Current challenges in understanding bruxism with implications for diagnosis and management

Bruxism represents a classical paradox in the fields of dentistry and the life sciences. In the clinic, most dentists have experienced bruxism, and have ideas and beliefs about what it is and how to treat it. Yet bruxism has been very difficult to define and operationalize, and not least from a research perspective, to understand the manifestations of normal physiology and pathophysiological consequences. This selective review will present and discuss some of the current issues and controversies related to the phenomenon of bruxism. Notwithstanding the importance of rigorous systematic reviews for the advancement of this field, the purpose of this narrative review is rather to stimulate critical thinking and question old dogmas and paradigms; moreover, it serves to increase awareness of new opportunities for the assessment and management of bruxism. First, the efforts related to definition and classification will be discussed. Second, the normal physiology of bruxism behavior and the potential pathophysiological consequences of bruxism will be reviewed, with particular focus on craniomandibular pain. Third, the assessment of bruxism will be described using self-reports, clinical examination, and additional tools such as polysomnographic (PSG) recordings and ambulatory electromyographic (EMG) devices. Finally, a short review on the treatment versus the management of bruxism will be presented, with special focus on the novel proposal to use so-called contingent electrical stimulation for the relaxation of the jaw muscles. Keywords: bruxism, electromyography, trigeminal physiology, craniofacial pain, contingent electrical stimulation