The effect of continuous bite jumping with the Herbst appliance on the masticatory system: a functional analysis of treated Class II malocclusions

Abstract

The effect of continuous bite jumping on the masticatory system was investigated in 20 boys with Class II, Division 1 malocclusion treated with the Herbst appliance for six months. The range of mandibular movement and dysfunction symptoms in the TMJ and associated musculature were examined clinically. Masticatory function was evaluated by a masticatory efficiency test combined with EMG registrations of temporal and masseter muscle activity. Lateral mandibular movement capacity was reduced by an average of 1.9 mm during six months of bite jumping, but increased to the pre-treatment level twelve months after appliance removal. The frequency of joint muscle tenderness increased during the first three months of bite jumping. After six months of treatment most symptoms had subsided. Masticatory efficiency and temporal and masseter muscle activity were markedly reduced during the first three months of bite jumping but increased, on average, to pre-treatment values after six months of treatment. Subjectively, the patients experienced chewing and biting difficulties only during the first 7–10 days of treatment. It was concluded that treatment of Class II malocclusions by continuous bite jumping with the Herbst appliance resulted in minor functional disturbances in the masticatory system. These disturbances were temporary, appearing mainly at the beginning of treatment.