Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2021 Mar;51(1):9-16.
doi: 10.5624/isd.20200095. Epub 2021 Jan 28.

Reliability of panoramic radiography in predicting proximity of third molars to the mandibular canal: A comparison using cone-beam computed tomography

Willy James Porto Nunes  1 , Aline Lisboa Vieira  1 , Letícia Drumond de Abreu Guimarães  2 , Carlos Eduardo Pinto de Alcântara  3 , Francielle Silvestre Verner  4 , Matheus Furtado de Carvalho  3
Affiliations

Reliability of panoramic radiography in predicting proximity of third molars to the mandibular canal: A comparison using cone-beam computed tomography

Willy James Porto Nunes et al. Imaging Sci Dent. 2021 Mar.

Abstract

Purpose: The purpose of this study was to analyze the reliability of 7 panoramic radiographic signs for predicting proximity of the root apices of mandibular third molars to the mandibular canal using cone-beam computed tomography and to correlate these findings with the Pell and Gregory and the Winter classification systems.

Materials and methods: An observational, cross-sectional, descriptive study was conducted on 74 patients with bilateral impacted mandibular third molars. Four panoramic radiographic signs were observed in the tooth root (darkening, deflection, and narrowing of the root apices, and bifid apices), and another 3 in the mandibular canal (diversion, narrowing, and interruption of the mandibular canal). Cone-beam computed tomography images were analyzed to identify disruption and diversion of the mandibular canal and root deflection.

Results: Binary logistic regression showed that only 4 of the 7 panoramic radiographic signs were able to predict proximity of the root apices of the mandibular third molars to the mandibular canal: darkening of the root, deflection of the root, narrowing of the root, and interruption of the mandibular canal (P<0.05).

Conclusion: Darkening, deflection, and narrowing of the root, in tandem with the interruption of the mandibular canal on panoramic radiographs, indicate that cone-beam computed tomography should be performed when planning the extraction of impacted mandibular third molars. Proximity between mandibular third molars and the mandibular canal is correlated with the Winter classification.

Keywords: Cone-beam Computed Tomography; Mandibular Nerve; Radiography, Panoramic; Third Molar.

PubMed Disclaimer

Conflict of interest statement

Conflicts of Interest: None

Figures

Fig. 1
Fig. 1. Radiographic images of the relationship between the root apices of the mandibular third molar and mandibular canal. A. Darkening of the root apices. B. Deflection of the root apices in contact with the mandibular canal. C. Abrupt narrowing of the distal root. D. Bifid apices. E. Interruption of the mandibular canal. F. Abrupt diversion of the mandibular canal. G. Abrupt narrowing of the mandibular canal.
Fig. 2
Fig. 2. Cone-beam computed tomography coronal (A and D) and sagittal (B and C) sections show the relationship between the mandibular third molar and mandibular canal. A. intimate contact with interruption of the mandibular canal. B. Deflection of the root, emphasizing the path of the mandibular canal. C. Diversion of the mandibular canal. D. Interruption of the mandibular lingual cortex.
Fig. 3
Fig. 3. Cone-beam computed tomography coronal sections show the position of the mandibular canal in relation to the third molar. A. Inferior. B. Buccal. C. Lingual. D. Interradicular.
Fig. 4
Fig. 4. Distribution of radiographic signs identified on panoramic radiographs.
Fig. 5
Fig. 5. Distribution of the number of panoramic signs found on the same tooth.
See this image and copyright information in PMC

References

    1. Cheung LK, Leung YY, Chow LK, Wong MC, Chan EK, Fok YH. Incidence of neurosensory deficits and recovery after lower third molar surgery: a prospective clinical study of 4338 cases. Int J Oral Maxillofac Surg. 2010;39:320–326. - PubMed
    1. Huang CK, Lui MT, Cheng DH. Use of panoramic radiography to predict postsurgical sensory impairment following extraction of impacted mandibular third molars. J Chin Med Assoc. 2015;78:617–622. - PubMed
    1. Carter K, Worthington S. Predictors of third molar impaction: a systematic review and meta-analysis. J Dent Res. 2016;95:267–276. - PubMed
    1. Sarikov R, Juodzbalys G. Inferior alveolar nerve injury after mandibular third molar extraction: a literature review. J Oral Maxillofac Res. 2014;5:e1 - PMC - PubMed
    1. Nakayama K, Nonoyama M, Takaki Y, Kagawa T, Yuasa K, Izumi K, et al. Assessment of the relationship between impacted mandibular third molars and inferior alveolar nerve with dental 3-dimensional computed tomography. J Oral Maxillofac Surg. 2009;67:2587–2591. - PubMed