Betancur-P., J.J., Carvajal-F., Álvaro, Jaramillo-V., P.M., García-B., J., Madrigal-M., N. and Lopera-A., M. 2009. Comparative study of the clinical effect produced by the first Class® and the pendulum in patients trated at the College of Dentistry, University of Antioquia: a radiographic and model analysis. Revista Facultad de Odontología Universidad de Antioquia. 18, 2 (Nov. 2009), 29–44. DOI:https://doi.org/10.17533/udea.rfo.2760.