EVALUATION OF ANB ANGLE IN DETERMINATION OF A-P POSITION OF MAXILLA AND MANDIBLE

Abstract

Introduction. The ANB angle has been recognized as a skeletal sagittal discrepancy indicator and has become the most commonly used measurement since that time. It seems this angle is affected by several factors other than the anteroposterior position of maxilla and mandible.
Methods. Tracing on lateral cephalometry films was done for 110 untreated cases with class I, II, III malocclusions. regression analysis was used to describe the proportion of the distorting factors caused by usual changes in the cranial and facial skeleton.
Results. ANB mean differences between malocclusion groups was significant. Regression analysis between ANB, SN/MP and SNA angles in all groups was significant. The highest coefficient of determination was found in class I sample and the lowest was found in class II sample.
Discussion. The results revealed that another factors can influence of ANB angle. These factors are rotation of SN plane, the length of the SN and rotation of jaws. Thus the use of normal range for ANB angle in determination of sagittal position of maxilla and mandible is incorrect and it must substitute with accurate parameters.