deformation of a support unit during an uncontrolled occlusal biting motion without any risk of being dislodged from between a corresponding set of upper and lower posterior teeth as the jaws are separated to their fullest extent fig4 is a perspective view of protection device 10 at an angle which illustrates a tooth retention surface 37 which is adapted to receive and support a corresponding set of posterior teeth therein during an epileptic seizure each tooth retention surface 37 is planar and abuts the same longitudinal end of each fin whether a first or second portion extending the entire length of a corresponding support unit the borders of the illustrated tooth retention surface 37 are defined by wall 41 which longitudinally protrudes from the lingual side thereof and by a portion 42 of rib 15 which longitudinally protrudes from the buccal side thereof fig4 a illustrates another tooth receiving means posterior teeth are received on and supported by tooth retention surface 47 from which protrude a plurality of curved protrusions 48 each protrusion 48 which is adapted to retain teeth on surface 47 during jaw movement extends the width of tooth retention surface 47 and is equally spaced from one another as shown each support unit 20 and 25 is provided with a lingual solid wall 49 to provide added rigidity to each support unit as shown in fig4 b each support unit 10 and 20 may be configured with as few as three fins 29 each fin may be chevron shaped as illustrated or any other suitable shape if so desired the ribs and fins may be made of the same material which is suitable for bearing the stress associated with increased interjaw.