Bruxism—commonly referred to as clenching or grinding—is a condition in which the upper and lower teeth repeatedly contact each other with significant force. Over time this mechanical loading leads to attrition, the gradual wearing away of enamel on the chewing surfaces of teeth. In the general population this process is problematic because it slowly shortens teeth and alters the vertical dimension of the bite. As enamel is lost, the face can take on a more collapsed appearance due to reduced occlusal height. Teeth attempt to compensate through a process known as passive eruption, where they continue to erupt slightly from the gums to maintain contact with opposing teeth. However, this compensatory process typically cannot keep pace with long-term attrition. In most individuals, these changes develop slowly over decades.
(Carranza & Newman, Clinical Periodontology; Lobbezoo et al., 2018)
Endurance athletes face a more complex situation. Research suggests that athletes may have a higher prevalence of bruxism, with pooled estimates around 34–38% in some athletic populations. Importantly, this includes both nocturnal and awake bruxism. Bruxism in athletes has been associated with factors such as physiological stress, sleep disruption, and altered neuromuscular control. Poor sleep and fatigue have been shown to correlate with decreased athletic performance, including reductions in endurance, strength output, and coordination.
(Lobbezoo et al., 2018; Manfredini et al., 2011)
Interestingly, the enamel surface of endurance athletes may behave differently due to the oral environment they experience during training. Frequent carbohydrate intake, acidic sports drinks, and reduced salivary flow can lead to repeated acid exposure and demineralization–remineralization cycles. Laboratory studies have demonstrated that acid-cycled enamel can develop a smoother surface morphology compared to sound enamel, which may change how the surface responds to attrition forces. One in-vitro investigation found that intact enamel lost approximately 25 µm of surface structure during simulated attrition, whereas acid-cycled enamel showed losses closer to 6–8 µm under similar conditions.
(Eisenburger & Addy, 2002)
Microscopically, the wear patterns also differ. When two surfaces of intact enamel grind against each other, the damage often appears as chipping, microfracturing, and crack propagation. In contrast, previously acid-softened enamel tends to show a more uniform “shaving” or polishing of the surface layer during attrition. While this does not make the tooth healthier, it illustrates how erosion and attrition interact in complex ways.
(Eisenburger & Addy, 2002; Shellis & Addy, 2014)
Reducing Damage
One of the most effective ways to reduce tooth-to-tooth wear from bruxism is the use of an occlusal guard (night guard). These appliances are typically fabricated from clear acrylic or thermoplastic material and act as a mechanical barrier between the upper and lower teeth. By preventing direct enamel contact, they significantly reduce attrition forces. Occlusal guards are also commonly used to reduce temporomandibular joint (TMJ) strain and muscle hyperactivity, though in endurance athletes their most immediate benefit may be simple mechanical protection of enamel surfaces.
(Koyano et al., 2008)
Another key contributor to enamel loss is abrasion, which refers to mechanical wear from external sources such as toothbrushing. After exposure to acids or fermentable carbohydrates, enamel temporarily becomes softened due to demineralization. Brushing during this period can remove the weakened surface layer much more easily. For this reason, many dental guidelines recommend delaying brushing after acidic exposure to allow saliva to promote remineralization. Waiting approximately 60–120 minutes before brushing can significantly reduce abrasive enamel loss. Using a soft-bristled brush and a low-abrasivity toothpaste further minimizes damage.
(Shellis & Addy, 2014; Attin & Wegehaupt, 2014)
Practical Application
For individuals who grind or clench—especially endurance athletes experiencing repeated acid exposure—an occlusal guard can be a useful protective tool. Over-the-counter guards are available at many pharmacies, though a custom guard fabricated by a dental professional typically provides superior fit, durability, and comfort.
A practical nighttime routine may include brushing with a low-abrasivity toothpaste, spitting out the excess foam without rinsing, and then inserting the occlusal guard before sleep. This approach allows beneficial ingredients in the toothpaste to remain on the tooth surface longer while the guard provides overnight protection from mechanical wear.
References
Attin T., & Wegehaupt F. (2014). Methods for assessment of dental erosion. Monographs in Oral Science.
Eisenburger M., & Addy M. (2002). Erosion and attrition of human enamel in vitro. Part 1: Interaction effects. Journal of Dentistry.
Koyano K., Tsukiyama Y., Ichiki R., & Kuwata T. (2008). Assessment of bruxism in the clinic. Journal of Oral Rehabilitation.
Lobbezoo F., Ahlberg J., Raphael K. et al. (2018). International consensus on the assessment of bruxism. Journal of Oral Rehabilitation.
Manfredini D., Winocur E., Guarda-Nardini L., Paesani D., & Lobbezoo F. (2011). Epidemiology of bruxism in adults. Journal of Orofacial Pain.
Shellis R.P., & Addy M. (2014). The interactions between attrition, abrasion and erosion in tooth wear. Monographs in Oral Science.