Sleep bruxism Associations and comorbid conditions

The general aim of this thesis was to assess the associations of sleep bruxism (SB) on the one hand and awake bruxism (AB), psychological factors, temporomandibular disorders (TMD), and insomnia on the other hand, using self-report and instrumental techniques to establish the presence of bruxism. This thesis’s findings were that objectively assessed SB and AB are not associated across individuals. Further, SB is conditionally independent from AB and TMD and the improvement of SB is not associated with TMD treatment. In contrast, a direct association between AB and TMD was found. Besides, this thesis investigated the association between SB and insomnia in a specific population sample as well as in a general population sample, by investigating the association of SB, assessed with self-report and polysomnography (PSG), with insomnia and psychosocial factors. The results showed that only self-reported SB, i.e., possible SB, was associated with insomnia and psychosocial factors. In contrast, PSG-confirmed SB, i.e., definite SB, was not associated with either insomnia or psychosocial factors. Based on the findings of this thesis, different assessments ranging from self-report to instrumental techniques suggest different clinical consequences and associated conditions of SB. SB is not directly associated with psychosocial factors and TMD, while AB is associated with those factors. In addition, evidence is accumulating that SB and AB are different entities. Furthermore, possible SB connects with insomnia through psychosocial factors, but the associations between definite SB and insomnia as well as psychosocial factors could not be confirmed.