Choi Chang-Hun, Back Seungwon, Kim Sunjai
Graduate School, Yonsei University College of Dentistry, Seoul 03722, Republic of Korea.
Department of Prosthodontics, Gangnam Severance Dental Hospital, Yonsei University College of Dentistry, Seoul 06273, Republic of Korea.
Bioengineering (Basel). 2025 Jul 17;12(7):772. doi: 10.3390/bioengineering12070772.
This pilot study aimed to evaluate how deviations in X-ray tube head angulation and digital sensor alignment affect the radiographic measurement of the profile angle in CAD-CAM abutments.
A mandibular model was used with five implant positions (central, buccal, and lingual offsets). Custom CAD-CAM abutments were designed with identical bucco-lingual direction contours and varying mesio-distal asymmetry for the corresponding implant positions. Periapical radiographs were acquired under controlled conditions by systematically varying vertical tube angulation, horizontal tube angulation, and horizontal sensor rotation from 0° to 20° in 5° increments for each parameter. Profile angles, interthread distances, and proximal overlaps were measured and compared with baseline STL data.
Profile angle measurements were significantly affected by both X-ray tube and sensor deviations. Horizontal tube angulation produced the greatest profile angle distortion, particularly in buccally positioned implants. Vertical x-ray tube angulations beyond 15° led to progressive underestimation of profile angles, while horizontal tube head rotation introduced asymmetric mesial-distal variation. Sensor rotation also caused marked interthread elongation, in some cases exceeding 100%, despite vertical projection being maintained. Profile angle deviations greater than 5° occurred in multiple conditions.
X-ray tube angulation and sensor alignment influence the reliability of profile angle measurements. Radiographs with > 10% interthread elongation or crown overlap may be inaccurate and warrant re-acquisition. Special attention is needed when imaging buccally positioned implants.
本初步研究旨在评估X射线管头角度和数字传感器对准的偏差如何影响计算机辅助设计与制造（CAD-CAM）基台轮廓角的放射学测量。
使用一个具有五个种植体位置（中央、颊侧和舌侧偏移）的下颌模型。针对相应的种植体位置，设计了具有相同颊舌向轮廓且近远中不对称性不同的定制CAD-CAM基台。在受控条件下，通过系统地改变垂直管角度、水平管角度以及水平传感器旋转角度（每个参数以5°增量从0°至20°变化）来获取根尖片。测量轮廓角、螺纹间距和近中重叠，并与基线STL数据进行比较。
轮廓角测量受到X射线管和传感器偏差的显著影响。水平管角度产生的轮廓角失真最大，尤其是在颊侧种植体中。垂直X射线管角度超过15°会导致轮廓角逐渐低估，而水平管头旋转会引入不对称的近远中变化。尽管保持垂直投影，但传感器旋转也会导致明显的螺纹伸长，在某些情况下超过100%。在多种情况下出现轮廓角偏差大于5°。
X射线管角度和传感器对准会影响轮廓角测量的可靠性。螺纹伸长或冠重叠超过10%的根尖片可能不准确，需要重新获取。对颊侧种植体成像时需要特别注意。
