It has been known for 70 years already that the head posture effects mandibular posture and occlusion, as well as vice versa. B tooth contacts, which are called stabilizing tooth contacts, have the most important role in stabilization of occlusion and jaw muscles hold the mandible exactly under this position. This is why inadequate iatrogenic changes of B contacts can cause postural changes of the mandible, head and body. Fixation of B contacts more posterior causes a shift of the habitual mandibular position backwards and constricts the airway. The spine compensates for the mandibular shift and opens up the airway. This compensatory mechanism brings about postural changes. The head is moved forward causing a progressive loss of cervical lordosis, shoulder blade inclination and an increase in thoracic kyphosis. Numerous clinical investigations are carried out in order to reexamine and prove the mentioned claims. Although the most of the investigations approve them, some of them refute them. However, it should be considered that by exceeding the organism’s structural tolerance, it comes to pathological changes of the whole stomatognatic system and postural mechanism. Therefore, it is necessary to adjust occlusion in a physiologically optimal position, and this is the upright body and head position.