Vol. 117 No. 5 May 2014
Relationships between third-molar juxta-apical radiolucencies and mandibular canals in panoramic and cone beam computed tomography images Rishabh Kapila, MDS,a Nana Harada, DDS,a Kazuyuki Araki, DDS, PhD,a Tsukasa Sano, DDS, PhD,a and Tazuko K. Goto, DDS, PhDb Showa University, Tokyo, Japan; University of Hong Kong, Hong Kong
Objective. This study aimed to determine the relationship between third-molar juxta-apical radiolucencies and mandibular canals on panoramic and cone beam computed tomography (CBCT) images. Study Design. Forty-two patients were included in this retrospective study. The root apices and the relationships of the juxtaapical radiolucencies to the mandibular canals were evaluated on both panoramic and CBCT images. The McNemar test (P < .05) was used to compare panoramic with CBCT findings. Results. Root apices were visualized clearly with CBCT in most cases for which the apices were not seen clearly on panoramic images. Similarly, juxta-apical radiolucencies were separate from the mandibular canals with CBCT in most cases. Conclusions. The present study found that there is no consistent intimate relationship between juxta-apical radiolucencies and the mandibular canals. Similar studies with larger sample sizes are required to further confirm these findings. (Oral Surg Oral Med Oral Pathol Oral Radiol 2014;117:640-644)
The extraction of mandibular third molars may result in complications such as postoperative paresthesia, owing to an intimate relationship between the roots of third molars and the mandibular canals, mandibular cortices, or both.1 Imaging examination is an essential tool for diagnosing and surgically managing impacted third molars. This is because imaging provides valuable information about tooth position, number/morphology of the roots, and the relationship of the tooth to adjacent structures.1 Traditionally, periapical radiographs and panoramic radiographs have been used before surgery to assess the relationship between the inferior alveolar canal and the adjacent third molar roots. Both conventional imaging modalities have their limitations, but perhaps the greatest limitation is the lack of 3-dimensional information.2 These limitations motivated investigators to use computed tomography (CT) and more recently cone beam computed tomography (CBCT) for improving the diagnostic utility of preoperative imaging. The benefits of CT and CBCT are the visualization of anatomic relationships in multiple planes (axial, coronal, and sagittal) and the generation of 3-dimensional reformations. Their disadvantages include the increased cost and radiation exposure for the typical adolescent or young adult patient.3 A number of radiographic signs have been studied that indicate possible injury of the inferior alveolar a
Department of Radiology, Showa University School of Dentistry. Oral Radiology, Oral Diagnosis & Polyclinics, Faculty of Dentistry, University of Hong Kong. Received for publication Oct 5, 2013; returned for revision Jan 1, 2014; accepted for publication Feb 7, 2014. Ó 2014 Elsevier Inc. All rights reserved. 2212-4403/$ - see front matter http://dx.doi.org/10.1016/j.oooo.2014.02.002 b
640
nerve during extraction of the mandibular third molar. These include diversion of the canal, darkening of the root (mostly owing to superimposition of the mandibular canal), deflection of the root, narrowing of the canal, and interruption of the canal.4 Recently, a new radiographic sign (periapical or paradontal radiolucent area [juxta-apical area]) has also been associated with paresthesia after mandibular third molar removal. This new radiographic sign is a well-circumscribed radiolucent area lateral to the root rather than at the apex.5 In a randomized clinical trial, the presence of juxta-apical area was one of the radiographic signs that was associated with injury to the inferior alveolar nerve.6 No study has analyzed the relationship between juxta-apical areas (radiolucencies) and their surrounding structures. The aim of the study was to use panoramic and CBCT images to examine the relationships between third-molar juxta-apical radiolucencies and mandibular canals.
MATERIALS AND METHODS A retrospective study was conducted of 42 patients (18 men and 24 women) aged 21 to 58 years (mean, 35 years). Data were collected for those patients who underwent panoramic radiography and CBCT for the
Statement of Clinical Relevance This study compares the usefulness of panoramic radiography and cone beam computed tomography (CBCT) for depicting the relationship of juxta-apical radiolucencies with surrounding structures and supports the use of CBCT for 3-dimensional analyses of impacted third molars.
OOOO Volume 117, Number 5
examination of impacted mandibular third molars. Panoramic radiography was performed with a HyperXF panoramic machine (Asahi, Kyoto, Japan) operated at 78 kV and 10 mA. CBCT was performed with a 3D Accuitomo 80 (J. Morita, Kyoto, Japan) operated at 90 kV and 4 mA, with a field of view that had a height of 4 cm and a diameter of 4 cm. Cases included in the study were juxta-apical radiolucencies seen on panoramic radiographs. Cases did not have carious involvement/trauma or any pathology such as a cyst or tumor. Approval from the Ethical Committee of Showa University was obtained (No. 2011-022), and the study was carried out in accordance with Helsinki guidelines. A checklist was prepared for the parameters that were evaluated on panoramic and CBCT images. Two radiologists independently evaluated all images based on the checklist. Subsequently, the 2 radiologists jointly reviewed the images and made consensus determinations for the panoramic and CBCT images. Panoramic images were evaluated for the type of impaction, based on the Winter classification, as vertical, horizontal, mesioangular, or distoangular. Impacted mandibular third molars on the right side were evaluated in 27 cases and on the left side in 15 cases. The apex of the root was evaluated with regard to whether or not it was clear, and the relationship between the juxta-apical radiolucency and mandibular canal was assessed. CBCT images were analyzed in all dimensions, to visualize the condition of the root apex, whether or not it was clearly seen, and to identify the relationship between the juxta-apical area and mandibular canal. Statistical analysis Data collected were tabulated and analyzed using SPSS, version 17 (SPSS Inc). The McNemar test was used to compare panoramic and CBCT image findings. The level of significance was set at P < .05.
RESULTS On panoramic images, the impaction status of the mandibular third molars was analyzed by the Winter classification, and the results are shown in Table I. Most of the mesioangular impacted mandibular third molar cases were associated with juxta-apical radiolucencies. On panoramic images, root apices were clear in 14 cases (Figure 1, A), whereas they were not clear in 28 cases (see Figure 1, B). Juxta-apical radiolucencies were seen contacting the mandibular canal in 25 cases (Figure 2, A), whereas in only 17 cases, the juxta-apical radiolucencies were separated from the mandibular canal (see Figure 2, B). With CBCT, root apices were clear in 30 cases (Figure 3, A) and not clear in 12 cases (see Figure 3, B). Juxta-apical radiolucencies were seen
ORIGINAL ARTICLE Kapila et al. 641
Table I. Impaction status of the studied participants Description
No. of cases
Vertical Horizontal Mesioangular Distoangular
5 15 22 0
contacting the mandibular canals in 12 cases (Figure 4, A), whereas they were separated in 30 cases (see Figure 4, B). A statistically significant difference (P < .05) was found between the findings with panoramic and CBCT images (Figures 5 and 6).
DISCUSSION Third molars are removed for pathologic or preventive reasons. Whereas removals are necessary in cases of pathologic findings, the benefit of preventive removal remains controversial. Injury to the inferior alveolar nerve is a complication associated with the removal of an impacted mandibular third molar. Both surgeons and patients wish to avoid such a complication. A preoperative radiographic examination is used to determine the proximity of impacted tooth to the mandibular canal. The examination may indicate that the planned surgical approach be altered or that an alternative, lowrisk surgical technique be used (such as coronectomy).7 A number of radiologic signs have been suggested to indicate a close proximity between the inferior alveolar canal and mandibular third molar roots. Recently, a new radiologic feature known as the juxta-apical area has been suggested to be predictive of an increased risk of injury to the mandibular canal.8 In a randomized controlled clinical trial, it was found that 2 radiographic signs, the presence of a juxta-apical area and a deviation of the canal at the apex, are more predictive of injury to the mandibular canal than other signs.6 In a study using dental computed tomography to evaluate the coronectomy procedure for mandibular third molars, dysesthesia occurred in a patient who had a preoperative juxta-apical area. The symptoms of dysesthesia ameliorated in 3 weeks.9 However, contrasting results were found in another study, which found that juxtaapical areas on CBCT scans appear to be large cancellous bony spaces and not a sign of increased risk.10 The juxta-apical areas represent superimpositions of the mandibular canals with large cancellous bone spaces; thus, juxta-apical areas are images created by cancellous bony architecture rather than pathology.10 In the present study we evaluated the anatomic relationship of the juxta-apical radiolucencies to mandibular canals on panoramic and CBCT images. Juxta-apical radiolucencies were seen as well-defined
ORAL AND MAXILLOFACIAL RADIOLOGY 642 Kapila et al.
OOOO May 2014
Fig. 1. Condition of the root apex on panoramic images. A, Root apex clear. B, Root apex not clear.
Fig. 2. Relationship between juxta-apical radiolucency and mandibular canal on panoramic images. A, Contacting. B, Separated.
Fig. 3. Condition of apex of root on CBCT images. A, Root apex clear. B, Root apex not clear.
radiolucencies lateral to root apices, in otherwise healthy teeth. We studied root apices and the relationship between juxta-apical radiolucencies and mandibular canals on panoramic and CBCT images. The panoramic findings were not consistent with CBCT findings. In a large number of panoramic images, it was difficult to visualize root apices clearly. This drawback
was overcome by using CBCT images, in which root apices were clearly seen in the majority of cases. It was also possible to visualize the number and morphology of roots on CBCT images, as compared with panoramic images. On panoramic images, juxta-apical radiolucencies were seen contacting the mandibular canals in most of the cases; however, with CBCT, it was seen
OOOO Volume 117, Number 5
ORIGINAL ARTICLE Kapila et al. 643
Fig. 4. Relationship between juxta-apical radiolucency (unfilled arrows) and mandibular canal (filled arrows) on CBCT images. A, Contacting. B, Separated.
Fig. 5. Comparison of condition of root apex on panoramic and CBCT scans (P < .05). (CBCT, cone beam computed tomography.)
Fig. 6. Comparison of relation of juxta-apical radiolucency and mandibular canal on panoramic and CBCT images (P < .05). (CBCT, cone beam computed tomography.)
that the juxta-apical radiolucencies were separated from the mandibular canals.
REFERENCES
CONCLUSION Panoramic images alone are not adequate for assessments of third-molar-apex-mandibular-canal anatomic relationships. The present study found that there is no definite intimate relationship between juxta-apical radiolucencies and mandibular canals on CBCT images. These results are contrary to previous studies in which juxta-apical radiolucencies were suggested to be predictive of injuries to mandibular canals.6,8,9 Further studies with larger sample sizes are required to confirm the findings of our study. Moreover, future prospective studies could be carried out to evaluate the effect of juxta-apical radiolucencies on cortical plates and their involvement in postoperative paresthesia.
1. Neves FS, Souza TC, Almeida SM, Haiter-Neto F, Freitas DQ, Boscolo FN. Correlation of panoramic radiography and cone beam CT findings in the assessment of the relationship between impacted mandibular third molars and the mandibular canal. Dentomaxillofac Radiol. 2012;41:553-557. 2. Mahasantipiya PM, Savage NW, Monsour PAJ, Wilson RJ. Narrowing of the inferior dental canal in relation to the lower third molars. Dentomaxillofac Radiol. 2005;34:154-163. 3. Susarla SM, Sidhu HK, Avery LL, Dodson TB. Does computed tomographic assessment of inferior alveolar canal cortical integrity predict nerve exposure during third molar surgery? J Oral Maxillofac Surg. 2010;68:1296-1303. 4. Harada N, Vasudeva SB, Joshi R, et al. Correlation between panoramic radiographic signs and high-risk anatomical factors for impacted mandibular third molars. Oral Surgery. 2013;6:129-136. 5. Frafjord R, Renton T. A review of coronectomy. Oral Surgery. 2010;3:1-7. 6. Renton T, Hankins M, Sproate C, McGurk M. A randomised controlled clinical trial to compare the incidence of injury to the inferior alveolar nerve as a result of coronectomy and removal of
ORAL AND MAXILLOFACIAL RADIOLOGY 644 Kapila et al.
7.
8. 9.
10.
mandibular third molars. Br J Oral Maxillofac Surg. 2005;43: 7-12. Hasegawa T, Ri S, Shigeta T, et al. Risk factors associated with inferior alveolar nerve injury after extraction of the mandibular third molarda comparative study of preoperative images by panoramic radiography and computed tomography. Int J Oral Maxillofac Surg. 2013;42:843-851. Renton T. Notes on coronectomy. Br Dent J. 2012;212:323-326. Hatano Y, Kurita K, Kuroiwa Y, Yuasa H, Ariji E. Clinical evaluations of coronectomy (intentional partial odontectomy) for mandibular third molars using dental computed tomography: a case-control study. J Oral Maxillofac Surg. 2009;67:1806-1814. Umar G, Bryant C, Obisesan O, Rood JP. Correlation of the radiological predictive factors of inferior alveolar nerve injury
OOOO May 2014 with cone beam computed tomography findings. Oral Surgery. 2010;3:72-82. Reprint requests: Rishabh Kapila, MDS Division of Radiology Department of Oral Diagnostic Sciences Showa University School of Dentistry 2-1-1 Kita-senzoku Ota-ku Tokyo 145-8515 Japan [email protected]
Relationships between third-molar juxta-apical radiolucencies and mandibular canals in panoramic and cone beam computed tomography images Rishabh Kapila, MDS,a Nana Harada, DDS,a Kazuyuki Araki, DDS, PhD,a Tsukasa Sano, DDS, PhD,a and Tazuko K. Goto, DDS, PhDb Showa University, Tokyo, Japan; University of Hong Kong, Hong Kong
Objective. This study aimed to determine the relationship between third-molar juxta-apical radiolucencies and mandibular canals on panoramic and cone beam computed tomography (CBCT) images. Study Design. Forty-two patients were included in this retrospective study. The root apices and the relationships of the juxtaapical radiolucencies to the mandibular canals were evaluated on both panoramic and CBCT images. The McNemar test (P < .05) was used to compare panoramic with CBCT findings. Results. Root apices were visualized clearly with CBCT in most cases for which the apices were not seen clearly on panoramic images. Similarly, juxta-apical radiolucencies were separate from the mandibular canals with CBCT in most cases. Conclusions. The present study found that there is no consistent intimate relationship between juxta-apical radiolucencies and the mandibular canals. Similar studies with larger sample sizes are required to further confirm these findings. (Oral Surg Oral Med Oral Pathol Oral Radiol 2014;117:640-644)
The extraction of mandibular third molars may result in complications such as postoperative paresthesia, owing to an intimate relationship between the roots of third molars and the mandibular canals, mandibular cortices, or both.1 Imaging examination is an essential tool for diagnosing and surgically managing impacted third molars. This is because imaging provides valuable information about tooth position, number/morphology of the roots, and the relationship of the tooth to adjacent structures.1 Traditionally, periapical radiographs and panoramic radiographs have been used before surgery to assess the relationship between the inferior alveolar canal and the adjacent third molar roots. Both conventional imaging modalities have their limitations, but perhaps the greatest limitation is the lack of 3-dimensional information.2 These limitations motivated investigators to use computed tomography (CT) and more recently cone beam computed tomography (CBCT) for improving the diagnostic utility of preoperative imaging. The benefits of CT and CBCT are the visualization of anatomic relationships in multiple planes (axial, coronal, and sagittal) and the generation of 3-dimensional reformations. Their disadvantages include the increased cost and radiation exposure for the typical adolescent or young adult patient.3 A number of radiographic signs have been studied that indicate possible injury of the inferior alveolar a
Department of Radiology, Showa University School of Dentistry. Oral Radiology, Oral Diagnosis & Polyclinics, Faculty of Dentistry, University of Hong Kong. Received for publication Oct 5, 2013; returned for revision Jan 1, 2014; accepted for publication Feb 7, 2014. Ó 2014 Elsevier Inc. All rights reserved. 2212-4403/$ - see front matter http://dx.doi.org/10.1016/j.oooo.2014.02.002 b
640
nerve during extraction of the mandibular third molar. These include diversion of the canal, darkening of the root (mostly owing to superimposition of the mandibular canal), deflection of the root, narrowing of the canal, and interruption of the canal.4 Recently, a new radiographic sign (periapical or paradontal radiolucent area [juxta-apical area]) has also been associated with paresthesia after mandibular third molar removal. This new radiographic sign is a well-circumscribed radiolucent area lateral to the root rather than at the apex.5 In a randomized clinical trial, the presence of juxta-apical area was one of the radiographic signs that was associated with injury to the inferior alveolar nerve.6 No study has analyzed the relationship between juxta-apical areas (radiolucencies) and their surrounding structures. The aim of the study was to use panoramic and CBCT images to examine the relationships between third-molar juxta-apical radiolucencies and mandibular canals.
MATERIALS AND METHODS A retrospective study was conducted of 42 patients (18 men and 24 women) aged 21 to 58 years (mean, 35 years). Data were collected for those patients who underwent panoramic radiography and CBCT for the
Statement of Clinical Relevance This study compares the usefulness of panoramic radiography and cone beam computed tomography (CBCT) for depicting the relationship of juxta-apical radiolucencies with surrounding structures and supports the use of CBCT for 3-dimensional analyses of impacted third molars.
OOOO Volume 117, Number 5
examination of impacted mandibular third molars. Panoramic radiography was performed with a HyperXF panoramic machine (Asahi, Kyoto, Japan) operated at 78 kV and 10 mA. CBCT was performed with a 3D Accuitomo 80 (J. Morita, Kyoto, Japan) operated at 90 kV and 4 mA, with a field of view that had a height of 4 cm and a diameter of 4 cm. Cases included in the study were juxta-apical radiolucencies seen on panoramic radiographs. Cases did not have carious involvement/trauma or any pathology such as a cyst or tumor. Approval from the Ethical Committee of Showa University was obtained (No. 2011-022), and the study was carried out in accordance with Helsinki guidelines. A checklist was prepared for the parameters that were evaluated on panoramic and CBCT images. Two radiologists independently evaluated all images based on the checklist. Subsequently, the 2 radiologists jointly reviewed the images and made consensus determinations for the panoramic and CBCT images. Panoramic images were evaluated for the type of impaction, based on the Winter classification, as vertical, horizontal, mesioangular, or distoangular. Impacted mandibular third molars on the right side were evaluated in 27 cases and on the left side in 15 cases. The apex of the root was evaluated with regard to whether or not it was clear, and the relationship between the juxta-apical radiolucency and mandibular canal was assessed. CBCT images were analyzed in all dimensions, to visualize the condition of the root apex, whether or not it was clearly seen, and to identify the relationship between the juxta-apical area and mandibular canal. Statistical analysis Data collected were tabulated and analyzed using SPSS, version 17 (SPSS Inc). The McNemar test was used to compare panoramic and CBCT image findings. The level of significance was set at P < .05.
RESULTS On panoramic images, the impaction status of the mandibular third molars was analyzed by the Winter classification, and the results are shown in Table I. Most of the mesioangular impacted mandibular third molar cases were associated with juxta-apical radiolucencies. On panoramic images, root apices were clear in 14 cases (Figure 1, A), whereas they were not clear in 28 cases (see Figure 1, B). Juxta-apical radiolucencies were seen contacting the mandibular canal in 25 cases (Figure 2, A), whereas in only 17 cases, the juxta-apical radiolucencies were separated from the mandibular canal (see Figure 2, B). With CBCT, root apices were clear in 30 cases (Figure 3, A) and not clear in 12 cases (see Figure 3, B). Juxta-apical radiolucencies were seen
ORIGINAL ARTICLE Kapila et al. 641
Table I. Impaction status of the studied participants Description
No. of cases
Vertical Horizontal Mesioangular Distoangular
5 15 22 0
contacting the mandibular canals in 12 cases (Figure 4, A), whereas they were separated in 30 cases (see Figure 4, B). A statistically significant difference (P < .05) was found between the findings with panoramic and CBCT images (Figures 5 and 6).
DISCUSSION Third molars are removed for pathologic or preventive reasons. Whereas removals are necessary in cases of pathologic findings, the benefit of preventive removal remains controversial. Injury to the inferior alveolar nerve is a complication associated with the removal of an impacted mandibular third molar. Both surgeons and patients wish to avoid such a complication. A preoperative radiographic examination is used to determine the proximity of impacted tooth to the mandibular canal. The examination may indicate that the planned surgical approach be altered or that an alternative, lowrisk surgical technique be used (such as coronectomy).7 A number of radiologic signs have been suggested to indicate a close proximity between the inferior alveolar canal and mandibular third molar roots. Recently, a new radiologic feature known as the juxta-apical area has been suggested to be predictive of an increased risk of injury to the mandibular canal.8 In a randomized controlled clinical trial, it was found that 2 radiographic signs, the presence of a juxta-apical area and a deviation of the canal at the apex, are more predictive of injury to the mandibular canal than other signs.6 In a study using dental computed tomography to evaluate the coronectomy procedure for mandibular third molars, dysesthesia occurred in a patient who had a preoperative juxta-apical area. The symptoms of dysesthesia ameliorated in 3 weeks.9 However, contrasting results were found in another study, which found that juxtaapical areas on CBCT scans appear to be large cancellous bony spaces and not a sign of increased risk.10 The juxta-apical areas represent superimpositions of the mandibular canals with large cancellous bone spaces; thus, juxta-apical areas are images created by cancellous bony architecture rather than pathology.10 In the present study we evaluated the anatomic relationship of the juxta-apical radiolucencies to mandibular canals on panoramic and CBCT images. Juxta-apical radiolucencies were seen as well-defined
ORAL AND MAXILLOFACIAL RADIOLOGY 642 Kapila et al.
OOOO May 2014
Fig. 1. Condition of the root apex on panoramic images. A, Root apex clear. B, Root apex not clear.
Fig. 2. Relationship between juxta-apical radiolucency and mandibular canal on panoramic images. A, Contacting. B, Separated.
Fig. 3. Condition of apex of root on CBCT images. A, Root apex clear. B, Root apex not clear.
radiolucencies lateral to root apices, in otherwise healthy teeth. We studied root apices and the relationship between juxta-apical radiolucencies and mandibular canals on panoramic and CBCT images. The panoramic findings were not consistent with CBCT findings. In a large number of panoramic images, it was difficult to visualize root apices clearly. This drawback
was overcome by using CBCT images, in which root apices were clearly seen in the majority of cases. It was also possible to visualize the number and morphology of roots on CBCT images, as compared with panoramic images. On panoramic images, juxta-apical radiolucencies were seen contacting the mandibular canals in most of the cases; however, with CBCT, it was seen
OOOO Volume 117, Number 5
ORIGINAL ARTICLE Kapila et al. 643
Fig. 4. Relationship between juxta-apical radiolucency (unfilled arrows) and mandibular canal (filled arrows) on CBCT images. A, Contacting. B, Separated.
Fig. 5. Comparison of condition of root apex on panoramic and CBCT scans (P < .05). (CBCT, cone beam computed tomography.)
Fig. 6. Comparison of relation of juxta-apical radiolucency and mandibular canal on panoramic and CBCT images (P < .05). (CBCT, cone beam computed tomography.)
that the juxta-apical radiolucencies were separated from the mandibular canals.
REFERENCES
CONCLUSION Panoramic images alone are not adequate for assessments of third-molar-apex-mandibular-canal anatomic relationships. The present study found that there is no definite intimate relationship between juxta-apical radiolucencies and mandibular canals on CBCT images. These results are contrary to previous studies in which juxta-apical radiolucencies were suggested to be predictive of injuries to mandibular canals.6,8,9 Further studies with larger sample sizes are required to confirm the findings of our study. Moreover, future prospective studies could be carried out to evaluate the effect of juxta-apical radiolucencies on cortical plates and their involvement in postoperative paresthesia.
1. Neves FS, Souza TC, Almeida SM, Haiter-Neto F, Freitas DQ, Boscolo FN. Correlation of panoramic radiography and cone beam CT findings in the assessment of the relationship between impacted mandibular third molars and the mandibular canal. Dentomaxillofac Radiol. 2012;41:553-557. 2. Mahasantipiya PM, Savage NW, Monsour PAJ, Wilson RJ. Narrowing of the inferior dental canal in relation to the lower third molars. Dentomaxillofac Radiol. 2005;34:154-163. 3. Susarla SM, Sidhu HK, Avery LL, Dodson TB. Does computed tomographic assessment of inferior alveolar canal cortical integrity predict nerve exposure during third molar surgery? J Oral Maxillofac Surg. 2010;68:1296-1303. 4. Harada N, Vasudeva SB, Joshi R, et al. Correlation between panoramic radiographic signs and high-risk anatomical factors for impacted mandibular third molars. Oral Surgery. 2013;6:129-136. 5. Frafjord R, Renton T. A review of coronectomy. Oral Surgery. 2010;3:1-7. 6. Renton T, Hankins M, Sproate C, McGurk M. A randomised controlled clinical trial to compare the incidence of injury to the inferior alveolar nerve as a result of coronectomy and removal of
ORAL AND MAXILLOFACIAL RADIOLOGY 644 Kapila et al.
7.
8. 9.
10.
mandibular third molars. Br J Oral Maxillofac Surg. 2005;43: 7-12. Hasegawa T, Ri S, Shigeta T, et al. Risk factors associated with inferior alveolar nerve injury after extraction of the mandibular third molarda comparative study of preoperative images by panoramic radiography and computed tomography. Int J Oral Maxillofac Surg. 2013;42:843-851. Renton T. Notes on coronectomy. Br Dent J. 2012;212:323-326. Hatano Y, Kurita K, Kuroiwa Y, Yuasa H, Ariji E. Clinical evaluations of coronectomy (intentional partial odontectomy) for mandibular third molars using dental computed tomography: a case-control study. J Oral Maxillofac Surg. 2009;67:1806-1814. Umar G, Bryant C, Obisesan O, Rood JP. Correlation of the radiological predictive factors of inferior alveolar nerve injury
OOOO May 2014 with cone beam computed tomography findings. Oral Surgery. 2010;3:72-82. Reprint requests: Rishabh Kapila, MDS Division of Radiology Department of Oral Diagnostic Sciences Showa University School of Dentistry 2-1-1 Kita-senzoku Ota-ku Tokyo 145-8515 Japan [email protected]
