The aim of this study is to examine the effects of bruxism on mandibular movement capacity, cervical proprioception, posture and quality of life in adolescents diagnosed with nocturnal bruxism (clenching and grinding teeth while sleeping) between the ages of 13-18 and to compare them with healthy adolescents.

Method: A total of 40 adolescents, 20 with nocturnal bruxism and 20 healthy, will be included in the study. Mandibular movement capacity will be evaluated with a caliper and ruler, cervical proprioception with a CROM device, posture with the New York Posture Scale, and quality of life with the PedsQL 13-18 age scale.

Hypotheses:

H1: Nocturnal bruxism reduces the movement capacity of the mandible in adolescents.

H2: Nocturnal bruxism reduces cervical proprioception in adolescents. H3: Posture disorder increases in adolescents with nocturnal bruxism. H4: Nocturnal bruxism affects the level of daily life quality in adolescents.

Bruxism is defined as repetitive jaw muscle activity characterized by clenching and grinding of teeth caused by mandibular movement.

In addition to being considered as a destructive parafunctional activity of the stomatognathic system, bruxism can cause abnormal tooth wear, damage to periodontal tissues, temporomandibular joints and muscles. Although they are often grouped and named together, there are two types of bruxism: during sleep or while awake. It is suggested that the etiology and physiopathology of bruxism seen during sleep and awake bruxism are different. However, it is stated that psychological factors such as depressive mood and stress are involved in the etiology of both types. While bruxism seen during sleep (nocturnal) is characterized by teeth grinding and clenching, the type seen while awake is more seen as teeth clenching. The pathophysiology of bruxism is still not fully known. Diagnosis and clinical evaluation of bruxism is a complex procedure. Bruxism can be diagnosed when family members observe the typical teeth clenching sound or when the dentist notices abnormal clusal wear. It is an important issue that patients with bruxism in childhood continue this habit in adulthood. Therefore, early diagnosis creates a perspective in terms of controlling the disease, as well as preventing damage to the chewing system components and increasing patient comfort. The most common clinical signs and symptoms observed in oral tissues as a result of bruxism are; wear of teeth, irregularities in supporting tissues, pulp hypersensitivity, tooth mobility, fractures in teeth or restorations, pain, temporomandibular irregularities, hypertrophy of the massater muscle, neck and headache. Wear that occurs as a result of bruxism is characterized by a parallel plane passing through the cutting edges of the teeth. Other intraoral-extraoral findings that may be associated with bruxism are facial asymmetry, inadequate lip closure, mouth breathing, and anterior and posterior crossbite. Although the etiology of bruxism is not fully known; It is suggested that various factors such as local (occlusal interferences), systemic (central nervous system disorders, asthma, rhinitis), psychological (stress, anxiety), occupational (competition sports), hereditary factors, sleep disorders and parasomnia are effective. There is a high probability of developing temporomandibular disorder (TMD) as a result of bruxism.

In these cases, during jaw opening and closing; The presence of deviation/deflection, which are sliding movements, the clicking/crepitation sound heard from the joint, and the mouth opening distance are examined. The stomatognathic system is active in chewing, breathing and speaking functions and is directly related to the cervical spine. Therefore, changes in this system may affect the normal position of the mandible, malocclusion, temporomandibular joint, head posture, and quality of life. The function of the stomatognathic system depends on the synergy of numerous muscles that also participate in other voluntary actions and reflexes. As a result, mandibular function affects both occlusal balance and postural balance. The correct position of the head in space depends on three planes; visual plane, transverse occlusal plane and auricular nasal plane. Together, these three planes maintain a parallel, horizontal relationship that provides stability of head posture through the action of mechanoreceptors in the upper 6 cervical spine. Postural changes have been associated with bruxism. This can be explained by the fact that bruxism affects not only the chewing muscles, but all the muscles of the craniofacial complex, neck and shoulders. Studies with children and adolescents have shown the importance of paying attention to the stage of development of the teeth, as head posture will be affected by dental occlusion. When the literature was examined, no study was found that examined the relationship between quality of life, posture, movement capacity of the mandible and cervical proception in adolescents with nocturnal bruxism. The investigators planned this study to aim to fill this gap in the literature.

Inclusion Criteria:

• Being diagnosed with nocturnal bruxism,
• Having received parental consent to participate in the study,
• Being between the ages of 13 and 18 (including 13,18 years old)
• Being in good mental state,
• Being able to understand and follow the locations in the work,
• Having a Class 1 occlusion.

Exclusion Criteria:

• Not consenting to participate in the study and withdrawing from the study,
• Not being able to cooperate well,
• Having a history of surgery,
• Having any physical disability or chronic disease,
• Having received dental treatment in the last six months,

20 patients with Nocturnal Bruxism and 20 non-Nocturnal Bruxism Adolescence will be included.