【摘要】 目的:观察下颌第二恒磨牙牙根及根管系统的解剖特点。方法:采集中国汉族患者拔除的下颌第二恒磨牙75个,分为双根组(n=32)和C形根组(n=43)。显微CT扫描后用Mimics10.01软件三维重建。比较2组髓室底形态以及各型根管、侧副管的发生情况。结果:双根组近中根根管多为1-1型(31.3%)及2-1型(34.4%),远中根多为1-1型(87.5%);近中根存在侧副根管牙根的发生率(65.6%)高于远中根(25.0%)(P<0.05)。C形根组以Ⅰ、Ⅳ型髓室底最为多见(均为30.2%);C形根管以MeltonⅢ型最为常见(58.1%),其次为MeltonⅠ型(27.9%)及MeltonⅡ型(14.0%)。双根组和C形根组存在侧副根管牙根的发生率分别为75%和51.2%(P>0.05)。结论:双根下颌第二磨牙近中根的根管系统较远中根复杂;而C形根常常对应一个复杂的C形根管系统。根管峡区不同部位、不同程度的带状牙本质融合会影响C形根管类。更多还原

【Abstract】 AIM: To observe the anatomic features of root and root canal systems of permanent mandibular second molars. METHODS: 75 extracted permanent mandibular second molars,32 with 2 roots (2R group) and 43 with one C-shaped root (CR group),from native Chinese subjects were scanned with micro-CT. 3D models of the teeth were reconstructed by Mimics 10. 01 software. The anatomy of the pulp chamber floor,incidence of various forms of root canals and accessory canals were determined. RESULTS: In 2R group,type 2- 1 (34. 4%) and 1- 1 canal systemss (31. 3%) were common in the mesial roots,and type 1- 1 canal system (87. 5%) was frequent in the distal roots. In CR group type I (30. 2%) and type IV (30. 2%) pulp chamber floor were common. The incidences of Melton Ⅰ,Ⅱ and Ⅲ canal form were 27. 9%,14. 0% and 58. 1% respectively. In 2R group the incidences of accessory canals of the mesial and distal roots were 65. 6% and 25. 0% respectively (P < 0. 05). The incidences of accessory canals in 2R and CR groups was 75. 0% and 51. 2% respectively (P > 0. 05). CONCLUSION: The root canal system of the mesial roots in 2-rooted mandibular second molars is more complex than that of the distal roots. The degree and location of the dentin confusion at the isthmus zones determine the type of the C-shaped canals.更多还原