Incidence of C-shaped root canal systems in mandibular second molars in the native Chinese population by analysis of clinical methods

The aims of the study were to investigate the incidence of C-shaped root canal systems in mandibular second molars in a native Chinese population using radiography and clinical examination under microscope and to compare the relative efficacies of these methods. For the recognition of C-shaped root canal system, 1 146 mandibular second molars were selected and examined. Teeth with C-shaped canal systems were categorized by using the radiographic classification criteria and the modified Melton＇s method. C-shaped canals were identified in 397 （34.64%） mandibular second molars by radiography （type I, 31.23%; type II, 38.29%; type III, 30.48%）. Clinical examination showed that 449 （39.18%） cases exhibited C-shaped canal systems （C1, 22.94%; C2, 48.11%; C3a, 15.59%; C3b, 13.36%）. As for the result of the radiographic and clinical combined examination, C-shaped root canals were found in 473 （41.27%） mandibular second molars （C1, 21.78%; C2, 45.67%; C3a, 16.70%; C3b, 15.86%）. The incidence of C-shaped root canal diagnosed by radiographic method was statistically different from that by clinical examination and the combined examination （P〈O.05）. The study indicated a high incidence of C-shaped canal system in a Chinese population. The combination of microscopic and radiographic examination is an effective method in identifying the C-shaped root canal system.

Root canal morphology and configuration of 123 maxillary second molars by means of micro-CT

The aim of this study was to investigate the root canal configuration, accessory canals and number of main foramina of 123 maxillary second molars by means of micro-computed tomography. The teeth were scanned and reproduced with 3D software imaging. The root canal configuration and number of main foramina were evaluated by means of a four-digit system. The morphological complexity of human maxillary second molars is depicted by the number of accessory and connecting canals. The most frequently observed root canal configurations in the mesiobuccal root were 2-2-2/2 （19.5%）, 2-2-1/1 （14.6%） and 2-1-1/1 （13.0%）. A 1-1-1/1 configuration was observed in 93.5% and in 96.7% in the distobuccal and palatal roots, respectively. The MB1 mot canal had one accessory canal （18.7%）, and 8.9% of the MB2 root canal had one or two accessory canals. The distobuccal （11.3%） and palatal （14.6%） root canals had at least one accessory canal, and connecting canals were observed in 16.3% of mesiobuccal roots. The MB1, MB2, distobuccal and palatal root canals had one main foramen in 99.2%, 43.1%, 98.4% and 99.2% of samples, respectively. In the mesiobuccal root, one accessory foramen was detected in 14.6%, two were detected in 7.3%, and three were detected in 5.7%. The distobuccal root showed one or two accessory foramina in 9.1% of samples. The root canal configuration of maxillary second molars is quite heterogeneous; the mesiobuccal root has predominantly two root canal entrances （58.4%, 1 in 41.1%） with one main foramen （54.4%）. Two main foramina were observed in 43.0%. Morphological variations, connecting and accessory canals were observed in all apical thirds.

Successful individualized endodontic treatment of severely curved root canals in a mandibular second molar:A case report

BACKGROUND The incidence rate of severely curved root canals in mandibular molars is low,and the root canal treatment of mandibular molars with this aberrant canal anatomy may be technically challenging.CASE SUMMARY A 26-year-old Chinese female patient presented with intermittent and occlusal pain in the left mandibular second molar.The patient had undergone filling restoration for caries before endodontic consultation.With the aid of cone beam computed tomography(CBCT),a large periapical radiolucency was observed,and curved root canals in a mandibular second molar were confirmed,depicting a severe and curved distolingual root.Nonsurgical treatments,including novel individualized preparation skills and techniques and the use of bioceramic materials as an apical barrier,were performed,and complete healing of the periapical lesion and a satisfactory effect were achieved.CONCLUSION A case of severely curved root canals in a mandibular second molar was successfully treated and are reported herein.The complex anatomy of the tooth and the postoperative effect were also evaluated via the three-dimensional reconstruction of CBCT images,which accurately identified the aberrant canal morphology.New devices and biomaterial applications combined with novel synthesis techniques can increase the success rate of intractable endodontic treatment.

Anatomic Variation in Palatal Root of Maxillary Second Molar: Endodontic Management

The aim of the present clinical case report is to describe the singular root canal anatomy and endodontic management of a maxillary second molar with two palatal roots and two separate canal orifices. A 60 years-old female Hispanic/Latino patient attended the Endodontic Department at University of Buenos Aires School of Dentistry with acute pain in her maxillary left second molar. Clinical radiographs examination revealed unusual root morphology. Cleaning and shaping were completed with 5.25% NaOCl irrigation, 15% EDTA solution and hand/rotary instruments. Filling was performed with gutta-percha points and resin-based sealer. After one year follow-up periapical radiographs and CBCT images showed healing in the area and patient was asymptomatic.

Root Canal System Variation in Mandibular Second Molar: Middle-Mesial Canal

Middle-mesial canals in mandibular molars are present in the population depending on age, sex and ethnicity. However, limited literature alludes to its prevalence. Troughing procedures may enhance identification, cleaning and shaping. This case report expresses the recognition and management of middle-mesial canal in a mandibular second molar of 24 years old Hispanic-Latino male.

Two Palatal Root Canals in a Maxillary Right Second Molar:One Case Report

牙根和根管的数目不是固定不变的,文献报道表明牙齿尤其是上颌磨牙根管存在着解剖变异。但是,上颌第二磨牙发生腭根双根管的可能性很低。在本文中,作者报道了一例右上颌第二磨牙腭根双根管的解剖变异。由于可能存在的上颌第二磨牙腭根管解剖变异,所以临床医生在牙髓病治疗过程中应注意术前对患牙进行影像学分析,术中可借助牙科手术显微镜等可视手段寻找可能存在的腭根解剖变异。

Maxillary Second Molar with Single Root and Single Canal—Case Report

The maxillary second molar contains three roots and three canals. Variations of the maxillary second molar are reported in numerous studies in vitro and in vivo. Dentists are required to have adequate knowledge related to root canal morphology and their possible variations. The aim of this study was to present a case report about a diagnosis and treatment in maxillary second molar with single root and single canal. It is concluded that the diagnosing of these unusual cases is of high importance for successful endodontic treatment of these teeth.

Three-dimensional computed topography analysis of a patient with an unusual anatomy of the maxillary second and third molars

We present a case of a patient with rare anatomy of a maxillary second molar with three mesiobuccal root canals and a maxillary third molar with four separate roots, identified using multi-slice computed topography （CT） and three-dimensional reconstruction techniques. The described case enriched/might enrich our knowledge about possible anatomical aberrations of maxillary molars. In addition, we demonstrate the role of multi-slice CT as an objective tool for confirmatory diagnosis and successful endodontic management.

A Case Report of Kissing Molars Class II

Kissing molars (KMs) is a condition of occlusal molar surfaces in a single follicular space with roots extending in opposite directions. Here, we have reported a case of KMs in a 58-year-old woman. The patient complained of pain in the right mandibular molar region and was diagnosed with KMs consisting of the right mandibular second and third molars. Because of the patient’s pain having subsided at the time of the visit and her unwillingness to undergo tooth extraction, the patient was followed up. KMs is classified into three classes (I-III) and is either true-KMs or pseudo-KMs and presents with or without cystic variants of dental follicles. The presents as true-KMs class II without a cystic variant. With reference to the literature and based on our analysis, the mean age of patients affected by this specific case of KMs is 31.7 years and unilateral KMs is relatively more common (85.7%). Histopathological findings of dentigerous cysts are more often indicated (42.9%). The treatment policy for KMs should therefore be based on the classification of KMs. Importantly, the focus should be on preserving the first and second molars as much as possible. The treatment approach, such as the employment of surgical removal or orthodontics, should be determined by considering the associated factors such as the crowns, tissues, and age of the patient.

改良数字化导板对第二磨牙游离缺失辅助种植的精确度

背景:静态数字化导板辅助种植可提高种植精度,但对于开口度小和种植位点牙合间距离小的患者后牙区使用较为受限,为此需要对数字化导板进行改良。目的:研究改良数字化导板对第二磨牙游离缺失辅助种植的精确度。方法:选择2020年7月至2023年7月就诊于广州医科大学附属第一医院的第二磨牙游离缺失患者40例,采用掷硬币法随机分为试验组(n=22)与对照组(n=18),分别接受改良数字化导板辅助种植手术与常规自由手种植手术。对患者术前及术后锥形束CT进行重叠分析,比较组间的颈部偏差、尖端偏差、深度偏差、角度偏差值。术后1周,通过目测类比评分评估患者对手术过程的满意度。结果与结论:①试验组植入25颗种植体(上颌12颗,下颌13颗),对照组植入23颗种植体(上颌8颗,下颌15颗),试验组患者颈部偏差、尖端偏差、深度偏差、角度偏差值均小于对照组(P<0.05,P<0.001);试验组组内上颌种植位点与下颌种植位点精确度比较无差异(P>0.05);②两组患者对手术过程的满意度比较差异无显著性意义(P>0.05);③结果表明,改良数字化导板对第二磨牙游离缺失辅助种植可提高手术精度,适用于开口度小和种植位点牙合间距离小的患者后牙区。

Extraction Timing of Heavily Destructed Upper First Permanent Molars

The first permanent molar as the first permanent tooth in the mouth and with a general insufficient oral hygiene of the children, is commonly subject to significant compromise which may arise due to caries or endodontic complication, or from developmental anomalies such as hypoplasia. Compromised teeth with questionable prognosis may result in short- and long-term clinical dilemmas. The aim of this research is to highlight the factors that require careful consideration when a compromised UFPM is detected and the importance of timely UFPM extraction to ensure the mesial drift of the upper second permanent molar (USPM) to fulfill the space of the extracted UFPM without any orthodontic intervention. For this purpose 52 heavily destructed UFPMs were extracted at age of 10.5 years old, 44 (84.6%) USPMs erupted exactly distal to the second premolar while only 7 (13.4%) USPMs erupted 1 mm distal to the second premolar. Clinically it is recommended to extract the heavily destructed upper first molars at age of 10.5 years old to ensure the complete closure of the extraction space by the passive mesial drift of upper second permanent molar.

利用锥形束CT观察上颌第二恒磨牙牙根形态及近颊根第二根管发生率

目的利用锥形束CT(CBCT)观察上颌第二磨牙牙根形态及近颊根第二根管(MB2)发生率。方法收集2021年9月至2022年12月在北京安贞医院口腔科就诊患者的CBCT,以60岁为界分为青中年组(<60岁)及老年组(≥60岁),分别观察上颌第二磨牙牙根数量、牙根形态、根管数量、根管形态,参照Vertucci根管分类法对近颊根根管进行分类,并测量近颊根第一根管MB与腭根根管P、近颊根第二根管MB2及腭根根管P间距离;MB-P与MB-MB2连线夹角α,以及根管口至第一次根管分叉距离l。使用卡方检验及t检验对两组数据进行统计分析。结果137颗上颌第二恒磨牙中(青中年组70颗,老年组67颗),93颗(67.88%)为普通3根形态,44颗(32.12%)为其他牙根形态。41颗有MB2(29.93%)(青中年组20颗(28.57%),老年组21颗(31.34%),两组间MB2发生率差异无统计学意义(P>0.05),不同牙位、性别间MB2的发生率差异无统计学意义(P>0.05)。在有MB2的牙齿中,两组均以II型即2-1型根管最多见,两组间MB-P距离、MB2-P距离、MB-MB2距离、以及夹角α差异均无统计学意义(P>0.05),长度l平均为2.6 mm。结论上颌第二磨牙3根形态最多,老年患者MB2发生率与中青年人无异,治疗中应认真寻找MB2,以提高根管治疗成功率。

上颌第二乳磨牙牙根及根管形态的CBCT研究

目的:通过对锥形束CT(cone beam computed tomography,CBCT)影像资料进行统计分析,研究上颌第二乳磨牙牙根和根管数目及分布情况。方法:对就诊于深圳市儿童医院口腔科144例4~8岁儿童的CBCT图像进行分析,统计上颌第二乳磨牙牙根和根管的数目及分布情况。应用SPSS 26.0软件比较上颌第二乳磨牙牙根数量、常见根管类型在性别间和左右侧间的分布差异。结果:纳入266颗上颌第二乳磨牙表现为3个(98.50%)或4个牙根(1.50%),牙根的数量在性别间(P=1.000)及左右侧间(P=0.123)的差异均无统计学意义;上颌第二乳磨牙根管类型分为7种,三根三根管占62.03%,三根四根管者占31.95%,这两种常见根管类型在性别(P=0.513)、左右侧(P=0.894)的差异无统计学意义。结论:上颌第二乳磨牙根管形态相当复杂,为了提高根管治疗的成功率,治疗前应掌握其常见根管类型。

[牙合]垫联合隐形矫治在第二磨牙锁[牙合]矫治中的应用

目的:比较[牙合]垫联合隐形矫治与单纯隐形矫治用于第二磨牙锁[牙合]矫治的效果。方法:选择第二磨牙中、重度锁[牙合]患者30例(女16例,男14例),均为双侧锁[牙合]。年龄16.5~28岁。5例接受单纯隐形矫治(对照组),25例首先戴用[牙合]垫加弹性牵引解除锁[牙合],再行隐形矫治(联合组)。比较两组的矫治效果。结果:联合组矫治进程顺利,平均用时18个月,其中应用[牙合]垫加弹性牵引解除锁结关系需1.5~3个月。而对照组患者均未能顺利完成矫治,在戴用约10副隐形矫治器后,仍易脱套,暂停隐形矫治,重启方案后,约10副隐形矫治器后解除锁[牙合],用时14~15个月,相对于联合组多花费约12个月。结论:对于中、重度第二磨牙锁[牙合],在隐形矫治前应用[牙合]垫加局部交互牵引可顺利完成治疗,减少治疗时间。

牙根先脱位法拔除下颌骨埋伏第三磨牙对邻近第二磨牙的影响

目的:评估牙根先脱位法拔除下颌骨埋伏第三磨牙(impacted lower third molar,ILTM)对邻近第二磨牙(mandibular second molar,M2M)远中成骨效果、牙髓状态和牙根外吸收(external root resorption,ERR)进展的影响。方法:选择2023年1月—2023年10月于新疆医科大学第一附属医院进行ILTM拔除的患者64例,其中,32例采用牙根先脱位法拔除ILTM(实验组),32例采用牙冠先脱位法拔除ILTM(对照组)。术前、术后记录M2M松动度、牙髓状态、ERR情况、术后疼痛视觉模拟评分(VAS),术后3、6个月拍摄CBCT,测量M2M骨缺损深度、M2M骨高度、骨高度百分比和骨灰度等指标。采用SPSS 26.0软件包对数据进行统计学分析。结果:实验组术后第3天疼痛VAS评分显著低于对照组(P<0.05),手术时间、M2M牙髓活力和松动度两组均无显著差异(P>0.05);实验组去骨量显著少于对照组(P<0.05)。实验组术后即刻近中颊侧、远中舌侧PD显著低于对照组(P<0.05)。不同程度的ERR中,实验组术后3个月和6个月骨缺损深度、骨高度、骨高度百分比和骨灰度显著低于对照组(P<0.05)。不同阻生类型的2组术后骨缺损深度、骨高度、骨高度百分比和骨灰度比较,差异有统计学意义(P<0.05)。阻生深度与ERR严重程度比较,差异无统计学意义(P>0.05)。所有患者术后均未出现感染和神经损伤等并发症。结论:牙根先脱位法拔除ILTM对M2M远中成骨效果具有一定引导作用,对M2M远中牙周健康改善和术后反应均有效果。

全瓷冠修复下颌第二磨牙远中缺损龈壁提升后的美学效果及生物力学性能研究

目的探讨下颌第二磨牙远中缺损龈壁提升后给予全瓷冠修复的美学效果及生物力学性能。方法选择2021年2月至2023年2月我院收治的因第二磨牙远中缺损行龈壁提升后给予全瓷冠修复的40例患者作为观察组,另选40例行龈壁提升后给予金属桩钴铬烤瓷冠修复的第二磨牙远中缺损患者作为对照组。比较两组患者修复后12个月的修复效果和各结构的生物力学性能分布;比较两组修复前及修复后12个月的牙周状况和美学效果评分;采用广义估计方程评价全瓷冠修复对患牙美学效果和生物力学性能的影响;比较两组患者的修复满意度。结果观察组在边缘密合性、颜色匹配、牙龈健康方面的修复成功率明显高于对照组(P<0.05);两组患者修复前的牙龈指数(GI)、牙周探诊深度(PD)、龈沟液(GCF)量、美学效果的主观评分和客观评分差异无统计学意义(P>0.05),两组患者修复后12个月的GI、PD、GCF、主观评分和客观评分较修复前均明显增加,观察组的GI、PD、GCF明显小于对照组,主观评分和客观评分明显高于对照组(P<0.05);观察组修复体、粘接剂、牙本质、牙釉质的垂直向载荷应力、斜向载荷应力较对照组均明显减小(P<0.05);广义估计方程评价结果显示,全瓷冠修复能够减轻对患牙牙周健康状况的影响,生物力学性能较好;观察组修复12个月后修复满意度评价为A级的患者比例明显高于对照组(P<0.05)。结论下颌第二磨牙远中缺损龈壁提升后给予全瓷冠修复能够提高美学效果评分,维持良好的生物力学性能,减轻对患牙牙周健康的影响。

铜丝结扎法治疗下颌第二恒磨牙异位萌出1例

第二恒磨牙异位萌出若未得到及时治疗,会导致相邻的第一磨牙牙体组织吸收、牙齿早失、咀嚼效率下降及其他严重的错𬌗畸形。及时发现和处理第二恒磨牙异位萌出,对预防青少年错𬌗畸形、建立正常咬合关系具有重要的意义。然而,目前针对下颌第二恒磨牙异位萌出的病例报告比较少见,大多治疗方法主要为手术及正畸的方式,且缺乏长期的随访。本文报道1例采用铜丝结扎法治疗下颌第二恒磨牙异位萌出,使恒牙顺利萌出并建立正常咬合。术后观察5年,咬合稳定,牙根发育、牙髓活力及牙周状况正常。本文为近中倾斜度不大且已经部分萌出的阻生年轻下颌第二恒磨牙提供一种治疗周期短、简便及微创的临床思路。

CBCT评价526颗上颌第二磨牙牙根根管形态及其与上颌窦的关系

目的研究上颌第二磨牙(MSM)的牙根、根管系统的解剖学特征以及根尖与上颌窦的关系。方法回顾性分析了263例患者526颗MSM的CBCT成像资料。记录并分析患者的年龄、牙根及根管数量、融合根数量、根管弯曲类型以及牙根与窦底的解剖关系。结果大多数上颌第二磨牙有3个根(59.1%)。三根三管的发生率最高(47.3%)。有192颗(36.5%)的牙齿出现牙根融合。两根两管和三根三管MSM的腭根管在颊舌方向的弯曲度大于近远中向。三根MSM的近中颊根有向上颌窦内延伸的趋势,腭根有远离上颌窦的倾向。MSM牙根到上颌窦底的距离随年龄增长而增加(P<0.05)。结论MSM的牙根和根管形状差异较大。

金属预成冠全冠式远中导板间隙保持器应用于第二乳磨牙早失的回顾性研究

目的:回顾性观察金属预成冠全冠式远中导板间隙保持器(distal shoe space maintainer,DSSM)在第二乳磨牙早失中的临床治疗效果。方法:收集2021年1月~2024年1月89例因第二乳磨牙早失行全冠式DSSM治疗病例,回顾性分析至少术后1年的临床资料和影像学资料,从DSSM保留率、保留状态、间隙丧失情况及DSSM维持时间4个方面分析临床治疗效果。结果:对57例完成随访到DSSM拆除病例进行数据分析,平均维持时间15(12.5,18.0)个月,其中16例出现脱落或提前拆除,第一乳磨牙的慢性炎症和脱焊在DSSM脱落失败的危险因素中有统计学意义(P<0.05),第一乳磨牙的慢性炎症在影响DSSM变形移位的危险因素中有统计学意义(P<0.05)。对84例完成1年随访病例进行数据分析,22例移位变形病例平均间隙丧失2.31(2.14,2.34)mm,62例在位状态良好病例平均间隙丧失0.13(0.09,0.18)mm,两组数据比较差异有统计学意义(P<0.05)。结论:全冠式DSSM在在位保留上有优势,在位良好的病例也达到了良好的间隙保持临床效果,对于术前第一乳磨牙根尖周状态的判断及治疗和咬合管理还需予以改进。

不同分级异位萌出第一恒磨牙治疗后的疗效评估及相关影响因素分析

目的:探讨不同分级异位萌出第一恒磨牙分别使用不同的矫治方法治疗的效果。方法:选择河南省儿童医院口腔科矫治第一恒磨牙异位萌出的患者20名,10例患者第一恒磨牙异位萌出分级程度为Ⅰ级或Ⅱ级,采用分牙皮圈或分牙簧进行矫治;10例患者第一恒磨牙分级程度为Ⅲ级或Ⅳ级,应用改良Halterman矫治器技术。分析两组年龄、性别及治疗时间的差异,测量不同分级异位萌出的第一恒磨牙矫治前后磨牙近中倾斜角度的变化,并与相关影响因素进行分析。结果:分牙组平均矫治年龄为7.3岁,矫治器组平均年龄为8.2岁,两组治疗时间最长为150 d,最短60 d,分牙组患者平均矫治时间为87 d,矫治器组平均矫治时间为125 d,两组年龄及治疗时间差异均有统计学意义。两组中男性患儿占比均高于女性患儿,两组治疗前后第一恒磨牙平均近中倾斜角度差值均有统计学意义。结论:使用分牙法和改良Halterman矫治器治疗异位萌出第一恒磨牙均能获得良好的治疗效果,第一恒磨牙异位萌出不同分级程度可能与年龄、治疗时间差异及治疗前后第一恒磨牙近中倾斜角度差值有关。