【摘要】 为对影响咬合板定位摄片系统稳定性的因素提出改进意见，作者研究了影响小型猪定位牙根尖片投照稳定性的因素。结果表明：影响牙片定位投照重复性的主要因素有咬合板印模深度、连接杆的强度等。为改善牙片数字减影的效果，定位咬合板印模深度应大于２．５ｍｍ，以达到牙龈缘（４ｍｍ±）为最佳。投照时应防止咬合板颊舌向轻微旋转翘动。连接杆的强度应足够大，以免连接杆变形变曲。当连接杆强度增大后，咬合板印模深度的要求可以适当放宽，以便扩大适用范围并提高减影质量。更多还原

【Abstract】 Objective: To investigate the registration parameters in the dental radiographs for digital subtraction, to find out the significance of them and try to improve the quality control of the registration of the dental radiograph for the digital subtraction.Method:Sixteen projections of molar and premolar of mandible of minipigs were investigated for stability of the registration system of the dental radiographs. The rotation and the movements of the bite plans were measured with different height of edge of the bite plan. The 128 radiographs with varying parameters of the projection were digital subtracted. The noise of the subtraction photograph was compared for analyses of the relationship between subtraction noise and the projection parameters.Results:The depth of the bite plan and the strength of the connect bar between the X ray tube and the bite plans are the most significant parameters for the stability of the registration system. The thicker bar the better of the registration was. When the strength of the connected bar is increased, the depth of the bite plan is permitted not too strict. There is not significant effect for digital subtraction with other parameters in this investigation. Conclusion: For the best stability of the registration of dental radiographs, the connected bar with 8 mm in diameter is strong enough and the depth of the bite plan between 2.5～4 mm are adequate.更多还原