Orthodontic-Surgical Treatment: Electromyographic and Electrognatographic Evaluation with Three Electromyographic Instruments

The introduction of electromyography in orthodontics determined the beginning of some studies about neuromuscolar system’s response to physiological and pathological oral alterations and the effect of masticatory muscles on facial morphology.1,2 Experimental studies demonstrated that a real change in muscolar function causes morphology alterations.1 Several studies in literature, from Watt e Williams, who studied in 1951 the effect of masticatory bolus on mouse maxillary and mandibular development, to Avis who in 1961 showed how muscolar function was important for gonial region development, connect morpholgy and function.3,4 In the last years masticatory muscles response to dento-skeletal discrepancies, alterations of breathing, swelling, speech and posture, to functional therapies, implant supported therapy and prosthetic rehabilitation has been studied.5 The definition of occlusion changed in time and it is now not based on mechanics theory but it includes functional aspects.6-10 In literature different positions about the compensatory muscolar aequilibrium in skeletal discrepancies can be found. A correct diagnosis is based not only on clinical and radiographic examination, but it is also important to analyze informations obtaining from neuromuscolar system.2 Knowing muscular action allows to obtain a correct diagnosis, prognosis and treatment planning and helps in avoiding failures.2 Electromyography allows to evaluate neuromuscolar system and equilibrium, mandibular movements alterations and the effects of orthodontic therapy on stomathognatic system.7 Nowadays, different kind of electromyographic instruments are available, each of them constructed following specific protocols and with different aims. It is well known that facial growth is influenced by both genetic and extrinsic factors and that muscle function exercises an important influence both on growth and on craniofacial morphology.11 Orthodontic-surgical treatment was born in order to reposition the skeletal bone basis in a normal position in subjects where their position was not correct.