Mandibular Third Molar Root Research Articles

Is 3T MR nerve-bone fusion imaging a viable alternative to MRI-CBCT to identify the relationship between the inferior alveolar nerve and mandibular third molar.

To investigate the feasibility of MRI nerve-bone fusion imaging in assessing the relationship between inferior alveolar nerve (IAN) / mandibular canal (MC) and mandibular third molar (MTM) compared with MRI-CBCT fusion. The MRI nerve-bone fusion and MRI-CBCT fusion imaging were performed in 20 subjects with 37 MTMs. The Hausdorff distance (HD) value and dice similarity coefficient (DSC) was calculated. The relationship between IAN/MC and MTM roots, inflammatory, and fusion patterns were compared between these two fused images. The reliability was assessed using a weighted κ statistic. The mean HD and DSC ranged from 0.62~1.35 and 0.83~0.88 for MRI nerve-bone fusion, 0.98 ~ 1.50 and 0.76 ~ 0.83 for MRI-CBCT fusion. MR nerve-bone fusion had considerable reproducibility compared to MRI-CBCT fusion in relation classification (MR nerve-bone fusion κ = 0.694, MRI-CBCT fusion κ = 0.644), direct contact (MR nerve-bone fusion κ = 0.729, MRI-CBCT fusion κ = 0.720), and moderate to good agreement for inflammation detection (MR nerve-bone fusion κ = 0.603, MRI-CBCT fusion κ = 0.532, average). The MR nerve-bone fusion imaging showed a lower ratio of larger pattern compared to MR-CBCT fusion (16.2% VS 27.3% in the molar region, and 2.7% VS 5.4% in the retromolar region). And the average time spent on MR nerve-bone fusion and MRI-CBCT fusion was 1min and 3min, respectively. Both MR nerve-bone fusion and MRI-CBCT fusion exhibited good consistency in evaluating the spatial relationship between IAN/MC and MTM, fusion effect, and inflammation detection. MR nerve-bone fusion imaging can be a preoperative one-stop radiation-free examination for patients at high risk for MTM surgery.

Effects of a Benzalkonium Chloride Surfactant-Sodium Hypochlorite Combination on Microhardness and Mineral Content of Dentin

This study aimed to investigate the impact of the combination of Benzalkonium chloride (BAC) and sodium hypochloride (NaOCl) and its application after ethylenediaminetetraacetic acid (EDTA) in root canal irrigation procedures on the microhardness and mineral content of dentin. Distal roots of mandibular third molars were embedded in auto-polymerizing acrylic resin, sectioned coronally to apically resulting in fifty-four root sections. Thirty sections underwent microhardness evaluation, and twenty-four sections were randomly chosen for mineral analysis. The microhardness assessment comprised three groups: Group 1 (2.5% NaOCl), Group 2 (2.5% NaOCl with 0.084% BAC), and Group 3 (2.5% NaOCl with 0.084 BAC post-17% EDTA). Initial and post-irrigation microhardness values were measured for each group. For mineral analysis, samples were categorized into four groups: distilled water, 2.5% NaOCl, 2.5% NaOCl with 0.084% BAC, and 17% EDTA+2.5% NaOCl with 0.084% BAC. X-ray photoelectron spectroscopy immediately measured magnesium, phosphorus, and calcium mineral contents on dentin surfaces post-irrigation. Results indicated a significant reduction in root dentin microhardness for all solutions (p<0.05). However, no statistically significant difference in the percentage of reduction was observed among the groups (p>0.05). XPS analysis revealed no significant disparity in dentin surface mineral content among the groups (p>0.05). In conclusion, the addition of Benzalkonium chloride to sodium hypochloride, either alone or after EDTA, did not induce a significant alteration in dentin microhardness or mineral content. These findings contribute to a nuanced understanding of dental irrigation protocols and their effects on dentin properties during endodontic procedures.

Root canal width as a mandibular maturity marker at the 18-year threshold in the Maltese population.

The determination of age of majority (the 18-year-old threshold) using the popular Demirjian tooth staging method is unreliable, so other maturity markers are required. This study examines whether the ratio of the root canal widths (RCW) of the mandibular first, second and third molars is a useful indicator of age. Nine hundred eighteen dental panoramic radiographs (DPT) were examined and the ratio of the mid-points of the distal roots of the left mandibular first, second and third molars assessed according to the RCW stages as described by Roberts (J Forensic Sci 62:351-354, 2017). Individuals who had reached stages RCW-A and RCW-B were represented in a wide range of ages spanning the 18-year-old threshold. Individuals who had reached Stage RCW-C were all above the 18-year-old threshold. It was not possible to analyse a large number of DPTs for various reasons. Individuals categorised as stage RCW-C may be deemed to have reached the 18-year-old threshold. These results are consistent with other published studies. Variation in root morphology and in the rate of development of the third molar limits the applicability of this method. RCW staging is an accurate method of determining the 18-year-old threshold. Its limited applicability requires the use of substitute markers in a large number of cases.

The relationship of the inferior alveolar nerve canal with the roots of impacted mandibular third molars in a group of the South Indian population

Aim/Objective: The aim of this study was to evaluate the topographic relationship between the inferior alveolar nerve canal (IANC) and the roots of impacted mandibular third molars. Materials and Methods: The study conducted at the Department of Oral Medicine and Radiology, Maratha Mandals NG Halgekar College of Dental Sciences and Research Center, Belgaum, Karnataka, India. A total of 100 patients (54 female and 46 male) visiting the outpatient department between the age group of 18 and 50 years, with a mean age of 24 years, were selected. Before starting the study, ethical clearance was taken from the ethical committee and informed consent was taken from each patient who underwent radiographic examination. The study included only those patients who had a full set of dentition in their mouth visible clinically. No cases with history of extraction or invisible (agenesis) cases were included in our study. Pre-operative orthopantomograms (OPGs) were examined and the proximity of the IANC to the roots of impacted mandibular third molars was categorized into the following groups: Superimposition, adjacent, perforation, grooving, notching or none. The categories notching, grooving and perforation were regrouped together and called the true relationship between the IANC and the root apices. The type of impaction, age and sex of the patient were also noted. Results: The greater number of impacted third molars was of mesioangular position and accounted for 98 (49%) of the total sample. Only six (3%) third molars were classified under the classification as aberrant. The prevalence of the impacted third molar was more common in the 18-30-year-old age group, with the mesioangular (98 [49%]) type of impaction being the most common type. The position of the IANC showed that 50 (25%) teeth were of superimposition, 41 (20.5%) teeth were of adjacent, 49 (24.5%) teeth were of grooving, 17 (8.5%) teeth were of notching and 30 (15%) teeth were of perforating categories in relation to the IANC. The remaining 13 (6.5%) teeth could not be placed under any of these categories and, therefore, were placed in the category none. The relationship between the IANC and the angular position of the mandibular third molars was found to be more common in mesioangular impactions (49%) than in any other type of impaction. Six impacted molars were in aberrant impaction (3%), and these fell into the superimposition category. Conclusion: The position of the IANC in relation to the roots of the impacted third molars varied according to the patient's age.

Evaluation of number of roots and root anatomy of permanent mandibular third molars in a Korean population, using cone-beam computed tomography.

Objective:The purpose of this study was to investigate the morphology and number of roots of Korean mandibular third molars, and to evaluate the prevalence of C-shaped, two-rooted, and three-rooted mandibular third molars using cone-beam computed tomography (CBCT).Materials and Methods:Serial axial CBCT images of the mandibles were gathered from 137 Korean patients. The total number of roots in the mandibular third molars of these patients was measured, and both the incidence and the correlations between left- and right-side occurrences, as well as between males and females, were analyzed.Results:Most of the mandibular third molars either had two roots (56.5%) or one root (37.9%). There was no significant difference regarding the incidence of the different types of roots according to gender (female versus male) or topology (right versus left side). A higher percentage (80.5%) of the patients had similar root morphology on both sides.Conclusion:The morphology and number of 214 mandibular third molars were examined using CBCT. There was a high prevalence of two-rooted mandibular and one-rooted mandibular third molars from this Korean population. Even though the anatomical variations in the mandibular third molars may not be high, these data regarding the occurrence and morphology of the roots will provide useful information to dentists performing these procedures.

Diagnostic accuracy of panoramic radiography, stereo-scanography and cone beam CT for assessment of mandibular third molars before surgery

Objective. To compare the diagnostic accuracy of panoramic imaging, stereo-scanography and cone beam computed tomography (CBCT) for assessment of mandibular third molars. Material and methods. One hundred and twelve patients (147 third molars) underwent radiographic examination by panoramic imaging, stereo-scanography and CBCT. Tooth angulation, root morphology, number of roots and relation to the mandibular canal were assessed. The same variables were assessed intra- and post-operatively and served as reference for the radiographic assessments. The diagnostic accuracy for each variable was compared between the three modalities and accuracy was further expressed as sensitivity and specificity and tested between the modalities for identifying the relation to the mandibular canal. Results. There were no significant differences between the modalities regarding tooth angulation, root morphology and number of roots. However, CBCT was more accurate than stereo-scanography for determining root bending in the bucco-lingual plane (p = 0.02). Moreover, sensitivity for direct contact to the mandibular canal (panoramic imaging: 0.29, stereo-scanography: 0.57, CBCT: 0.67) was higher for CBCT than for panoramic images (p = 0.05) and specificity for no direct contact to the mandibular canal (panoramic imaging: 0.78, stereo-scanography: 0.53, CBCT: 0.68) was higher for panoramic images and CBCT than for scanograms (p < 0.001). Conclusion. Panoramic imaging, stereo-scanography and CBCT seem equally valuable for examination of tooth angulation, number and morphology of roots of mandibular third molars. However, CBCT was more accurate for assessment of root bending in the bucco-lingual plane and more accurate than panoramic images to identify direct contact to the mandibular canal.

The Relationship of the Inferior Dental Canal to the Roots of Impacted Mandibular Third Molars in Jordanian Population

The aim of this study was to evaluate the topographic relationship between the inferior dental canals (IDCs) and the roots of impacted mandibular third molars. Preoperative orthopantomograms (OPGs) were examined and the proximity of the IDC to the roots of impacted mandibular third molars was categorized into the following: groups: superimposition, adjacent, perforation, grooving, notching, or none. The categories notching, grooving, and perforation were regrouped together and called the true relationship between the IDC and the root apices. The type of impaction, age, and sex of the patient were also noted. The positional category of 96.1% of the radiographs with bilateral impactions was identical on both sides of the mandible. Out of 2526 impacted mandibular third molars examined, 1146 (45.3%) belonged to the superimposition category, 663 (26.2%) were adjacent, 312 (12.3%) showed grooving, 78 (3.08%) showed notching, and 9 (0.35%) were actually perforating the IDC. The results showed 15.7% of the total cases were in true relationship with the IDC. There was a significant association (p = 0.000) between patient's age and true relationship. Identical positional relationship of the bilateral impacted third molars to the IDC was noted in 96.1% of the radiographs. The position of the IDC in relation to the roots of impacted third molars varied according to the patient's age.

A preliminary radiographic study of mandibular para-radicular third molar radiolucencies

Objectives To determine the frequency and describe a poorly documented radiographically observed variation of normal associated with the roots of mandibular third molars—the mandibular third molar para-radicular radiolucency (MPR). Study design A systematic random sample of 822 dental school surgery and emergency charts was reviewed for radiographic evidence of the MPR. The frequency was determined and the variation in radiographic appearance was described. Clinical signs and symptoms were correlated with the presence of an MPR. Results The frequency of the MPR was 7.8% with a female-to-male ratio of 2.6:1.0. Of 6 bilateral cases (9.4%) all occurred in female patients. The most common location was the distal surface of the mandibular third molar. Most (58.6%) were oval in shape. Conclusion This radiographic finding most likely represents a variation of normal anatomy and based on this retrospective study does not appear to require treatment.

The relationship of the roots of mandibular third molars to the inferior dental canal

Attention is drawn to possible trauma to the inferior dental canal and its contents during the removal of unerupted and impacted mandibular third molars. The position of the canal in the developing mandible is discussed, its relationships to the mandibular third molar are classified, and their diagnosis by means of radiographic examination is mentioned. The forms of trauma that can be inflicted upon the canal and its contents, as well as the ensuing symptoms, are discussed. Finally, precautions to minimize the risk of such injuries are briefly mentioned.