Morphological Characteristics Research Of Central Incisor Alveolar Bone In Class Ii Division1and Division2Malocclusion Through Cbct

The appearance of anterior teeth is the key which both orthodonticdoctors and patients particularly concern about.The incisors in Class IIdivision1and division2show totally different clinical features,whichdetermine the different ways to move the tooth to the suitable positionduring orthodontic treatment.The alveolar bone remodeling is thebiological basis of orthodontic tooth movement and the three-dimensionalstructure of the alveolar bone directly determines the extent of toothmovement.Therefore, it is necessary to get a clear understanding of themorphological characteristics of incisor alveolar bone before treatment inorder to ensure good orthodontic results and reduce root resorption, bonefenestration and bone dehiscence, etc. The lateral cephalogram orPanoramic radiographs was mainly applied during previous studies toevaluate the morphology of the alveolar bone, but the accuracy is generallylimited by its insufficient information of just two-dimensional view. While CBCT, well known as a dental professional CT, provides a reliable andconvenient tool for3D image measurement of alveolar bone structure. Soour research is to use CBCT to investigate the alveolar condition of theupper and lower incisor regions in Class II division1and division2malocclusion, summarize the incisor alveolar bone structure characteristics,contrast the differences and aim to provide reference for clinical treatment.ObjectiveThis study is to measure the alveolar bone structure of central incisorregion in Class II malocclusion through CBCT and to compared thealveolar bone morphology between the Class II division1and division2,meanwhile evaluate the correlation of class II malocclusion buccolingualinclination of incisors and alveolar bone morphology, aim to provide atheoretical basis for orthodontic diagnosis and treatment in Class II division1and division2malocclusion.MethodsThe sample consisted of96patients with Class Ⅱ malocclusion: ClassII division1Malocclusion55patients (average age:18.5years);Class IIdivision2Malocclusion41patients(average age:20years).The CBCTimages before orthodontic treament were reconstructed by INVIVO5.0image processing software.The maxillary adopt SN plane and PP plane,mandibular with mandibular plane (MP plane) as the benchmark plane. The alveolar height, thickness and inclination of the incisors were measured. Allmeasurements were repeated three times. Statistical tests were performedusing SPSS17.0software package. Correlations and differences betweenthe measured variables were tested by t-test and linear regression analysis.Results1.In the same malocclusion,there were no significant differencebetween the upper right and left central incisors;also between the lowerright and left central incisors.∠U1-SN,∠U I-PP, IMPA in division1patient presented greater than division2while incisal angle is on thecontrary.2.At the upper central incisors, the alveolar height and thicknessbetween Class II division1and division2Malocclusion showedsignificantly differences(P<0.05):First, division2patients showed a greateralveolar bone thickness than division1, except upper incisor apex-buccalAlveolar thickness(UA), the root apex of the upper incisors were closer tothe buccal cortex in division2; Second, the upper incisor lingual cort heightand upper incisor apex-PP height,A-PP height in division1presentedgreater than division2.3.At the lower central incisors, the alveolar thickness at18mm indivision1patients presented greater than division2; In division2, the rootapex of the lower incisors was farther away from the lingual cortex than division1patients; division1patient showed a greater alveolar height thandivision2.4.In Class II malocclusion, inclination of upper and lower centralincisors and alveolar bone morphology correlation results showed:Theupper incisor inclination angle∠UI-SN with UA and ULH were positivelycorrelated;∠UI-SN with UAT-15mm, UAT-20mm, UAT-A, UP werenegatively correlated,The lower incisor inclination angle∠LI-MP withLAT-B and LA were positively correlated.ConclusionsThe alveolar thickness of Class II division2malocclusion wereoverall greater than division1,The alveolar bone form of the maxillary andmandibular central incisor region were short and wide;Conversely,thealveolar bone in division1were high and narrow；in division2, the Apicalwas closer to the buccal cortical bone,Even part of the root had been out ofthe buccal cortical bone;The distance from the upper and lower incisorsroot apex to PP and MP plane respectively,division2were shorterobviously than division1.Meanwhile incisor inclination had great effect onthe morphology of the alveolar bone,With the increase of inclination,themaxillary incisor alveolar bone become thinning.So we should Consider the relationship between the teeth position andalveolar bone shape comprehensively,Especially in division2,the Alveolar bone limit should be carefully considered when incisors are intruded.wecan not excessive move the tooth to compensate skeletaldiscrepancy.Choose the right plane and avoid root resorption,alveolar boneloss,fenestration and other adverse reactions.