Complicated Root Canal Morphology of Mandibular Lateral Incisors Is Associated with the Presence of Distolingual Root in Mandibular First Molars: A Cone-beam Computed Tomographic Study in a Taiwanese Population

Introduction

The aim of this study was to assess the root canal configurations in permanent mandibular lateral incisors (PMLIs) and the correlation between the root canal configurations of PMLIs with the appearance of a distolingual root (DLR) in permanent mandibular first molars (PMFMs) using cone-beam computed tomographic (CBCT) imaging.

The Presence of Distolingual Root in Mandibular First Molars Is Correlated with Complicated Root Canal Morphology of Mandibular Central Incisors: A Cone-beam Computed Tomographic Study in a Taiwanese Population

Introduction

The aim of this study was to assess the prevalence of complicated root canals in permanent mandibular central incisors (PMCIs) and its correlation with the presence of a distolingual root (DLR) in permanent mandibular first molars (PMFMs) using cone-beam computed tomographic imaging in a Taiwanese population.

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.     

Evaluation of Root and Canal Morphology of Maxillary Permanent First Molars in a North American Population by Cone-beam Computed Tomography

Introduction

The purpose of this study was to evaluate the number of roots and canal morphology of maxillary permanent first molars in a North American population.

Methods

Three hundred seventeen cases with bilateral maxillary first molars were included. All images from cone-beam computed tomography were carefully reviewed by 2 endodontists. Frequency of number of roots, presence of an additional mesiobuccal canal (MB2), and Vertucci canal type for each root were tabulated. Age, gender, and ethnicity differences were calculated with the χ² test. The intra-rater reliability was assessed by using the Cohen kappa statistic.

Results

The fused root rate was 0.9%. The occurrence of 3-rooted maxillary first molars differed between left and right sides (P = .03). MB2 occurrence only showed statistically significant differences among age groups (P = .005). In the mesiobuccal roots, the most common Vertucci classifications of canal types were type IV (2-2, 41.9%), type I (1, 28.3%), and type II (2-1, 26.3%). There was a statistically significant difference in Vertucci classification of canal type among 5 ethnic groups (African American, Asian, Hispanic, Other, and Non-Hispanic white, P < .001).

Conclusions

Cone-beam computed tomography facilitates the identification of root and canal configuration. The information gained about the tooth anatomy and canal morphology before treatment could potentially facilitate root canal therapy.     

Morphology of Mandibular First Molars Analyzed by Cone-beam Computed Tomography in a Korean Population: Variations in the Number of Roots and Canals

Introduction

The aim of this study was to determine the root and canal morphology of the mandibular first molars in a Korean population of Mongolian origin by retrospective analysis of a large number of cone-beam computed tomography (CBCT) images.

Methods

A total of 976 subjects with bilateral mandibular first molars were examined by using in vivo CBCT methods. The number and configuration of roots, the number of root canals, and the canal configuration based on Vertucci's classification were determined.

Results

Overall, 25.82% of examined molars had 3 roots, 73.51% had 2 roots, and 0.67% had 1 root. The incidence of fourth canal was 50.36%. A right-sided predominance was noted for extra distal roots (P < .001), whereas a left-sided predominance was observed for extra distal canals (P < .001). No significant sex-related differences were shown for their prevalence. The bilateral prevalence rate was 69.13% for extra distal roots and 78.08% for extra distolingual (DL) canals. In the mesial roots, type IV canal was the most frequent (76.86% for 2-rooted molars and 72.96% for 3-rooted molars). In the distal roots, type l was the most common (66.62% for 2-rooted molars and 99.40%–100% for 3-rooted molars). The incidence of 2 canals in distobuccal roots, first reported in this study, was 0.15%.

Conclusions

Among mandibular first molars, there is a high prevalence of a separate DL root and/or a separate DL canal, and such molars commonly have 4 canals in the Korean population. CBCT is a useful tool for determining root and canal morphology.     

Four-year Outcome of Nonsurgical Root Canal Retreatment Using Cone-beam Computed Tomography: A Prospective Cohort Study

IntroductionThe purpose of this prospective study was to investigate the 4-year outcome and prognostic factors of nonsurgical root canal retreatment determined by measuring the volumetric change of periapical radiolucencies on cone-beam computed tomographic (CBCT) scans.MethodsNinety-seven endodontically treated teeth from 80 patients diagnosed as apical periodontitis and indicated for root canal retreatment were included. Retreatment was performed by 7 endodontic specialists using a standardized treatment protocol. The teeth were reexamined clinically and radiographically 48–67 months after retreatment. The volume of preoperative and postoperative periapical radiolucencies on CBCT images was independently measured by 2 examiners. Radiographic outcome is presented in 4 categories: absence, reduction, enlargement, or unchanged. Reduction or enlargement was determined when the volumetric change of radiolucency was 20% or more. Multivariate logistic regression was performed for predictor analysis.ResultsSixty-two teeth (63.9%) from 50 patients returned for follow-up. Fifty-eight teeth were included in the prognostic analysis, all of which were symptom free. The 4 remaining teeth that had been extracted because of fracture were excluded. The total volume of periapical radiolucencies at 4 years postoperatively decreased by 94.6% compared with that preoperatively (P < .001), with an average reduction of 83.4% (95% confidence interval, 69.2%–97.5%). The periapical radiolucencies were determined as absence in 44 teeth (75.9%), reduction in 10 teeth (17.2%), unchanged in 1 tooth (1.7%), and enlargement in 3 teeth (5.2%). Tooth type was identified as an outcome predictor (P < .05).ConclusionsThe 4-year outcome of endodontic retreatment is predictable, with a significant volumetric reduction in periapical radiolucencies.     

CBCT与RVG对下颌恒切牙根管形态评估的对比研究

目的:对比CBCT法与数字化X线成像法(RVG)对下颌恒切牙根管形态评估的差异。方法:对101颗离体牙进行唇舌向及近远中向数字化X线片拍摄和CBCT高清牙列模式扫描,对图像进行根管数目、Vertucci根管分型、根管钙化和根尖口开口位置的评估,并通过CBCT图像建立偏角度投照的三角函数模型,计算偏向投照的角度。结果:CBCT法显示有30颗为双根管,RVG近远中向投照显示有36颗为双根管,卡方检验显示对根管数目和Vertucci根管分型两种方法均具有显著性差异(P<0.05)。两种方法对根管钙化和根尖口开口位置的评估均不具有显著性差异。30颗双根管牙中下颌恒切牙唇舌向双根管的最大距离(LaL)在0~1.5 mm之间的,85.7%的为Vertucci III型,LaL在1.5~2 mm之间的,66.7%为Vertucci IV和V型。以根尖片上双根管显示距离为1 mm计算,LaL在1~2 mm之间的,偏向投照角度为26.6°~45.0°,LaL在0.1~1 mm之间的,偏向投照角度为45.0°~84.3°。结论:CBCT高清牙列模式扫描和RVG投照对于根管数目和Vertucci根管分型的评估具有显著性差异,对于根管钙化和根尖口开口位置的评估不具有显著性差异。LaL在1~2 mm之间时,偏角度投照的临床可操作性较强。     

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).

Three-dimensional Analysis of Root Canal Curvature and Direction of Maxillary Lateral Incisors by Using Cone-beam Computed Tomography

Introduction

Root canal curvature can affect the technical quality of endodontic treatment. Prior studies measured canal curvature mainly by 2-dimensional radiography. The aim of this study was to measure the 3-dimensional (3D) root canal curvature and canal direction of maxillary lateral incisors by using cone-beam computed tomography (CBCT) and mathematical modeling.

Methods

The CBCT images of 186 maxillary lateral incisors from 110 patients were used to measure 3D root canal curvature by using V-works and kappa software. In addition, the direction of each root canal was determined by measuring the orientation of the apical one-third with respect to the coronal two-thirds.

Results

All 186 maxillary lateral incisors were found to have canal curvature that was mainly oriented in the disto-palatal direction. The point of maximum curvature was located 0.5 mm from the root apex.

Conclusions

Maxillary lateral incisors have 3D canal curvature that is maximal near the root apex, oriented in the disto-palatal direction. These CBCT analyses provide valuable information for root canal instrumentation of maxillary lateral incisors.     

Anatomic Study of Mandibular Posterior Teeth Using Cone-beam Computed Tomography for Endodontic Surgery

Introduction

The present study aimed to anatomically assess mandibular posterior teeth using cone-beam computed tomographic (CBCT) imaging for endodontic surgery.

Symmetry of Root and Root Canal Morphology of Maxillary and Mandibular Molars in a White Population: A Cone-beam Computed Tomography Study In Vivo

Introduction

The aim of the present study was to use cone-beam computed tomography (CBCT) to analyze root canal anatomy and symmetry of maxillary and mandibular first and second molar teeth of a white population.

Methods

A total of 201 patients who required CBCT examinations as part of their dental diagnosis and treatment were enrolled in the present study. Overall, 596 healthy, untreated, well-developed maxillary and mandibular molar teeth (161 maxillary first molars, 157 maxillary second molars, 117 mandibular first molars, and 161 mandibular second molars) were examined by CBCT to establish the symmetry in root and canal anatomy between right and left sides in the same patient by evaluating the number of roots and root canals and the root canal configuration.

Results

Three separate roots with 3 separate canals was the normal anatomy of maxillary first and second molars. Most mandibular first and second molars had 2 separate roots, and the majority had 3 canals. In the present study, first molars, both maxillary and mandibular, exhibited greater asymmetry than the second molars. Maxillary first molars were found to be symmetrical in 71.1% of patients, whereas maxillary second molars were symmetrical in 79.6%. The remaining 28.9% and 20.4% of patients, respectively, showed asymmetry. Around 30% of the mandibular first molars and 20% of the mandibular second molars showed asymmetry.

Conclusions

The results of the present study reported a percentage of symmetry that varied from 70%–81%. These variations in symmetry should be taken in high consideration when treating 2 opposite molars in the same patient, because their anatomy may be different in up to 30% of the cases.     

A Cone-beam Computed Tomographic Study of Root and Canal Morphology of Maxillary First and Second Permanent Molars in a Thai Population

Introduction

Understanding tooth anatomy is crucial for effective endodontic treatment. This study investigated the roots and root canal morphology of maxillary first and second permanent molars in a Thai population using cone-beam computed tomographic (CBCT) imaging.

Rare Root Canal Configuration of Mandibular Second Premolar Using Cone-beam Computed Tomographic Scanning

The aim of this case report was to demonstrate how the use of cone-beam computed tomographic (CBCT) imagery is beneficial when treating a tooth with an unusual anatomic variation. A 43-year-old female patient presented to our private practice after a referral from her general dentist. Endodontic therapy was previously initiated and unable to be completed because of suspicious anatomic anatomy. CBCT imagery confirmed the presence of a C-shaped root configuration and 3 canals within the tooth. Root canal treatment was completed successfully without complications. The use of CBCT imaging was valuable in determining the root morphology and rare canal anatomy to enhance treatment and success.     

The Global Prevalence of Middle Mesial Canal in Mandibular First and Second Molars Assessed by Cone Beam Computed Tomography: A Systematic Review and Meta-Analysis

IntroductionThis meta-analysis sought to identify the in vivo prevalence and influencing factors of middle mesial canal (MMC) in mandibular first and second molars based on cone-beam computed tomography (CBCT) scans.MethodsMEDLINE/PubMed, Web of Science, Scopus, SciELO, Google Scholar databases/search engines were searched in period between 15^th and 21^st November 2022, to retrieve the in vivo CBCT-based studies that assessed the prevalence of MMC in mandibular first and/or second molars. The studies were strictly assessed using predefined inclusion and exclusion criteria for relevancy and eligibility through screening the title and abstract, and then assessed through reading the full texts using the same criteria. Subsequently, the fulfilled studies were assessed qualitatively using the Newcastle-Ottawa Quality Assessment Scale, and quantitatively using meta-analysis to calculate the pooled prevalence rates of MMC. The publication bias was assessed using funnel plot and Egger's test.ResultsOut of 1122 studies, 33 studies comprised of 13,349 and 7624 mandibular first and second molars, respectively, were eligible for inclusion. Twenty studies scored high quality, while 13 scored moderate quality. The global prevalence of MMC in the first molar was 4.4% (95% CI = 0.035–0.053, P < .001), significantly higher than that of the second molar which was 1.3% (95%, CI = 0.008–0.018, P < .001). Gender, molar side, and age were not influencing factors of MMC prevalence.ConclusionsThe prevalence of MMC is not uncommon, being higher in the mandibular first molar compared to the mandibular second molar. The prevalence of MMC is not influenced by age, molar's side, and gender.     

Root Canal Morphology of South Asian Indian Mandibular Premolar Teeth

Introduction

The purpose of this study was to study the root canal morphology of South Asian Indian mandibular premolars using a tooth clearing technique.

Methods

Two hundred mandibular premolar teeth were collected from different dental schools and clinics in India. After pulp tissue removal and root canal staining with Indian ink, the specimens were decalcified with 5% nitric acid, dehydrated in ethyl alcohol, and subsequently cleared in methyl salicylate.

Results

Of the 200 mandibular premolars, 100 were first premolars and 100 were second premolars. Of the first premolars, 94% had a single root, whereas 6% were 2 rooted. Seventy-six percent had a single canal, 22% had 2 canals, and 2% had 3 canals. Eighty-two percent had a single apical foramen, 16% had 2 foramens, and 2% teeth had 3 apical foramens. Eighty percent of teeth had type I, 6% had type II, 10% had type IV, 2% had type V, and 2% teeth had type IX root canal anatomy. Of the 100 second premolars, 92% had a single root, whereas 8% teeth were 2 rooted and fused. Fifty-eight percent of teeth had a single canal, and 42% had two canals. Eighty-eight percent had a single apical foramen, and 12% had 2 foramens. Sixty-six percent had type I, 30% had type II, and 4% had type V root canal anatomy.

Conclusions

A high prevalence of 2 canals was noted in the first and second premolars. Also, 20% of first premolars and 34% of second premolars had a root canal anatomy other than type I.     

Incidence of Middle Mesial Canals Based on Distance between Mesial Canal Orifices in Mandibular Molars: A Clinical and Cone-beam Computed Tomographic Analysis

IntroductionThis study evaluated the presence of midmesial canals (MMCs) in a random sample of mandibular molars and the relationship of the intracanal distance between mesiobuccal (MB) and mesiolingual (ML) canal orifices.MethodsFifty-one extracted mandibular molars were divided into samples of 3 to 4 teeth, mounted in plaster and boxing wax, and immersed in water before cone-beam computed tomographic (CBCT) imaging. Two endodontic residents completed the access openings. The teeth and the CBCT images were interpreted for the presence of MMCs and the mesial intracanal distance. CBCT software measured the distance between the buccal of the MB canal to the lingual of the ML canal at the pulpal floor to determine the average length between the canals.ResultsSeven distinct MMCs were seen both clinically (incidence of 13.725%) and on the CBCT images. Twenty-seven teeth (52.94%) had ambiguous broad isthmi between the MB and the ML orifices. MMCs were present at the furcation level but merged with the MB or ML canal toward the apex in 6 of 7 teeth (85.71%). The mean distance between the mesial canals in teeth with MMCs was 3.643 mm, and it was 3.818 mm for teeth without MMCs. According to independent sample t testing, the P value was >.05.ConclusionsThe incidence of MMCs in mandibular molars appears consistent with the literature. However, there does not appear to be a statistically significant difference in the mesial intracanal distance in teeth with and without MMCs. Visualization of MMCs on CBCTs may be subjective. There does not appear to be a correlation between the presence of MMCs and an increased or decreased mesial intracanal distance.     

The Validity of Cone-beam Computed Tomography in Measuring Root Canal Length Using a Gold Standard

Introduction

The distance between a coronal reference point and the major apical foramen is important for working length determination. The aim of this in vitro study was to determine the accuracy of root canal length measurements performed with cone-beam computed tomographic (CBCT) scans using a gold standard.

Methods

A total of 162 teeth (198 root canals) in 16 dry human dentulous mandibles were scanned using a 3DX-Accuitomo CBCT scanner (Morita 3DX; J Morita Mfg Corp, Kyoto, Japan). The root canal length was measured with CBCT data. All teeth were extracted atraumatically and endodontically accessed; the root canal length was measured blindly using a #10 K-file (Dentsply Maillefer, Ballaigues, Switzerland) and served as the gold standard.

Results

The mean absolute difference of the CBCT-based root canal length from the gold standard was 0.46 mm (95% confidence interval, 0.41–0.50 mm). Only in 9 of 198 (4.5%) roots did the difference between the CBCT-based root canal length and the gold standard exceed 1 mm.

Conclusions

CBCT-based root canal length measurements are accurate and reliable when compared with a gold standard.     

锥体束CT对上颌第一磨牙近中颊根管形态的研究

目的：通过锥体束CT（cone--beam computed tomography,CBCT）成像系统分析上颌第一磨牙近中颊根根管形态及第二（second mesiobuccal,MB2）根管的发生率。方法：选择95名进行CBCT扫描的患者,共计180颗上颌第一磨牙,观察近颊根根管形态、MB2根管的发生率、左右侧发生比率及男女发生比率差异。结果：上颌第一磨牙近颊根管形态以Ⅲ型为主,MB2根管发生率为79．4％,左右侧发生比率无统计学差异（P=0．846）,男性发生率明显高于女性（P=0．043）。结论：上颌第一磨牙近颊根MB2根管的发生率较高,可通过CBCT有效的发现MB2根管,为临床诊疗提供依据。     

上颌第一、第二恒磨牙牙根和根管系统的锥形束CT研究

目的：运用锥形束CT（CBCT）观察中国人群双侧上颌第一、第二磨牙的牙根和根管系统的解剖形态,为临床根管治疗提供依据。方法：选择200名患者的双侧上颌第一、第二恒磨牙（上颌第一恒磨牙354颗、上颌第二恒磨牙360颗）的CBCT扫描数据,使用NNT软件分析上颌第一、第二恒磨牙的牙根数、根管数、根管分型以及双侧对称情况。结果：上颌第一、第二磨牙主要为三根（99.44%和84.44%）。上颌第二磨牙的单根和双根较多见（15.28%）,其根管系统形态复杂,在根尖区有融合趋势。上颌第一磨牙的根管系统主要为3根四根管（78.97%）。上颌第二磨牙的三根管和四根管发现率接近（分别为47.37%和51.64%）。上颌第一磨牙的近颊根管系统主要根管分型为：Ⅳ型（57.79%）、Ⅱ型（19.83%）和Ⅰ型（15.58%）。上颌第二磨牙的近颊根管系统主要根管分型为：Ⅰ型（48.14%）、Ⅳ型（30.43%）和Ⅱ型（17.39%）。上颌第一、第二磨牙的远颊根和腭根主要为单根单根管,存在少量和罕见的变异。上颌第一、第二磨牙近颊根的根管数目和根管分型左右对称。结论：上颌第一磨牙近颊根管系统变异普遍存在,MB2根管为其主要的变异形式。上颌第二磨牙牙根数目和根管形态变异类型多,单根牙和双根牙的根管走向复杂多变。CBCT可以为识别根管形态提供准确依据。     

Diagnosis of Vertical Root Fractures by Cone-beam Computed Tomography in Root-filled Teeth with Confirmation by Direct Visualization: A Systematic Review and Meta-Analysis

IntroductionThe purpose of this review was to determine the diagnostic accuracy of cone-beam computed tomographic (CBCT) imaging in detecting vertical root fractures (VRFs) in root-filled teeth compared with a reference standard (direct visualization).MethodsElectronic searches were performed in Medline, Scopus, Cochrane, and gray literature for English language articles until June 2020. Prospective and retrospective clinical studies using CBCT imaging to diagnose VRFs in root-filled teeth were included. Case reports and in vitro studies were excluded. The Quality Assessment of Diagnostic Accuracy Studies 2 tool was used to assess the risk of bias and applicability concerns. Meta-analysis was performed using Stata 16.1 software (StataCorp, College Station, TX) via the MIDAS v.3.0 package and METANDI module. Publication bias was evaluated using Deeks’ funnel plot analysis. Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) was performed to evaluate the certainty of evidence. This systematic review was registered in the Open Science Framework (10.17605/OSF.IO/7JKE2).ResultsEight articles were included in this systematic review and meta-analysis. Risk of bias assessment showed that 5 articles in the patient selection domain had low risk of bias with low applicability concern. In the index test and reference standard domains, 7 articles had moderate risk of bias with moderate applicability concern. Three articles had high RB in the flow and timing domain. There was no publication bias. CBCT imaging had a pooled sensitivity and specificity of 0.78 (95% confidence interval [CI], 0.64–0.88) and 0.80 (95% CI, 0.63–0.91), respectively, and an accuracy of 0.86 (95% CI, 0.83–0.89). CBCT imaging also had pooled positive and negative likelihood ratios of 4 and 0.2, respectively. In GRADE analysis, the quality of evidence was low for sensitivity and moderate for specificity when CBCT imaging was used for the diagnosis of VRF.ConclusionsThe overall quality assessment of the included articles showed that in the patient selection domain, the risk of bias was low, and it was moderate in the index test and reference standard domains. Evidence from this systematic review and meta-analysis indicates that CBCT imaging is still not a good tool for diagnosing VRFs in root-filled teeth compared with direct visualization.