Using your jaws sharpens your teeth… and mind!

Abstract

Teeth grinding (bruxism) is commonly considered sheer jaw abuse because of its purported negative consequences like tooth wear and jaw-muscle pain. However, already in 1960, R.G. Every published a Point of View in the Lancet stating that bruxism-related tooth wear may be positive for the individual, the wear process being a means to sharpen the teeth to be used as tools or weapons.¹ Now, we would like to propose another possible positive outcome of bruxism, namely improved cognitive function. Based on a comprehensive literature review, Weijenberg et al.² concluded that both animal and human studies suggest an association between chewing and cognition. Klineberg et al.³ elaborated on this conclusion by stating that the increased cerebral blood flow that is associated with mastication could explain its positive effect on cognitive function. Importantly, they also stated that impaired cognition arises from a complex interplay of multiple factors. This was confirmed by Lin⁴ who provides some critical aspects that need to be incorporated into future research. For example, since most of the currently available clinical and epidemiological data are derived from cross-sectional studies, Lin emphasises the importance of prospective cohort studies to enable causal inferences.⁴ Recently, Kim and Han⁵ investigated the effects of reduced chewing ability on the incidence of cognitive impairment over 10 years in a large general population sample. Their findings, namely an about 1.3 times higher odds ratio for cognitive impairment in poor chewers as compared to good chewers, confirmed that reduced masticatory efficiency causally contributes to cognitive decline.⁵ Since both chewing and bruxism are essentially jaw-muscle activities, that is, ways of using the jaws that both improve cerebral blood flow, we carefully assume that chewing-related findings can be extrapolated to bruxism. To further determine the evidence base for the association between jaw usage and cognition, a quick scan of the available literature was performed in PubMed on June 1, 2024, using the query “((“Mastication”[Mesh]) OR “Bruxism”[Mesh]) AND “Cognition”[Mesh].” This search yielded 115 papers, of which 56 did not deal with the topic of interest. Of the remaining 59 papers, only six reported no (or a negative) association between jaw usage and cognition, while 53 confirmed the likely presence of such associations. In some cases, even a causal relationship was claimed. Of note, only one of these 53 papers dealt with bruxism; the others with chewing. Hence, more research on bruxism in association with cognition is needed, bearing in mind that designing such studies will be a major challenge. Nevertheless, based on the above, we dare to conclude that using your jaw, either by bruxing or by chewing, not only sharpens your teeth, but also your mind.

All authors contributed equally and substantially to the conception, drafting and critical revision of this correspondence, and approved the final version. They are all responsible for all aspects of the work.

No funding was obtained for this manuscript.

FL receives research grants from Sunstar Suisse, S.A., Vivisol-Resmed, Health Holland and the Dutch Research Council (NWO), unrelated to this Correspondence. FL is an unsalaried member of the Academic Advisory Board of Sunstar Suisse S.A. for GrindCare. CSL, MT, AK and MCV report no competing interests.