Efficacy of CBCT for assessment of impacted mandibular third molars: a review – based on a hierarchical model of evidence

Abstract

A radiographic examination of mandibular third molars is meant to support the surgeon in establishing a treatment plan. For years panoramic (PAN) imaging has been the first choice method; however, where an overprojection is observed between the third molar and the mandibular canal and when specific signs suggest a close contact between the molar and the canal, CBCT may be indicated. The present review provides an evaluation of the efficacy of CBCT for assessment of mandibular third molars using a six-tiered hierarchical model by Fryback and Thornbury in 1991. Levels 1-3 include studies on low evidence levels mainly regarding the technical capabilities of a radiographic method and the diagnostic accuracy of the related images. Levels 4-6 include studies on a higher level of evidence and assess the diagnostic impact of a radiographic method on the treatment of the patient in addition to the outcome for the patient and society including cost calculations. Only very few high-evidence studies on the efficacy of CBCT for radiographic examination of mandibular third molars exist and, in conclusion, periapical or PAN examination is sufficient in most cases before removal of mandibular third molars. However, CBCT may be suggested when one or more signs for a close contact between the tooth and the canal are present in the two-dimensional image-if it is believed that CBCT will change the treatment or the treatment outcome for the patient. Further research on high-evidence levels is needed. Dentomaxillofacial Radiology (

Economic and health implications of routine CBCT examination before surgical removal of the mandibular third molar in the Danish population

“…A recently published review emphasizes this lack of relevant evidence. 17 Therefore, the actual GRADE categorization could be challenged claiming that the evidence level is "D" rather than "C". This means that there is little reliable knowledge concerning the consequences of pre-operative use of CBCT in the management of mandibular third molars, for neither the patients nor society.…”

“…Whether this concept is anchored in scientific facts is not the subject of this study, but it seems that incitements for implementing new technology will tend to follow market rules and not entirely scientific or ethical standards. 17 There could be a discrepancy between the financial interests of the health provider and the society's demand for evidence-based practice. From the patient's point of view, the total price for surgical removal of a mandibular third molar in DK most probably will double if CBCT imaging becomes the routine.…”

Case Report. Practical Advantages of CBCT in the Surgical Treatment of Impacted Lower Third Molar

“…Cone Beam imaging method named CBCT is based on a perfected computed tomography technology applicable throughout the dentistry area. [7] In maxillo-facial osseous conditions, CBCT provides information on the precise location of various pathological processes developed in the jaws or facial soft tissues and data about the adjacent anatomical structures. [8] The presence of certain radiological signs on panoramic radiography such as narrowing, darkening or deflection of the root, dark, bifid or island-shaped apex, interruption of the mandibular canal cortical contour, canal deflection or narrowing, are associated with a veritable relationship between the roots of the third molar and the mandibular canal.…”

Radiographic methods used before removal of mandibular third molars among randomly selected general dental clinics

“…Furthermore, it could help to select the adequate surgical technique and to establish the foundation of the patient's informed consent. Sensory disturbances in the innervation area of the IAN have been reported to vary between 0.4% and 6% 2 and constitute a serious complication.…”

“…3 Recently, a review on radiographic examination of mandibular third molars reported that there is little evidence that CBCT will change either the treatment or the post-operative patient outcome. 2 Moreover, it has been documented that the use of CBCT is connected with higher costs and radiation to the patient than conventional methods. [4][5][6][7][8] Currently, no exact protocol of the radiographic examination of mandibular third molars exists, and therefore no strict guidelines for general practitioners (GPs) to follow have been advocated.…”