Effects of chincap force on the timing and amount of mandibular growth associated with anterior reversed occlusion (Class III malocclusion) during puberty.

The effects of chincap force on the amount and timing of mandibular growth associated with anterior reversed occlusion (Class III malocclusion) were studied during the pubertal period in 26 Japanese girls. Their records consisted of serial lateral cephalometric roentgenograms, wrist-hand roentgenograms, periodic data of standing height, and time records of chincap use. The stage of pubertal growth was first evaluated by the change of ossification events of hand bones and incremental change of standing height. Mandibular measurements were assessed on this maturational basis. The findings indicated that application of chincap force (500 to 600 g, average 11 to 12 hours per day) hardly alters the general pattern of mandibular growth timing at puberty. With regard to inhibition of growth amounts, the effects seem to take place independently in different parts of the mandible. The length of time of force application per day in the range from 6 to 15 hours did not have a significant role in the change of growth amount and/or timing in the clinical use of the chincap. Individual reactions to the chincap force varied in the effects on mandibular growth variables. Further study of the effects of retrusive orthopedic force on the mandible during the rapid growth phase of puberty is indicated.