espanolIntroduccion y objetivo: La radiografia es el principal medio usado por el endodoncista para verificar las caracteristicas del sistema de conductos, el problema es su caracter bidimensional, que puede esconder informacion importante para garantizar el exito del tratamiento, lo que hace necesario evaluar medios de contraste coadyuvantes que aumenten la sensibilidad del instrumento. Determinar validez y confiabilidad de dos tecnicas de identificacion de conductos laterales. Materiales y metodos: Estudio de prueba diagnostica en 82 premolares inferiores de humanos recien extraidos, con formacion radicular completa. Las mediciones se realizaron en radiografias periapicales de dientes con y sin medio de contraste, usando tres dimensiones (orto-mesio y disto-radial). Para el analisis se utilizaron pruebas de sensibilidad y especificidad con un nivel de significancia del 5%. La confiabilidad de la prueba para el tipo de conducto se evaluo con el Kappa Cohen. Resultados: La tecnica radiografica con medio de contraste con orientacion distal fue la mas sensible (p=0,000). Mientras que la tecnica radiografica sin medio de contraste con orientacion mesial fue la mas especifica (p=0,000). No se encontro concordancia entre las dos tecnicas para la identificacion de conductos. Conclusion: La tecnica radiografica con medio de contraste presento baja sensibilidad para identificar las variantes anatomicas en el conducto radicular, excepto en los conductos tipo delta, donde los resultados se sobreestimaron. No hubo concordancia entre las dos tecnicas para identificar el tipo de conducto, lo que sugiere no ser confiable al momento de utilizarla para tratamientos de conductos. EnglishIntroduction and objective: Radiograph is the head tool used for the endodontist to verify the characteristics of the root canal system; the problem is its two-dimensional character that could hide important information to ensure the success of the treatment, for that reason, it is necessary to evaluate the coadjutant contrast methods that increase the sensitivity of the instrument. To determine validity and reliability of two identifying techniques of radicular lateral ducts. Materials and methods: A diagnostic study was carried out in 82 recently extracted human lower premolars, with complete radicular formation. The measures were carried out by means of periapical radiographs with and without contrast media, using three dimensions (ortho-radial, medialradial and distoradial). For the analysis, tests of sensitivity and specificity were used with a level of significance of 5%. Reliability of the test for the type of radicular duct was evaluated by means of Kappa Cohen. Results: Radiographic technique with the contrast media and with distal orientation was the most sensitive (p=0.000). While the radiographic technique without contrast media and with mesial orientation was the most specific (p=0.000). No concordance was found between both techniques for the identification of radicular ducts. Conclusions: Radiographic technique with contrast media showed a low sensitivity to identify anatomic variants in the radicular duct, except in delta type ducts, where the results were overestimated. There was no concordance between both techniques to identify the type of duct what suggests not to be reliable at the moment of being used to endodontic treatment.