Pupil size as a sensitive marker of acute stress dynamics.

Bruxism is a repetitive jaw-muscle activity characterized by clenching or grinding of the teeth and/or bracing or thrusting of the mandible. It has two distinct circadian manifestations: sleep bruxism (SB), which occurs during sleep, and awake bruxism (AB), which occurs during wakefulness. Bruxism is not classified as a movement or sleep disorder, but is rather seen as a motor behavior that may or may not be linked to clinical consequences such as dental wear. Bruxism activity is thought to originate from the central autonomic nervous system. The global prevalence of bruxism (sleep and awake) is 22.22%. The global prevalence of SB is 21% and AB is 23%. SB in childhood and adolescence ranges between 7.0% and 15.1%, with girls apparently more frequently affected. Bruxism can have a significant impact on the lives of children and adolescents, affecting their oral health and general well-being. Excessive pressure on the teeth can lead to tooth wear, dental sensitivity, jaw pain, and frequent headaches, impairing oral health-related quality of life. Sleep disturbances associated with nighttime bruxism can also result in daytime tiredness and difficulty concentrating. These consequences may be more severe in children due to the structural and morphofunctional characteristics of deciduous dentition. The etiology of bruxism is complex and multifactorial, with its pathophysiology still not fully understood. While AB is mainly attributed to psychosocial factors, the pathophysiology of SB appears more complex and centrally mediated. A meta-analysis examined factors linked to bruxism, emphasizing the significant role of emotional symptoms (e.g., nervousness and anger) and psychological disturbances (e.g., anxiety) in its occurrence among children. Other identified predictors include sex, genetic traits, sleep disorders, and habits like object biting (parafunctional) and sedentary behavior ( lack of physical activity and screen time). Screen time refers to the time spent on various types of screens, like watching television or movies, playing video games, or using smartphones and tablets. Cross-sectional studies have reported that over 40% of children engage in excessive screen time. Among adolescents, global estimates indicate that the prevalence of excessive screen time and television viewing was 70.9% and 58.8%, respectively. The association between screen time and bruxism in children and adolescents can be explained by several factors. Screen exposure may impact neurotransmitters, such as dopamine, and contribute to sleep disturbances and stress. Excessive screen time is linked to issues like longer sleep onset, insomnia, and poor sleep quality, which disrupt circadian rhythms and affect mood, cognitive development, and behavior. The main mechanisms include time displacement, psychological stimulation from media content, and the effects of light from screens on circadian rhythms and alertness. However, divergent results have been reported regarding the association between screen exposure and bruxism. Thus, a global synthesis of the available literature on the subject could provide a broader perspective on the impact of exposure to screen devices on the occurrence of bruxism. Therefore, this study aimed to systematically review the literature regarding the association between bruxism and the use of screen devices among children and adolescents.