Most of the dento-skeletal problems found in patients during their growth is boosted by a multifactorial cause (etiology): inheritance, hembrional developing defects, traumas and functional influences.
Some anomalies of behaviour, the so called defective attitudes, create non harmonic pressures on oro-facial muscles, causing the uprising of occlusal problems.
Form and function are strictly entwined between them and are reciprocally conditioned: inso much as a correct function determines a harmonic mouth development, just the like and altered function may deform the dental arches and the maxillary bones.
Let's now analyze these defective attitudes.
The pacifier suction can be considered to be used within the first 24 months of life, so as not to give way to a molocclusion.
Much more problematic is the sucking of the thumb, that, if prolonged over the 4th year, may cause occlusal problems like open bite and atypical deglution.
The finger also presses on the palatine vault, pushing the upper incisives forward. the compression of the perioral muscles, causes a reduction of cross diameters and narrow dental arches.
The oral breathing: this is a pathological situation in which the air passage happens mainly through the mouth and this stimulates neuro muscular alterations with consequences on the cranio-facial shape.
Lips are called incompetent (they don't lock properly) there may be vestibolirized incisives, atypical deglutition with narrow upper jaw.
Also the atypical deglutition can be considered a defective attitude; the tongue's thrust is directed forward and not upwards, and this determines the lack of contact between dental arches, the upper incisives pushed forward, the ogival palate and the lower narrow arch.