多根管下颌第一前磨牙根管形态的显微CT分析

目的: 采用显微CT技术扫描并三维重建多根管下颌第一前磨牙根管系统,分析其解剖特点。方法: 收集32例多根管离体下颌第一前磨牙,采用显微CT扫描并三维重建,分析根管数目、形态、分叉位置及5种细微结构（侧支根管、根尖分歧、峡部、袢形结构、根尖三角区）并进行统计。结果: 32例下颌第一前磨牙中,96.88%含有根面凹陷（沟）,Vertucci分型中Ⅱ型、Ⅲ型、Ⅴ型均为3.12%,Ⅳ型31.25%,Ⅷ型9.38%,Ⅸ型15.62%,C形34.38%;62.50%的根管分叉于根中1/3,37.50%分叉于根尖1/3。细微结构中,侧支根管占56.25%,根尖分歧占43.75%,峡部占40.62%,袢形结构占21.88%,根尖三角区占6.25%。侧支根管在根管不同位置均可见,其余都发生于根中1/3和根尖1/3。结论: 多根管下颌第一前磨牙多含有根面凹陷（沟）,根管系统结构复杂,显微CT三维重建可清晰、准确地显示其根管形态。

Micro-CT study of root canal morphology of mandibular first premolars with multi-canals

PURPOSE: To observe root canal system of multi-canal mandibular first premolars and to analyze the morphology of them by micro-CT and three-dimensional reconstruction. METHODS: Thirty-two extracted mandibular first premolars with multiple root canals were selected and scanned by micro-CT. The number and morphology of canals, location of bifurcation and 5 subtle structures (lateral canals, apical ramification, isthmus, loops, apical delta) were analyzed. RESULTS: In the 32 specimens, 96.88% contained radicular depressions or grooves. The canal configuration was type Ⅱ, Ⅲ, Ⅴ: 3.12%, type Ⅳ: 31.25%, type Ⅷ: 9.38%, type Ⅸ: 15.62% and C-shaped canal: 34.38% by Vertucci's classification. 62.50% of the canals bifurcated at the middle third of roots, comparing with 37.50% at apical third. The incidence of the lateral canals, apical ramification, isthmus, loops and apical delta was 56.25%, 43.75%, 40.62%, 21.88% and 6.25%, respectively, which were all found at the middle and apical third of roots except that lateral canals were found at all depth of canals. CONCLUSIONS: Most mandibular first premolars with multiple canals contain radicular depression or grooves, of which root canal system are complicated. Micro-CT can provide clear and accurate three-dimensional information of canal morphology.