The anterior loop of the inferior alveolar nerve. A radiographic study of panoramic
radiographs and review of the literature
Panagiota PAPANICOLAOU, Konstantinos VLASTOS, Dimitris FRAGISKOS, Fragiskos FRAGISKOS
Department of Oral and Maxillofacial Surgery, Dental School, National and Kapodistrian University of Athens, Greece (Head: Professor C. Alexandridis)
Hellenic Archives of Oral & Maxillofacial Surgery (2014) 1, 27-36
SUMMARY: The inferior alveolar nerve sometimes extends anteriorly beyond the mental foramen and runs outward, upward and backward before it reaches the mental foramen, creating what is known as the anterior loop. Placement of dental implants in this area, has a high risk of injury to the inferior alveolar nerve. Aim: This study seeks to investigate the visualisation of the anterior loop on panoramic radiographs. Material and methods: 100 panoramic radiographs were analysed in terms of loop visualisation. Results: Anterior loop was observed in 34% of the radiographs. Its prevalence was higher in males (70.5%) and in patients between 40-60 years old (47%). In most cases the loop was located bilaterally (64.7%), while the interforaminal area was mostly edentulous (64.7%). The loop length ranged between 0.5-8 mm, with an average length of 4.37mm. Conclusions: An analysis of the findings shows that implants should be placed at least 5-8mm anteriorly to the mental foramen. According to a review of the literature, computed tomography is more accurate than panoramic radiography in identifying the anterior loop.
KEY WORDS: anterior loop of the inferior alveolar canal, anterior loop of the mental canal
REFERENCES
Apostolakis D, Brown JE: The anterior loop of the inferior alveolar nerve: prevalence, measurement of its length and a recommendation for interforaminal implant installation based on cone beam CT imaging. Clin Oral Implants Res 23:1022-1030, 2012.
Arzouman MJ, Otis L, Kipnis V, Levine D: Observations of the anterior loop of the inferior alveolar canal. Int J Oral Maxillofac Implants 8:295-300, 1993. Babbush CA: Transpositioning and repositioning the inferior alveolar and mental nerves in conjunction with endosteal implant reconstruction. Periodontol 2000 17: 183-190, 1998.
Bartling R, Freeman K, Kraut RA: The incidence of altered sensation of the mental nerve after mandibular implant placement. J Oral Maxillofac Surg 57: 1408-1412, 1999.
Bavitz JB, Harn SD, Hansen CA, Lang M: An anatomical study of mental neurovascular bundle-implant relationships. In J Oral Maxillofac Implants 8:563-567, 1993.
Benninger B, Miller D, Maharathi A, Carter W: Dental implant placement investigation: is the anterior loop of the mental nerve clinically relevant? J Oral Maxillofac Surg 69:182-185, 2011.
Bertram KA, Bertram SR, Emshoff R: Use of high-resolution ultrasonograhy for analysis of the anterior mental loop. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 101:E6, 2006.
Bou Serhal C, Jacobs R, Flygare L, Quirynen M, van Steenberghe D: Perioperative validation of localization of the mental foramen. Dentomaxillofac Radiol 31:39-43, 2002.
Cavalcanti MG, Yang J, Ruprecht A, Vannier MW: Accurate linear measurements in the anterior maxilla using orthoradially reformatted spiral computed tomography. Dentomaxillofac Radiol 28:137-140, 1999.
Dao TT, Mellor A: Sensory disturbances associated with implant surgery. Int J Prosthodont 11:462-469, 1998.
Elian N, Mitsias M, Eskow R, Jalbout ZN, Cho SC, Froum S, Tarnow DP: Unexpected return of sensation following 4.5 years of paresthesia: case report. Implant Dent 14:364-370, 2005.
Ellies LG, Hawker PB: The prevalence of altered sensation associated with implant surgery. Int J Oral Maxillofac Implants 8:674-679, 1993.
Ellies LG: Altered sensation following mandibular implant surgery: a retrospective study. J Prosthet Dent 68:664-671, 1992.
Greenstein G, Tarnow D: The mental foramen and nerve: clinical and anatomical factors related to dental implant placement: a literature review. J Periodontol 77:1933-1943, 2006. Jacobs R, Mraiwa N, van Steenberghe D, Gijbels F, Quirynen M: Appearance, location, course, and morphology of the mandibular incisive canal: An assessment on spiral CT scan. Dentomaxillofac Radiol 31:322-327, 2002.
Jacobs R, Mraiwa N, van Steenberghe D, Sanderink G, Quirynen M: Appearance of the mandibular incisive canal on panoramic radiographs. Surg Radiol Anat 26:329-333, 2004.
Kaya Y, Sencimen M, Sahin S, Okcu KM, Doğan N, Bahcecitapar M: Retrospectıve radiographıc evaluation of the anterior loop of the mental nerve:comparison between panoramic radiography and spiral computerized tomography. Int J Oral Maxillofac Implants 23: 919-925, 2008.
Kieser J, Kuzmanovic D, Payne A, Dennison J, Herbison P: Patterns of emergence of the human mental nerve. Arch Oral Biol 47:743- 747, 2002.
Kingsmill VJ, Boyde A: Mineralisation density of human mandibular bone: Quantitative backscattered electron image analysis. J Anat 192:245-256, 1998.
Kingsmill VJ, Boyde A: Variation in the apparent density of human mandibular bone with age and dental status. J Anat 192:233-244, 1998.
Klinge B, Petersson A, Maly P: Location of the mandibular canal: Comparison of macroscopic findings, conventional radiography, and computed tomography. In J Oral Maxillofac Implants 4:327-332, 1989.
Kraut RA, Chahal O: Management of patients with trigeminal nerve injuries after mandibular implant placement. J Am Dent Assoc 133:1351-1354, 2002. Kuzmanovic DV , Payne AG , Kieser JA , Dias GJ: Anterior loop of the mental nerve: A morphological and radiographic study. Clin Oral Implants Res 14:464-471, 2003.
Liang H, Frederiksen NL, Benson BW: Lingual vascular canals of the interforaminal region of the mandible: evaluation with conventional tomography. Dentomaxillofac Radiol 33:340-341, 2004.
Lindh C, Petersson A, Klinge B: Measurements of distances related to the mandibular canal in radiographs. Clin Oral Implants Res 6:96- 103, 1995.
Lindh C, Petersson A: Radiologic examination for location of the mandibular canal: A comparison between panoramic radiography and conventional tomography. Int J Oral Maxillofac Implants 4:249-253, 1989.
Mardinger O, Chaushu G, Arensburg B, Taicher S, Kaffe I: Anatomic and radiologic course of the mandibular incisive canal. Surg Radiol Anat 22:157-161, 2000. Misch CE, Crawford EA: Predictable mandibular nerve location-a clinical zone of safety. Int J Oral Implantol 7:37-40, 1990.
Misch CE: Contemporary implant dentistry, In: Misch CE:. Implant Dentistry. Mosby 1999α, 2nd ed, pp: 349-350.
Misch CE: Root form surgery in the edentulous mandible: Stage I implant insertion, In: Misch CE, Implant Dentistry. Mosby 1999β, 2nd ed, pp: 347-370. Mraiwa N, Jacobs R, van Steenberghe D, Quirynen M: Clinical Assessment and Surgical Implications of Anatomic Challenges in the Anterior Mandible. Clin Implant Dent R 5:219-225, 2006.
Neiva RF, Gapski R, Wang HL: Morphometric analysis of implant-related anatomy in caucasian skulls. J Periodontol 75:1061-1067, 2004.
Ngeow WC, Dionysius DD, Ishak H, Nambiar P: A radiographic study on the visualization of the anterior loop in dentate subjects of different age groups. J Oral Sci 51:231-237, 2009.
Ngeow WC, Nambiar P: Assessment of the anterior loop should include the mandibular incisive canal. J Oral Maxillofac Surg 69:2688, 2011.
Ngeow WC: The “Missing” Anterior Loop. J Oral Maxillofac Surg 69:2076-2077, 2011.
Peker I, Alkurt MT, Michcioglu T: The use of 3 different imaging methods for the localization of the mandibular canal in dental implant planning. Int J Oral Maxillofac Implants 23:463-470, 2008.
Ritter L, Neugebauer J, Mischkowski RA, Dreiseidler T, Rothamel D, Richter U, Zinser MJ, Zoller JE: Evaluation of the course of the inferior alveolar nerve in the mental foramen by cone beam computed tomography. Int J Oral Maxillofac Implants 27:1014-1021, 2012.
Department of Oral and Maxillofacial Surgery, Dental School, National and Kapodistrian University of Athens, Greece (Head: Professor C. Alexandridis)
Hellenic Archives of Oral & Maxillofacial Surgery (2014) 1, 27-36
SUMMARY: The inferior alveolar nerve sometimes extends anteriorly beyond the mental foramen and runs outward, upward and backward before it reaches the mental foramen, creating what is known as the anterior loop. Placement of dental implants in this area, has a high risk of injury to the inferior alveolar nerve. Aim: This study seeks to investigate the visualisation of the anterior loop on panoramic radiographs. Material and methods: 100 panoramic radiographs were analysed in terms of loop visualisation. Results: Anterior loop was observed in 34% of the radiographs. Its prevalence was higher in males (70.5%) and in patients between 40-60 years old (47%). In most cases the loop was located bilaterally (64.7%), while the interforaminal area was mostly edentulous (64.7%). The loop length ranged between 0.5-8 mm, with an average length of 4.37mm. Conclusions: An analysis of the findings shows that implants should be placed at least 5-8mm anteriorly to the mental foramen. According to a review of the literature, computed tomography is more accurate than panoramic radiography in identifying the anterior loop.
KEY WORDS: anterior loop of the inferior alveolar canal, anterior loop of the mental canal
REFERENCES
Apostolakis D, Brown JE: The anterior loop of the inferior alveolar nerve: prevalence, measurement of its length and a recommendation for interforaminal implant installation based on cone beam CT imaging. Clin Oral Implants Res 23:1022-1030, 2012.
Arzouman MJ, Otis L, Kipnis V, Levine D: Observations of the anterior loop of the inferior alveolar canal. Int J Oral Maxillofac Implants 8:295-300, 1993. Babbush CA: Transpositioning and repositioning the inferior alveolar and mental nerves in conjunction with endosteal implant reconstruction. Periodontol 2000 17: 183-190, 1998.
Bartling R, Freeman K, Kraut RA: The incidence of altered sensation of the mental nerve after mandibular implant placement. J Oral Maxillofac Surg 57: 1408-1412, 1999.
Bavitz JB, Harn SD, Hansen CA, Lang M: An anatomical study of mental neurovascular bundle-implant relationships. In J Oral Maxillofac Implants 8:563-567, 1993.
Benninger B, Miller D, Maharathi A, Carter W: Dental implant placement investigation: is the anterior loop of the mental nerve clinically relevant? J Oral Maxillofac Surg 69:182-185, 2011.
Bertram KA, Bertram SR, Emshoff R: Use of high-resolution ultrasonograhy for analysis of the anterior mental loop. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 101:E6, 2006.
Bou Serhal C, Jacobs R, Flygare L, Quirynen M, van Steenberghe D: Perioperative validation of localization of the mental foramen. Dentomaxillofac Radiol 31:39-43, 2002.
Cavalcanti MG, Yang J, Ruprecht A, Vannier MW: Accurate linear measurements in the anterior maxilla using orthoradially reformatted spiral computed tomography. Dentomaxillofac Radiol 28:137-140, 1999.
Dao TT, Mellor A: Sensory disturbances associated with implant surgery. Int J Prosthodont 11:462-469, 1998.
Elian N, Mitsias M, Eskow R, Jalbout ZN, Cho SC, Froum S, Tarnow DP: Unexpected return of sensation following 4.5 years of paresthesia: case report. Implant Dent 14:364-370, 2005.
Ellies LG, Hawker PB: The prevalence of altered sensation associated with implant surgery. Int J Oral Maxillofac Implants 8:674-679, 1993.
Ellies LG: Altered sensation following mandibular implant surgery: a retrospective study. J Prosthet Dent 68:664-671, 1992.
Greenstein G, Tarnow D: The mental foramen and nerve: clinical and anatomical factors related to dental implant placement: a literature review. J Periodontol 77:1933-1943, 2006. Jacobs R, Mraiwa N, van Steenberghe D, Gijbels F, Quirynen M: Appearance, location, course, and morphology of the mandibular incisive canal: An assessment on spiral CT scan. Dentomaxillofac Radiol 31:322-327, 2002.
Jacobs R, Mraiwa N, van Steenberghe D, Sanderink G, Quirynen M: Appearance of the mandibular incisive canal on panoramic radiographs. Surg Radiol Anat 26:329-333, 2004.
Kaya Y, Sencimen M, Sahin S, Okcu KM, Doğan N, Bahcecitapar M: Retrospectıve radiographıc evaluation of the anterior loop of the mental nerve:comparison between panoramic radiography and spiral computerized tomography. Int J Oral Maxillofac Implants 23: 919-925, 2008.
Kieser J, Kuzmanovic D, Payne A, Dennison J, Herbison P: Patterns of emergence of the human mental nerve. Arch Oral Biol 47:743- 747, 2002.
Kingsmill VJ, Boyde A: Mineralisation density of human mandibular bone: Quantitative backscattered electron image analysis. J Anat 192:245-256, 1998.
Kingsmill VJ, Boyde A: Variation in the apparent density of human mandibular bone with age and dental status. J Anat 192:233-244, 1998.
Klinge B, Petersson A, Maly P: Location of the mandibular canal: Comparison of macroscopic findings, conventional radiography, and computed tomography. In J Oral Maxillofac Implants 4:327-332, 1989.
Kraut RA, Chahal O: Management of patients with trigeminal nerve injuries after mandibular implant placement. J Am Dent Assoc 133:1351-1354, 2002. Kuzmanovic DV , Payne AG , Kieser JA , Dias GJ: Anterior loop of the mental nerve: A morphological and radiographic study. Clin Oral Implants Res 14:464-471, 2003.
Liang H, Frederiksen NL, Benson BW: Lingual vascular canals of the interforaminal region of the mandible: evaluation with conventional tomography. Dentomaxillofac Radiol 33:340-341, 2004.
Lindh C, Petersson A, Klinge B: Measurements of distances related to the mandibular canal in radiographs. Clin Oral Implants Res 6:96- 103, 1995.
Lindh C, Petersson A: Radiologic examination for location of the mandibular canal: A comparison between panoramic radiography and conventional tomography. Int J Oral Maxillofac Implants 4:249-253, 1989.
Mardinger O, Chaushu G, Arensburg B, Taicher S, Kaffe I: Anatomic and radiologic course of the mandibular incisive canal. Surg Radiol Anat 22:157-161, 2000. Misch CE, Crawford EA: Predictable mandibular nerve location-a clinical zone of safety. Int J Oral Implantol 7:37-40, 1990.
Misch CE: Contemporary implant dentistry, In: Misch CE:. Implant Dentistry. Mosby 1999α, 2nd ed, pp: 349-350.
Misch CE: Root form surgery in the edentulous mandible: Stage I implant insertion, In: Misch CE, Implant Dentistry. Mosby 1999β, 2nd ed, pp: 347-370. Mraiwa N, Jacobs R, van Steenberghe D, Quirynen M: Clinical Assessment and Surgical Implications of Anatomic Challenges in the Anterior Mandible. Clin Implant Dent R 5:219-225, 2006.
Neiva RF, Gapski R, Wang HL: Morphometric analysis of implant-related anatomy in caucasian skulls. J Periodontol 75:1061-1067, 2004.
Ngeow WC, Dionysius DD, Ishak H, Nambiar P: A radiographic study on the visualization of the anterior loop in dentate subjects of different age groups. J Oral Sci 51:231-237, 2009.
Ngeow WC, Nambiar P: Assessment of the anterior loop should include the mandibular incisive canal. J Oral Maxillofac Surg 69:2688, 2011.
Ngeow WC: The “Missing” Anterior Loop. J Oral Maxillofac Surg 69:2076-2077, 2011.
Peker I, Alkurt MT, Michcioglu T: The use of 3 different imaging methods for the localization of the mandibular canal in dental implant planning. Int J Oral Maxillofac Implants 23:463-470, 2008.
Ritter L, Neugebauer J, Mischkowski RA, Dreiseidler T, Rothamel D, Richter U, Zinser MJ, Zoller JE: Evaluation of the course of the inferior alveolar nerve in the mental foramen by cone beam computed tomography. Int J Oral Maxillofac Implants 27:1014-1021, 2012.
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