The Study Of Soft And Hard Tissue Changes Before And After Orthodontic Treatment In Class Ⅱ Division 2 Malocclusion With Non-extraction

Objective:By means of the cephalometric analysis, the present study was to compare the changes of soft and hard tissues in both adolescent and adult Angle ClassⅡDivision 2malocclusion after nonextraction orthodontic treatment, and studied the growth pattern of this malocclusion. Discussion the orthodontic effect in different ages with ClassⅡDivision 2 malocclusion at the same time, thus to provide theoretical basis for clinical diagnosis and treatment.Methods:Select 31 cases of Angle Class Ⅱ Division 2 malocclusion patients as experimental group and 33 cases of Angle ClassⅠmalocclusion patients as control group according to the standard classification from 2013 January to 2015 December in the First Affiliated Hospital of Zhengzhou University Department of Orthodontics.The selected cases are from Zhengzhou area. Take the lateral cephalometric X-ray radiographs before and after the treatment in both the experimental group and controlgroup. Analyse the differences of the soft and hard tissue of Angle ClassⅡDivision 2malocclusion by comparing the differences of the same age group in experimental group and control group, and the changes after the orthodontic treatment in experimental group in the different age group respectively. Then we tried to provide the theoretical basis for clinical diagnosis and treatment of these type of patients.Results:Compared with Angle Class Ⅰ measurements, the soft and hard tissue measurements in adolescent group of Angle ClassⅡDivision 2 malocclusion showed that: ANB, AB-NP, NA-PA, S-Go/N-Me, U1-L1, EP-UL, Bs-H were larger, with significant difference(P < 0.05). The MP-FH, Ar Go Me, N-Me, ANS-Me,ANS-Me/N-Me, the line distances and angles between U1-NA, the line distances and angles between L1-NB, U1-SN, L1-MP were smaller in adolescent group of Angle ClassⅡDivision 2 malocclusion compared with Angle ClassⅠmeasurements(P<0.05). In adult group, the soft and hard tissue measurements of Angle Class ⅡDivision 2 malocclusion showed that: ANB, AB-NP, NA-PA, A-NP, U1-L1, Bs-H were larger than Angle ClassⅠmeasurements, with significant difference(P<0.05).The SNB, NP-FH, MP-FH, Ar Go Me, N-Me, ANS-Me, the line distances and angles between U1-NA, the angles between L1-NB, U1-SN were smaller in adult group of Angle ClassⅡDivision 2 malocclusion compared with Angle ClassⅠmeasurements(P<0.05). Compared with the adult group, the hard tissue measurements of Angle ClassⅡDivision 2 malocclusion in adolescent group showed that: the SNB was larger,the ANB, NA-PA, A-NP, the line distances between L1-NB were smaller, with significant difference(P < 0.05). The differences had no statistical significance in soft tissue measurements of Angle ClassⅡDivision 2 malocclusion in two different age groups(P>0.05).Study Ⅱ showed that: A number of soft and hard tissues were significantly changed compared with measurements before treatment in two different age groups of Angle ClassⅡDivision 2 malocclusion(P<0.05). In adolescent group, the SNB,MP-FH, N-Me, S-Go, ANS-Me, ANS-Me/N-Me, the line distances and anglesbetween U1-NA, the line distances and angles between L1-NB, U1-SN, L1-MP, Bs-H were significantly increased after the treatments; The ANB, NA-PA, A-NP, U1-L1 were significantly decreased after the treatments. In adult group, the MP-FH, the line distances and angles between U1-NA, the line distances and angles between L1-NB,U1-SN, L1-MP, Bs-H were significantly increased after the treatments; The A-NP,U1-L1 were significantly decreased after the treatments. The rest of hard and soft tissue measurements also had changes before and after treatments, but the differences had no statistical significance(P > 0.05). The comparison of hard and soft tissue measurements changes before and after the orthodontic treatment had significant differences in two different age groups of Angle ClassⅡDivision 2 malocclusion,such as SNB, ANB, NA-PA, MP-FH, N-Me, S-Go, ANS-Me, ANS-Me/N-Me, the angle between U1-NA, U1-L1, L1-MP, EP-UL, EP-LL, Bs-H. The rest of hard and soft tissue measurements changes before and after the orthodontic treatment had no statistical significance in two different age groups(P>0.05).Conclusion:The hard and soft tissue of Angle ClassⅡDivision 2 malocclusion were mainly characterized as: A ClassⅡskeletal pattern in the sagittal direction; A short length of lower third face in the vertical direction; A hypodivergent facial type and mandibular rotated clockwise; Lingual tipping deep overbite in upper incisors. The total facial profile looked relatively well with a harmonious relationship of nose, lips and chin.The ClassⅡskeletal pattern became severer with aging. It indicated that the Angle ClassⅡDivision 2 patients should receive orthodontic treatment as early as possible.In adolescent and adult groups, many hard tissue measurements changed significantly. Mandibular moved forward significantly with a clockwise rotation growth trend in adolescent patients. While mandibular reconstruction in adult patients was not obviously seen, mainly relying on teeth labial inclined to compensatory insufficient development of mandibular. In adolescent and adult groups, almost all soft tissues showed no significant difference. Meanwhile the soft tissue profile of adult group improved less than that of adolescent group. Early treatment wasbeneficial to promote the normal mandibular growth and development and improve the soft tissue side. Thus, ClassⅡDivision 2 malocclusion patients should be treated as early as possible.