A mandibular advancement device is proposed which comprises both an upper and a lower base plate, whereby engagement of the plates during closing of the jaws causes protrusion of the mandible and allows relative lateral movement between the jaws. In one particular form the invention relates to a device for positioning upper and lower jaws, including a cam associated with one of the jaws and a follower associated with the other jaw, the follower having an engagement surface which translates across the cam to advance one of the jaws relative to the other as the jaws are closed.
