An intraoral dental device includes an insert for protecting the teeth, dental arches, mandible, maxilla, temporal mangila joint and lips of the wearer from impact that may arise in athletic activities. The insert is an open cell structure which may optionally contain a fluid material, such as hydrogels, amorphous solids, semisolids, liquids and/or gases. The insert may be permanently or resiliently deformable whereby a portion of the fluid material, if present, is expelled from the insert's cells. The inserts are replaceable after they are rendered ineffective from the sustained impact.