Clinical Oral Investigations

, Volume 22, Issue 7, pp 2505–2509 | Cite as

Distance between mandibular canal and third molar root among 20-year-old subjects

  • Kaisa Rytkönen
  • Irja VentäEmail author
Original Article



The aim of the study was to evaluate the proximity of the mandibular third molar (M3) and the inferior alveolar canal (IAC) in a panoramic radiograph of 20-year-old subjects. The specific aim was to assess differences in this proximity over time.

Materials and methods

Two similar samples of panoramic radiographs taken in a routine oral health examination with 20-year time interval were examined retrospectively and images with both mandibular M3s were included. The material consisted of 300 subjects (25% men, mean age 20.5 ± 0.6 years). The radiographic relationship between the mandibular M3 root and the IAC was assessed as follows: the M3 root was either apart from, tangential to, superimposed with, or inferior to the IAC. Differences between frequencies were tested using the chi-squared test.


In the combined samples, only 16% of the M3s located apart from the IAC, 15% located tangential to, 61% superimposed with, and 8% inferior to the IAC. The proportion of the intimate locations had increased during the 20-year time interval from 79 to 88% (P < 0.01) and especially in females (P < 0.05).


The vast majority of the mandibular M3s situated very close to the mandibular canal.

Clinical relevance

Our results suggest that in the cohort of 20-year-old non-extraction subjects, most of the M3s are possibly at risk for inferior alveolar nerve injury at removal, as judged from the panoramic radiograph, and also the number of such teeth has increased over the 20-year period.


Molar third Panoramic radiograph Inferior alveolar canal Extraction 


Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Informed consent

For this type of study, formal consent is not required.


  1. 1.
    Gulicher D, Gerlach KL (2001) Sensory impairment of the lingual and inferior alveolar nerves following removal of impacted mandibular third molars. Int J Oral Maxillofac Surg 30(4):306–312. CrossRefPubMedGoogle Scholar
  2. 2.
    Jerjes W, El-Maaytah M, Swinson B, Upile T, Thompson G, Gittelmon S, Baldwin D, Hadi H, Vourvachis M, Abizadeh N, al Khawalde M, Hopper C (2006) Inferior alveolar nerve injury and surgical difficulty prediction in third molar surgery: the role of dental panoramic tomography. J Clin Dent 17(5):122–130PubMedGoogle Scholar
  3. 3.
    Jerjes W, Upile T, Shah P, Nhembe F, Gudka D, Kafas P, McCarthy E, Abbas S, Patel S, Hamdoon Z, Abiola J, Vourvachis M, Kalkani M, al Khawalde M, Leeson R, Banu B, Rob J, el Maaytah M, Hopper C (2010) Risk factors associated with injury to the inferior alveolar and lingual nerves following third molar surgery—revisited. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 109(3):335–345. CrossRefPubMedGoogle Scholar
  4. 4.
    Valmaseda-Castellon E, Berini-Aytes L, Gay-Escoda C (2001) Inferior alveolar nerve damage after lower third molar surgical extraction: a prospective study of 1117 surgical extractions. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 92(4):377–383. CrossRefPubMedGoogle Scholar
  5. 5.
    Cheung LK, Leung YY, Chow LK, Wong MCM, Chan EKK, Fok YH (2010) Incidence of neurosensory deficits and recovery after lower third molar surgery: a prospective clinical study of 4338 cases. Int J Oral Maxillofac Surg 39(4):320–326. CrossRefPubMedGoogle Scholar
  6. 6.
    Rood JP, Shehab BA (1990) The radiological prediction of inferior alveolar nerve injury during third molar surgery. Br J Oral Maxillofac Surg 28(1):20–25. CrossRefPubMedGoogle Scholar
  7. 7.
    Szalma J, Lempel E, Jeges S, Szabó G, Olasz L (2010) The prognostic value of panoramic radiography of inferior alveolar nerve damage after mandibular third molar removal: retrospective study of 400 cases. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 109(2):294–302. CrossRefPubMedGoogle Scholar
  8. 8.
    Nakagawa Y, Ishii H, Nomura Y, Watanabe NY, Hoshiba D, Kobayashi K, Ishibashi K (2007) Third molar position: reliability of panoramic radiography. J Oral Maxillofac Surg 65(7):1303–1308. CrossRefPubMedGoogle Scholar
  9. 9.
    Miloro M, DaBell J (2005) Radiographic proximity of the mandibular third molar to the inferior alveolar canal. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 100(5):545–549. CrossRefPubMedGoogle Scholar
  10. 10.
    Ventä I, Ylipaavalniemi P, Turtola L (2004) Clinical outcome of third molars in adults followed during 18 years. J Oral Maxillofac Surg 62(2):182–185. CrossRefPubMedGoogle Scholar
  11. 11.
    Ventä I, Turtola L (2008) Changes in the oral health of university students during the first three years of studies. Finnish Student Health Service, Helsinki. Accessed 15 Jan 2018
  12. 12.
    Nakamori K, Fujiwara K, Miyazaki A, Tomihara K, Tsuji M, Nakai M, Michifuri Y, Suzuki R, Komai K, Shimanishi M, Hiratsuka H (2008) Clinical assessment of the relationship between the third molar and the inferior alveolar canal using panoramic images and computed tomography. J Oral Maxillofac Surg 66(11):2308–2313. CrossRefPubMedGoogle Scholar
  13. 13.
    Ghaeminia H, Meijer GJ, Soehardi A, Borstlap WA, Mulder J, Bergé SJ (2009) Position of the impacted third molar in relation to the mandibular canal. Diagnostic accuracy of cone beam computed tomography compared with panoramic radiography. Int J Oral Maxillofac Surg 38(9):964–971. CrossRefPubMedGoogle Scholar
  14. 14.
    Maegawa H, Sano K, Kitagawa Y, Ogasawara T, Miyauchi K, Sekine J, Inokuchi T (2003) Preoperative assessment of the relationship between the mandibular third molar and the mandibular canal by axial computed tomography with coronal and sagittal reconstruction. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 96(5):639–646. CrossRefPubMedGoogle Scholar
  15. 15.
    European Commission (2012) Radiation protection No 172. Cone beam CT for dental and maxillofacial radiology. Evidence-based guidelines. pp 71–73. Accessed 15 Jan 2018
  16. 16.
    Susarla S, Dodson T (2007) Preoperative computed tomography imaging in the management of impacted mandibular third molars. J Oral Maxillofac Surg 65(1):83–88. CrossRefPubMedGoogle Scholar
  17. 17.
    Neugebauer J, Shirani R, Mischkowski RA, Ritter L, Scheer M, Keeve E, Zöller JE (2008) Comparison of cone-beam volumetric imaging and combined plain radiographs for localization of the mandibular canal before removal of impacted lower third molars. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 105(5):633–642. CrossRefPubMedGoogle Scholar
  18. 18.
    Bayram M, Özer M, Arici S (2009) Effects of first molar extraction on third molar angulation and eruption space. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 107(2):e14–e20. CrossRefPubMedGoogle Scholar
  19. 19.
    De-la-Rosa-Gay C, Valmaseda-Castellon E, Gay-Escoda C (2006) Spontaneous third-molar eruption after second-molar extraction in orthodontic patients. Am J Orthod Dentofac Orthop 129(3):337–344. CrossRefGoogle Scholar

Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Municipal Health CenterHelsinkiFinland
  2. 2.Department of Oral and Maxillofacial Diseases, Faculty of MedicineUniversity of HelsinkiHelsinkiFinland

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