Temporomandibular disorders, commonly abbreviated as TMD, encompass a range of painful conditions affecting the jaw joint and the muscles that control chewing. Sufferers often experience jaw pain, clicking or popping sounds when opening the mouth, difficulty chewing, headaches, and in severe cases, locking of the jaw. The condition is notoriously multifactorial, with stress, sleep disturbances, parafunctional habits such as clenching, and occlusal abnormalities all implicated. What has remained largely unexplored until now is whether the ambient acoustic environment itself, a chronic low-grade stressor that millions of city dwellers endure around the clock, might tip susceptible individuals toward these disorders.

The research team, led by Abdullah Hasan A. Alshehri and colleagues, enrolled 300 adults in New Delhi, India, splitting them evenly between residents of high-traffic and low-traffic areas. Rather than relying on subjective impressions of noise, the investigators measured individual-level exposure objectively, recording the equivalent continuous sound level over a full 24-hour period, denoted LAeq,24h. Each participant was then evaluated with validated clinical instruments. Temporomandibular disorders were diagnosed using the Diagnostic Criteria for Temporomandibular Disorders, the internationally recognized Axis I framework. Bruxism, the involuntary grinding or clenching of teeth, was assessed with established screening tools, as was malocclusion. The researchers also administered the Perceived Stress Scale, known as the PSS-10, and the Pittsburgh Sleep Quality Index to capture psychological and sleep-related factors that could confound the relationship.

The differences between the two groups were striking. Among residents of high-traffic areas, 61.3 percent met diagnostic criteria for temporomandibular disorders, compared with just 25.3 percent of those living in quieter neighborhoods. Bruxism followed a similar pattern, affecting 42.7 percent of the high-exposure group against 14.0 percent of the low-exposure group. Malocclusion, or a misaligned bite, was also more prevalent in the noisy areas, at 52.0 percent versus 26.0 percent. All three comparisons reached a high level of statistical significance, and the researchers confirmed a dose-response relationship, meaning that as noise exposure increased, so did the likelihood of these oral health conditions, a pattern that strengthens the plausibility of a genuine association.

To disentangle the effects of noise from other risk factors, the team performed multivariable logistic regression, a statistical technique that adjusts for the influence of competing variables. The analysis revealed that high noise exposure was the strongest independent predictor of temporomandibular disorders, with an adjusted odds ratio of 3.10 and a 95 percent confidence interval spanning 2.00 to 4.80. In practical terms, after accounting for other measured factors, residents of the noisiest environments faced roughly three times the odds of developing TMD compared with their quieter counterparts. This is a substantial effect size for an environmental exposure, comparable to or exceeding the influence of many traditional risk factors for jaw disorders.

The study then probed the mechanism behind this association using exploratory mediation analysis. The findings pointed to a plausible biological pathway: bruxism and perceived stress together accounted for 41.4 percent of the association between noise and TMD. This pattern is compatible with a well-established model in which chronic noise activates the body’s stress response, elevating cortisol and sympathetic nervous system activity, which in turn promotes muscle tension and involuntary clenching of the jaw muscles. Over time, repeated clenching and grinding can overload the temporomandibular joint, inflame the surrounding musculature, and produce the characteristic pain and dysfunction of TMD. Sleep disturbance, another well-documented consequence of nighttime noise, may amplify this cycle, since poor sleep both heightens stress reactivity and is itself associated with sleep bruxism.

The authors are careful to note an important caveat regarding malocclusion. While the cross-sectional association between traffic noise and misaligned bites was statistically robust, they caution that it more likely reflects pre-existing skeletal or occlusal characteristics of the populations studied than any causal effect of noise. Bite alignment is largely determined by genetics and childhood development, and adults’ jaw structures do not remodel in response to ambient sound. People with certain occlusal patterns may also be more vulnerable to the effects of stress and clenching, which could make them overrepresented among symptomatic residents of noisy areas. The researchers explicitly advise interpreting the malocclusion finding with caution, in contrast to the noise-bruxism-TMD pathway, which is biologically coherent and supported by the mediation results.

As with any cross-sectional study, the design measures exposure and outcomes at a single point in time, which precludes establishing temporal precedence. It remains theoretically possible that people with painful jaw conditions perceive or respond to noise differently, or that unmeasured characteristics of high-traffic neighborhoods, such as air pollution, housing density, or socioeconomic strain, contribute to the observed differences. The mediation analysis, while suggestive, is exploratory and cannot prove causation. Nevertheless, the dose-response gradient, the objective noise measurements, the use of standardized diagnostic criteria, and the alignment with the broader literature on noise and stress physiology collectively lend considerable weight to the findings.

The public health implications are considerable. Environmental noise pollution is already recognized by the World Health Organization as the second most harmful environmental stressor in Western Europe, after air pollution, contributing to cardiovascular disease, sleep disturbance, and cognitive impairment in children. This study extends that concern to an underappreciated domain of health: the masticatory system. If the findings are confirmed by longitudinal research, they would suggest that the burden of traffic noise includes a substantial share of preventable jaw pain and dysfunction, conditions that degrade quality of life, impair eating and speech, and generate significant healthcare costs.

The authors argue that their results support two complementary policy responses. The first is noise abatement: traffic management, quieter road surfaces, speed restrictions, noise barriers, and urban planning that separates residential zones from major thoroughfares could reduce exposure at the population level. The second is targeted oral health screening in high-traffic urban environments, where clinicians might reasonably raise their index of suspicion for TMD and bruxism among patients exposed to chronic noise. For individuals, the study is a reminder that the soundscape of a home is not merely an amenity but a health variable, one that may be quietly shaping the tension carried in the jaw. As cities grow denser and louder, the humble temporomandibular joint may prove to be an unexpected barometer of urban environmental quality, and the study’s message is clear: what harms the heart and the mind through noise may also, quite literally, set teeth on edge.

Subject of Research: The association between environmental traffic noise exposure and temporomandibular disorders, bruxism, and malocclusion in urban adults

Article Title: Environmental noise pollution and its association with temporomandibular joint disorders, malocclusion, and bruxism: A Comparative cross-sectional study of adults in high-traffic and low- traffic areas

Article References: Hasan A. Alshehri, A., Ali F. Alshadidi, A., Aldosari, L. I. N., Kaleem, S. M., Gurumurthy, V., Vyas, R., & Vaddamanu, S. K. (2026). Environmental noise pollution and its association with temporomandibular joint disorders, malocclusion, and bruxism: A Comparative cross-sectional study of adults in high-traffic and low- traffic areas. PLOS One, 21(10), e0360667. https://doi.org/10.1371/journal.pone.0360667

Image Credits: AI Generated

DOI: 10.1371/journal.pone.0360667

Keywords: noise pollution, temporomandibular disorders, bruxism, malocclusion, traffic noise, stress, sleep quality, urban health, public health, cross-sectional study, New Delhi, oral health