下颌第二磨牙C形根管水平投照X线影像特点

The parallel radiographic characteristics of the C-shaped root canals in mandibular second molars

目的探讨下颌第二磨牙C形根管水平投照X线影像特点。方法对77颗离体下颌第二磨牙进行水平投照,两周后集中读片,将X线表现与离体牙牙根、根管形态和分型情况进行比较,总结离体牙C形根管水平投照X线影像特点。结果具C形根管的下颌第二磨牙的水平投照X线影像在牙根、髓腔、根管三方面有共同特点。牙根影像:①牙根影像呈单根,根尖锥形或结节状,中间有条索状或棒锤状X线低密度区;②似双根,根尖呈较宽的方圆形,“两根”之间由X线密度降低区连接,X线低密度区由根分歧处较窄渐向根尖区轻度增宽,“两根”尖部较圆钝。髓腔影像:髓腔深窄,髓室底近远中根管口距离近,一般不大于髓室底水平处牙根直径的1/3。根管影像:双根管或三根管影像,在根尖1/3汇合,或者有靠近趋势后又分开。除外粗大单根管影像。结论下颌第二磨牙C形根管X线影像具有一系列特点,对临床判断有一定帮助。

Objective To explore the radiographic characteristics of the C - shaped root canals in mandibular second molars in vitro. Methods Preoperative radiographs of 77 mandibular second molars were taken by X - ray with a 90°angulation to the tooth in a buccolingual direction. The radiograph data were collected after two weeks, and then compared with root and canals morphology of the teeth. Results From preoperative radiographs, extracted mandibular second molars with C- shaped canal system had common of root, pulp chamber and canal morphology. ①Radiographs showed single root image with cone - shaped or tuberculous apex; ②The root image appeared to have two distinct roots with obtuse roots apex, but there was a low density area between the ‘ two roots＇. The pulp chamber image of the C - shaped molars were deeper and narrower than normal morphology, and the distance between the mesial and distal orifice was less than or equal to the 1/3 root width at the the bottom level of pulp chamber, And the canal image of the C- shaped molars showed two or three canals converged at apex. Conclusion The mandibular second molars with C - shaped canal system have a series of radiographic characteristics, which could assist preoperational diagnosis.