Recording of the retruded position of the mandible in patients with mandibular dysfunction.

The precision (reproducibility) of active and passive recordings of the retruded position of the mandible was studied by two examiners on 10 patients with mandibular dysfunction symptoms. The position of the mandible was recorded with an intra-oral graphic method, before and after treatment of the symptoms. The precision of the recording was highest when the retruded position was recorded by passive hinge movement and lowest when it was recorded by active hinge movement and when recording habitual closure. Both systematical and accidental errors tended to be somewhat larger among these patients than that previously found among individuals without signs or symptoms of mandibular dysfunction. The accidental errors in antero-posterior and medio-lateral directions were the same fo both examiners and of the same magnitude before and after treatment of the symptoms. Both examiners recorded the retruded position on the average 0.20 mm more posterior after treatment than before. The results showed that because of its good reproducibility the retruded position of the mandible can be recommended as a reference position in functional analysis of occlusion and for jaw recordings also in patients with TMJ muscle-pain dysfunction symptoms. During the recording the conventional technique with passive hinge movement and a posterior pressure should be used.