Introduccion: el presente estudio pretendio determinar el comportamiento mecanico entre tramos protesicos rigidos y no rigidos de una protesis fija de cinco unidades con pilar intermedio utilizando el analisis de elementos finitos (AEF) Metodos: se diseno un modelo rigido de cinco unidades con 124,469 nodos y 76,215 elementos y un modelo no rigido con 125,130 nodos y 77,396 elementos, conformados por hueso esponjoso, hueso cortical, ligamento periodontal, pulpa, dentina, raiz, cemento resinoso, coronas metal-ceramica y ajuste tuve-lock (Sterngold®, Implamed Attleboro MA). El tramo protesico comprendio un incisivo central, un incisivo lateral, un canino, un primer premolar y un segundo premolar superior. Se aplico una fuerza de 200 N con direccion oblicua y vertical. Las variables incluidas en el modelado fueron modulo de elasticidad, razon de Poisson y el ajuste no rigido. Fueron calculados los esfuerzos von Misses, maximos principales y minimos principales para cada grupo. Resultados y conclusiones: el analisis del comportamiento mecanico indico que en el tramo protesico rigido hubo mejor distribucion de los esfuerzos en relacion con el modelo no rigido. El comportamiento de cada grupo indico que el modelo rigido transmitio menos esfuerzo a la raiz y al hueso subyacente. La influencia de poner un ajuste no se justificaria segun los resultados de este estudio. ABSTRACT. Introduction: the purpose of this study is to establish the mechanical behavior between rigid and non-rigid fixed dental prosthesis of five units with an intermediate abutment using the finite element analysis (FEA). Methods: a five unit rigid model with 124.469 nodes and 76.215 elements and a non-rigid model with 125.130 nodes and 77.396 elements were designed. It consisted of trabecular bone, cortical bone, periodontal ligament, pulp, dentine, root, resinous cement, metal ceramic crowns and tube-lock adjustment (Sterngold®, Implamed Attleboro MA). The fixed dental prosthesis included a central incisor, lateral incisor, canine, first and second upper premolars. A force of 200 N was applied with an oblique and vertical direction. The variables included in the model were modulus of elasticity, Poisson’s ratio and non-rigid adjustment. Von Misses stresses, main, maximum and minimum, were calculated for each group. Results and conclusions: the analysis of the mechanical behavior indicated that the rigid fixed dental prosthesis showed a better distribution of the stresses in comparison with the non-rigid model. The behavior of each group indicated that the rigid model transmitted less stress to the underlying root and bone. The indication to use an adjustment would not be justified according to the results of this study.