Abstract:

Objective    To investigate the effect of different angle of digital X-ray on detective rate of multiple canals in mandibular first premolar in order to find the best angle. Methods    Totally 46 mandibular first premolars were collected，white wax dental models with mandibular first premolar were fabricated，digital X-ray films for each first premolar were taken from orthotopic，mesio-clination （10，20°）and distal-clination（10，20°）. All films were evaluated and compared with the results of operation microscope（OM）observation under 8 fold eyesight，whose roots were cross sected from root cervical，mid and apical part. The root canal numbers of each cross section were recorded as gold standard. SPSS13.0 software was employed and consistency test of each projection angles with gold standard was analyzed. Results    For mandibular first premolar，at mesial or distal projection of 20°，consistency of detective rate of multiple canals was better. Sensitivity at mesial projection of 20°was the highest. Conclusion    Mesial projection of 20° for mandibular first premolar is the optimal angle in detecting multi-canals.

Key words: root canal, digital X-ray, projection angle

摘要：

目的    探讨不同角度数字X线片对下颌第一前磨牙非单根管检出率的影响，筛选出最佳投照角度。方法       收集2010年1月至2013年2月盘锦市中心医院口腔治疗矫形科因正畸需要拔除的下颌第一前磨牙46颗，分别灌注白蜡牙列模型，对模型采取正位、近中投照（10、20°）、远中投照（10、20°）拍摄X线片，采集的数码图像存入电脑，阅片后评定出非单根管的牙齿数。横断所有牙的牙根，分为牙根颈部（距根尖> 6 mm）、牙根中部（距根尖3 ~ 6 mm）、根尖部（距根尖< 3 mm），在8倍手术显微镜下进行观察，记录每个断面的根管数作为金标准。采用SPSS13.0软件对5个投照角度的非单根管检出率与金标准进行一致性统计分析，并进行诊断试验，确定最佳投照角度。结果    下颌第一前磨牙近中20°和远中20°投照的X线片判读结果与显微镜下观察结果的一致性相对较好，近中20°投照比远中20°投照的敏感度高。结论    下颌第一前磨牙近中20°投照更有利于发现非单根管牙。

关键词: 根管, 数字X线片, 偏位投照