Indications for night guard appliance Indications Tenderness and stiffness in jaw muscles. When there is increased wear of tooth which results in loss of occlusal morphology and flattening of the occlusal tooth surface. What is a night guard used for? A night guard, also known as a dental mouth guard, occlusal guard, or a bite guard, is an appliance prescribed to patients to treat teeth grinding (bruxism). In general, it protects the teeth and other vital structures by offering a protective barrier between the upper and lower teeth.