Hard Acrylic Splint/Night Guard: This is the original design for this type of appliance and while very basic, it is still quite effective. A thin coat of cold-cured acrylic covers all of the teeth on one arch (usually the maxillary) and the opposing teeth contact the occlusal surface of the appliance each at a single point. The occlusal surface of the appliance must be smooth and free of interferences so that the patient’s teeth glide across the surface. By placing a layer of acrylic between the arches, the patient’s mandible is held in an open position, vertically unloading the TMJ and thereby relieving pressure. The smooth surface eliminates occlusal interferences that can cause trauma to the joints. The damage done by bruxing (clenching and grinding) is prevented because the layer of acrylic covering the teeth prevents the wear normally associated with this habit, the idea being that the acrylic is slowly worn away rather than the surfaces of the teeth.