Effects oftherapeutic exercise on masticatory function inpatients withprogressive muscular dystrophy

SUMMARY Theslope ofthecurverelating integrated electromyographic activity ofmasseter muscle tobiting force, thelatency ofthejaw-jerk reflex, andmasticatory performance were estimated in patients withDuchenne typeofprogressive muscular dystrophy before andduring therapeutic exercise ofthesomatognathic system. Theslope andlatency wereslightly decreased, andmasticatory performance was increased during exercise. Theseresults suggest thattherapeutic exercise ofthe stomatognathic systemiseffective inimproving masticatory function inpatients withprogressive muscular dystrophy. Previous electromyographic study' analysing masticatory function inpatients withtheDuchenne typeof progressive muscular dystrophy (PMD)hasshown thattheslopeofthecurverelating integrated electromyographic activity ofthemasseter muscles tobiting force during rapid isometric contraction ofthejaw(slope ofthevoltage/tension curve) was steeper inpatients withmuscular dystrophy than inhealthy subjects. Itwasalsoshownthatthe latency ofthejaw-jerk reflex waslonger andthe masticatory performance was considerably less inmuscular dystrophy thanina healthy subject. However, there werenodifferences between those withandwithout anopen-bite, whichischaracteristicofDuchennetypeofmuscular dystrophy, for allofthetests. Fromthese findings, theauthors suggested that themasticatory disturbance inpatients withmuscular dystrophy isduemoretoneuromuscular disturbances inthemasticatory system rather thantomalocclusion suchasanopen-bite. Itwastherefore considered thatthemasticatory disturbance inmuscular dystrophy couldnotbe improved bysimply increasing thecontact points between upperandlower teeth. Therapeutic exercise hasbeenrecommended for