craniocortical posture and mandible position which are sites of attachment for myofascal chains [8; 38]. Therefore, a good body posture is important in the prevention methods of malocclusions, especially in growing patients. Moreover, a proper oral posture, and correct tongue resting position, maintain the normal function of maxillofacial muscles and the normal growth and development of them. In our paper, we summarized the evidence of the position that the mandible takes in the anterior-posterior direction considering different craniocortical postures in the same plane. According to the included studies, increased neck flexion and head extension are associated with distal mandible position. These findings could be considered a reflection of poor public health in terms of the relationship between the high prevalence of malocclusion and low muscle tone [3; 4]. The latter induces FHP that is associated with lower mandible and tongue position, which leads to crooked teeth due to a lack of support from the palatal side [15]. More importantly, this condition compromises airways and can cause obstructive sleep apnea that afflicts at least one in twenty people [39], whereas malocclusion affects one out of two individuals worldwide [40; 41]. Therefore, efforts should be put in toreducing environmental factors such as bad posture. Limitations of this review are a wide age range of participants, experimental heterogeneity, and the relatively low number of included studies. Also, one of the methodological weaknesses of some studies was a standardized fixation of the head, which prevented the assessment of natural head and neck position. Considering these limitations, more clinical trials with enhanced methodology are needed. It is very important that specialists such as dentists, pediatricians, family doctors, otolaryngologists, and physiotherapists would work as a team to prevent or correct poor body posture in adults and, even more significantly, in growing patients.