Comparative evaluation of intraoral and extraoral periapical radiographic techniques in determination of working length: An in vivo study

Abstract

Objectives/aims: This study was designed to determine the endodontic working length (WL) of root canals using digital extraoral periapical radiography (EOPAR) technique and comparing its accuracy with the standard digital intraoral periapical radiography (IOPAR). Materials and methods: Sixty single-rooted mandibular first premolars indicated for orthodontic extraction were radiographed preoperatively to ensure closed apices. After gaining endodontic access, WL was determined by IOPAR using paralleling technique, followed by EOPAR, by placing a cone at +35° from the contralateral side. Accessed tooth was then extracted to obtain the actual root canal length and was compared with the radiographic lengths. Data were subjected to statistical analysis using paired t test. Results: The actual length and the extraoral radiographic length showed no statistical significant difference (p = 0.326). The difference between the mean WL obtained by IOPA and EOPA was also not statistically significant (p = 0.096). The accuracy of IOPA technique was 97.87 ± 0.91% and that of EOPA technique was 94.65 ± 2.57%. Conclusion: The EOPA technique with an angulation of +35° can be used as an alternative to IOPA for mandibular premolars in apprehensive children, dental phobic patients with low pain threshold, neurological difficulties, and exaggerated gag reflex.