[[Study of the mandibular changes after treatment of Class Ⅱ division 2 malocclusion in adolescents]]

To evaluate the mandibular and dentoalveolar changes in Class Ⅱ division 2 malocclusion adolescents after treatment.

Thirty-six patients treated in our hospital were selected. Twelve skeletal Class Ⅱ division 2 adolescents were served as the experimental group, while 12 skeletal Class Ⅱ division 2 adults were selected as the control group 1, 12 skeletal Class Ⅰ adolescents were selected from those who have undergone fixed orthodontic treatment as the control group 2. Cone-beam CT (CBCT) was taken before and after treatment. The lateral cephalometric radiographs generated from CBCT data were committed to explore the changes of the mandible and dentoalveolar bone before and after orthodontic treatment among three groups. Statistic analysis was completed by SPSS 21.0 software package.

After orthodontic treatment, the mandibular length (Go-Gn), mandibular ramus height (Co-Go), mandibular protrusion (SNB), mandibular dentoalveolus protrusion (SNId), lower facial height (S-Go, ANS-Me, ANS-Me/N-Me) increased and the fossa of chin decreased significantly in Class Ⅱ division 2 adolescents (P<0.05). The differences of SNB, SNId, ANS-Me/N-Me between Class Ⅱ division 2 and Class Ⅰ adolescents decreased.

The growth potential of the mandible is released after treatment of Class Ⅱ division 2 malocclusion adolescents, promoting mandibular growth and reconstruction.