上颌前磨牙桩道预备后剩余根管壁厚度和抗折强度的研究

目的:探讨上颌前磨牙桩道预备后剩余根管壁厚度及对抗折强度的影响。方法:对100颗单、双根管上颌 前磨牙,用1#～5#P型钻进行桩道预备,用光学显微镜分别测量各组牙冠方和根方剩余根管壁厚度,并观察桩道预 备对抗折强度的影响。结果:单根管上颌前磨牙,1#～2#P型钻预备后,各壁剩余厚度均大于1mm;而对于双根管 上颌前磨牙,1#～3#P型钻预备后,各壁剩余厚度均大于1mm。另外,1#～5#P型钻预备后,牙根抗折强度逐渐变小 (P 0.01),且相同直径器械预备后,双根管抗折强度大于单根管(P 0.01)。结论:用P型钻预备桩道时,单根 管牙最大可用2#P型钻预备,双根管牙最大可用3#P型钻预备,且剩余牙质的量与牙齿的抗折强度成正相关。     

Use of Cone-beam Computed Tomography to Evaluate Root Canal Morphology and Locate Root Canal Orifices of Maxillary Second Premolars in a Chinese Subpopulation

Introduction

The aim of this study was to investigate root canal morphology and locate root canal orifices of maxillary second premolars in a Chinese subpopulation using cone-beam computed tomographic imaging.

Methods

A total of 392 cone-beam computed tomographic images of maxillary second premolars were obtained from 238 patients who required a preoperative assessment for implant surgery or orthodontic treatment. The number of roots and root canals and root canal configuration were investigated and categorized using Vertucci's criteria. The distance between the root canal orifice and the anatomic apex and the distance between root canal orifices in those teeth with 2 root canals were measured and evaluated. The Fisher exact test was used to analyze the correlation between the number of roots and sex.

Results

Among the 392 teeth, 86.5% (n = 339) had 1 root; 45.4% (n = 178) of the teeth had 1 root canal, and 54.3% (n = 213) had 2 root canals that ranged from type II–type V. The majority of teeth with 2 root canals showed a type IV canal configuration (n = 79, 20.2%) followed by type II (n = 64, 16.3%), type III (n = 45, 11.4%), and type V (n = 25, 6.4%). Only 1 tooth had 3 root canals. No significant difference was found between the number of roots and sex (P > .05). Among the 213 teeth with 2 root canals, the most frequent distribution of the distance between the root canal orifice and the anatomic apex was 5–10 mm (n = 157). The distance between the 2 orifices of 189 teeth was 1–4 mm.

Conclusions

The frequency of teeth with 2 root canals was high in maxillary second premolars. The internal morphology of teeth with 2 root canals was variable. This study provided useful information about the root canal morphology of maxillary second premolars in a Chinese subpopulation.     

显微CT法研究中国人上颌第一前磨牙分支根管形态

目的:使用显微CT扫描法研究中国人离体上颌第一前磨牙分支根管解剖形态。方法:收集63颗中国人上颌第一前磨牙,使用显微CT扫描并构建根管系统三维可视化模型。观察并记录分支根管、根尖三角区发生情况,分析分支根管发生率、分布和开口特征。结果:共有50颗上颌第一前磨牙含有分支根管,发生率为79.37%。共记录到124个分支根管,其中95.16%发生于根尖1/3。分支根管开口于近中和远中方向的分别为33.06%和23.39%。根尖三角区的发生率为7.94%。结论:上颌第一前磨牙分支根管发生率高,根管系统形态复杂,了解其分支根管发生规律对于提高根管治疗成功率具有重要意义。     

Effects of Ultrasonic Removal of Fractured Files from the Middle Third of Root Canals on the Resistance to Vertical Root Fracture

IntroductionThis study aimed to analyze the effects of ultrasonic removal of fractured files from the middle third of root canals on the vertical root fracture resistance.MethodsThis study was an extension of a previous study assessing the effects of fractured file removal on dentinal microcracks. It included 18 bilaterally matched pairs of human mandibular incisors prepared and analyzed in the previous study. Briefly, 1 member of each pair was assigned to an ultrasonic or a control group. In the ultrasonic group, K-files were fractured in the middle third of canals followed by ultrasonic file removal and canal preparation. In the control group, the root canals were simply prepared. Micro–computed tomographic imaging was performed before and after treatment, and the cross-sectional root images were screened for microcracks. For the present study, 3-dimensional reconstruction was performed for volumetric assessments. The fracture resistance was measured using a universal testing machine. All data were statistically analyzed.ResultsFracture loads were significantly smaller in the ultrasonic group (P < .05). The percentage increase in the canal volume significantly influenced the root fracture resistance (P < .05), whereas microcracks had no significant effect (P > .05).ConclusionsUltrasonic removal of fractured instruments from the middle third of root canals lowers the vertical root fracture resistance, with increased dentin removal being the primary cause.     

An Ex Vivo Study of Root Canal System Configuration and Morphology of 115 Maxillary First Premolars

IntroductionThe aim of this study was to investigate the root canal system morphology of maxillary first premolars by means of micro–computed tomographic imaging in a Swiss-German population.MethodsThe root canal configuration (RCC) of 115 maxillary first premolars (Mx1Ps) were investigated by means of micro–computed tomographic imaging and 3-dimensional imaging. The RCC and the physiological foramina results are described by a 4-digit system code.ResultsTwelve different RCCs were observed in 30 single-rooted Mx1Ps; 2-2-2/2 (30.0%), 1-2-2/2 (13.3%), 1-2-1/2 (10%), and 2-2-1/2 (10.0%) were the most frequent ones. Seven different RCCs were observed in 2-rooted Mx1Ps (n = 81) in which the 1-1-1/1 (56.8%), 1-1-1/2 (29.6%), and 1-1-2/2 (8.6%) in the buccal root and 1-1-1/1 (92.6%) and 1-1-1/2 (6.2%) in the palatal root RCCs appeared most frequently. Three-rooted Mx1Ps (n = 4) showed a 1-1-1/1 (100.0%) RCC in all roots. The buccal root canal in 2-rooted Mx1Ps had 1 physiological foramen in 59.3% and 2 in 40.7% and 1 to 6 accessory foramina in 38.2%. The palatal root canal showed 1 physiological foramen in 93.8% and 2 in 6.2% and 1 to 2 accessory foramina in 14.8%. Single-rooted Mx1Ps showed 1 physiological foramen in 10.0%, 2 in 70.0%, 3 in 13.3%, and 4 in 6.7% and 1 to 3 accessory foramina in 46.7%.ConclusionsThe results of this study provide detailed morphologic RCC information of Mx1Ps in a Swiss-German population. Single-rooted Mx1Ps showed morphologic diversifications more frequently than 2- or 3-rooted Mx1Ps. Within 2-rooted Mx1Ps, the buccal root had higher RCC variety, accessory canals, and foramina number than the palatal root.     

Radicular Grooves and Complex Root Morphologies of Mandibular Premolars Among Israeli Population

IntroductionMandibular premolars usually have one root and one root canal. Different studies found that up to 30% of mandibular premolars have more than one root canal, and up to 24% of mandibular premolars have C-shape canals. The purpose of this study was to investigate the root anatomy and the prevalence of complex root canal morphology in mandibular premolars in Israeli population.MethodsA total of 1020 Israeli patients' cone-beam computed tomography scans were screened and evaluated. A total of 1835 mandibular first premolars and 1678 mandibular second premolars were examined. Irregular root anatomy and different root canal morphologies were recorded and analyzed.ResultsThe overall prevalence of complex root morphology (types II–VIII) in mandibular first and second premolars was 21% and 2.8%, respectively. The bilateral prevalence of complex root morphology in mandibular first and second premolars was 46% and 29%, respectively. The prevalence of radicular grooves in mandibular first and second premolars with complex root morphology was 48% and 36%, respectively. No significant difference was found according to gender or the side of occurrence. However, complex root canal morphology was significantly found in mandibular premolars with radicular grooves.ConclusionsComplex root canal morphology frequently occurs in mandibular first premolars in the population of Israel. Radicular groove existence in mandibular first and second premolars is significantly related to complex root canal morphology.     

In Vivo Detection of Subtle Vertical Root Fracture in Endodontically Treated Teeth by Cone-beam Computed Tomography

IntroductionThe purpose of this study was to evaluate the diagnostic accuracy of cone-beam computed tomographic (CBCT) imaging in the detection of subtle vertical root fractures (VRFs) in endodontically treated teeth in vivo and to discuss direct and indirect evidence for the diagnosis of subtle VRFs.MethodsTwenty-nine endodontically treated teeth with suspected VRFs from 29 patients were examined using CBCT imaging. CBCT images were scored based on evaluation of the fracture line and vertical buccopalatal (lingual) bone loss. VRF was diagnosed only when a definite fracture line was detected on CBCT images, and findings of periodontal exploration or surgical extraction were considered the gold standard. The diagnostic sensitivity, specificity, and accuracy were assessed.ResultsOf the 29 teeth, 27 were positive and 2 were negative for VRF according to the gold standard. Sensitivity, specificity, and accuracy were 33.3%, 100%, and 37.9%, respectively, based on the direct finding of a fracture line on CBCT images. However, vertical buccopalatal (lingual) bone loss was found in 25 of 27 teeth with VRFs.ConclusionsAlthough the accuracy of CBCT imaging for the diagnosis of subtle VRFs in endodontically treated teeth in vivo was poor, vertical buccopalatal (lingual) bone loss is an important indirect sign for the diagnosis of VRFs, which can be found on CBCT images.     

Vertical root fractures in adjacent maxillary premolars: an endodontic-prosthetic perplexity

Vertical root fractures in endodontically treated teeth occur frequently in teeth or roots in which their mesiodistal dimension is narrow, such as the maxillary upper premolars. Two cases of vertical root fractures in two adjacent maxillary reconstructed teeth are presented. As in many cases of vertical root fractures, the primary diagnosis was of endodontic treatment failure. The final diagnosis of the fractures was made either by the radiograph showing separation of root segments in one case, or by surgical exploration in the other. In both cases, tooth extraction was unavoidable.     

Clinically Relevant Dimensions of 3-rooted Maxillary Premolars Obtained Via High-resolution Computed Tomography

Introduction

This study aimed to characterize the dimensions of a selection of 3-rooted maxillary premolars through high-resolution computed tomographic analysis considering measures of clinical interest for root canal treatment, such as root wall thickness, canal diameters, and distances between 2 canals in fused roots and between the root apex and foramen.

Methods

Fifteen 3-rooted human maxillary premolars extracted for therapeutic reasons were individually scanned using a high-resolution desktop high-resolution computed tomographic system. Starting from the apical foramen, the selected cross-sectional images corresponding to each millimeter of the roots were evaluated. Measures of clinical interest were determined using Image J software (version 1.41; National Institutes of Health, Bethesda, MD).

Results

Root wall thickness as thin as 0.4 and 0.6 mm was detected in the apical portion of buccal and palatal roots, respectively. In the cervical portion, buccal roots had narrower root walls (0.817–1.670 mm) compared with palatal roots (1.361–2.720 mm). In all thirds, the palatal canal was wider compared with the mesiobuccal and distobuccal canals. In the buccopalatal direction, all roots had thicker root walls toward the furcation, whereas in the mesiodistal direction the mesiobuccal and distobuccal roots had the thinnest walls along their distal and mesial aspects, respectively. Both buccal canals revealed dentin apposition 2 mm from the canal orifice, resulting in cervical constriction. Generally, the distance between the root apex and the foramen was greater in distobuccal roots in comparison with the others with a tendency for foramina to be eccentric.

Conclusions

Three-rooted premolars are a clinical challenge not just because of their low frequency and difficulties regarding diagnosis and root canals access but also because of their fragile roots. These phenomena are critical in terms of the amount of dentin removed during the preparation of root canals and during post space preparation.     

35颗牙根纵裂的临床分析

目的 探讨牙根纵裂的原因、诊断及其预防方法。方法 对32例35颗患牙的临床表现及X线片进行临床分析。结果 牙根纵裂好发于中老年人第一磨牙的近中(颊)根，均有不同程度的咬合创伤及牙周炎。结论 咬合创伤是牙根纵裂的主要原因，X线检查有助诊断，牙根纵裂缺乏有效的治疗方法，应以预防为主。     

Influence of Metal Post in Adjacent Teeth in the Detection of Vertical Root Fracture Using Cone-beam Computed Tomography with Different Acquisition Parameters

IntroductionThe aim of the present study was to evaluate the detection of vertical root fracture (VRF) in the presence of adjacent teeth restored with a metal post and the influence of acquisition parameters (tube current and metal artifact reduction [MAR] algorithm) on this diagnostic task.MethodsCone-beam computed tomographic images of 10 single-rooted teeth were acquired before and after the simulation of VRF. The acquisitions were set up to simulate different conditions regarding the presence of adjacent teeth restored with a metal post (control, 1 adjacent tooth, and both adjacent teeth), different tube currents (4, 8, and 10 mA), and the use of MAR (without MAR and with MAR). Images were assessed by 5 oral and maxillofacial radiologists using a 5-point scale for the presence of VRF. Diagnostic values were calculated and compared by 2-way analysis of variance (significance level of 5%).ResultsThe area under the receiver operating characteristic curve (Az) values for VRF detection were affected by the presence of adjacent teeth and the variation of milliamperes. For 4 mA, when both restored teeth were present, Az values were significantly lower than the control group (P ≤ .05). In the presence of both restored teeth, 8 mA presented significantly higher Az values compared with 4 mA (P ≤ .05).ConclusionsThe presence of both adjacent teeth restored with a metal post impairs VRF detection; however, an increase in tube current up to 8 mA may aid in this diagnostic task. Moreover, the MAR tool does not seem to be efficient in those cases.     

2种根尖定位仪诊断牙根纵裂的临床研究

目的研究RootZX和ProPex根尖定位仪用于诊断牙根纵裂的可靠性与准确性。方法分别用RootZX和ProPex根尖定位仪测量临床上疑为牙根纵裂患牙的根管工作长度,按照测量长度插入诊断丝,拍摄X线片。正常根管中诊断丝止于距根尖孔0．5～1．0mm范围内,诊断丝终止位置距根尖孔长度为牙根长度1／3及以上者初步诊断为牙根纵裂。拔除患牙后测量根管实际长度与纵裂根管长度,与电测长度进行比较。结果临床疑似牙根纵裂患牙48颗,经根尖定位仪联合X线检查初步诊断牙根纵裂48颗,拔牙后确诊牙根纵裂42颗,确诊率为87．5％。42颗牙根纵裂患牙中,RootZX电测长度平均值为（8．78±0．87）mm;ProPex电测平均值为（8．73±0．85）mm;根管实际长度平均值为（19．26±0．82）mm;纵裂根管长度平均值为（8．61±0．78）mm。RootZX和ProPex2种根尖定位仪的电测长度皆小于根管实际长度（P〈0．001）;RootZX电测值、ProPex电测值、纵裂根管长度之间差异无统计学意义（F=1．342,P〉0．05）。结论根尖定位仪有助于牙根纵裂的临床诊断。     

Relationship of the Incidence of C-shaped Root Canal Configurations of Mandibular First Premolars with Distolingual Roots in Mandibular First Molars in a Taiwanese Population: A Cone-beam Computed Tomographic Study

Introduction

The aim of this study was to determine the prevalence of C-shaped canal configurations (CSs) and radicular grooves (RGs) in permanent mandibular first premolars (MPs) and to investigate the relevance of such complexities with the presence of distolingual roots (DLRs) in permanent mandibular first molars (MMs).

The Performance of a Zirconium-based Root Filling Material with Artifact Reduction Properties in the Detection of Artificially Induced Root Fractures Using Cone-beam Computed Tomographic Imaging

Introduction

Limited field of view cone-beam computed tomographic (CBCT) imaging has been used to augment clinical testing of vertical root fractures (VRFs); however, the presence of gutta-percha (GP) in the canal space generates substantial imaging artifacts that make fracture detection difficult. The purpose of this study was to evaluate the influence of a zirconium (Zr)-based root filling material with radiologic properties that reduce beam hardening (BH) artifacts using CBCT imaging in the in vitro diagnosis of VRFs.

47例冠根纵折的临床分析

目的：对47例冠根纵折的患牙进行分析，探讨最佳的治疗方法和预防措施。方法：通过观察47例冠根纵折的病例，对牙位、牙髓状态、牙髓治疗情况进行回顾性分析。结果：牙冠纵折多见后牙，以上颌第一磨牙为多见，其中无髓牙33例，牙折裂前有近一半曾作过根管治疗，活髓牙14例，存在不同程度的牙隐裂，牙周炎和咬合创伤。结论：牙折裂只要采取及时有效的治疗，部分患牙是可以保留的。积极诊治牙隐裂、合理的牙髓治疗及全冠修复是预防牙折裂的有效方法。     

Risk Factors for and Clinical Presentations Indicative of Vertical Root Fracture in Endodontically Treated Teeth: A Systematic Review and Meta-analysis

IntroductionThe aim of this study was to identify specific clinical signs or symptoms and potential risk factors which are most likely associated with the presence of a vertical root fracture (VRF) in endodontically treated teeth (ETT).MethodsElectronic databases (MEDLINE via PubMed, EMBASE via Ovid, Scopus, and Web of Science) were searched by 2 reviewers in October 2022 for clinical studies, in which at least either the clinical presentation or potential risk factors associated with a VRF were assessed. Risk of bias was assessed using the Newcastle-Ottawa scale. Meta-analyses of odds ratios (ORs) were performed separately for several signs or symptoms and risk factors.ResultsFourteen sources reporting on 2877 teeth (489 with VRF and 2388 without VRF) were included in the meta-analyses. Regarding the clinical presentation, the presence of sinus tracts (OR = 4.87; 95% confidence interval [CI], 1.58–15.0), increased periodontal probing depths (OR = 13.24; 95% CI, 5.44–32.22), swelling/abscess (OR = 2.86; 95% CI, 1.74–4.70), and tenderness to percussion (OR = 1.76; 95% CI, 1.18–2.61) were significantly associated with the presence of a VRF (P_adj. value < .05). None of the assessed risk factors (sex, type of teeth, tooth location, posts, indirect restoration, and apical extension of the root canal filling) were found to be significantly associated with the presence of a VRF (P_adj. value > .05).ConclusionsFour clinical presentations were identified to be the most significant signs or symptoms for a VRF in ETT: presence of sinus tracts, increased probing depths, swelling/abscess, and tenderness to percussion. None of the assessed risk factors pointed out to be significantly associated with a VRF. Registration: CRD42022354108 (PROSPERO).     

Accuracy of High-resolution Small-volume Cone-Beam Computed Tomography in the Diagnosis of Vertical Root Fracture: An In Vivo Analysis

IntroductionThe purpose of this in vivo study was to evaluate the accuracy of small-volume cone-beam computed tomographic (CBCT) imaging compared with conventional periapical radiography (CPR) in the diagnosis of vertical root fractures (VRFs) using exploratory surgery as the reference standard.MethodsEighty-two dental records of 85 teeth with suspected VRFs that underwent CPR, CBCT imaging, and exploratory surgery were included. Two observers assessed CPR and CBCT images independently for the presence or absence of root fractures, and findings from the exploratory surgery were considered the reference standard. Diagnostic sensitivity, specificity, accuracy, and the receiver operating characteristic curve values were obtained. The effect of single- and multirooted teeth on diagnostic accuracy as well as the association between clinical symptoms and the presence of VRFs were also assessed.ResultsVRFs were surgically detected in 64 of the 85 teeth (75.3%), of which 62.5% were multirooted and 76.6% had intracanal posts. CBCT imaging was more sensitive and accurate (65.6% and 64%) than CPR (27.3% and 40.5%). Both CPR and CBCT diagnostic accuracies were higher in single- than multirooted teeth. Pain on percussion, a localized periodontal pocket, and tooth mobility were associated with the presence of VRFs (P < .05; odds ratio = 4.15, 13.5 and 4.1, respectively).ConclusionsThe accuracy of CBCT imaging for the diagnosis of VRFs was poor, although it was higher than with CPR. Multirooted teeth in the presence of intracanal posts may limit its diagnostic value.     

Middle Mesial Canal Preparation Enhances the Risk of Fracture in Mesial Root of Mandibular Molars

IntroductionThe aim of this investigation was to evaluate the effect of the presence and preparation of middle mesial (MM) canals on the fracture resistance of the mesial root of mandibular molars.MethodsForty intact mesial roots of mandibular first molars having 2 (n = 20) or 3 (n = 20) independent canals from the furcation level for up to at least 5 mm apically were selected based on preoperative micro–computed tomographic scanning. The selected roots were then distributed into 2 experimental (n = 10) and 2 control groups (n = 10) according to the root length, canal configuration (2 or 3 independent canals), and root thickness at the furcation level. In the experimental groups 1 (2 independent canals) and 3 (3 independent canals), root canals were enlarged up to the ProTaper Next X3 rotary instrument (Dentsply Sirona, Ballaigues, Switzerland), whereas in groups 2 (2 independent canals) and 4 (3 independent canals) root canals were not prepared. The specimens were embedded in acrylic resin after their surfaces were coated with a thin layer of silicone and subjected to a fracture strength using a universal testing machine. The types of fracture extension and course were recorded and statistically compared with the chi-square test, whereas fracture strength was analyzed using 1-way analysis of variance and post hoc Tukey tests (α = 5%).ResultsNo statistical difference in fracture strength was observed between nonprepared roots with 2 (group 2, 696.1 ± 186.3 N) or 3 (group 4, 558.4 ± 154.6 N) independent canals (P > .05), whereas the lowest values were obtained in the prepared roots with an MM canal (groups 3, 377.1 ± 77.2 N) (P < .05). The mean fracture strength observed in the prepared roots with 2 canals (group 1, 528.4 ± 134.3 N) showed no statistically significant difference compared with nonprepared roots with 3 canals (group 4, 558.4 ± 154.6 N) (P > .05). The chi-square test revealed no significant differences in fracture extent, types, and courses among groups (P > .05). Fracture extensions in all groups were mostly central and buccal-central types, whereas the highest frequency of fracture course was the curved and zigzag types.ConclusionsThe fracture resistance of the mesial roots of the mandibular molars decreased after the preparation of mesial canals with large-tapered instruments. Preparation of the MM canal further diminished the fracture resistance of the mesial roots. The resultant fracture displayed a distinct pattern in the buccolingual plane.     

Occurrence of Vertical Root Fractures after Apical Surgery: A Retrospective Analysis

IntroductionVertical root fractures (VRFs) are among the most frequent causes of tooth loss, mainly of endodontically treated teeth. However, very few data is available about the occurrence of VRFs following apical surgery.MethodsPatient charts from 864 patients with 1058 teeth treated with apical surgery (September 1999 to December 2018) were retrospectively evaluated, if a VRF had occurred after surgery. The following, possibly influencing factors were analyzed: sex and age, type of treated tooth, primary versus resurgery, technique of root-end preparation, and timepoint of VRF diagnosis. Endpoints were either tooth extraction or the last follow-up.ResultsThe study cohort (55% women, 45% men) had a mean age of 52.00 ± 13.97 years (range 9–93 years). The overall rate of VRFs after apical surgery was 4% (42 of 1058 teeth). Among these 42 teeth, 33.3% were mandibular first molars and 26.2% were maxillary second premolars. The most frequently affected root was the mesial root of mandibular first molars (28.6%). With regard to the study parameters, significant differences of VRF rates were observed only for the type of tooth treated.ConclusionsA low VRF rate of 4% was observed in this study. VRFs commonly occurred in maxillary premolars and mandibular molars, with the mesial root of mandibular first molars affected most frequently. This is in line with previous reports about VRFs in endodontically treated teeth without additional apical surgery.     

热牙胶垂直加压充填根管后即刻纤维桩树脂核桩冠修复短期疗效观察

目的评价热牙胶垂直加压充填根管后即刻纤维桩树脂核桩冠修复牙体缺损的短期疗效。方法 31例患者共88颗患牙,热牙胶垂直加压技术充填根尖4～5mm后,即刻行纤维桩树脂核桩冠修复。观察评价根管充填效果、术后疼痛情况及修复1年后患牙功能状况。结果 88颗患牙根管三维充填致密,恰填,桩道预备无侧穿等并发症发生。4例患者的4颗患牙24h内有二级疼痛,口服消炎止痛药物后疼痛在1周内消失;1年后复诊X线片均无根尖阴影出现,无纤维桩脱落,成功率100%。结论采用热牙胶垂直加压技术充填根管后即刻行纤维桩树脂核桩冠修复,简便易行,治疗周期短,短期疗效可靠。