Radiographic Signs of IAN Damage Following Lower Third Molar Extraction PDF

Radiographic signs associated with IAN damage following lower third molar extraction - Proximity of the lower third molar (LTM) to the inferior alveolar canal is considered a risk factor for damage to the inferior alveolar nerve - Incidence is approximately 1.1% - OPG is the diagnostic method to e...

Radiographic signs associated with IAN damage following lower third molar extraction - Proximity of the lower third molar (LTM) to the inferior alveolar canal is considered a risk factor for damage to the inferior alveolar nerve - Incidence is approximately 1.1% - OPG is the diagnostic method to evaluate the surgical extraction of lower third molars. However others prefer using CT as a better technique for evaluations. - Routine usage of CT in the extraction of LTM is not recommended due to: - High radiation dose - Cost Radiographic indicators of the close relationship between lower third molars and inferior alveolar nerve canals (7 indicators/signs) A. Four observed in the teeth: - Darkening of the root - De ection of the root - Narrowing of the root - A bi d root apex, B. Three in the canals: - Diversion of the canal - Narrowing of the canal - Interruption in the white line of the canal General Notes: - The majority of the studies recommend using CT when radiographic signs (diversion, narrowing and interruption in the white line of the canal, and darkening of the root) appear in the OPG, indicating a direct relationship between the LTM and the inferior alveolar canal. - It can be seen from the studies that diversion of the canal was the radiographic sign associated with nerve damage in the majority of the published studies. Narrowing of the root was the least associated sign. - The published studies describe the probability of nerve damage in the presence of associated radiographic signs, also known as positive predictive value (PPV). The PPV values varied between 2.2% and 3% in the majority of studies - The negative predictive value (NPV) is the probability of not damaging the nerve when these radiographic signs are absent; and vary between 97 and 99% - Exposure of the nerve during extraction of the LTM has been related with an increased risk of fi fl nerve damage. Conclusion: - OPG is a good method for preoperative evaluation of surgical LTM extraction. - Absence of radiographic signs associated with a relationship between the LTM and the canal indicates a minimum risk of nerve damage. - Exposure or damage to the nerve following extraction of LTM has been related with the absence of cortical bone of the canal in CT. - CT is recommended when radiographic signs appear in the OPG that show a direct anatomical relationship between the LTM and the canal. - None of the published studies dem- onstrate that the preoperative use of CT signi cantly re- fi duces nerve damage during surgery of LTM.