C-shaped root canals in mandibular second molars in a Chinese population

Abstract The purpose of this investigation was to study the prevalence of C-shaped roots, root canal orifices, and root canals in the mandibular second molars of a Chinese population. A total of 581 second mandibular molars were collected in Hong Kong and Taiwan. The teeth were demineralized and placed in methyl salicylate to induce transparency. The pulp chamber floor was examined to ascertain the number of root canal orifices. Chinese ink was then injected into the root canal system to demonstrate the root canal anatomy. The mandibular second molars had separate roots in 66.4%, cone-shaped roots in 2.1% and C-shaped roots in 31.5%. The C-shaped roots had C-shaped canal orifices in 68.3% (21.5% of whole material). True C-shaped root canals were observed in 65.8% of the teeth with C-shaped orifices and in 13.9% of the whole material. Separate root canals were seen in 34.2% of the teeth with C-shaped orifices. Separate canal orifices were found in 31.7% of the C-shaped roots and 7.4% of these roots had true C-shaped canals. In the whole material 0.9% of the roots with individual canal orifices had C-shaped canals. In conclusion, C-shaped root canals were common in mandibular second molars in the Chinese subjects studied. The C-shaped root canals were often, but not always recognized because of a C-shaped canal orifice.     

C-shaped root canals in mandibular second molars in a Saudi Arabian population

AIM: The aim of this study was to determine the frequency of C-shaped canals in mandibular second molars in a population in Saudi Arabia and to establish a classification for the most common configurations. METHODOLOGY: One hundred and fifty-one mandibular second molars scheduled for root-canal treatment were examined over a 1-year period. The C-shaped canals were detected by radiographic and clinical examination. Teeth with C-shaped canal systems were categorized by using a modification of the classification of Melton. RESULTS: Of the 151 molars, 16 (10.6%) exhibited C-shaped canals. Five molars were classified as category I, and three were considered category II. The remaining eight cases were classified as category III, with two in subdivision I, two in subdivision II, and the remaining four in subdivision IIL. CONCLUSIONS: The C-shaped canals in mandibular second molars vary considerably in their anatomical configuration with the result that debridement, obturation, and restoration may be difficult.     

3 种方法充填下颌第二磨牙C型根管的实验研究

目的:探讨ObturaⅡ、冷侧压法与Thermafil充填下颌第二磨牙C型根管的效果。方法:分别用ObturaⅡ、冷牙胶侧压与Thermafil3种方法充填下颌第二磨牙C型根管,每组7例,X线观察气泡、侧枝和网状根尖三角的出现几率;透明牙法观测根尖渗漏;牙根切片比较牙胶、糊剂、空隙占根颈、根中、根尖三横截面管腔面积百分比。结果:Thermafil组网状根尖三角出现概率最高(4/7),P<0.05;冷侧压法染色线最长(1.47±0.14)mm,与其他2组比较差异有统计学意义(P<0.01);Thermafil组牙胶占根中、根尖横截面面积百分比最高(P<0.05),糊剂在三截面中占比例最低(P<0.05)。ObturaⅡ组在根中截面空隙比例最低(P<0.05)。结论:在3种充填方法中,Thermafil组C形根管根尖充填效果好,ObturaⅡ组在根中充填效果好。     

C-shaped canals in mandibular molars of a Brazilian subpopulation: prevalence and root canal configuration using cone-beam computed tomography

Objectives

To assess C-shaped root canal configuration by identifying its prevalence and each configuration type proportion, according to tooth (mandibular first or second molar) and demographic characteristics in a Brazilian population, using cone-beam computed tomography (CBCT). Moreover, it was verified if there is a relationship between root canal configuration observed in two-dimensional reconstructions of CBCT and presence of C-shape.

Methods

Mandibular jaw CBCT scans (184 males and 220 females, aged 15 to 80 years), which presented 1464 mandibular molars (710 first molars and 754 second molars), were assessed. Teeth were evaluated for the presence and type of C-shaped root canals by observing the roots at five levels in CBCT axial reconstructions. Root canal configuration was assessed in panoramic reconstructions. Data were statistically analyzed at a significance level of 5%.

Results

Of the 1464 mandibular molars, 125 (8.5%) were classified as C-shaped. This variation was more prevalent in females (n = 107, 85.6%) and in second molars (n = 108, 86.4%). C1 (uninterrupted C-shaped canal) was the most prevalent type of C-shaped configuration (41.76%), while C5 (no canal lumen) was the least prevalent type (0.96%). Single root with single canal in panoramic reconstructions was the most predominant configuration for C-shaped teeth (n = 54, 43.2%). Fused roots presented 17.2 higher odds of being associated with C-shaped root canals than non-fused roots.

Conclusions

C-shaped root canals were more prevalent in mandibular second molars and in females. Additionally, clinicians should bear in mind the greater possibility of C-shaped configuration in mandibular molars with fused roots.

Clinical relevance

Mandibular molars with C-shaped canals present a clinical challenge. A higher C-shaped proportion was noted in radiographic fused root types, which had 17.2 higher odds of presenting such anatomy when compared to radiographic non-fused roots. Root radiographic features may help in diagnosis of complex C-shaped morphologies.

     

GuttaFlow常温流动牙胶在下颌第二磨牙C形根管中的应用

目的 评价GuttaFlow 常温流动牙胶在下颌第二磨牙C形根管中的疗效。方法 选择需要治疗的下颌第二磨牙C形根管76例80颗牙,随机分为两组,每组40颗牙,实验组常温流动牙胶+牙胶尖充填根管,对照组碧兰糊剂+冷牙胶尖侧压充填根管。比较两组在充填时间、X线片根管充填质量、术后1周内疼痛以及术后1年复查疗效。结果 实验组充填时间平均每根管65 s,对照组425 s;实验组术后疼痛3例,对照组16例;实验组根管适充37颗牙（92.5%）,对照组根管适充29颗牙（72.5%）。实验组成功39例（97.5%）,对照组成功32例（80.0%）,两组差异有显著性（P<0.05）。结论 常温流动牙胶在下颌第二磨牙C形根管中充填简便疗效显著,值得在临床上推广应用。     

下颌第二恒磨牙C形根管的影像学分析

目的通过比较分析离体下颌第二恒磨牙C形根管的X线片和锥形束CT(CBCT)表现,为临床诊疗提供参考。方法收集我院因牙周病拔除的下颌第二恒磨牙110颗,模拟临床拍摄颊舌向X线片,并进行CBCT扫描。统计C形根管的发生率及其类型。结果 110颗离体下颌第二恒磨牙中,通过X线片诊断为C形根管的46颗(41.81%),通过CBCT影像确诊为C形根管显示66颗(60.00%)。通过CBCT诊断为C形根管的离体牙中,其中Ⅰ类(融合型)26颗,Ⅱ类(对称型)22颗,Ⅲ类(不对称型)18颗。Ⅰ类中,C4截面形态主要在根管下段出现的频率较高,Ⅱ类中,C3在整个根管各段中出现的频率较高。Ⅲ类中,C1和C2主要出现在根管上段。结论具有C形根管的下颌第二磨牙基本可以通过X线片初步诊断,但如需了解其根管的详细信息则要通过CBCT扫描分析。     

口腔锥形束CT在下颌第二磨牙C形根管诊治中的应用

目的探讨口腔锥形束CT(cone-beam computed tomography,CBCT)在根管治疗中诊断治疗下颌第二磨牙C形根管的临床应用。方法选取初次根管治疗失败的下颌第二磨牙62颗,根尖片不能确定根管解剖形态以及可疑遗漏根管,患牙采用CBCT进行扫描三维重建。结果使用CBCT确定下颌第二磨牙中52颗为C形根管,C形根管发生率达83.87%,C形根管中28颗为C1型变异根管(53.84%),18颗为C2型变异根管(34.62%),6颗为C3型变异根管(11.54%)。52颗患牙除2颗因根管侧穿导致根管治疗失败外,其余50颗患牙通过热牙胶充填与垂直加压技术将软化的牙胶充入不规则的根管系统,达到严密充填根管,根管再治疗后患牙成功治疗的有50颗(96.15%),均无不适症状。CBCT在根管治疗中辅助定位变异根管,定位准确率较高。结论 CBCT影像精密度高,可从三维角度分析根管,在根管治疗中诊断治疗下颌第二磨牙C形根管具有临床指导意义。     

下颌第二磨牙C形根管的特点和临床治疗

目的探讨下颌第二磨牙C形根管的发生率、临床诊断和治疗方法。方法通过对152例下颌第二磨牙拍摄术前X线片和术中根管探查,按照Melton标准诊断C形根管;采用机用镍钛器械Hero642进行根管预备,次氯酸钠超声冲洗,热牙胶垂直加压技术充填根管。记录C形根管的发生率及临床特点,根据治疗前、中、后的X线片评价根管预备和充填的效果。结果下颌第二磨牙C形根管的发生率为32.2%,79.6%的C形根管患牙X线片表现为锥形融合牙根,20.4%表现为近、远中独立牙根;所有患牙均无根管内并发症发生,治疗效果好。结论下颌第二磨牙C形根管主要存在于融合牙根,根管探查结合X线片可诊断C形根管;机用镍钛器械预备根管、次氯酸钠超声冲洗和垂直加压技术充填根管可获得良好的治疗效果。     

Anatomical and histological features of C-shaped canals in mandibular second molars.

The mandibular second molar has many root canal variations. This investigation used two evaluation methods to examine the canal morphology of mandibular second molars having C-shaped canals. Fifteen extracted mandibular second molars with a conical root and C-shaped canal orifice were separated into two groups. A polyester cast resin technique allowed three-dimensional visualization of the root canal system in eight teeth; the remaining seven molars were prepared for histological examination in cross-section in the coronal, middle, and apical thirds for study under the light microscope. The results illustrated that C-shaped canals in mandibular second molars can vary in number and shape along the length of the root with the result that debridement, obturation, and restoration in this group may be unusually difficult.     

下颌第二磨牙C形根管的临床诊断和治疗

目的：探讨下颌第二磨牙C形根管的临床诊断和治疗。方法：选择需进行治疗的下颌第二磨牙104个,通过术前拍摄X线片和术中根管显微镜下髓腔探查,按照AL-Fouzan术前X线诊断标准和Melton分类标准分别诊断是否为C形根管。采用手用Protaper进行根管预备,热牙胶垂直加压技术充填根管。记录C形根管口的类型,统计两种方法诊断的成功率。根据治疗前、中、后的X线评价根管预备和充填的效果,3～6个月后复查。结果：下颌第二磨牙C形根管术前X线片和根管显微镜的诊断率分别为72.1%和90.7%,所有患牙均无根管内并发症发生,治疗效果好。结论：术前X线片和根管显微镜相结合大大提高了下颌第二磨牙C形根的诊断率,镍钛器械预备根管和热牙胶垂直加压技术充填根管可获得良好的治疗效果。     

Root canal anatomy of mandibular second molars

The root canal anatomy of 19 mandibular second molars with C-shaped canals was investigated by rendering the roots transparent and allowing the canal system to be observed by black ink infiltration. The presence of three root canals was most frequent, and lateral canals were found in all roots. Transverse anastomoses were found in 15 of the 19 roots. The apical foramen was most commonly situated away from the apex, and apical deltas were found in 16 of the 19 roots. The C-shaped canals were found more frequently in Asians than in other racial groups (P less than 0.02). The formation of C-shaped roots and their racial predilection is discussed. A case report of the root canal treatment of a C-shaped canal is included and suggestions are made concerning suitable procedures for use in root canal treatment of these complex canal systems.     

下颌第二磨牙C形根管水平投照X线影像特点

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熙，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”尖部较圃钝。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。     

三种方法预备下颌第二磨牙C形根管成形效果的比较

目的 评价3种常用根管预备方法对C形根管的成形效果,为临床治疗提供参考.方法 对临床拔除的具有C形根管的下颌第二恒磨牙60颗,应用改良Bramante技术,于距根尖2mm、5 mm和8mm处将牙根横断.选择手用不锈钢K锉逐步后退技术(Step-Back组)、逐步深入技术(Step-Down组)和机用旋转镍钛锉ProTaperTM系列冠向下预备技术(Crown-Down组)预备不同类型的C形根管,比较预备前后根管横截面形态的数码图像,对3种不同方法的成形效果进行评价.结果 3种方法预备离体下颌第二磨牙C形根管后均有遗漏.不锈钢K锉逐步后退技术和不锈钢K锉逐步深入技术分别在根冠部[遗漏面积百分比分别为(0.177±0.071)%、(0.068±0.074)%]和根尖部[遗漏面积百分比分别为(0.236±0.167)%、(0.295±0.171)%]遗漏较少(P＜0.05).CⅠ、CⅡ型遗漏出现在近远中多于颊舌侧,将其分为独立的2～3个根管预备可减少遗漏.不同方法预备根尖区的遗漏均显著高于根管中上部(P＜0.05).结论 早期开敞根管上段,将C形根管分为2～3个独立的根管进行预备,可以增进根管预备的成形效果.     

C-shaped canal system in mandibular second molars: Part I--Anatomical features

The purpose of this study was to investigate the anatomical features of C-shaped root canal system in mandibular second molars using micro-computed tomography (microCT). Fifty-eight extracted mandibular second molars with fused roots were collected from a native Chinese population. The teeth were scanned into layers of 0.5-mm thickness by microCT and measurements were made at eleven levels. The ratio of the depth of the deepest part of the groove to the buccal-lingual thickness of the cross-section of the root was calculated for each tooth. The canal shapes of the scanned cross-sections were assessed and classified according to a modified Melton's method. Results were subject to the Kruskal-Wallis test. Of the 58 molars, 54 had a C-shaped canal system with a mean groove-to-thickness ratio of 47.96%; the four teeth without a C-shaped canal had a mean ratio of 14.82%. Most orifices (98.1%) were found within 3 mm below the cementoenamel junction. Of teeth with a C-shape canal system, a majority demonstrated an orifice with an uninterrupted "C" configuration. Seventeen canals divided in the apical portion, most of which did so within 2 mm from the apex. The cross-sectional shape varied drastically along the length of the canal. Teeth with a high groove-to-thickness ratio had at least one section with C1, C2, or C3 configuration. The canal shape in middle and apical thirds of C-shaped canal systems could not be predicted on the basis of the shape at the orifice level. Section 2 of this paper addressed the correlation between the radiographic appearance and these microCT images.     

Diagnosis, classification, and frequency of C-shaped canals in mandibular second molars in the Lebanese population.

C-shaped canals are mostly found in mandibular second molars. Studies have shown that frequency ranges from 2.7 to 31%. This study was undertaken to provide further knowledge of the distribution of such canal anatomy, by determining the frequency of C-shaped canals in a sample representing the Lebanese population. Ninety-four mandibular second molars with scheduled endodontic treatment were examined over a 1-yr period. Of the 94 treated molars, 18 exhibited C-shaped canals that would represent 19.1% of the sample. The geographical position of Lebanon could represent an explanation for this phenomenon.     

C-shaped canal system in mandibular second molars: Part II--Radiographic features

The purpose of this study was to investigate the relation between the radiographic features of C-shaped mandibular second molars and the cross-sectional shapes of their root canal system. Fifty-eight extracted mandibular second molars with fused roots were collected from a native Chinese population. The teeth were scanned at 0.5-mm interval thickness by micro-computed tomography (microCT) and observed at 11 levels. The 54 teeth that possessed a C-shaped canal system were further examined. Their radiographic appearances were classified into three types according to discernible radiographic features. The results were subject to the Kruskal-Wallis statistical test. In these 54 molars, 16 teeth (29.63%) showed a type I radiographic image, 22 (40.74%) type II, and 16 (29.63%) type III. In the type I category, the C1 and C4 canal configurations were mostly found in the apical area. Categories C2 and C3 were the main configurations in the middle and apical areas in type II and III. The type III had more C2 canals in middle area than type II. These results suggested that it was possible to predict the presence and the configuration of C-shaped canal system by the radiographic appearance.     

C-shaped canal configurations in mandibular molars.

Three cases of C-shaped mandibular second molars are described. These clinical findings were similar for each case:--It was impossible to diagnose the condition on the preoperative radiograph.--All three cases had normal anatomy of the pulp floor and separate canal orifices.--Continuous hemorrhage and sensitivity were encountered when instruments were used.     

C-shaped root canals of mandibular second molars in a Korean population: clinical observation and in vitro analysis

AIM: To investigate the incidence and morphology of C-shaped root canals of the mandibular second molar in a Korean population. METHODOLOGY: Through clinical observation, randomly selected 272 mandibular second molars of Korean patients were accessed and evaluated after taking radiographs for determination of working length. In an in vitro analysis, 96 extracted mandibular second molars of Korean patients were collected and embedded in resin using an Endodontic cube technique, and were sectioned at intervals of 1 mm. The specimens were then observed with a surgical microscope and were photographed. Canal configurations were assigned to one of three categories: Category I defined a C-shaped outline without any separation; Category II referred to those with canal configurations, where dentine separated one distinct canal from a buccal or lingual C-shaped canal; Category III had two or more discrete and separate canals. RESULTS: In clinical observation, 89 of 272 teeth (32.7%) had C-shaped canals. Of the 96 teeth examined in vitro, 30 (31.3%) had C-shaped canals. Upon in vitro analysis, only 1 tooth at the subpulpal level and 10 teeth at the apical 1 mm level were categorized under Category III. CONCLUSION: There was high prevalence of C-shaped root canals in the mandibular second molars of Koreans. C-shaped canals having semicolon and continuous shapes at the canal orifice have a high possibility of being divided into two or three canals in the apical region.     

下颌第二磨牙扇形根管的出现率与牙根形态的关系

目的：调查下颌第二磨牙扇形根管的出现率与牙根形态的关系。方法：通过进行根管治疗的202个下颌第二磨牙的临床检查，对其牙根形态和根管形态分类计数，调查扇形根管的出现率。结果：分叉根的扇形根管出现率为18．7％，平行根为35．5％，锥形根为76．3％。结论：近中根与远中根相距越近，扇形根管的出现率越高。