Correlation Of Alveolar Bone Of Mandible Anterior Region And Vertical Facial Type In Skeletal Class â…¢ Malocclusion

Skeletal Class Ⅲ jaw deformity is one of the common clinicalmaxillofacial deformities，affecting the patient’s appearance, voice andmasticatory function. The treatments by growing reshaping treatment,orthodontic treatment or conceal surgery alone can not obtain satisfactoryresults in Adult patients with severe deformity. In orthodontic and surgicalcombination treatment procedure, the extent of compensatory anteriorregion in preoperative orthodontic treatment is one of the limiting factorsdetermining the distance of moving mandibular setback. Proper anteriorocclusion is the focus of particular concern doctors and patients, the correctpositioning of the upper and lower incisors finally have a significant impacton facial aesthetic, and also is most apparent at relapse. Alveolar boneremodeling with macrophage is the biological prelude of teeth movement,in orthodontics.three-dimensional morphology of the alveolar bone directlydetermines the limits of tooth movement in skeletal Class Ⅲ malocclusion,alveolar bone thickness in the high-angle face with perpendicular growthtype is thinner than in low angle with surface horizontal growth pattern, and root apex was more accessible to cortical bone, and it is morevulnerable to root exposure, absorption and other complications, inhigh-angle other than in patients with other type treatment in patients. Toprove the correlation between the different vertical facial type in skeletalClass Ⅲ and the morphology of the patient’s lower anterior alveolar inadults, one would need to perform a retrospective study to further accessthe differences of alveolar morphology with vertical facial type groupingstudy, in order to select the appropriate treatment and to gain effectivecontrol of tooth roots movement to avoid these adverse consequences, andto select the appropriate treatment and effective control of the incisor rootmove. Therefore it is necessary to comprehensive assess the lower anterioralveolar bone morphology during orthodontics treatment, therebyaccurately control in the treatment of tooth movement in thinner alveolarbone, reducing root resorption, bone perforation, bone cracking and otheradverse reactions. Previous studies have mainly used cephalometric,panoramic radiographs, such as two-dimensional imaging technology,;cone-beam CT (Cone Beam Computer Tomography, CBCT) couldprovides an accurate and reliable and convenient imaging tools, as aprofessional Dentofacial CT for alveolar structure and thethree-dimensional measurement with high resolution. Therefore, withCBCT imaging technology,this experiment is aimed to measuredimensional morphology and alveolar process of change in the incisor area in the preoperative orthodontics treatment, to summarizes morphologycharacteristics in the lower anterior alveolar, compared to their differencesfor clinical diagnosis, treatment plan formulation, efficacy prediction, riskaversion provide references.Objectiveon the basis of the CBCT technology, the study intended to comparethe alveolar bone morphology of lower anterior teeth before treatment andafter preoperative orthodontic decompensation in patients with SkeletalClass Ⅲ, by measuring the axial central incisors in the lingual side of themaximum width of the levels of absolute,relative bone loss, relative rootlength, absolute and relative value, high-angle studies apical alveolar bonethickness,and to evaluate the lower anterior teeth alveolar bone loss inthree subcategories of patients along the preoperative orthodontic treatmentprocedure, for orthodontics and orthognathic surgeons to treat patientsbefore the exchange, forecasting bone loss of lower anterior teeth alveolar,as well as the choice of treatment technologies to provide a reference in thecourse of orthodontic treatment basis.MethodThe sample consisted of46were Selected from stomatology Hospitalof Chongqing Medical University orthodontic since2010and receiptedsurgical treatment of skeletal class Ⅲ malocclusion,and were divided intothree group: high-angle of SN-MP (>39°,14patients) who were angle (30-37°,20) people, low-angle (<28°,12) whose CBCT were used as theoriginal image. Then, the CBCT images before treatment and afterpresurgical orthodontics in three groups were performed in INVIVO5.0image processing software. Sagittal slices was chosen at the labio-linguallywidest point of the mandibular central incisor were evaluated.Measurement of the amount of vertical alveolar bone levels and alveolarbone thickness of the labial and lingual plate at the root apex was made tomeasure the axial dimension of the incisors in the maximums width of thelingual side of the absolute and relative values of alveolar bone loss,absolute and relative values of alveolar bone width of the apical region toevaluate the alveolar bone morphology in skeletal Ⅲ malocclusiondeformity.ResultsThe comparison of SNA, ANB and FHr in three groups: low-angle,average angles were greater than the high-angle group (p <0.05), whereasFH: GO-ME plane angle in low-angle was smallest, high-angle maximum(p <0.05).Before treatment, length of anterior alveolar bone thickness(LA) wasshorter than length of posterior alveolar bone thickness(LP), LA,LP andLA+LP in both average angle and high angle was less than low-angle (P<0.05), and no statistically differences between average angle andhigh-angle. There was no significant difference about LABL, LPBL and relative absorption (%LABL,%LPBL) among the three groups.PEARSON statistical correlation analysis showed that the IMPA angleand alveolar bone morphology was no significant linear relationship.However, the mandibular plane (SN: Go-Me)was increasing, alveolar bonethickness related indicators (LP, LA+LP) had decreased.After presurgical orthodontic treatment, LA was equivalent to LP,however LA value showed no significant difference among the threegroups, high-angle, low-angle angle is less than average (P <0.05)onLP,LA+LP%and LA+LP, with no statistically significant differencebetween the average angle and high angle, whereas LABL and%LABLvalue in average angle and low angle was less than in high angle, and itshowed opposite results about LPBL value, with no statistically significantabout%LPBL.In the course of preoperative orthodontic treatment, the height of theapical alveolar bone thickness and relative thickness (LA, LP, LA+LP,%LA+LP) and labial alveolar bone loss (LABL,%LABL,) were significantlinear correlation with facial type (P <0.05);apical thickness of the alveolarbone thickness (LP, LA+LP,%LA+LP) and labial alveolar bone loss(LABL,%LABL)were related to preoperative orthodontic treatment(p<0.05), but only the apical point lingual alveolar bone thickness(LP)variation was related to interactions between facial type andorthodontic treatment. ConclusionIn skeletal Ⅲ malocclusion, the morphology of the mandibularanterior region alveolar, due to stimulation of muscle function andcompensatory eruption of the front teeth, decreases down while face angleincreases the compensatory lingual inclination of the lower incisor did notaffect the thickness and height loss of alveolar bone. during preoperativeorthodontic treatment, the apical thickness of the alveolar bone may notaccurately reflect the change in thickness, due to root resorption. The lossof alveolar bone height is affected by presurgical orthodontic treatment andfacial type. Therefore, in skeletal class Ⅲ malocclusion orthodontictreatment plan should be combined with facial type and alveolar bonemorphology to develop individualized treatment programs to protect theweak areas of alveolar bone and special care should be taken to prevent ornot aggravate preexisting alveolar bone loss in the lower anterior teeth inthe mandible.