耳点的准确性及其对头影测量值影响的研究

目的 探讨耳点的准确性及其对头影测量值的影响。方法 选取年龄在11－15岁的年轻恒牙列患者50名，在正中咬合位时拍摄头颅定位侧位片，测量机械耳点与解剖耳点的距离以及不同耳点定位FH平面时NPg－FH、SGn-FH、MP-FH、FMIA、OP－FH的测量值。结果 50例中有46例机械耳点位于解剖耳点的前下方，4例机械耳点位于解剖耳点的上方；机械耳点与解剖耳点的距离集中在3．5－6．5mm范围内，共有26例。以不同耳点定位FH平面时除FMIA外，其余4种项目的测量值相差显著并影响临床诊断。机械耳点与解剖耳点的距离越大，所选的五个指标折测量值差异越大。结论 耳点的准确性影响头影测量值及临床上分析和诊断的结果。

Accuracy of porion and its influences on cephalometric measurements

Objective To detect the accuracy of the porion and its influences on cephalometric measurements.Methods 50 cephalometric radiographs of patients with early permanent dentition were analysed. The liner distance between ear rod porion and anatomic porions were measured. Five items including NPg FH?SGn FH?MP FH?FMIA ?OP FH were measured according to different porion and then the measurements were statistically analysed . Results The liner distance between ear rod porions and anatomic porion were mainly located from 3.5 mm to 6.5 mm. Significant differences were found in measurements of NPg FH?SGn FH?MP FH?OP FH. but not in that of FMIA . There are correlation between the liner distance of porion and measurements of NPg FH?SGn FH?MP FH?FMIA ?OP FH.Conclusion The accuracy of the porion affects cephalometric measurements of NPg FH?SGn FH?MP FH?FMIA ?OP FH as well as the reliability of diagnosis.