Sleep bruxism and the associated factors

On Wednesday, February 7, 2024, Thiprawee Chattrattrai will defend her thesis entitled ‘Sleep Bruxism: Associations and Comorbid Conditions’ at the University of Amsterdam. Her promotors are prof. dr. F. Lobbezoo and prof. dr. G. Aarab. Her co-promotors are prof. dr. E.J.W. van Someren and dr. T.F. Blanken. Thiprawee Chattrattrai received a contribution from the NVGPT for the thesis printing. Below, a summary of her thesis is provided.

Sleep bruxism (SB) has been suggested to be associated with psychosocial factors such as stress, depression, and anxiety, and temporomandibular disorders (TMD). In addition, SB is associated with sleep disorders such as insomnia. The assessment of SB can be based on self-report, clinical investigation, and polysomnography (PSG) that includes electromyography (EMG). This thesis aimed to assess the associations of SB on the one hand and awake bruxism (AB), psychological factors, TMD, and insomnia on the other hand, using self-report and instrumental techniques to establish the presence of bruxism.
The first part of the thesis investigated whether SB and AB are associated. In addition, the associations of SB and AB with psychosocial factors and TMD were assessed. A study in female TMD patients and controls used PSG to assess SB and EMG to assess AB at rest and during stress-related activity. This study found that SB is mainly characterized by grinding activity, while AB is mainly clenching activity. In addition, SB was not associated with AB at rest or AB during stress-related activity. In contrast, AB at rest was positively associated with AB during stress-related activity. Another study in a Thai TMD-patient population investigated the association between SB, AB, TMD pain and dysfunction, and stress with a novel statistical method called ‘Network analysis’. The network model showed that self-reported SB was not associated with either AB, TMD pain and dysfunction, or stress. Meanwhile, self-reported AB was directly associated with TMD pain and indirectly associated with stress via TMD pain.  In addition, six weeks of receiving regular TMD treatment, including counselling, physical therapy, and/or psychological therapy, may increase patients’ awareness on their AB activity but not on SB activity. This part of the thesis suggested that SB and AB are different entities.
The second part of the thesis investigated the associations of SB with insomnia, demographic, psychosocial, and lifestyle factors in sleep-interested and general populations. Network models from these two populations showed that self-reported SB, i.e., possible SB, was associated with insomnia and anxiety in both populations. However, PSG-assessed SB, i.e., definite SB, was not associated with any factors in the network model. Based on this finding, it is suggested that the cut-off criteria of definite SB should be considered in a continuum spectrum. Interestingly, the tripartite association between anxiety, depression, and insomnia was found in both populations. This emphasizes that the management of SB and insomnia requires multidisciplinary expertise, including sleep medicine, dentistry, and psychiatry.
This thesis concluded that using different assessment methods to assess SB yields different clinical consequences of SB. SB was not directly associated with psychosocial factors and TMD, while AB was associated with TMD and psychosocial factors. Evidence is accumulating that SB and AB are different entities. In addition, possible SB connects with insomnia through psychosocial factors, but the possible associations between definite SB and insomnia as well as psychosocial factors could not be confirmed.