平行和偏移投照根尖片在确诊上颌第一磨牙近中颊根第二根管中的作用

目的：探讨X线片检查在确诊上颌第一磨牙近中颊根第二根管（MB2）中的作用。方法：选取临床上需要进行上颌第一磨牙牙髓治疗 患者59例作为实验对象。每个患牙均需拍摄术前X线正位投照片、X线偏移投照片和诊断丝正位、偏移投照片。患牙经根管治疗术后，计算MB2的发现率。比较4种X线投照方法与MB2发生率的相关关系。结果：59例59个患牙中，存在MB2的患牙为24个，占40.7%。X线正位投照片发现根管偏移的占49.2％，X线偏移投照片发现根管偏移的占52.5%，诊断丝正位投照片发现根管偏移的占44.1%，诊断丝偏移投照片发现根管偏移的占55.9%。统计学分析显示：X线正位投照片和诊断丝正位投照片中根管偏移比率与MB2发生率无显著性差异（P＞0.05）；应用偏移投照，发现二者之间存在显著性差异（P＜0.05）。结论：根据不同角度X线片和诊断丝照相，分析根管影像偏移程度，有助于寻找和确定MB2根管的存在。

Usage of parallel and angulated radiograph in detection of MB2 canal of maxillary first molar

AIM:To explore the effect of dental radiograph in detection of MB2 canal of maxillary first molar. METHODS:Fifty-nine maxillary first molars were selected from fifty-nine patients. Four kinds of radiographs were taken for each tooth. They were periapical radiograph, mesially angulated radiograph, periapical radiograph with files, and mesially angulated radiograph with files. After root canal therapy, the percentage of MB2 was obtained. The relationship between the four kinds of radiographs and the percentage of MB2 was assessed. RESULTS:There were 24 teeth with MB2 canal. The percentage of MB2 was 40.7%. The percentage of root canal not in the center of the root in radiograph is as following: 49.2% in periapical radiograph, 52.5% in mesially angulated radiograph, 44.1% in periapical radiograph with files and 55.9% in mesially angulated radiograph with files. There was no significantly difference between the percentage of root canal not in the center of the root in periapical radiograph, periapical radiograph with files,and the percentage of MB2(P>0.05).But there was significant difference between the percentage of root canal not in the center of the root and the percentage of MB2 (P<0.05).CONCLUSION:Periapical parallel and angulated radiograph with or without files in canals are useful for detection and diagnosis of MB2 canal in maxillary first morlar.