Abstract: A mandibular advancement device including upper and lower dental plates which operatively fit over at least part of the upper and lower teeth of a user, said upper and lower dental plates being made from a flexible material, the lower dental plate having two pairs of spaced apart pillars, each pair consisting of an anterior and posterior pillar, said pairs being on opposing sides of the lower dental plate, two removably attachable horizontal displacement inserts, mounted in the buccal region on opposite sides of the upper dental plate, two removably attachable vertical displacement inserts mounted in the lower dental plate, placed in a manner to provide correct vertical registration of the teeth, such that operatively each horizontal displacement insert is retained between the respective anterior and posterior pillars to maintain an advancement of the mandible. A method for production of the mandibular advancement device is also claimed.