Reliability of orthopantamogram in lower third molar surgery: Inter- and intra-observer agreement

Context: The evaluation of relationship between the roots of impacted lower third molar (IL3M) and inferior alveolar nerve injury (IAN) with orthopantamogram (OPG) is mandatory before performing de-impaction surgery. An investigation is considered reliable if it can be reproduced by various examiners. Assessment of OPG is subjective and varies among examiners. OPG is reliable to clinicians if the interpretation is not a product of guess work. Aim: The aim of this study was to evaluate the magnitude of agreement among oral surgeons and oral radiologist in observing intimate relationship between IL3M and mandibular canal. Materials and Methods: OPGs were evaluated by two oral surgeons and one oral radiologist for nerve root relationship. All the three were from different institutions with 10-15 years of experience. The three observers were blinded from each other's findings. A total of 127 OPGs were evaluated for inter-observer agreement. Fifty OPGs were evaluated after 60 days for intra-observer agreement.The agreement was evaluated based on Cohen's κ statistics. Results: Our results denote that the interpretation of OPG among specialists is not in good agreement. We suggest development of methods to standardize evaluation of OPG and the exposure technique to improve inter-observer agreement among the dental specialists.