# Temporomandibularibular Disorders and Bruxism in Patients Attending a Tinnitus Clinic
## 1 Introduction
According to numerous studies, awake bruxiism is more prevalent in women, while no sex-related differences have been shown for sleep bruxiism in either children or adults [13; 14; 15; 16; 17; 18; 19]. In 2018 a report of \"work in progress\" to establish a consensus regarding bruxiism had offered a grading system with respect to bruxiism: 1. Possible bruxiism (based on self-report), 2 Probable bruxiism (based on clinical examination with or without self-report), 3 Definite Bruxiism (based on instrumental assessment with or without self-report and/or clinical assessment). Instrumental diagnosis of definite bruxiism is not a readily available clinical test nor is it standardized hence bruxiism in this study is graded a \"Probable Bruxiism\" [20]. Tinnitus is defined as a sound that is perceived in the absence of real acoustic stimuli. Patients may describe a variety of sounds [21]. Objective tinnitus can also be heard by the examiner, and the sound is often caused by a noise created in the patient's body such as jaw clicking or blood vessel malformation. Subjective tinnitus is perceived only by the patient [22]. Some patterns of tinnitus have a somatic component: this kind of tinnitus is directly influenced by the upper somatosensory system of the cervical and head area. Consequently, activating this system via muscle contractions of the head and neck can lead to either modulating ongoing tinnitus perception, occurring in 80% of the cases, or arousing sounds that might be considered as tinnitus, occurring in 50% of the cases of people not presenting with tinnitus [23]. The phenomenon of somatic tinnitus was explained physiologically. According to [PERSON] et al. (2007), afferent fibers conveying the temporomandibular somatosensory to the brain (which are projecting from the trigeminal ganglion), also project on their way to the central auditory system since they are adjacent and overlapping. This explains why the auditory system is influenced by the somatosensory system causing what is called tinnitus [24]. TMD and tinnitus are two different medical conditions which derive from two anatomically separate yet adjacent structures, the TMJ and the ear. This proximity might suggest their co-occurrence. According to the somatosensory tinnitus theory, the communication between these structures relates to the dorsal cochlear nucleus [21]. The somatosensory tinnitus theory was first described by [PERSON] in 1999, according to which, the DCN is disinhibited due to somatosensory input [25]. Since then, numerous studies have shown that this theory is clinically valid, although no neuroanatomical study was published. Tinnitus and TMD were reported to significantly co-occur. [PERSON] et al. [3] found that 30.6% of the patients presenting with TMD reportedtinnitus as well. Other studies demonstrated rates of co-occurrence of TMD and tinnitus ranging between 8-25% [26]. Bruxism has also been shown to be related to the severity of tinnitus, and chronic facial pain was higher among patients presenting with both sleep bruxism and tinnitus [27]. The current study aimed to investigate the prevalence and correlation of coexisting TMD and bruxism among patients presenting to the tinnitus clinic in a tertiary medical center, and evaluate the effect of these medical conditions on the patients' mood.