1. Finger or thumb sucking New interpretation and therapeutic inplications.  An. Ferrante1, A. Ferrante3, 1 Myofunctional Therapy Master, I Faculty of Medicine and Sur. “Federico II” University Naples, Pisa University, Italy 2 MD Spec. Physical Medicine and Rehabilitation Institute, DO
Introduction: Sucking habit is a behavior that has not yet found a univocal interpretation. In the past it was referred to as psychological stress or emotional problems. At the moment an accredited theory is the one that associates the sucking habit act as an attempt to settle unbalanced muscular chains (Clauzade, 2004). But, really, nobody knows why the child sucks the finger or thumb. The effects of the sucking habit has been studied above all by orthodontists for the damage it can cause to the development of the upper dental arch (Larsson 1994) and for the palate constriction caused by hyperactivity of the buccinator muscles (Linder 1991) that has been studied by using surface electromyography (EMG) (Ahlgren 1995). The aim of this study is to suggest a new explanation and to investigate the effects of the sucking habit on orofacial and body musculature through surface EMG and on balance and posture through stabilometry and baropodometry and try to explain why the child sucks its thumb. The explanation is based on the finding of many esteroceptors in nasopalatal nerve (Halata, Bauman 1999). Physiologically a correct swallowing action involves the tip of the tongue being placed on the palatal spot and a progressive raising of the body of the tongue towards the palate. The tip of the tongue should always touch the palatal spot even at rest . Sucking the thumb, the child presses the nerve stimulating a neurological response. These receptors are related to a brain nucleus named “Locus Coeruleus”, that is related to the secretion of serotonin, nor-adrenaline, acetilcoline and dopamine. We tested changes during sucking and can affirm that the child sucks its thumb to “feel better”.
Point pressed by thumb coincides with the emergence of nasopalatal nerve
Methods: 40 thumb sucking subjects with ages ranging from 5 to 25 years and a control group of 20 non thumb sucking subjects with correct swallowing patterns were analysed evaluating postural and neurological effects of thumb sucking. All subjects underwent the following tests: swallowing assessment through the Payne Fluorescine method; three closed eyes stabilometric trials (normal condition, with tongue placed on palatine spot – the nasopalatal hole- and during thumb sucking act); static baropodometry under the same conditions of stabilometry trials; surface EMG of anterior temporal, masseter, sterno-cleido-mastoideus, trapezius, paravertebralis and latissimus dorsi muscles under the same conditions as the stabilometric trials.
EMG at rest EMG sucking thumb
Results: Stabilometric results showed no significant changes within conditions in the control group, while sucking habit subjects presented two different behaviors: subjects with no anatomical constrains (short frenum, ankylotic tongue) showed a significant reduction of confidence ellipse and path length during thumb sucking trials, while anatomical constrains showed variable results. Children with less tongue mobility improve only during sucking. EMG shows that muscular values balance and hypertone decreases when tongue or thumb press palatal Spot (where nasopalatal nerve outcrop in the palate).
Green: habitual, Red: sucking thumb
Conclusions: The fundamental element for muscular wellbeing is the regulating action achieved by the stimulation of the trigeminus receptors on the palatal Spot . The results tend to explane the thumb sucking habit no longer in psycological terms, but rather in neurological and neuromuscolar terms. The stimulation of the palatal receptors achieved sucking tumb or finger leads the child with reduced tongue mobility to receive the same neurological benefits that child with correct tongue action is able to achieve simply by constantly raising the tongue to the palatal Spot.