A mandibular protrusion device includes an upper dental tray to be placed on the upper dental arch of a patient and a lower dental tray to be placed on the lower dental arch, as well as two lateral links for connecting both trays in order to advance or draw back the lower dental arch during a vertical movement between both dental arches, each lateral link including an element of traction attached to the trays via its ends. Each lateral link includes ball pivots having an opening for receiving an end of an element of traction, and each tray includes two lateral seats for accommodating a ball pivot connected to an element of traction so that the lateral links are connected to the trays via a ball pivot joint. A corresponding lateral link and a method for assembling the mandibular protrusion device are also disclosed.