Is Panoramic Imaging Equivalent to Cone-Beam Computed Tomography for Classifying Impacted Lower Third Molars?

Danieli Moura Brasil; Eduarda H L Nascimento; Hugo Gaêta-Araujo; Christiano Oliveira-Santos; Solange Maria de Almeida

doi:10.1016/j.joms.2019.03.041

Is Panoramic Imaging Equivalent to Cone-Beam Computed Tomography for Classifying Impacted Lower Third Molars?

J Oral Maxillofac Surg. 2019 Oct;77(10):1968-1974. doi: 10.1016/j.joms.2019.03.041. Epub 2019 Apr 11.

Authors

Danieli Moura Brasil¹, Eduarda H L Nascimento², Hugo Gaêta-Araujo², Christiano Oliveira-Santos³, Solange Maria de Almeida⁴

Affiliations

¹ PhD Student, Division of Oral Radiology, Department of Oral Diagnosis, Piracicaba Dental School, University of Campinas (UNICAMP), Piracicaba, Brazil. Electronic address: danielibrasil@hotmail.com.
² PhD Student, Division of Oral Radiology, Department of Oral Diagnosis, Piracicaba Dental School, University of Campinas (UNICAMP), Piracicaba, Brazil.
³ Professor, Division of Oral Radiology, Department of Stomatology, Public Health, Forensic Dentistry, School of Dentistry of Ribeirao Preto, University of Sao Paulo, Ribeirão Preto, Brazil.
⁴ Professor, Division of Oral Radiology, Department of Oral Diagnosis, Piracicaba Dental School, University of Campinas (UNICAMP), Piracicaba, Brazil.

PMID: 31075253
DOI: 10.1016/j.joms.2019.03.041

Abstract

Purpose: Preoperative recognition of the relative position of the mandibular third molars may contribute to more reliable treatment planning, avoiding injuries and decreasing surgical and recovery times. The research questions for this study were as follows: 1) Is panoramic radiography (PR) equivalent to cone-beam computed tomography (CBCT) in determining the degree of mandibular third molar impaction? 2) For PR, is the external oblique ridge a more reliable reference to determine the degree of mandibular third molar impaction?

Materials and methods: This retrospective case-series study assessed whether the imaging modalities (primary predictor variable) are equivalent in determining the degree of impaction of third molars (primary outcome variable) according to the parameters of the Pell and Gregory classification. Two oral and maxillofacial radiologists evaluated PR and CBCT images presenting at least 1 mandibular third molar. The degrees of impaction related to the ascending ramus and related to the external oblique ridge (secondary outcome variables) also were assessed. The agreement rates between PR and CBCT were presented, and the imaging modalities were compared by the McNemar-Bowker test (α = .05).

Results: A total of 173 patients were included (66 male and 107 female patients). Among these patients, 313 mandibular third molars were assessed. In relation to the occlusal plane, the agreement rate between PR and CBCT was 82.1% for Pell and Gregory class A, 90.5% for class B, and 65.6% for class C (P = .116). The overall agreement rate between the classifications in relation to the mandibular ramus on PR and CBCT ranged from 66.8% (considering the ascending ramus, P < .001) to 76.4% (considering the external oblique ridge, P < .001).

Conclusions: PR performs similarly to CBCT in the classification of impaction in relation to the occlusal plane. However, PR shows a tendency to underestimate the space for accommodation of the third molar compared with CBCT. Furthermore, the external oblique ridge is not a reliable alternative landmark on PR.

MeSH terms

Cone-Beam Computed Tomography*
Female
Humans
Male
Mandible
Molar, Third*
Radiography, Panoramic
Retrospective Studies
Tooth, Impacted* / diagnostic imaging