Signs and symptoms
Most people who brux are unaware of the problem, either because there are no symptoms, or because the symptoms are not understood to be associated with a clenching and grinding problem. The symptoms of sleep bruxism are usually most intense immediately after waking, and then slowly abate, and the symptoms of a grinding habit which occurs mainly while awake tend to worsen through the day, and may not be present on waking. Bruxism may cause a variety of signs and symptoms, including:

A grinding or tapping noise during sleep, sometimes detected by a partner or a parent. This noise can be surprisingly loud and unpleasant, and can wake a sleeping partner. Noises are rarely associated with awake bruxism. Other parafunctional activity which may occur together with bruxism: cheek biting (which may manifest as morsicatio buccarum and/or linea alba), and/or lip biting. A burning sensation on the tongue (see: glossodynia), possibly related to a coexistent "tongue thrusting" parafunctional activity. Indentations of the teeth in the tongue ("crenated tongue" or "scalloped tongue"). Hypertrophy of the muscles of mastication (increase in the size of the muscles that move the jaw), particularly the masseter muscle. Tenderness, pain or fatigue of the muscles of mastication, which may get worse during chewing or other jaw movement. Trismus (restricted mouth opening). Pain or tenderness of the temporomandibular joints, which may manifest as preauricular pain (in front of the ear), or pain referred to the ear (otalgia). Clicking of the temporomandibular joints.
Headaches, particularly pain in the temples, caused by muscle pain associated with the temporalis muscle. Excessive tooth wear, particularly attrition, which flattens the occlusal (biting) surface, but also possibly other types of tooth wear such as abfraction, where notches form around the neck of the teeth at the gumline. Tooth fractures, and repeated failure of dental restorations (fillings, crowns, etc.). Hypersensitive teeth, (e.g. dental pain when drinking a cold liquid) caused by wearing away of the thickness of insulating layers of dentin and enamel around the dental pulp. Inflammation of the periodontal ligament of teeth, which may make them sore to bite on, and possibly also a degree of loosening of the teeth.Bruxism is usually detected because of the effects of the process (most commonly tooth wear and pain), rather than the process itself. The large forces that can be generated during bruxism can have detrimental effects on the components of masticatory system, namely the teeth, the periodontium and the articulation of the mandible with the skull (the temporomandibular joints). The muscles of mastication that act to move the jaw can also be affected since they are being utilized over and above of normal function. Pain
Most people with bruxism will experience no pain. The presence or degree of pain does not necessarily correlate with the severity of grinding or clenching. The pain in the muscles of mastication caused by bruxism can be likened to muscle pain after exercise.