Study Of The Cone-beam CT In Clinical Of Orthodontic Diagnosis And Analysis

According to the World health Organization (World healthOrganization, the WHO),Malocclusion is one of the three major oral cavitydisorders.It will do serious harm to facial appearance and oral function.Atpresent,the commonly recognized clinical treatment solution is throughOrthodontics.In theory,through Cephalometric measurements andanalysis,the structure and the relationship between the soft and hardcraniofacial tissues of the various parts can be clearly understood,themodel analysis can reflect teeth,tooth bow,alveolar bone,themorphological of palatal and relationship of jaw.Which contributes to thevery basis for orthodontic diagnosis,case analysis and clinical treatmentsolution.The traditional two-dimensional X-ray cephalometry measurementtechnology underwent a change from hand-drawing to the application ofcomputer technology,The data obtained is still two-dimensional withoverlapping shadow,making it impossible to distinguish some finestructures,hence lost a large number of important information about thethree-dimensional structures and accurdte reflection of the true state of the three-dimensional craniofacial structure.Besides,manual measurementbeing the most commonly used model for sub-regulation analysis,it wasnot only time-consuming,but laborious and prone to error.With the development of the three-dimensional images,Cone beamcomputed tomography(Cone beam computed tomography,the CBCT)tech－nology is applied to the three-dimensional of teeth,jaws,face,craniofacialand can be on3D cephalometric and digital dentural defect analysis of themodel combined with the third software.Therefore,the study of Cone-beam CT with mature Invivo5softwaremeasurement analysis will be proposed,for reference of Cone-beam CT inthe further research and application of orthodontic.Ⅰ.A comparative study of3D by Cone-beam CT and traditional2DX-ray cephalometyr measurent and its reproducibility.A random sample of40newly diagnosed patients(18m ale,22fem-ale,aged from12to18years,Han nationalityf orthodontic treatment in edentulous(excludingthird molars),no history of trauma,no partial tooth together, no metal-freerestorations in the mouth,no jaws or teeth tumor,mandibular fractures inpermanent dentition;the40patients’X-ray cephalograms and CBCT pieceswere shot and the images are clear. A Steiner and Tweed measurementanalysis of the two paired tests was made.Results:p＜0.05,statisticallysignificant. Randomly selected from40patients one X-ray cephalograms andCBCT three-dimensional piece.Use Winceph8.015cephalometricmeasurentment,the CBCT piece of the same patient to the use Invivo5cephalometric measurentment15,and describe the statistical discretetrends.Results:the degree of dispersion of the data is too large between2Dand3D,indicating that compared with the three-dimensional cephlometricmeasurentment has rich reproducibility.Ⅱ.The use of cone-beam CT to establish the reference value of normalocclusion population in ChongqingTwo orthodontic physicians from the affiliated hospital ofstomatology,Chongqing Medical University has conducted a surveyamongthe college students in Chongqing.General criteria:①18to23years old②both the students and theirarents are native Chongqing of Han nationality③no history of orthodontictrenament④no history of surgery and craniofacial trauna⑤no respiratorydisorders and tonsillar hypertrophy,in good physical condition⑥facialcoordination,no significant bimaxillary protrusion skeletaldeformities,partial occlusion and II,III class.Standard in the mouth:①median teeth timely,bilateral molars neutral②the front teth cover the scots cover nomally③the dentition is complete,allthe teeth are arranged in neat rows④no fixed partial dentures,implantdenture nor metal fillings.Extracted40cases with normal occlusion to the hospital radiology;shot their CBCT pieces;established a three-dimensionalmeasurent of Steiner and Tweed reference value;thus,providing referencedata for further research in three-dimensional measurments.Excluding standard: Don’t meet the inclusion criteria are excluded.Ⅲ.A preliminary study of the Cone-beam CT in orthodontic modelanalysisExtracted30models from the newly diagnosed patients from the1stpart of the experiment and shot their CBCT,measured the index of eachdeputy model Blot on the Pont index,crowded;30patients with newlydiagnosed plasterv model of the manual measurement and two groups ofpaired t-test and consistency coefficient of inspection(the consistencycorrelation coefficient,theCCC).p＜0.05was statistically significant.Resul-ts:CBCT analysis and manual measurement of the plaster model has nosignificant difference (p＞0.05);CBCT plaste model can replace manualmeasurement, the consistency is very good.To sum up,the CBCT can show the three-dimensional images of the truecraniofacial structure, more accurate fixed-point, more accurate and reliableangle measurement value,and higher accuracy in line spacing of the hardtissue. CBCT can get a1:1image without magnification according to thereconstruction. CBCT reconstruction of dentition from the virtual model cancompensating for the deficiency of clinical oral examination. In addition，compared with traditional orthodontic research model,it is also much less timing-consuming,for the traditional plaster model could be easilydeformed, and hard to store up. Along with the further explore of CBCT inorthodontics, its applications will be further improved.