Martins Jorge N R, Francisco Helena, Ordinola-Zapata Ronald
Department of Endodontics, Faculdade de Medicina Dentária, Universidade de Lisboa, Lisbon, Portugal.
Department of Oral Surgery, Faculdade de Medicina Dentária, Universidade de Lisboa, Lisbon, Portugal.
J Endod. 2017 Jun;43(6):890-895. doi: 10.1016/j.joen.2017.01.008. Epub 2017 Apr 25.
The mandibular premolar C-shaped anatomy has been presented as a complex morphology to be treated. The objective of this retrospective observational study was to evaluate and characterize, in in vivo conditions, the incidence of these morphologies using cone-beam computed tomographic (CBCT) technology.
Mandibular premolar CBCT samples were collected from a preexisting database. All teeth were analyzed in 3 planes (axial, coronal, and sagittal), and the C-shape classification was performed at 3 different axial levels (coronal, middle, and apical). C-shape presence and configuration were recorded as well as the number of roots, the presence of a radicular groove, and Vertucci classification. The Z test for proportions was used to analyze the differences between independent groups. Intraobserver reliability was tested using the Cohen kappa test.
Two thousand twelve mandibular premolars were included in this study. A prevalence of C-shaped morphologies was noted in 2.3% and 0.6% of mandibular first and second premolars, respectively. This clinical condition was mostly unilateral. The C-shaped configuration (C1 and C2) was found mainly in the middle axial level. Its presence was uncommon in the apical level and null in the coronal level; 61.5% of all mandibular first premolar C shapes were identified in Vertucci type V roots. Differences were observed among sex, teeth, and Vertucci root configuration at P < .05.
Although the mandibular premolar C-shaped anatomy has a low prevalence ratio, a clinician should be aware of its existence, mainly when treating roots with Vertucci type V configuration. The prevalence was statistically higher in first premolars and males.
下颌前磨牙的C形解剖结构被认为是一种复杂的形态，需要进行治疗。这项回顾性观察研究的目的是在体内条件下，使用锥形束计算机断层扫描（CBCT）技术评估和描述这些形态的发生率。
从一个现有的数据库中收集下颌前磨牙的CBCT样本。所有牙齿均在三个平面（轴向、冠状面和矢状面）进行分析，并在三个不同的轴向水平（冠部、中部和根尖部）进行C形分类。记录C形的存在情况和形态、牙根数量、根沟的存在情况以及韦尔图奇分类。使用比例Z检验分析独立组之间的差异。使用科恩kappa检验测试观察者内信度。
本研究纳入了2012颗下颌前磨牙。在下颌第一前磨牙和第二前磨牙中，C形形态的患病率分别为2.3%和0.6%。这种临床情况大多为单侧。C形形态（C1和C2）主要在轴向中部水平发现。在根尖水平其存在不常见，在冠部水平不存在；所有下颌第一前磨牙C形中61.5%在韦尔图奇V型牙根中被发现。在性别、牙齿和韦尔图奇牙根形态方面观察到差异，P<0.05。
尽管下颌前磨牙的C形解剖结构患病率较低，但临床医生应意识到其存在，尤其是在治疗韦尔图奇V型形态的牙根时。第一前磨牙和男性的患病率在统计学上更高。
