[Individual growth study of the effects of chin cap force to the mandible].

This study was undertaken to investigate a certain regulation of the chin cap force to a growing human mandible, especially with regard to the effect on the growth amount and timing by means of allometric relation between stature and craniofacial complex. Materials were consisted of roentgencephalograms which had been taken from fifteen Japanese females with skeletal class III malocclusion and records of time length of chin cap use and stature. The results were as follows: 1. Chin cap had a great influence on mandible during the preadolescent and adolescent periods (P less than 0.01). 2. What was most influenced by orthopedic force was intercondylar width, followed by mandibular length, intergonial width, mandibular body length, and ramus height. 3. Restraint of growth was found in mandibular length, mandibular body length, and ramus height, but on the other hand acceleration of growth in intercondylar width and intergonial width was also found. In conclusion, it would be possible to say that if it is used propertly, chin cap therapy can be effective within certain limits for skeletal class III malocclusions in view of restraint and acceleration of mandibular growth.