Root canal morphology of mandibular incisors.

In this study, 100 mandibular central and lateral incisors were used to determine the number of root canals and their types, the ramifications of the root canal, the location of apical foramina, and the frequency of apical deltas. The teeth were immersed in India ink, decalcified, and cleared. The examination of root canal systems of the teeth was based on Vertucci's classification. Two more root canal types which are not defined in that classification have also been determined and grouped as new types.     

Root canal morphology of mandibular premolars.

Four hundred mandibular first premolars and 400 mandibular second premolars were decalcified, injected with dye, and made transparent to determine the number of root canals, their type, the ramifications of the main root canal, the location of apical foramina and transverse anastomoses, and the frequency of apical deltas. The mandibular first premolar had one canal at the apex in 74.0% of the teeth, two canals at the apex in 25.5%, and three canals at the apex in 0.5% of the teeth. The mandibular second premolar had one canal at the apex in 97.5% and two canals at the apex in 2.5% of the teeth.     

234颗多生牙临床特征及继发影响分析

目的: 应用锥形束CT（CBCT）分析多生牙相关特征,为临床诊疗提供参考。方法: 选择2019年1月—2020年12月内蒙古医科大学附属医院口腔科经CBCT确诊的234颗多生牙作为研究对象,分析其生长发育特征及继发影响。采用SPSS 25.0软件包对数据进行统计学处理。结果: 患者平均年龄11.16±7.61岁,以7~12岁最多。男女比例为1.6∶1。汉族占85.0%。多数单侧生长,数量多为1颗。多生牙生长区域多数为上颌骨切牙区,下颌骨前磨牙区。切牙区多生牙多见于7~12岁,尖牙区和前磨牙区多见于13~18岁,磨牙区多见于≥19岁。切牙区多生牙好发于男性,以圆锥形为主;其余区域多生牙好发于女性,以结节形为主,差异均有统计学意义（P<0.05)。发育情况为≥19岁年龄组高于其他3组,磨牙区高于其他区域,上颌骨高于下颌骨,差异均有统计学意义（P<0.05);位于两恒牙牙根之间的多生牙高于其他3组,差异无统计学意义（P>0.05)。萌出情况为部分牙根形成和完全形成高于牙冠形成,正向高于其他方向;位于两恒牙牙根之间的多生牙高于其他3组,差异均有统计学意义（P<0.05)。继发影响为各生长区域及位于恒牙唇侧、根尖部和两恒牙牙根之间的多生牙主要影响邻近恒牙,位于恒牙腭侧的多生牙多数无继发影响,差异均有统计学意义（P<0.05)。结论: CBCT可精确分析多生牙相关特征,利于临床制定完善诊疗方案,提高治疗效果。     

Root canal anatomy of the human permanent teeth

Two thousand four hundred human permanent teeth were decalcified, injected with dye, and cleared in order to determine the number of root canals and their different types, the ramifications of the main root canals, the location of apical foramina and transverse anastomoses, and the frequency of apical deltas.     

隐裂牙临床特征分析及CBCT影像学研究

目的: 通过对临床上非外伤性隐裂牙的临床特征进行分析并对其锥形束CT(Cone beam computed tomography, CBCT)的影像学表现进行总结。方法: 对105名患者的105颗明确冠隐裂牙的临床特征及CBCT影像学特征进行统计,收集临床资料包括患者的性别、年龄、牙位,同时对其CBCT上牙根折裂情况,牙槽骨及根尖周骨质吸收情况进行评价和统计。结果: 105例患者中,男性49.52%,女性50.48%;在50岁之前,随着年龄增加,隐裂牙发生比例增加,其中41~50岁发生率最高(34.29%),之后下降。105例隐裂牙中有5例发生在前磨牙区,其余均发生在磨牙区,其中第一磨牙发生率最高(59.05%)。105颗隐裂牙,CBCT检查有16颗(15.24%)可观察到牙根存在不完全折裂,仅4颗(3.81%)可见牙根完全折裂。其余85颗(80.95%)隐裂牙牙根未见明显异常。结论: 隐裂牙好发于上下颌第一磨牙,CBCT检测下大多数的冠隐裂牙并没有发生牙根折裂。     

Coronal and Root Decay Experience in Older Adults in Ontario, Canada

This paper describes the coronal and root caries experience of subjects aged 50 years and older living in four communities in Ontario, Canada. The data were obtained as part of a comprehensive epidemiologic study of the oral health and treatment needs of this population. Caries experience was defined as the number of decayed and filled coronal and root surfaces per subject. Of 907 subjects interviewed and clinically examined, 78.3 percent were dentate and retained a mean of 18.9 teeth. The mean number of coronal decayed and filled surf aces was 23.9; 95.6 percent of subjects had at least one coronal DFS. The mean number of decayed and filled root surfaces was 3.6; 70.9 percent had at least one root DFS. The percent D/DFS was 3.5 for coronal and 20.0 for root caries. In linear regression analysis the number of teeth, making regular preventive visits, being born in Canada, and educational status emerged as predictors of coronal DFS. Predictors of root DFS were the number of surf aces with recession, the number of coronal DFS, the number of teeth, age, sex, and smoking status. These variables accounted for 42 percent and 35 percent of the variance in the number of coronal and root DFS, respectively.     

INFLUENCE OF SMEAR LAYER REMOVAL ON THE OBTURATION OF ROOT CANAL RAMIFICATIONS

Objective:

This study evaluated whether smear layer removal has any influence on the filling of the root canal system, by examining the obturation of lateral canals, secondary canals and apical deltas.

Material and Methods:

Eighty maxillary and mandibular canines were randomly divided into two groups, according to their irrigation regimen. Both groups were irrigated with 1% NaOCl during canal shaping, but only the teeth in Group II received a final irrigation with 17% EDTA for smear layer removal. The root canals were obturated with lateral condensation of gutta-percha and the specimens were cleared, allowing for observation under the microscope.

Results:

In Groups I and II, 42.5% and 37.5% of the teeth, respectively, presented at least one filled canal ramification. Although a larger number of obturated ramifications was found in Group I, there were no statistically significant differences between the two groups (p = 0.4957).

Conclusion:

Smear layer removal under the conditions tested in this study did not affect the obturation of root canal ramifications when lateral condensation of gutta-percha was the technique used for root canal filling.     

3种技术诊断离体第一第二磨牙根管系统对比研究

目的以透明牙技术为参照,探讨牙科数字成像系统（radiovisiography,RVG）和显微CT（micro-computed tomography,MCT）扫描两种检查技术在研究离体磨牙根管系统解剖结构中的作用,为磨牙根管治疗提供影像学依据。方法253颗离体磨牙分别摄颊舌向、近远中向RVG和行MCT扫描,再制作根管染色透明牙,应用RVG、MCT和透明牙对各牙根中上2/3、根尖1/3区根管系统结构和管间交通支进行分类统计,以评估RVG、MCT技术在根管结构诊断中的应用价值。结果透明牙、MCT两组显示牙根中上2/3区根管系统均显著优于RVG（P〈0.05）;MCT与透明牙对磨牙中上2/3区根管系统的显示差异无统计学意义（P〉0.05）。MCT、透明牙、RVG对磨牙根尖1/3区根管系统的显示差异有统计学意义（P〈0.05）,根管显示率透明牙为100%,MCT为89.84%,RVG为77.97%。结论MCT与透明牙在显示牙根中上2/3区根管系统方面基本等效;在根尖1/3区透明牙对变异细小分歧根管的显示优于MCT及RVG技术,MCT技术在根尖1/3区细小分歧的显示明显优于RVG。     

The tilted posterior tooth. Part I: Etiology,syndrome, and prevention

The extraction of a tooth may have far-reaching ramifications on adjacent teeth, opposing teeth, occlusal scheme, and the periodontium. The best treatment is prevention.     

Periodontal response after tooth movement into intrabony defects

The present study was undertaken since conflicting evidence exists regarding the effect of such tooth movement on levels of connective tissue attachment. Localized intrabony pockets were produced around isolated incisors in four rhesus monkeys. The root surfaces were planned to the level of the bone at the base of the angular bony defects. An oral hygiene regime was begun and continued for the remainder of the study. The experimental teeth were moved orthodontically into, and through, the original area of the intrabony defect. Two months after cessation of active tooth movement, block specimens were removed for histologic analysis. Control specimens comprised those teeth with induced periodontal defects, but without tooth movement. In specimens not subjected to tooth movement, angular bony defects were present and epithelium lined the root surface to the apical extent of instrumentation. The alveolar bone adjacent to the orthodontically moved teeth no longer had angular defect morphology. On the pressure side, epithelium lined the root surface, was interposed between root surface and bone and terminated at the apical limit of root instrumentation. On the tension side, the crest of the bone was located apical to the level of root planing, and epithelium lined the instrumented portion of the root surface. It was concluded that orthodontic tooth movement into intrabony periodontal defects was without effect upon the levels of connective tissue attachment.     

牙科数字成像系统、锥形束CT及透明牙对离体第一恒磨牙根管系统诊断价值的对比性研究

目的 对比分析牙科数字成像系统（RVG）、锥形束CT（CBCT)及透明牙3种检查方法在诊断离体第一磨牙根管系统的价值,分析第一磨牙根管影像解剖学与根管解剖学的对应关系,为第一磨牙根管治疗提供影像解剖依据。方法 拍摄269颗离体第一磨牙颊舌向、近远中向RVG和CBCT后,再制作根管染色透明牙,应用RVG、CBCT和透明牙对各牙根中上2/3、根尖1/3区根管系统和管间交通支进行分类统计,以评估CBCT在根管诊断中的应用价值。结果 CBCT对第一磨牙主根管中上2/3区的显示率达96.55%;CBCT、透明牙对第一磨牙根尖1/3区根管系统的显示差异有统计学意义（P<0.05）。上、下颌第一磨牙近中根变异较大,双或多根管与管间交通支发生率均较高。结论CBCT与透明牙在显示第一磨牙主根管系统（牙根中上2/3区）方面基本等效;在根尖1/3区透明牙对细小分歧根管的显示明显优于CBCT;RVG对多根管牙根、根尖细小分歧根管的显示明显受限;上、下颌第一磨牙近中根双或多根管与管间交通支发生率均较高。CBCT对牙根、根管的显示具有清晰直观、准确快捷的优点,是目前无创诊断根管疾病最可靠方法。     

牙源性皮瘘病例报告及文献回顾

目的：通过病例分析,总结牙源性皮瘘的年龄分布及患牙位,为临床诊断、治疗及疗效评价提供依据。方法：展示6例牙源性皮肤瘘管的术前和术后面部和口内照片、X 线牙片,回顾以往报道的皮瘘病例60例,分析牙源性皮瘘的面部好发部位、及其对应的患牙位。结果：牙源性皮瘘主要好发在颊部、颏部、鼻旁和下颌下部4个部位,对应的患牙位分别是下颌第三磨牙、下颌切牙、上颌尖牙及下颌第一、第二磨牙,以下颌牙齿为主（71．2％）;相对于鼻旁和下颌下部皮肤瘘管好发于中老患者,颊部、颏部皮肤瘘管好发于年轻患者。对慢性牙周炎病灶牙进行根管治疗,拔除无需治疗的病灶牙,牙源性皮瘘均可痊愈。结论：对病灶牙的正确治疗是治疗牙源性皮瘘的主要方法。     

A Comparative Study on the Frequency,Location, and Direction of Accessory Canals Filled With the Hydraulic Vertical Condensation and Continuous Wave of Condensation Techniques

The present study compared the frequency, location, and direction of accessory canals filled with two different filling techniques. Sixty-four mandibular first molars were accessed, prepared, and divided into two groups of 32 teeth each. The teeth from group A and group B were filled using the hydraulic vertical condensation technique and the continuous wave of condensation technique, respectively. The specimens were then decalcified, dehydrated, rendered transparent, and analyzed by three independent evaluators. There was no significant difference (t test, p < 0.05) between the two groups in relation to the total number of filled ramifications. Moreover, there was no significant difference among the three thirds of the roots in relation to the number of filled ramifications (analysis of variance, p < 0.05). The filled ramifications were more frequently detected toward lingual, buccal, distal-lingual, and distal-buccal directions. It was concluded that the two filling techniques are not different in relation to the frequency, location, and direction of the ramifications filled.     

Prognosis of luxated non-vital maxillary incisors treated with calcium hydroxide and filled with gutta-percha. A retrospective clinical study.

A material of 885 luxated, non-vital incisors was evaluated radiographically with respect to healing of periodontal tissues including inflammatory root resorption and occurrence of ankylosis and cervical root fractures. The results were assessed after completion of calcium hydroxide treatment and 4 years after filling of the root canal with gutta-percha. After treatment with calcium hydroxide, periapical healing occurred in 95% of the teeth. Four years after filling with gutta-percha, periapical healing was present in 91% of the teeth. In the remaining teeth, recurrent or persistent periapical radiolucency was more frequent in overfilled than adequately filled teeth (P = 0.0001). There was no difference between immature and mature teeth. Inflammatory root resorption healed in 192 of 197 teeth (97%); in 5 teeth it developed into ankylosis. Ankylosis occurred in 13 teeth, all of which were intruded into the alveolar bone at the time of injury. The frequency of cervical root fractures was markedly higher in immature than mature teeth (P greater than 0.0001). Among immature teeth, the frequency of fractures was dependent on the stage of root development (chi 2 = 31.6) and ranged from 77% in teeth with the least to 28% in teeth with the most developed roots. The frequency of fractures was also related to the defects after healing of inflammatory root resorption in the cervical area of the root, significant at P less than 0.0001.     

Micro-computed tomography: a new tool for experimental endodontology

AIM: Micro-computed tomography (MCT) using conebeam geometry is a method of producing true 3D images of the structure of small samples. A prototype MCT unit was adapted for imaging teeth to examine whether it could be used to quantify the instrumentation of root canals. METHODOLOGY: Ten mandibular first molar teeth that had intact crowns and fully formed roots were scanned using MCT at a resolution of 0.081 mm and 3D-rendered images created; root canals were segmented from this. Reproducibility of MCT was verified for root canal shape and size. Access cavities were prepared into the pulp space and root canals enlarged to a continously tapering preparation using a crowndown technique. Each tooth was scanned again to allow comparison of pre- and post-instrumentation images. The roots were then sectioned at five predetermined horizontal levels for video-digitized measurement of dimensions of roots and root canals. The video images had a resolution of 0.025 mm. Video-digitized images of the physical cut surfaces were compared with equivalent MCT reconstructed images. The total area of the root canals (internal) and root (external) at each level were calculated from both MCT reconstructions and video-digitized images, and compared. RESULTS: There was a highly significant correlation between MCT and video images for both external and internal areas (r = 0.94). Rendered 3D images were constructed to show the root canal systems of teeth. The total volumes of the apical 7.5 mm of root canals were calculated from rendered images of nine teeth before and after instrumentation. The mean amount of dentine removed by instrumentation was 3.725 mm3, which was 28% of the original canal volume. CONCLUSIONS: Micro-computed tomography was shown to be accurate for experimental endodontology.     

Bacterial status in root-filled teeth exposed to the oral environment by loss of restoration and fracture or caries--a histobacteriological study of treated cases

AIM: To describe histological and microbiological findings in teeth where root fillings had been exposed to caries and the oral environment for a prolonged period. METHODOLOGY: For inclusion in the study, only teeth with a follow-up period of 3 years or more and those that had been without proper restoration for at least a period of 3 months were considered. Some root fillings had been without restoration for several years. In all, 39 roots representing 32 teeth were examined by histology. RESULTS: The majority of the specimens were without a discernible periapical bone lesion as assessed by radiography. Osteolytic lesions were seen with five roots. Longitudinal tissue sections stained with a modified Brown/Brenn staining technique revealed presence of stainable bacteria in abundance at the canal entrance and in dentinal tubules but were absent mid-root and apically in all but two specimens. Soft tissue attached to the root tip and in apical ramifications displayed distinct inflammatory cell infiltrates, suggesting microbial exposure in 7 of the 39 roots examined. In all other specimens, inflammatory cell infiltrates were either nonexistent or sparse and then associated with extruded sealer material. CONCLUSIONS: Well-prepared and filled root canals resist bacterial penetration even upon frank and long-standing oral exposure by caries, fracture or loss of restoration.     

Prognosis of luxated non-vital maxillary incisors treated with calcium hydroxide and filled with gutta-percha. A retrospective clinical study

Abstract A material of 885 luxated, non-vital incisors was evaluated radiographically with respect to healing of periodontal tissues including inflammatory root resorption and occurrence of ankylosis and cervical root fractures. The results were assessed after completion of calcium hydroxide treatment and 4 years after filling of the root canal with gutta-percha. After treatment with calcium hydroxide, periapical healing occurred in 95% of the teeth. Four years after filling with gutta-percha, periapical healing was present in 91% of the teeth. In the remaining teeth, recurrent or persistent periapical radiolucency was more frequent in overfilled than adequately filled teeth (P = 0.0001). There was no difference between immature and mature teeth. Inflammatory root resorption healed in 192 of 197 teeth (97%); in 5 teeth it developed into ankylosis. Ankylosis occurred in 13 teeth, all of which were intruded into the alveolar bone at the time of injury. The frequency of cervical root fractures was markedly higher in immature than mature teeth (P>0.0001). Among immature teeth, the frequency of fractures was dependent on the stage of root development [x²= 31,6) and ranged from 77% in teeth with the least to 28% in teeth with the most developed roots. The frequency of fractures was also related to the defects after healing of inflammatory root resorption in the cervical area of the root, significant at P< 0.0001.     

Histobacteriologic Conditions of the Apical Root Canal System and Periapical Tissues in Teeth Associated with Sinus Tracts

Introduction

This histobacteriologic study described the pattern of intraradicular and extraradicular infections in teeth with sinus tracts and chronic apical abscesses.

Endodontic instrumentation —quo vadis?*

The flaring of root canal preparations in order to improve instrumentation and enhance root filling condensation has been stressed in recent endodontic literature. Some authors, however, have suggested that too much flaring could be hazardous in molar root canals. This study was prompted by the occurrence of stripping-type perforations and post perforations in the buccal roots of upper molars and in the mesial roots of lowers. Ten operators instrumented 22 molars utilizing a variety of techniques. The teeth were horizontally sectioned and remaining wall thicknesses were measured under magnification. Excessively thin walls were found on the furcation surfaces of the buccal roots of upper molars and the mesial roots of lowers at a level 2–4 mm apical to the trifurcation or bifurcation. A potential for root stripping and post perforation, which was not readily apparent in pre-operative radiographs, was confirmed. The ramifications of these findings are discussed.     

Root surface measurements of the mandibular first molar

The root surface area (RSA) per millimeter of root length was determined for 20 extracted mandibular first molars. The molars were cross-sectioned at 1-mm increments, and each section photographed, projected and measured with a calibrated opisometer. The RSA and per cent RSA were calculated for each 1 mm of root length (1-mm section), the root trunk and the individual roots. Also measured was the location of the root separations from the root trunk, the location of the first detectable root concavity, and the prevalence of "intermediate bifurcation ridges" (IBRs). Mean measurements indicated that the greatest RSA per millimeter of root length was 4 to 7 mm apical to the cementoenamel junction (CEJ) in the area of the furcation. Of the total RSA, 48.7% was located in the coronal 6 mm of a root (mean length, 14.4 mm). Root separation occurred 4.0 mm apical to the CEJ with no tooth having a root trunk longer than 6 mm. Buccal and lingual root concavities were first present 0.7 mm and 0.3 mm apical to the CEJ, respectively. Fourteen (70%) of the 20 teeth had IBRs. According to the mean measurements, the mesial root was larger than the distal root by a ratio of 1.0:0.88. Horizontal attachment loss of 6 mm affecting both the buccal and lingual surfaces of the mandibular first molar would have resulted in a through and through (grade 3) furcation involvement of all the teeth studied.