不同X线投照角度对下颌第一磨牙根管治疗的评价

Evaluation of effects of X-ray projection at different angles on the treatment of mandibular first molar root canals

目的探讨能清晰显示下颌第一磨牙全部根管的X线最佳投照角度,为根管治疗提供准确的信息。方法选取需行根管治疗且扩大针探查具有4个根管的下颌第一磨牙245例,完成根管治疗后,分别拍摄X线常规投照片、远中偏位投照片,判断所显示的根充效果。每颗牙拍摄角度分别为常规0°、远中偏30°、远中偏45°。由一个技师单独完成拍片,4位医师统一阅片,诊断牙根内的根管数目、形态及根管治疗情况。结果 X线常规投照片和远中偏30°位和45°位,显示下颌第一磨牙有四个根管的比例分别为36%、82%和95%。X线远中偏位投照片显示颊、舌向根管的比例大于常规投照片(P<0.001)。结论采用远中偏移30°～45°X线投照,能充分显示下颌第一磨牙的根管数目、形态,更好的评价根管治疗后根管显示情况。

Objectives To discuss the best projection angle which can clearly show all the mandibular first molar root canals so as to provide accurate information for root canal treatment. Methods Chose 245 mandibular first molars which needed root canal therapy and had 4 root canals probed with root canal reamer. After root canal therapy, shoot X-ray conventional cast photos,far offset cast pho- tos respectively, and judge their root filling effects. Angles for shooting teeth were conventional 0~, far offset 30~, far offset 45 o respec- tively. The photos were taken by one technologist. The photos were red by four observers independently, diagnosing numbers of root ca- nals within roots and its treatment situations. Results Proportions of X-ray photos at conventional 0~ , far offset 30~ , far offset 45 o show- ing four root canals in mandibular first molars were 36% , 82% and 95% respectively. Far offset X-ray projection was obviously better than conventional projection in showing buccolingual canals（P 〈 0. 001 ）. Conclusions Adopting far offset 300-45 X-ray projection can show root canal numbers in mandibular first molars and their morphology, and evaluate better the root canal situation after root ca- nal therapy.