• The korean journal of orthodontics
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• v.30 no.1 s.78
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• pp.33-41
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• 2000

Although it is well known that the chincup, used to correct a skeletal class III malocclusion in growing children, reduce the mandibular prognathism by arresting the growth of the mandibular length and rotating the mandible posteroinferiorly, the majority of the studies about chincup is focused on condylar head that plays an Important role in mandibular growth. The aim of this study was to evaluate the morphologic change of the mandibular symphysis where extraoral force is applied directly during chincup treatment. The data lot this study were obtained from lateral cephalometric radiographs of 62 growing children(chincup group:32, control group:30) with mixed dentition who had been accepted lot the orthodontic treatment at Chonbuk National University Dental Hospital. The results were as follows : 1. Symphysis height was increased both in chincup therapy group and control group during treatment. Symphysis depth was decreased or maintained the initial values in chin cup therapy group, whereas increased in control group. Posterior symphysis depth was decreased both in chin cup therapy group and control group, but anterior svmphysis detph was increased in control group, whereas decreased in chincup therapy group. 2. Chin depth and chin curvature were increased in control group, whereas maintained or decreased in chincup therapy group during treatment. Chin angle, menton ang1e and symphysis angle were decreased in control group, whereas increased in chincup therapy group. It suggested that bone deposition in pogonion area that occur normally with mandibular growth was supressed by direct contact of chincup. 3. When growing children wear chincup, symphysis morphology was maintained due to inhibition of forward growth at mandibular symphysis. It may be due to the suppression of bone deposition in anterior part of symphysis.

• The korean journal of orthodontics
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• v.28 no.4 s.69
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• pp.517-531
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• 1998

The purpose of this study was to investigate the changes in the craniofacial skeleton subsequent to chincap therapy in the juvenile skeletal Class III malocclusion with more appropriate control samples. The experimental group consisted of 29 Korean children(14 males, 15 females) who had skeletal Class III malocclusion with prognathic mandible and were undergone chincap thorny from the beginning of treatment. The control group was composed of 21 Korean children(10 males, 11 females) who had no orthodontic treatment, but with similar skeletal discrepancies to experimental group. Lateral cephalometric radiographs at the age of 7, and 2 years later were analyized and compared with student's t-test(p<0.05). The results of this study were as follows; 1. The control group without chincap therapy had not shown any improvement of the skeletal discrepancies, but had grown to be much severe. This means that the untreated Class III patient with prognathic mandible would not be corrected by growth. For the experimental group with chincap therapy, the anterior-posterior skeletal discrepancies and mandibular prognathism were both improved. 2. Neither significant restraint nor acceleration of growth was found in the cranial base and maxilla by chincap treatment. 3. The inhibition of mandibular growth could not be accepted, but the changes of the direction of growth and morphological changes were found. 4. Vertical growth tendency was increased with chincap therapy. 5. When Putting together the results of the analyses , it seems to be the rotation and displacement of the mandible that the major treatment effects of chincap we. The changes of the direction of growth and the morphological changes also seems to contibute to the treatment effect partly. In summary, the chincap doesn't restrain the mandibular growth. But, it is considered as a useful treatment modality for correction of skeletal discrepancies and reduction of mandibular prognathism in growing Class III patients with madibular prognathism.