数字化曲面体层摄影中颌弓长度及宽度对下颌后牙区影像垂直失真度的影响

Effect of mandibular arch width and length on uprightness distortion ratio of the mandibular posterior area in digital pantomography

目的 以锥形束CT（CBCT）为参照,研究数字化曲面体层摄影中不同颌弓宽度和长度对下颌后牙区影像垂直失真度的影响。方法 选取150例下颌颌弓正常患者的数字化曲面体层片及同期的CBCT,测量下颌后牙区相应邻牙近远中牙槽骨的高度,进行失真度的分析对比。结果 以CBCT中测量值为标准,数字化曲面体层片中磨牙区影像失真率为（3.85±2.03）%,前磨牙区影像失真率为（4.78±2.15）%,其中颌弓宽度在40.3-42.5 mm,颌弓长度在20.5-23.4 mm时,影像的垂直失真度最小,磨牙区为（1.95±0.13）%,前磨牙区为（2.88±0.25）%。结论 不同颌弓长度和宽度对数字化曲面体层片中颌骨垂直失真度有重要影响。

Objective To discuss the effect of different mandibular arch widths and lengths on uprightness distortion ratio of the mandibular posterior areain digital pantomography with cone beam CT （CBCT） as the reference. Methods 150 cases of patients with pantomography and CBCT were selected. The mesial and distal alveolar bone heights between adjacent teeth in mandibular posterior area were both measured, and the results were analyzed. Results Compared with CBCT,indigital pantomography,the uprightness distortion ratio of the mandibular molar area was （3.85 ± 2.03 ）% ,while that of the premolar area was （4.78 ± 2.15 ）%. When the arch width was 40.3 -42.5 mm and the length was 20.5 -23.4 mm, the distortion ratio was in its minimum, and the ratio was （1.95 ± 0.13）% in molar area and （2.88 ±0. 25 ） % in premolar area. Conclusions The width and length of mandibular arch are important factors affecting uprightness distortion ratio inthe digital pantomography.