Micro–Computed Tomography Analysis of the Root Canal Anatomy and Prevalence of Oval Canals in Mandibular Incisors

Introduction

This study aimed to describe the anatomy of the mandibular incisors by using micro–computed tomography.

Methods

Mandibular incisors (n = 340) were scanned at 19-μm voxel size resolution, and the numbers of canals were classified according to Vertucci classification, as well as the major and minor diameters of the root and root canals, presence of oval canals, and three-dimensional analysis of the apical third were also measured. Data were presented in terms of median and range for each anatomic classification.

Results

Overall, the specimens had 1 root canal (N = 257). The second most prevalent anatomy was Vertucci type III (N = 56). These anatomies represent 92% of the sample. The medians of the major diameter at the 1-, 2-, and 3-mm level of the most prevalent anatomies were 0.36, 0.39, and 0.47 mm for type I and 0.41, 0.51, and 0.66 mm for type III, respectively. The apical volume appears to be constant among these anatomies (0.63 and 0.59 mm³). Oval canals were found at the 1-mm apical level, with a prevalence of 16.7% for Vertucci type I and 37.5% for Vertucci type III. The presence of oval canals increased at the 3-mm apical level to 32.4% and 76.2% for Vertucci type I and III classifications, respectively.

Conclusions

Type I and III configurations represent 92% of the mandibular incisors studied. Within these anatomic configurations, oval-shaped canals in the apical third were not uncommon and more prevalent in the type III anatomy.     

Does the Orifice-directed Dentin Conservation Access Design Debride Pulp Chamber and Mesial Root Canal Systems of Mandibular Molars Similar to a Traditional Access Design?

Introduction

Despite the increasing reports on mechanical aspects of contracted endodontic access cavities (CECs), we believe that the biological aspects (debridement) have not been adequately investigated. This study examined if 1 type of CEC (orifice-directed dentin conservation [DDC] access) was able to debride the pulp chamber, root canals, and isthmus of mesial roots of mandibular molars similar to a traditional endodontic access cavity (TEC).

Geometric Analysis of the Distolingual Root and Canal in Mandibular First Molars: A Micro–computed Tomographic Study

IntroductionThe purpose of this study was to comprehensively assess by micro–computed tomographic imaging the anatomic features of distolingual (DL) roots and canals in mandibular first molars collected from 1 population.MethodsOne hundred two specimens were examined for the location and initial direction of the DL canal and the relationship between the distance of apical deviation and the angle of root curvature.ResultsAll DL roots had only 1 canal. A new 7-category classification system is proposed for the DL roots of mandibular first molars. Most DL roots were type IV (28 teeth), type III (26 teeth), and type V (25 teeth). The average canal curvature in all root types was over 25°. There was a positive correlation between the angles of root and canal curvature for types II, IV, and V (P < .05) but not for types I and III (P > .05). In the buccolingual view, most DL roots were straight, whereas in the mesiodistal view the root curvature was close to the maximum value. The orifice of the DL canal was 4 times further from the line that bisects a line between the mesiobuccal and mesiolingual canal orifices than the distobuccal canal. The angle between the mesiobuccal-mesiolingual line and the horizontal projection of the coronal third of the DL canal on the pulp floor was 8.1° ± 10.0° and 6.1° ± 8.2° for teeth from the left and right side, respectively. The angle between the inserted simulated file and the cementoenamel junction was 57.9° ± 6.3°. Seventy-three percent of the DL canals had no constriction in the apical area. The DL canals were narrow and had a conical frustum-like shape with a 0.04 taper at the apical portion.ConclusionsThe novel classification of the DL roots helps to better understand the clinically challenging anatomy of the root and canal.     

Analysis of Instrumentation Protocols Regarding the Quality of Mesial Canal Preparation in Mandibular Molars: A Micro–computed Tomographic Study

IntroductionThis study aimed to use micro–computed tomographic imaging to analyze the quality of the endodontic preparation of mesial canals in mandibular molars provided by 3 instrumentation protocols.MethodsForty-five extracted mandibular molars with 2 independent mesial canals were selected, and the initial micro–computed tomographic imaging was performed. The initial volume values of the canals were submitted to statistical analysis for paired division. The groups were determined according to the final enlargement of the canal and the working length adopted (ie, G25.06/+1 mm, G35.05/foramen, and G50.01/−1 mm). At the end of each instrumentation sequence, the root canals were scanned and analyzed with regard to the increase in the total and apical volume, centralization, and preparation transportation and the percentage of the total and apical uninstrumented walls.ResultsFor the intragroup comparison, the Wilcoxon test was used, and for the intergroup analysis, the Kruskal-Wallis and Dunn tests were used (P < .05). In the analysis of the canal total volume, a statistical difference was found between G25.06/+1 mm and the remaining groups (P < .05). In the apical third, a statistical difference was observed between G25.06/+1 mm and G50.01/−1 mm (P < .05). No statistical difference was found between the groups in terms of centralization and transportation of the preparation or in terms of the percentage of the total or apical uninstrumented walls.ConclusionsThe preparation of the mesial canals of mandibular molars up to larger tip files but with a lower taper at 1 mm before the foramen resulted in a larger volume of apical preparation, kept the preparation centralized, and provided safe apical dentin wear without excessive cervical wear.     

Deviations of Mesial Root Canals of Mandibular First Molar Teeth at the Apical Third: A Micro–computed Tomographic Study

Introduction

The present study aimed to quantitatively analyze apical foramen deviations of mesial root canals of mandibular first molar teeth by means of micro–computed tomographic (micro-CT) imaging.

Effect of Residual Dental Pulp Tissue on Regeneration of Dentin-pulp Complex: An In Vivo Investigation

Introduction

Current pulp revascularization procedures in teeth with necrotic pulps and open apices have produced histologic evidence of connective tissue growth, cementum, and bone within the root canals of experimental animals. This study aims to investigate the effect of maintaining uninflamed residual apical pulp tissue on the histologic outcome of pulp-dentin complex regeneration after a revascularization procedure in immature ferret cuspid teeth.

Cell Viability and Tissue Reaction of NeoMTA Plus: An In Vitro and In Vivo Study

Introduction

The aim of this study was to evaluate the cell viability and tissue reaction of NeoMTA Plus (NMP; Avalon Biomed Inc, Houston, TX) compared with mineral trioxide aggregate (MTA; Angelus, Londrina, PR, Brazil) and Biodentine (BD; Septodont, Saint-Maur-de-Fossés, France).

Surface Changes of PathFile after Glide Path Preparation: An Ex Vivo and In Vivo Study

Introduction

The aim of this study was to evaluate the changes in the surface profile of rotary nickel-titanium (NiTi) files designed to prepare a glide path and conventional stainless steel (SS) hand files when used in extremely narrow canals both in clinical and experimental conditions.

Adjunctive Steps for the Removal of Hard Tissue Debris from the Anatomic Complexities of the Mesial Root Canal System of Mandibular Molars: A Micro–Computed Tomographic Study

IntroductionThis in vitro study sought to compare the efficacy of a sonic irrigant activation device with ultrasonic activation and needle irrigation in removing hard tissue debris (HTD) from anatomic complexities of the root canal system.MethodsTwenty-seven mesial roots of extracted human mandibular molars with 2 canals connected by an isthmus were selected based on micro–computed tomography scans (12-μm voxel size). The mesial canals were mechanically prepared to ProTaper Next X3 (Dentsply Maillefer, Ballaigues, Switzerland) and anatomically distributed into 3 groups (n = 9) according to the final irrigation protocol: sonically activated irrigation (SAI) using the EDDY system (VDW GbmH, Munich, Germany) for 3 × 20 seconds, ultrasonically activated irrigation (UAI) using a size 20 Irrisafe tip (Satelec Acteon, Mérignac, France) for 3 × 20 seconds, and conventional irrigation using a 30-G needle adapted to a syringe. Micro–computed tomographic scans were taken after instrumentation and after supplementary activation of the irrigant. After reconstruction and coregistration, the volume filled with HTD before and after irrigant activation was calculated, and the mean percentage of HTD reduction after final irrigation was compared within and among groups using the paired sample t test and 1-way analysis of variance post hoc Tukey test, respectively (α = 5%).ResultsA significant reduction in the volume filled with HTD after irrigant activation was observed in all groups (P < .05). The percentage reduction of HTD in the UAI group (66.8%) was significantly higher than that in the SAI group (36.4%) (P < .05), whereas the conventional irrigation group result (43.7%) did not differ statistically from the UAI or SAI groups (P > .05).ConclusionsAll tested supplementary irrigation steps significantly reduced the amount of debris created during root canal preparation. Ultrasonic activation resulted in the highest mean debris reduction.     

The Radix Entomolaris and Paramolaris: A Micro–Computed Tomographic Study of 3-rooted Mandibular First Molars

Introduction

The morphology of the supernumerary third root (radix) in mandibular first molars was examined by micro–computed tomography (μCT) scanning.

Methods

Nineteen permanent mandibular first molars with radix were scanned in a μCT device to evaluate their morphology with respect to root length, root curvature direction, location of radix, apical foramen, accessory canals and apical deltas, and distance between canal orifices as well as 2- and 3-dimensional parameters of the canals (number, area, roundness, major/minor diameter, volume, surface area, and structure model index). Quantitative data were analyzed by 1-way analysis of variance and the Tukey test (α = 0.05).

Results

The mean length of the mesial, distal, and radix roots was 20.36 ± 1.73 mm, 20.0 ± 1.83 mm, and 18.09 ± 1.68 mm, respectively. The radix was located distolingually (n = 16), mesiolingually (n = 1), and distobuccally (n = 2). In a proximal view, most radix roots had a severe curvature with buccal orientation and a buccally displaced apical foramen. The spatial configuration of the canal orifices on the pulp chamber floor was mostly in a trapezoidal shape. The radix root canal orifice was usually covered by a dentinal projection. The radix differed significantly from the mesial and distal roots for all evaluated 3-dimensional parameters (P < .05). The radix canal had a more circular shape in the apical third, and the mean size of the minor diameter 1 mm short of the foramen was 0.25 ± 0.10 mm.

Conclusions

The radix root is an important and challenging anatomic variation of mandibular first molars, which usually has a severe curvature with a predominantly distolingual location, and a narrow root canal with difficult access.     

Stress Analyses of Retrograde Cavity Preparation Designs for Surgical Endodontics in the Mesial Root of the Mandibular Molar: A Finite Element Analysis—Part II

IntroductionThe aim of this study was to investigate the influence of apical filling material and the modification made to the apical preparation design in surgical endodontics on the areas of stress concentration in the mesial root of a mandibular molar using finite element analysis.MethodsThe filling material was injected under 2 conditions (ie, with or without mineral trioxide aggregate retrograde filling). The apical preparation design was modified by extending the preparation mesially while maintaining a similar prepared area. We contained the displacement of all the nodes at the base of the supporting bone and applied a force of 150 N to the vertical axis. We analyzed stress generation and concentrations numerically for all cavity design groups.ResultsIn the presence of retrograde filling, the von Mises stress decreased gradually according to the enlargement of the prepared cavity in the subgroups. When the retrograde filling was absent, the von Mises stress increased as the prepared cavity enlarged. The modification of the apical preparation extending in the mesial direction showed a drastic decrease in stress concentration.ConclusionsWithin the limitations of this study, it was advantageous to perform mesial retrograde preparation within the mesial root dentin to maintain a balanced root dentin on both sides of the apical preparation and create a low-stress field. The surgeon should be careful not to wash out or dislodge the retrograde filling material during obturation to avoid failure of surgery.     

Comparative Analysis of the Anesthetic Efficacy of 0.5 and 0.75?% Ropivacaine for Inferior Alveolar Nerve Block in Surgical Removal of Impacted Mandibular Third Molars

Introduction

Ropivacaine belongs to pipecoloxylidide group of local anesthetics. There are reports supporting the use of ropivacaine as a long acting local anesthetic in oral and maxillofacial surgical procedures, with variable data on the concentration that is clinically suitable.

Materials and Methods

A prospective randomized double-blind study protocol was undertaken to assess the efficacy of 0.5 and 0.75 % ropivacaine for inferior alveolar nerve block in surgical extraction of impacted mandibular third molars. A total of 60 procedures were performed, of which thirty patients received 0.5 % and thirty received 0.75 % concentration of the study drug.

Results

All the patients in both the study groups reported subjective numbness of lip and tongue. The time of onset was longer for 0.5 % ropivacaine when compared to 0.75 % solution. 90 % of the study patients in 0.5 % ropivacaine group reported pain corresponding to VAS ≥3 during bone guttering and 93.3 % patients reported pain corresponding to VAS >4 during tooth elevation. None of the patients in 0.75 % ropivacaine group reported VAS >3 at any stage of the surgical procedure. The duration of soft tissue anesthesia recorded with 0.75 % ropivacaine was average 287.57 ± 42.0 min.

Conclusion

0.75 % ropivacaine was found suitable for inferior alveolar nerve blocks in surgical extraction of impacted mandibular third molars.     

Accuracy of High-resolution Small-volume Cone-beam Computed Tomography in Detecting Complex Anatomy of the Apical Isthmi: Ex Vivo Analysis

Introduction

The purpose of this study was to evaluate the accuracy of small-volume cone-beam computed tomography (CBCT) to detect and measure isthmi in the apical root canals of mandibular molars by using micro–computed tomography (μ-CT) as the reference standard.

The Application of Pre-operative Three-Dimensional Models in the Management of Mandibular Pathology: Is it Really Useful? An Institutional Study

AimTo assess the usefulness of 3D models for the surgical management of mandibular pathology requiring resection with continuity defects reconstructed using reconstruction plates. Patients and MethodA bidirectional study was conducted in 40 patients, 20 each in group 1 and 2. Group 1 included those patients taken up for resection with continuity defects and reconstruction using reconstruction plates without using 3D models and Group 2 included those patients managed similarly with 3D models. Pre-operative pathological model and mirrored model was fabricated for accurate placement and pre-bending of plates and determining the position and length of the screws. The level of understanding of the patients with regards to the diagnosis and extent of the disease (VAS 0–10), treatment planning (VAS 0–10), accuracy of fixation by a blinded surgeon (VAS 0–5), operative time, change in the mouth Opening, occlusal disturbance, implant-related complications was assessed as outcome measures and tested statistically. ResultsThe level of understanding of the patients with regards to the diagnosis and extent of the disease, treatment planning, operative time and accuracy of fixation was found to be statistically significant with superior performance in Group 2. No statistical significance was elicited in the change in mouth opening. No limitation in the mandibular range of movements and occlusal disturbance was found in any patient. No implant-related complications were found during the follow-up. Conclusion3D model fabrication can serve as a valuable adjunct in improving clinical outcomes with minimal operating time, increased patient compliance and radiological accuracy of fixation.     

In Vitro Comparative Study of the Influence of Instrument Taper on the Fracture Resistance of Endodontically Treated Teeth: An Integrative Approach–based Analysis

Introduction

The objective of this study was to examine the influence of instrument taper on the fracture resistance of endodontically treated roots under in vitro experimental conditions.