Bone scintigraphy results were compared with changes shown on orthopantomographic radiographs in a patient with facial asymmetry, before, during, and after Herbst treatment, and followed up with control of growth activity in the temporomandibular joints (TMJs) after long-term retention. The present study showed that new bone formation (modelling) was initiated asymmetrically in TMJs during treatment. The results indicate that late development of right/left asymmetry in the occlusion can be

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... cted and normalized using the Herbst appliance therapy, stimulating a differentiated 'catch up' growth (modelling) in the TMJ with condyles. After treatment, original growth with asymmetric activity in the TMJ was re-established. This growth activity may re-establish the asymmetry in the sagittal occlusion and the face of the patient. It is therefore recommended that the occlusion should be maintained with an appliance which stabilizes the occlusion until cessation of the primary, endochondral growth.