As the various systems in the body are inter-connected to form a single structural unit, a pathological condition in one area can also affect other areas. In particular, the skeletal muscles play a decisive role in the coincidence of various disorders, because of the continuous anatomical and functional “chain” they form between the skull, lower jaw, spine, limbs and pelvis [1–5].
Indeed, if a situation of muscular high tension arises in one of the links in this chain (mandible, hyoid, vertebrae, pelvis and limbs), it is immediately transmitted to the rest of the body. As a consequence, the body loses its state of equilibrium, giving rise to compensation mechanisms, for example muscular tension in other antagonistic parts of the body. In this way, dental malocclusion can be associated with misalignment of the mandible, one of the links in the muscular chain, leading to hyper-contraction of the masticatory muscles . This tension forces the rest of the body to react, imposing postural modifications brought about by the contraction of other muscles in the chain. In fact, the incidence of malocclusion in orthopedic patients reported in the literature ranges from 83% to 87% . Furthermore, it is now widely recognized that problems involving the stomatognathic apparatus and alterations in feet posture can cause kinetic dysfunction, leading to pathologies in the ascending and descending spinal tracts [7, 8].
Perinetti et al.  investigated malocclusal traits correlated with body posture alterations. A limited number of significant correlations were observed, mainly for overbite, when using multivariate models.
Moreover, it has become increasingly evident that disorders of the sensory nervous system can have a considerable influence on regulation of motor function . In fact, modifications in these sensory neurons can cause parafunctional alterations and pathologies in apparently unrelated body districts, For instance, dental malocclusion can cause pain elsewhere in the body. Because of its position, misalignment of the mandible can also cause the position of the pupillary line to be momentarily altered, provoking the intervention of ocular muscles to keep the gaze straight.
There are many known correlations between the visual and motor systems, and the importance of visual function, particularly the paracentral peripheral field of view, in motor coordination, ambulation and the maintenance of balance has been amply demonstrated . In fact, to follow an object in motion, the eye needs to be able to coordinate the movement of the head and neck. The musculature controlling eye movement is closely connected to the stomatognathic system. Fibers emerging from the muscle spindles and palisade endings in the oculomotor muscles, especially the lateral rectus muscle, form pathways to the oculomotor nuclei and the trigeminal nucleus [11–13]. Ocular defects that can be linked to dental malocclusion are convergence defects, heterophoria, heterotrophia and esodeviations.
This study is based on three presuppositions: 1) a mandibular shift may cause a positional head adaptation ; 2) ocular phorias may cause a head compensation posture called ocular torticollis ; and 3) a head compensation posture causes body adaptation positions, to maintain a center of gravity compatible with the upright position . Head positions enhance postural compensation phenomena; thereby head position is a key point in body balance. This is demonstrated by the great incidence of cervical pain due to muscular tension, which means head posture controls hyperfunctions [16, 17].
In this study, the aim was to determine if these disorders occur with significant frequency in children (aged 7–10 years). We analyzed in primis dental malocclusions (by an orthodontist) and subsequently orthophoria was recorded (by an orthoptist). Then the cranio-sacral respiratory rhythm was tested (by an osteopath). The incidence and concomitant frequency of these disorders were statistically analyzed to understand whether a causal connection existed in situations where patients were forced to carry out functional compensations in different body districts.