The Reliability Evaluation For Thirteen Parameters Descibing Anteroposterior Apical Base Relationship In Angle Class Ⅱ Division 1 Patients

Objective:The anteroposterior/ sagittal relationship of the maxilla to the mandible is a most important diagnostic and treatment planning criterion. The clinician uses this relationship to establish detailed treatment goals and proper treatment mechanics. This study was undertaken to study the 13 different cephalometric measurements of the anteroposterior jaw relationship in angle class â…¡ division 1 statistically and geometrically, to discuss the effects of various factors on this relationship, and then to choose the most adequate measurements. Method:120 patients with skeletal malocclusion angle class â…¡ division 1 were selected according to some standard. The sample consisted of 60 men and 60 women between 12 to 20 years of age. Lateral cephalometric radiographs for each patients were taken in natural head posture by the same operator. The wire plumb line and suspended weight recorded the true vertical on each radiograph, The subject is then asked to determine the self-balanced position of the head, After determining the self-balanced neutral position, the subject is asked to look into his/her own eyes in the mirror. The ANB angle, A-B plane angle, the Wits appraisal, the AF-BF distance, the AFB angle , the AB/SN₄ distance, the AB/PP distance, the AXD/SN angle, the AD/SN distance, theSGn/AB angle ,the APDI ,the FABA angle ,the beta angle and the AB/THP distance were measured.. Means and standard deviations of the above variables were established. Coefficient correlations among measurements were tabulated to determine which combination would produce a higher value. Make fuzzy grouping analysis. Result:There were no statistically significant differences between sexes in any of the measurements. Statistically significant and highly correlated relationships were found among many measurements except the Wits appraisal and the SGn/AB angle. The thirteen measurements can be dividatured by five clusters. Conclusion:1.The above cephalometric measurements except the Wits appraisal and the SGn/AB angle can be used to evaluate anteroposterior jaw relationship.2. The AB/SN4distance is the most adequate measurements. The ANB angle, A-B plane angle, the AF-BF distance, the AFB angle, the AB/PP distance, the APDI ,the FABA angle and the beta angle are similar in describing anteroposterior apical base relationship in angle class II division 1 patients.