A cephalometric evaluation of high-pull molar headgear and face-bow neck strap therapy.
The effects of two different extraoral appliances were evaluated over a 1-year period. Of the thirty-seven cases selected for study, twenty were treated with a face-bow neck strap and seventeen were treated with a high-pull molar headgear. Patients ranged in age from 10.10 to 16.6 years and averaged 13.4 years. The appliances exerted less than 600 Gm. of force per side and were worn for 12 to 16 hours per day. All cases were fully banded, and extraction and nonextraction treatment were included. An analysis of pretreatment data revealed a high degree of selection. Patients selected for high-pull treatment generally exhibited larger anterior face heights, steeper mandibular plane angles, and a greater amount of tooth eruption of the upper first molars than the patients selected for neck strap therapy. A control group of ten untreated subjects was matched to each treatment group to permit assessment of the impact of treatment on growth. Relative to normal growth, treatment with face-bow neck strap traction tended to direct the maxilla and mandible downward and backward. The palatal plane was lowered anteriorly and point A was retracted. The maxillary molars were extruded, and concomitantly an increase in anterior face height and mandibular plane angle was observed. On the other hand, the high-pull molar headgear traction resulted only in increased mandibular molar eruption. However, there was also a nonsignificant tendency for point A to be held back and for lower anterior face height to increase. The comparison of the two treatment samples revealed that the functional occlusal plane was tipped down at the back as the maxillary molars were more extruded in the neck strap sample. In the high-pull sample, the functional occlusal plane was unchanged and the mandibular molars were more extruded than they were in the neck strap group.
D000293:Adolescent; D002508:Cephalometry; D002648:Child; D003818:Dentition, Mixed; D005115:Extraoral Traction Appliances; D005145:Face / Q000033:anatomy & histology; D005260:Female; D006801:Humans; D008297:Male; D008310:Malocclusion / Q000628:therapy; D008334:Mandible / Q000033:anatomy & histology; D008445:Maxillofacial Development; D008963:Molar / Q000033:anatomy & histology; D009968:Orthodontic Appliances, Removable; D012690:Serial Extraction; D013314:Stress, Mechanical; D014087:Tooth Movement Techniques