The paper presents the human implanted mandible behavior under the action of muscle forces creating different stress distributions depending on the kind of motion performed. The mandible is treated in accordance to the classical mechanics methods. The model is based on the mandible actual shape, taking into account the correct geometric parameters. By imposing the motion conditions during mastication and by considering the real forces developed by muscles during this motion, the reaction forces acting in the temporal-mandible joint and on each tooth have been computed. The aim of the paper is to establish a connection between the implant number and the jaw mechanical behavior.