It is a basic prerequisite for the successful completion of endodontic treatment to thoroughly understand the root canal space anatomy. With the development of dental devices in dentistry, the root canal morphology of the mandibular first premolars can be presented in more detail. Before conducting root canal therapy on the mandibular first premolar with complex root canal morphology, it should be necessary to evaluate the potential difficulties and risks for making an appropriate treatment plan. The present paper reviews the research progress on the diversities of root canal morphology in mandibular first premolars in recent years, and then makes technologic recommendations based on the morphology diversities.
Humans ; Dental Pulp Cavity/diagnostic imaging* ; Bicuspid/anatomy & histology* ; Mandible ; Tooth Root/anatomy & histology* ; Root Canal Therapy

Root canal therapy and endodontic surgery are conventional treatments for pulpal and periapical diseases. Compared with naked-eye operations, the application of dental operating microscope has enhanced the procedural accuracy and prognosis efficiently. However, root canals with pulp calcification/obliteration, apical lesions with thick cortical bone or adjacent to important anatomic structures are even challenging for experienced operators to achieve predictable clinical outcomes. Recently, with the advances in the field of digitalized information sciences, the above mentioned complicated endodontic cases can be solved under static and dynamic guidance. Before the treatment begins, virtual path is designed from data collected by cone-beam CT and oral image scanning using guidance software. Afterwards, root canal therapy and endodontic surgery can be performed precisely under the assistance of three-dimensional printed guide or dynamic guidance system. The present review describes the classification, features and clinical applications of the guided endodontics.
Cone-Beam Computed Tomography ; Dental Pulp Cavity ; Endodontics ; Humans ; Periapical Diseases/diagnostic imaging* ; Root Canal Therapy

Objectives: To evaluate the diagnostic consistency of working lengths by observing endodontic files in root canals and periapical subtle structures in digital intraoral radiographs presented in two smartphones, a tablet and a laptop computer. Methods: A dried human skull embedded in an acrylic compound was used for exposing radiographs of the upper and lower second premolars and first molars with two endodontic files (Kerr files size 10 and 15) positioned to the full length of the roots or 1.5 mm short of apexes. A total of 100 radiographs were taken for each of the file sizes. Five observers were asked to assess all the 200 digital radiographs according to a 5-category scale in smartphone A (HUAWEI P9 Plus), smartphjone B (Apple iPhone 7), tablet (Apple iPad 2018) and laptop computer (Lenovo Thinkpad E480), respectively. The gold standard for receiver operating characteristic curve (ROC) analysis was determined with the endodontic Kerr file size 20. A total of 150 roots with files were radiographed, 75 of which with files reaching the radiographic apexes of the respective roots and 75 of which with files 1.5 mm short of the radiographic apexes for each endodontic file size. Results from ROC analysis was analyzed with one-way ANOVA and independent sample t test. Results: For the Kerr file size 10, the area under the ROC curve for laptop, tablet and two smartphones were 0.891±0.037, 0.869±0.037, 0.870±0.017 and 0.849±0.037, while for the Kerr file size 15 the ROC values were 0.957±0.02, 0.961±0.02, 0.961±0.01 and 0.961±0.02, respectively. There were no significant differences for diagnostic accuracy for observing endodontic file positions among digital radiographs presented in the two smartphones, one tablet and one laptop devices (endodontic file size 10: F=1.39, P=0.281; endodontic file size 15: F=0.05, P=0.985). A significant difference was found in the diagnostic accuracy of endodontic file positions between size 10 and 15 files in different display devices (t=-10.65, P<0.001). Conclusions: There was a high diagnostic consistency in the determination of working length and periapical subtle structures of roots by observing digital radiographs displayed on smartphones, tablet and laptop computer.
Dental Instruments ; Dental Pulp Cavity/diagnostic imaging* ; Electronics ; Humans ; Molar ; Observer Variation ; Root Canal Preparation

OBJECTIVE: To investigate the short-term clinical effect of lumbar nerve root canal injection under X-ray angiography in the treatment of sciatica. METHODS: The clincal data of 78 patients with sciatica underwent lumbar nerve root canal injection under X-ray angiography from December 2017 to February 2020 was retrospectively analyzed. Including 31 males and 47 females, aged from 22 to 88 years old with a median of 65 years. There were 55 cases of lumbar disc herniation and 23 cases of lumbar spinal stenosis, the course of disease ranged from 1 to 8 weeks with a median of 3 weeks. There were 71 cases of single segment disc herniation or stenosis, including L_3,4 of 5 cases, L_4,5 of 61 cases, L₅S₁ of 5 cases, and 7 cases of multisegment herniation or stenosis. The pain visual analogue scale (VAS) was recorded and Macnab was used to evaluate the clinical effect. RESULTS: All patients completed standardized treatment without serious adverse reactions. VAS were (3.21±0.76) scores immediately after treatment, (2.89±0.33) scores 1 hour after treatment, (1.80±0.27) scores 6 hours after treatment, (1.10±0.20) scores 24 hours after treatment, (2.53±0.35) scores 1 week after treatment and (4.27±0.36) scores 1 month after treatment. There were significant differences in VAS between before treatment(7.83±0.56) and each time period after treatment(P<0.05). According to Macnab low back pain evaluation standard, 42 cases were effective, 34 cases were markedly effective and 2 cases were ineffective within 24 hours after treatment, with an effective rate of 97.4%;38 cases were effective, 25 cases were markedly effective, 15 cases were ineffective within one week after treatment, the effective rate was 80.0%;32 cases were effective, 22 cases were markedly effective, 24 cases were ineffective within one month after treatment, the effective rate was 69.2%. CONCLUSION The short-term clinical effect of nerve root canal injection under X-ray radiography in the treatment of sciatica is good and it is an effective method to relieve sciatica.
Adult ; Aged ; Aged, 80 and over ; Angiography ; Dental Pulp Cavity ; Female ; Humans ; Intervertebral Disc Displacement/diagnostic imaging* ; Lumbar Vertebrae/diagnostic imaging* ; Male ; Middle Aged ; Retrospective Studies ; Sciatica/drug therapy* ; Treatment Outcome ; X-Rays ; Young Adult

OBJECTIVEThis research aimed to analyze the three-dimensional position of mandibular canal (MC) and man of MC and its relationship with the surrounding structures dibular morphology of normal young males and females by using data from cone beam computed tomography (CBCT), as well as to provide an anatomical basis for clinical surgery of the mandible.

METHODSNormal occlusion and CBCT scans of 29 normal young people were conducted. InVivo 5 software was used to reconstruct the mandible, anchor the points, and measure the jaw shape and three-dimensional course of MC. All measurements were analyzed with SSPS 17.0 software.

RESULTSThe MC lingual bone cortex was thinner than the MC buccal bone cortex, and the distance of the MC to the buccal bone cortex gradually increased. However, the distance of the MC to the tongue bone cortex and alveolar crest gradually decreased from proximal to distal. In addition, the distance of the MC to the mandibular lower margin was minimal at the first molar and reached the maximum at the second premolar. No significant difference was observed among the heights, widths, and thicknesses of the left and right sides of the cortical bone of the mandibular body cross sections. From the midline to the farthest point, the height and lower one-third thickness of the lingual cortical bone of the mandibular body cross sections gradually decreased, whereas the width of the upper cross section and upper one-third thickness of the buccal cortical bone gradually increased. Significant difference was observed in some measured values.

CONCLUSIONAfter MC enter into the mandibular foramen, it moved away from the lingual to the buccal bone but gradually returned to the lingual bone; its general course is closer to the lingual bone. The mandibles of males are thicker than those of females. CBCT can accurately display the course of MC and its relationship with the surrounding structures.

Alveolar Process ; Bicuspid ; Cone-Beam Computed Tomography ; methods ; Dental Pulp Cavity ; Female ; Humans ; Hyoid Bone ; Male ; Mandible ; anatomy & histology ; diagnostic imaging ; Molar ; Software ; Surveys and Questionnaires ; Tongue ; Zygoma

Cone-Beam Computed Tomography ; Dental Pulp Cavity ; diagnostic imaging ; Humans ; Root Canal Therapy ; instrumentation

This case report is to present a maxillary first molar with one O-shaped root, which is an extended C-shaped canal system. Patient with chronic apical periodontitis in maxillary left first molar underwent replantation because of difficulty in negotiating all canals. Periapical radiographs and cone-beam computed tomography (CBCT) were taken. All roots were connected and fused to one root, and all canals seemed to be connected to form an O-shape. The apical 3 mm of the root were resected and retrograde filled with resin-modified glass ionomer. Intentional replantation as an alternative treatment could be considered in a maxillary first molar having an unusual O-shaped root.
Adult ; Anatomic Variation ; Apicoectomy ; methods ; Cone-Beam Computed Tomography ; methods ; Dental Pulp Cavity ; diagnostic imaging ; pathology ; Glass Ionomer Cements ; therapeutic use ; Humans ; Male ; Maxilla ; Molar ; diagnostic imaging ; pathology ; Periapical Periodontitis ; therapy ; Retrograde Obturation ; methods ; Root Canal Filling Materials ; therapeutic use ; Root Canal Preparation ; methods ; Tooth Replantation ; 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<0.05). 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.
Adult ; Aged ; Anatomic Variation ; Asian Continental Ancestry Group ; Chi-Square Distribution ; China ; Dental Pulp Cavity ; anatomy & histology ; diagnostic imaging ; Female ; Humans ; Male ; Mandible ; Microscopy ; Middle Aged ; Molar ; anatomy & histology ; Radiography, Dental ; Tooth Root ; anatomy & histology ; Young Adult

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.
Adult ; Asian Continental Ancestry Group ; China ; Dental Pulp Cavity ; anatomy & histology ; diagnostic imaging ; Female ; Humans ; Imaging, Three-Dimensional ; Maxilla ; Molar ; anatomy & histology ; diagnostic imaging ; Molar, Third ; anatomy & histology ; diagnostic imaging ; Root Canal Therapy ; Tomography, X-Ray Computed ; methods ; Tooth Root ; anatomy & histology ; diagnostic imaging

The aim of this study was to analyze the specific influence of root canal anatomy on the accessibility of working length during root canal therapy. Four hundred seventy-six root canal therapy cases (amounting to a total of 1 005 root canals) were examined. The anatomy risk factors assessed in each case included: tooth type (tooth location), root canal curvature, and root canal calcification, as well as endodontic retreatment. The investigation examined the correlation between each of these anatomic factors and the working length, with statistical analysis consisting of Chi-square tests and multiple logistic regression analysis. In an independent factor analysis, tooth type (tooth location), root canal curvature, canal calcification, and endodontic retreatment were determined to be the primary risk factors. In a multiple-factor regression model, root curvature and canal calcification were found to most significantly influence root canal working length accessibility (P<0.05). Root canal anatomy increases the difficulty of root canal preparation. Appropriate consideration of tooth anatomy will assist in accurate determination of preparation difficulty before instrumentation. This study alerts clinical therapists to anatomical factors influencing the working length accessibility, and allows for a direct estimate of success rate given in situ measurements of tooth factors during the root canal treatment procedure.
Chi-Square Distribution ; Dental Pulp Calcification ; pathology ; Dental Pulp Cavity ; anatomy & histology ; diagnostic imaging ; Humans ; Logistic Models ; Odontometry ; Radiography ; Retreatment ; Risk Factors ; Root Canal Preparation ; instrumentation ; Tooth Apex ; Tooth Root ; anatomy & histology