Cephlometric Analysis Of Class Ⅱ～1 Malocclusion With Different Vertical Type In Adolescences

Angle class II1 malocclusion is one of the most common malocclusion in orthodontic clinic.Scholars make a lot of study about the formative mechanism of Angle class II1 malocclusion. They consider that its mechanism is complex and it has many clinical appearances.The general diagnosis of malocclusion is angle claaification.The orthodontists often recognize the anteroposterior malocclusion but ignore the incongruity of the vertical direction.In recent years,we gradually realize that the significance of the vertical face type in the diagnosis and treatment of malocclusion,and it effect the success of the treatment.This study choose 60 normal occlusion,42 II1 malocclusion of high-angle group and 48 II1 malocclusion of low-angle group.All of them are in early permanent teeth period.We make cephalometry of the lateral projection by computer and analysis the measured value between the normal occlusion and the Angle class II1 malocclusion in different vertical skeletal and face type.Then we review the characteristics and vertical incongruity of Angle class II1 malocclusion in different vertical skeletal and face type,we get some conclusions as below:①II1 malocclusion of high-angle group: The angle of SN-FH,FMS-SE-PM(CF-PM)and BA-SE-FMS increase,but the effective growth height of vertical direction decreases.II1 malocclusion of low-angle group: The angle of N-S-Ar,Ba-SE-PM,FMS-SE-PM(CF-PM),Ba-SE-FMS increase。②II1 malocclusion of high-angle group:Both of SNA and SNB are smaller than that of the normal occlusion group,but ANB is larger than normal occlusion group's.The length of the mandibular basal bone (Go-Po)and the height of mandible ramus (Ar-Go) are decrease significantly.The protrution of the chin(Po-NB) is diminished. The angle of MP-SN,MP-FH,OP-FH and PP-FH are all increasing.II1 malocclusion of low-angle group:SNA and SNB are normal,ANB increase a little.The height of mandible ramus(Ar-Go) are larger than that of the normal occlusion. The protrution of the chin(Po-NB) increases obviously. But the change of MP-SN,MP-FH are opposite.③Most of the patients of II1 malocclusion have the same symptom:The upper anterior teeth are protruded,the lower anterior teeth are erect.L1-NB(mm) are a little smaller in high-angle group but opposite in low-angle group.L6-SN decrease gradually from the low-angle group to normal group then to high-angle group of II1 malocclusion. U6-OP and U6-SN of high-angle group are larger than that of the normal group.The height of supramaxillary dental alveolus U6-PP(mm) of the two groups are smaller than that of the normal group. The height of mandibular dental alveolus L6-MP(mm) increase gradually from the high-angle group to normal group then to low-angle group.The angle of upper and low molars decrease from low-angle group to normal group then to high-angle group.④To compared with normal group, In high-angle group of II1 malocclusion,the anterior upper face height (N-ANS) are normal,but the anterior lower face height (ANS-Me) are larger,and the posterior face height (S-Go) are smaller. So the index of S-Go/N-Me,ANS-Me/N-Me,N-ANS/ANS-Me have obvious difference with that of the normal group.In low-angle group of II1 malocclusion, the anterior upper/lower face height and the index of N-ANS/ANS-Me are normal;But compared with normal group,the posterior face height(S-Go) and the index of S-Go/N-Me are larger.In early permanent teeth period ,there are great difference in different vertical skeletal and face type of angle class II1 malocclusion. So we must make correct diagnosis and reasonable treatment on the basis of different characteristic in in orthodontic clinic.