A mouthguard for protecting lips against impact trauma on orthodontic appliances (braces), protecting teeth from sports trauma, protecting teeth from clashing together or grinding; and, protecting the temporomandibular joint (T.M.J.) from traumas due to a blow to the mandible. The mouthpiece comprises a curved flexible element, having two or more substantially central apertures extending therethrough and a notched portion on the upper and lower surface thereof. On the inner posterior surface of the element, an inwardly projecting portion extends at right angles thereto on each side of the aperture and designed to be grasped by the teeth. The mouthguard lays against the outer surface of the teeth with the curved flexible element and extends into the buccal folds superiorly and interiorly of the cheek where the muscles hold it in place. A groove is positioned lengthwise along the posterior curved element above and below the right angle of the projecting portion for purposes of flexibility and to allow the muscles of the cheek to press the element close to the bone for better retention and comfort. The teeth engage both sides of the inwardly projecting element which prevent the teeth from clashing together and protects the temporomandibular joint (T.M.J.). The anterior central apertures permit easy breathing. The mouthguard is retained by the muscles of the lips and cheeks, causes no gag reflex and is simple, comfortable and protective.