Correlation between panoramic radiographic signs and high‐risk anatomical factors for impacted mandibular third molars
Nana HaradaSubash Beloor VasudevaRucha K JoshiKazuhiko SekiKazuyuki ArakiYukiko MatsudaTsubasa Okano
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Abstract Aim To determine the relationship between radiographic signs on panoramic radiographs and anatomic features of thinning of the cortical plates and closeness of the root of the third molar to the mandibular canal on cone beam computed tomography images ( CBCT ). Methods Panoramic images were analysed for the relationship of the root of the third molar to the mandibular canal. The CBCT images were analysed for the relation between mandibular canal and the third molar root. The results were tabulated, and C hi square test ( P < 0.05) was used for the assessment of the relationship between the panoramic sign and the CBCT findings. Results The panoramic signs, especially, darkening of the root and interruption of the white line of the canal correlated with the location of the mandibular canal to the impacted tooth, thinning of the lingual cortical plate and the closeness of the canal and the molar. Conclusion Darkening of the root and interruption of the white line of the canal on panoramic radiograph can predict lingual cortical plate thinning and close relation between third molar root and the mandibular canal.Keywords:
Mandibular third molar
Panoramic radiograph
Mandibular canal
Mandible (arthropod mouthpart)
Untreated middle mesial canals (MMCs) of mandibular permanent molars can result in endodontic treatment failure.The aim of this retrospective study was to investigate the incidence of MMC of mandibular molars in a Romanian population.In total, there were evaluated 144 mandibular first permanent molars and 140 mandibular second permanent molars by using cone-beam computed tomography (CBCT) scans.The MMC was identified in 5.67% of mandibular first permanent molars, respectively in 4.28% of mandibular second permanent molars. The male∕female ratio of MMC presence was 1:3 of mandibular first molars and inverted for mandibular second molars (5:1). The presence of MMC in mandibular first molars was associated in all cases of our study with a second distal canal, unlike the mandibular second molars where no second distal canal was associated with a MMC.In Romanian population, the MMC of mandibular first molars, when present, is commonly associated with a second distal canal, unlike the mandibular second molars where the occurrence of a MMC was associated with only one distal canal. When performing the preoperative evaluation, it has also to be considered the patient gender, since the male∕female ratio of MMC was 1:3 in mandibular first molars and 5:1 in mandibular second molars.
Mandibular canal
Mandible (arthropod mouthpart)
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To locate the mandibular canal accurately in the mandibular body of the young women and provide anatomic data for the mandibular angle plasty.60 women whose age ranged from 20 to 39 years old were randomly selected, the average was 25.32 years old. CT scanning and 3-D reconstruction were applied to their mandibles. After the points were determined, the distances of the points to inferior mandibular borders were measured. The data was analyzed by SPSS 11.5.The distance between the mandibular canal and the inferior mandibular border was least in the area which responsed to the second premolar. It decreases from the posterior margin of the third molar to the anterior margin of the first molar. It increases from the posterior margin to the mental hole.The mandibular canal between the posterior and anterior margins of the second pre-molar is prone to be injuried and should be paid more attention to during mandibular angle plasty.
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Mandibular third molar
Mandibular lateral incisor
Mandible (arthropod mouthpart)
Mandibular molar
Premolar
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Background: The relationship between impacted mandibular third molar and mandibular canal is important for removal of this tooth. Panoramic radiography is one of the commonly used diagnostic tools for evaluating the relationship of these two structures. Objectives: To evaluate the accuracy of panoramic radiographic findings in predicting direct contact between mandibular canal and impacted third molars on 3D digital images, and to define panoramic criterion in predicting direct contact between the two structures. Methods: Two observers examined panoramic radiographs of 178 patients (256 impacted mandibular third molars). Panoramic findings of interruption of mandibular canal wall, isolated or with darkening of third molar root, diversion of mandibular canal and narrowing of third molar root were evaluated for 3D digital radiography. Direct contact between mandibular canal and impacted third molars on 3D digital images was then correlated with panoramic findings. Panoramic criterion was also defined in predicting direct contact between the two structures. Results: Panoramic findings of interruption of mandibular canal wall, isolated or with darkening of third molar root were statistically significantly correlated with direct contact between mandibular canal and impacted third molars on 3D digital images ( p < 0.005), and were defined as panoramic criteria in predicting direct contact between the two structures. Conclusion: Interruption of mandibular canal wall, isolated or with darkening of third molar root observed on panoramic radiographs were effective in predicting direct contact between mandibular canal and impacted third molars on 3D digital images. Panoramic radiography is one of the efficient diagnostic tools for pre-operative assessment of impacted mandibular third molars.
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Pre-operative radiographic assessment of the anatomical relationship between the roots of the mandibular third molar and the inferior alveolar nerve (IAN) is a must to minimize the risk of IAN injury during surgery.To compare the radiographic signs of digital orthopantomogram (OPG) and cone-beam computed tomography (CBCT). An additional objective was to assess the cortex status between the mandibular canal and third molar on CBCT images in relation to the demographic characteristics, region (right or left side), and angulation of mandibular molar.In this retrospective study, a total of 350 impacted mandibular third molars with a close relationship between the inferior alveolar canal (IAC) and impacted mandibular third molars on digital OPG were further referred for CBCT imaging for assessment of the position of the mandibular canal. The study was conducted between August 2018 and February 2020. Digital OPGs were evaluated for radiographic signs like interruption of the mandibular canal wall, darkening of the roots, diversion of the mandibular canal, and narrowing of the mandibular canal. The age and sex of patients, site of impacted third molar, Winter's classification of mandibular third molar, position of IAC relative to impacted molar, and the radiographic markers of OPG were assessed for cortical integrity using CBCT. Chi square testing was applied to study the values of difference and binomial logistic regression was done to assess the factors associated with cortication. Statistical significance was set at p ≤ 0.05.Among 350 patients, 207 (59.1%) were male and 143 (40.9%) were female with a mean age of 36.8 years. The most common OPG sign was interruption of white line, seen in 179 (51.1%) cases. In total, 246 cases (70.3%) showed an absence of canal cortication between the mandibular canal and the impacted third molar on CBCT images. Cortication was observed in all cases with a combination of panoramic signs which was statistically significant (p = 0.047). Cortication was observed in 85 (50.6%) cases where IAC was positioned on the buccal side, 11 (16.9%) in cases of inferiorly positioned IAC, and just 8 (7.6%) for cases of lingually positioned IAC which was statistically significant (p = 0.003). Statistically insignificant (p > 0.05) results were noted for cortex status in CBCT images with regards to the age, sex, site, and angulation of impacted third molars.CBCT imaging is highly recommended for those cases where diversion of the mandibular canal is observed on OPG and when the roots are present between canals.
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Mandibular third molar
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Abstract We report an unusual case of anatomical changes of the mandibular canal, displacement of a tooth fragment and post‐operative inferior alveolar nerve neurosensory deficits after removal of a mandibular third molar. This article analyses the possible cause of anatomical changes of the mandible canal, and makes a contribution to studies in the literature about non‐surgical treatment of displaced tooth fragment and low‐level laser therapy of post‐operative inferior alveolar nerve neurosensory deficits after removal of a mandibular third molar.
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Objective:To provide anatomic basis for the mandibular dental implant operation of the clinical oral surgery.Methods:10 fresh mandibles,18 adult mandibles with total teeth and 20 volunteers without agomphosis were selected and exposed the inferior alveolar neurovascular bundle,the mandibular canal and the dental root of mandibular posterior teeth,scanned in series by CT,and then its three-dimensional image were reconstructed.The relationship of the inferior alveolar nerve with the inferior alveolar vessels were observed,the dental root of mandibular posterior teeth to the superior wall of mandibular canal was measured with vernier caliper and three-dimensional reestablish working station respectively.Results:The mandibular canal was traveling through the bottom of alveolar fossa.Its lingual side was thick,the inferior alveolar vessels were laid above the inferior alveolar nerve in the mandibular canal.The distance was near from the distal root of mandibular molar to the mandibular canal than that of the mesial root.The distance from the dental root of first premolar,second premolar,first molar,second molar,third molar to the superior wall of mandibular canal were 8.36±2.34 mm,8.42±2.42 mm,7.36±2.21 mm,7.52±2.18 mm,3.22±1.40 mm,3.36±1.85 mm,2.96±1.54 mm,2.84±1.55 mm,3.64±1.72 mm and 3.88±1.76 mm in specimen and imaging separately.Conclusions:(1) The distance from the second molar to the mandibular canal was the nearest than that of the others,it was the second molar,first molar,third molar,second premolar and first premolar from the near to the far.(2) It is significant for choosing appropriate length of dental implantation,which avoid the injury for the inferior alveolar nerve.
Mandibular canal
Inferior alveolar nerve
Premolar
Calipers
Posterior teeth
Mandible (arthropod mouthpart)
Mandibular lateral incisor
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Statement of the problem: It is important for oral surgeons to deter-mine the precise location of mandibular third molar before extraction. The close relationship of mandibular canal and mandibular third molar is a risk factor for alveolar nerve damage. Objective: The purpose of this study is to assess the relationship between mandibular canal and the mandibular third molar which has alre-ady been seen in close relationship on panoramic radiograph (PR) by the comparison of findings of the cone-beam computed tomography (CBCT) and the PR. Materials & Methods: Close relationship between the mandibular third molar and mandibular canal was scanned in 180 patients by the PR. Images were also obtained by CBCT from patients among which a close-relationship was detected between mandibular canal and mandibular third molar. Results: Close relationship was detected between mandibular third molar and mandibular canal on 26 of 180 PR and evaluated 46 mandibular third molars. In 41 cases, both the findings in PR and in CBCT images showed compliance with each other. As a result it was clearly seen that the mandibular third molars which were detected to be in close relationship on PR were mostly also in close relationship with mandibular canal on CBCT-images. Conclusions: If the close relationship is not seen on the panoramic images then there is no need to get CBCT for extracting the mandibular third molars. By this way complication risks are eliminated with less radia-tion. However CBCT should be definitely used in cases which complete as-sessment cannot be made in no way due to artifacts such as superposition in PR.
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Mandibular third molar
Inferior alveolar nerve
Mandible (arthropod mouthpart)
Panoramic radiograph
Mandibular molar
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Objective To study the method in accurately deciding the three-dimensional positional relationship when impacted mandibular third molar was overlapped with mandibular canal on the panoramic X-ray film,so as to use appropriate clinical methods to extract the mandibular third molar.Methods Fifty-seven impacted mandibular third molars were checkedby CBCT,which were overlapped with mandibular canal on the panoramic X-ray film,and then a detailed classification and appropriate surgical plan were made.Results The position relationship types on CBCT were as follows:22 impacted mandibular third molars' roots were inside the mandibular canal;30 impacted mandibular third molars
Mandibular third molar
Mandibular canal
Mandibular molar
Mandible (arthropod mouthpart)
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The positional relationship between the mandibular canal and corresponding third molars is a key anatomic factor of inferior alveolar nerve (IAN) injury. The aim of the present study is to classify the anatomic three-dimensional relationship between the mandibular third molar and the mandibular canal on cone-beam computed tomography (CBCT) images.This study used CBCT images to classify the positional relationship between the mandibular canal and corresponding third molars. CBCT images of 749 patients (1296 mandibular third molars) were analyzed to draw up a classification.On a total of 1296 third molars, the mandibular canal relative to the roots of the mandibular third molar was on the apical side (88.1%), followed by the buccal side (7.9%), the lingual side (3.5%), and then between the roots (0.5%). Ninety-five (7.1%) third molars had a close relation with the mandibular canal, while 1201 (92.7%) third molars had no direct contact. The percentage of the mandibular canal contacts with the mandibular third molar was higher when the mandibular canal was lingually positioned.The anatomic structures of the mandibular third molar and the mandibular canal may be helpful to make adequate surgical planning to avoid or reduce nerve involvement.
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Inferior alveolar nerve
Mandibular third molar
Mandible (arthropod mouthpart)
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AIM: To analyze the anatomic relationship between mandibular canal and the roots of impacted mandibular third molar by cone beam computed tomography(CBCT).METHODS:15174 teeth in 7751 patients were diagnosed as the impaction of mandibular third molar in the author's hospital from April 2010 to April 2012.518 teeth in 401 patients showed roots overlapping with mandibular canal on panoramic radiography were examined by CBCT.During tooth extraction the relationship between mandibular canal and the roots of the impacted teeth was observed.Statistics analysis was performed by χ2 test.RESULTS:On CBCT 343 of the 518 teeth(66.22%)showed root in touch with mandibular canal,mostly the canal was between 2 roots of the molars followed by on the lingual side,below the root tip and on the buccal side(P﹤0.05).During tooth extraction exposure of the inferior nerve was found in 87 teeth(16.80%) which were shown roots overlapping with mandibular canal on panoramic radiography,while in 25.36%(87/343) on CBCT(P﹤0.05).CONCLUSION: CBCT can provide more precise information than panoramic radiography for the analysis of anatomic relationship between mandibular canal and the roots of impacted mandibular third molar.
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Mandibular third molar
Impaction
Mandibular lateral incisor
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