A mandibular subluxation device (MSD) is provided. The device includes an upper MSD component and a lower MSD component. The upper MSD component includes and upper tooth guide connected to an upper plate having a pair of depending legs. The upper MSD component further includes an upper force receiving plate. The MSD also includes a lower MSD component. The lower MSD component includes a lower tooth guide connected to a lower plate. The lower MSD component further includes a lower force receiving plate. The upper and lower MSD components are connected in a way that allows relative longitudinal movement between the two components between a neutral position and a plurality of extended positions. A ratchet mechanism inhibits movement of the lower plate from any extended position toward the neutral position. The ratchet mechanism may be manually disengaged to allow the lower MSD component to return to the neutral position.