Accuracy of Panoramic Radiograph in Assessment of the Relationship Between Mandibular Canal and Impacted Third Molars
Weeraya TantanapornkulDarika MavinJaruthai PrapaiphittayakunNatnicha PhipatboonyaratWanchanok Julphantong
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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.Keywords:
Mandibular canal
Mandibular third molar
Panoramic radiograph
Mandible (arthropod mouthpart)
The chances of neurological complications following surgical removal of impacted mandibular third molar increase when there is close contact between the inferior alveolar nerve and the tooth root. Thus, it is important to evaluate the topographic relationship between them preoperatively. AIMS AND OBJECTIVES- To assess the possible nerve injury following extraction of impacted mandibular third molar by comparing the relevant panoramic features with cone beam computed tomography (CBCT) ndings and evaluate the diagnostic accuracy of OPG. MATERIAL AND METHODS –A total number of 30 patients requiring surgical removal of impacted mandibular third molar under local anesthesia and having a close relationship between impacted mandibular third molar and inferior alveolar canal in panoramic radiograph were included in the study and were advised for CBCT evaluation. Statistically signicant association w RESULTS - as found between darkening of the root in OPG and absence of narrowing of the canal in CBCT with P value 0.008 (P<0.05) while distribution of darkening of the root (OPG) according to presence or absence of corticalisation (CBCT) was not statistically signicant . The panorami CONCLUSION - c radiographs may be useful to assess the close relationship between mandibular canal and third molar root tip but it cannot appraise the type of intimate relationship present between them for which CBCT is the reliable tool.
Inferior alveolar nerve
Mandibular third molar
Mandibular canal
Panoramic radiograph
Mandible (arthropod mouthpart)
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OBJECTIVESThe aim of this study was to evaluate the relation of distal caries of second molar with patterns of impacted third molar.METHODOLOGYA retrospective study was carried out from January 2017 to June 2017.A total of 160 patients and 276 impacted teeth were selected with an age > 18 years. A single researcher assigned the diagnosis of caries and patterns of impacted teeth through clinical notes and orthopantomogram(OPG)which was reviewed by Head of Department. Winter’s and Pell and Gregory classification was used for impaction classification. The data was analyzed using SPSS 22.0 version. P ≤ 0.05 was considered as statistically significant.RESULTSFemale (56.3%) were predominant than male (43.8%) with mean age presentation was 24.2 ± 4.7 years.271 mandibular second molars were present. Vertical (64.5%) impaction was found to be the most frequent followed by mesioangular (19.6%). Pearson correlation showed that vertical impaction was significantly related to distal caries of second molar(Right side, r=.262 p=.002 and Left side, r=.240 p=.006).CONCLUSIONVertical impaction was positively related with distal caries therefore prophylactic removal of lower impacted teeth is recommended.
Impaction
Panoramic radiograph
Mandibular third molar
Impacted tooth
Mandibular molar
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Cone-beam-computed-tomography (CBCT) has been useful in providing insights of relevant anatomy prior to surgical procedures, including the assessment of the proximity of impacted mandibular-third-molar to the inferior-alveolar-canal (IAC).It is important to understand the reliability of conventional panoramic-radiograph in the assessment of this criterion since it is more commonly used as first line radiographic approach due to its availability and lower radiation dose.This study aimed to investigate the reliability of conventional panoramic-radiograph in the evaluation of the proximity of impacted mandibular-third-molar root tip to the IAC by correlating the results with CBCT.A total of 65 root tips of impacted mandibular-third-molars that had both panoramic radiographs and CBCT images were included in this retrospective study.Two trained observers participated in all image evaluations.A prepared standard 1 cm ruler was used to measure the proximity of the third-molar root apices to the IACs.Measurements recorded in this study were categorized into positive (root apex above a roof of IAC), zero (root apex was superimposed on IAC) and negative (root apex below a roof of IAC).Data analysis was carried out using student t-test.In this study, both observers recorded statistically significant differences in the measurement between third-molars root apices and the IAC from panoramic radiographs and CBCT images.The low reliability of panoramic radiograph to assess the vertical proximity between these two anatomical structures suggests the importance of additional assessment with CBCT in cases where panoramic radiograph shows superimposition of the third molar root on the roof of the canal and presence of root below the roof of the IAC.
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Panoramic radiograph
Chest radiograph
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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.
Mandibular canal
Mandibular third molar
Panoramic radiograph
Mandible (arthropod mouthpart)
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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.
Inferior alveolar nerve
Mandibular canal
Panoramic radiograph
Mandible (arthropod mouthpart)
Mandibular third molar
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Background and objective: Extraction of an impacted mandibular third lower molar tooth is one of the common surgical procedures that may lead to the damage of inferior alveolar nerve due to roots proximity to the mandibular canal.This study aimed to know the relative relationship and proximity of the mandibular third molar roots to the inferior alveolar canal in relation to gender, age, depth of impaction, relation with ramus, and type of angulation of the impacted tooth in Kurdistan population.Methods: A sample of 366 digital panoramic radiographs of patients with impacted mandibular third molar was studied.Panoramic radiographic signs images were evaluated for the presence of root contact with the superior border of the mandibular canal, darkening of the roots apex, deflected roots, narrow root, superimposition of the canal, interruption of the white line, diversion of the inferior alveolar canal, and narrowing of the inferior alveolar canal.The depths of impaction, relation with ramus, and type of angulation were also studied.Results: Significant relation of the proximity of the mandibular third molar roots to the inferior alveolar canal with the gender (P = 0.001) and age (P <0.001) were seen.A significant relation of the proximity of the mandibular third molar roots to the inferior alveolar canal with the depth of impaction (P <0.001), relation with the ramus (P = 0.004), and angulation of impaction were also seen (P <0.001).Conclusion: Significant relation of the proximity of the mandibular third molar roots to the inferior alveolar canal with gender, age, depth of impaction, relation with the ramus, and angulation of impaction were seen.
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Mandibular third molar
Mandibular molar
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A Case of the Extraction of Impacted Mandibular Second and Third Molars by Sagittal Splitting Method
The extraction of impacted mandibular third molar is a frequently performed as minor oral surgery. We report a case of the extraction of impacted mandibular second and third molars by sagittal splitting method.A 31-year-old woman referred to our hospital because of the pain and the swelling of right mandibular angle. She was diagnosed as pericoronitis of second and third molar of the right mandible. Panoramic radiograph revealed that the second molar was impacted in the lower region of the mandible. We judged that it was difficult to extract this tooth by a normal method. Then, we extracted by sagittal splitting of the lateral cortical bone under general anesthesia. The course after the operation was good and the paresthesia of right mental region did not appear.
Pericoronitis
Mandible (arthropod mouthpart)
Mandibular third molar
Wisdom tooth
Panoramic radiograph
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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.
Mandibular canal
Mandibular third molar
Inferior alveolar nerve
Mandible (arthropod mouthpart)
Panoramic radiograph
Mandibular molar
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Mandibular third molars are usually located near the inferior alveolar nerve. Their surgical removal may damage the nerve and cause dysesthesia of the lower lip. Panoramic radiography is often used preoperatively to estimate the distance between the mandibular third molars and the inferior alveolar nerve. However, the buccolingual relation of these structures cannot be determined by this method.Three-dimensional Computed tomography (3 D-CT) is more useful in diagnosis than panoramic radiography. This study was designed to assess the diagnostic value of 3 D-CT.A total of 209 mandibular third molars in 138 patients were evaluated by both 3 D-CT and panoramic radiography. We classified the radiographic relation between tooth roots and the mandibular canal into 5 types. The types were recorded for each panoramic radiograph and 3 D-CT scan.3 D-CT findings: 49 teeth showed Type 1; 45 of 49 teeth showed exposure of the inferior alveolar nerve.Panoramic radiograph findings: 82 teeth showed Type 1; 38 of 82 teeth showed exposure of the inferior alveolar nerve. There was a significant difference between 3 D-CT findings and panoramic radiographic findings (p<0.05).Patients with loss of the superior white line of the canal on panoramic radiographs had a high incidence of nerve exposure during surgery (p<0.005). There was also a correlation between radiographic loss of the superior white line and closeness of the tooth and canal on 3 D-CT (p<0.05). These findings are clinically important.We conclude that 3 D-CT provides clinically useful information with respect to the relation between the mandibular third molars and the mandibular canal.
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Mandibular canal
Panoramic radiograph
Mandibular nerve
Mandibular third molar
Mandible (arthropod mouthpart)
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Panoramic radiographs are routinely employed for surgical planning of unerupted third molars. The objective of this study was to evaluate distortions in the position of mandibular third molars on panoramic radiographs.Panoramic radiographs of 14 patients with indication for extraction of the mandibular third molars were used. Transurgical impressions of the crowns of the teeth to be extracted and adjacent second molars (n=19) were achieved with addition silicone and poured with type IV plaster for comparison of the inclinations of the third molars on the radiographs and study casts.There was a mean difference of -5.37 degrees between the position of the third molar on the panoramic radiograph and on the study cast (standard deviation 1.46, P<0.05, Student's t-test).There is distortion in the position of teeth on the panoramic radiograph, which may influence the surgical planning; however, this does not invalidate it as the main tool for diagnosis and surgical planning of mandibular third molars.
Panoramic radiograph
Mandibular third molar
Mandible (arthropod mouthpart)
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