Article
We highlight a case of bony trabecular pattern mimicking a peri-apical radiolucency associated with a lower third molar, illustrating the sensitivity and specificity of cone beam computed tomography (CBCT) in detecting peri-apical pathology, or the lack thereof in this case, where conventional plain film radiography may be limited or misleading.
A patient was referred to the dental hospital with a painful lower right third molar. She reported pain that had been ongoing for several years, with a recent flare up of symptoms. She described a constant, throbbing pain that kept her awake at night, which was relieved by salt-water rinses and paracetamol.
Medically she was well, other than gastric reflux, for which she was taking lansoprazole. She was a non-smoker, with occasional alcohol intake.
On examination, the lower right third molar was partially erupted, covered by an operculum, with localized mild periodontal pocketing present.
A dental panoramic radiograph was taken, showing the LR8 roots superimposed on the inferior dental canal, with a well-defined radiolucency in the region of the LR8 apices (Figure 1).
The patient was diagnosed with recurrent pericoronitis associated with the LR8, given the clinical and radiographic findings.
The patient subsequently had a CBCT examination to further investigate the nature of the radiolucency in the LR8 region, the differential diagnoses for which included a cystic lesion or other peri-apical pathology.
The CBCT showed the inferior dental canal to be lingual to the middle third of the LR8 mesial and distal roots, adjacent to the lingual cortex, with narrowing of the canal, and partial loss of the cortical outline. Sparse bony trabeculation was noted in the LR8 region, with no other pathology noted in this region (Figure 2).
Several treatment options were discussed with the patient. She was offered conservative management including irrigation and debridement of the LR8, as well as the options of coronectomy, or surgical extraction. The patient elected to have a coronectomy of the LR8, given the intimate relationship of the inferior dental nerve with the LR8 roots that was revealed in the CBCT.
Coronectomy is indicated as a treatment option to prevent iatrogenic damage to the inferior dental nerve when third molars require removal.1
Therefore, the indications for CBCT in this case were two-fold: first to assess relationship of the LR8 apices to the inferior dental canal, as the panoramic showed signs of high risk of nerve damage; and secondly to assess the nature of the radiolucent area, which would subsequently alter management options.
The option of coronectomy was only possible given that there was no peri-apical pathology associated with the tooth, as this would have contraindicated treatment.
The use of CBCT versus panoramic radiography to evaluate for radiographic signs of pathology in mandibular third molars has been reported.2 While routine use of CBCT is not suggested, it has been recommended when the clinician has specific questions that cannot be answered with panoramic or intra-oral imaging, or where it may change the treatment outcome, as it did in this case.3,4 Moreover, the higher sensitivity of CBCT than plain film imaging in the assessment of peri-apical pathology has also been reported in the literature.5
In this case, the specificity of CBCT is demonstrated, ie the ability to correctly identify those without a disease, where plain film imaging may suggest otherwise.
Reliance on plain film imaging in this scenario may have resulted in the area being mistaken for pathological radiolucency, such as a cystic lesion or other peri-apical pathology. This may have precluded the patient from having a coronectomy, with the alternative option being surgical removal with a high risk of inferior alveolar nerve damage.
Therefore, we would like to emphasize to clinicians the value of CBCT imaging as a sensitive and specific imaging modality, which should be considered in cases such as this one, for investigation of suspected peri-apical pathology where conventional radiography does not provide definitive answers.
In this case, the patient's treatment options depended on the accurate recognition of the radiolucent area seen on the panoramic radiograph as sparse bony trabeculae; a variant of normal. There was a high diagnostic yield of the CBCT here, as it meant that the patient avoided a potentially unnecessary extraction with a high-risk of nerve damage.