| ObjectiveTo compare the morphology and the root position in alveolar bone and root movement ranges in different labial-lingual inclination of upper teeth of Angle Ⅱclasses malocclusion by CBCT.MethodsPre-treatment CBCT films of 90 adult classⅡmalocclusions were divided into 3groups according to U1-PP,including labial inclination group(U1-PP>120°);normal group(110°<U1-PP<120°),and lingual inclination group(U1-PP<110°).Every group includs 30 cases(10males and 20 females).Three-dimensional reconstruction was made for CBCT by Invivo 5.2 image processing software.Alveolar thickness,root movement ranges and labial-lingual inclination were measured on sagittal section of the upper and lower central incisors in CBCT images.The data was analyzed with SPSS 19.0 software package.Results1.The alveolar bone thickness:(1)the labial inclination group of maxillary central incisor of the labial thickness of alveolar bone [left(1.98±1.12)mm,right(1.91±1.36)mm] and the root labial rotation range [left(15.65±8.76)°,right(15.16 +9.55)°] is greater than the lingual inclination group of the labial thickness of the alveolar bone [left(0.28±0.35)mm,right(0.39±0.40)mm] and the root labial side rotation range [left(3.13±4.03)°,right(2.77±2.64)°].(2)Between different groups,maxillary lingual alveolar bone thickness of root apex point is less different than labial’s,only in the left maxillary central incisor shows the lingual alveolar bone thickness and root lingual rotation range of labial group greater than lingual group.Specific thickness is as follows: the lingual alveolar bone thickness of the maxillary central incisor of the labial inclination group [left(3.72±1.87)mm,right(3.65±1.49)mm] and the root lingual rotation range [left(26.89±13.70)°,right(25.53±9.03)°];the lingual alveolar bone thickness of the lingual inclination group [left(6.35±2.30)mm,right(5.69±2.66)mm] and the root lingual rotation range[left(46.19±17.00)°,right(39.02±21.79)°].Percentage of alveolar bone thickness at apex to CEJ width(total apex bone thickness divideC bone thickness * 100%)only on the left upper central incisor of normal group is more than 100%,the rest of the groups are less than 100%,especially the lower central incisor,the percentage of alveolar bone thickness at apex to CEJ width is only 74% or so.The percentage tooth of alveolar bone thickness at apex to CEJ width of all the upper central incisors was57.32%,and the lower was 95.00%.2.Root position in the alveolar bone: maxillary central incisor is located in labial side of alveolar bone [in accordance with the distance calculation left(37±17)%,right(34±15)%;in accordance with the rotate left(38±21)%,right(37±12)%] is greater than the lingual inclination group in accordance with the distance calculation left(5±5)%,right(9±9)%;in accordance with the rotate calculation left(7±10)%,right(11±11)%].The thickness of alveolar bone thickness and root position in the lower middle incisors were not significantly different between those groups.Conclusion1.Angle Ⅱ classes malocclusion’s left and right alveolar bone thickness of upper central incisor and root position are not the same.2.The different labial-lingual inclination had no significant effect on the total alveolar bone thickness of the upper and lower central incisors in Angle Class II malocclusion patients,but had a greater influence on the location of the upper and lower central incisors.3.The apical position basically in 2/5 of alveolar bone in different group.And the root position of the mandibular central incisor is basically in the center of the alveolar bone.4.Comparing to CEJ width,the anterior alveolar bone thickness of Angle Class II malocclusion is thin,especially the mandibular incisors. |
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