By: Noha Gomaa, Schulich School of Medicine and Dentistry, Western University
“Show me your teeth, and I will tell you who you are.” This almost 300-year-old quote by the French naturalist and father of paleontology George Cuvier was initially intended to describe how the structure of teeth varied by the type of diet that was consumed by different populations. Cuvier’s remark, although unintentionally, has proven to extend beyond its comparative anatomy connotation to portray the stark differences in oral health between socially advantaged and disadvantaged groups of the population. Oral health today continues to be determined by and reflect one’s social and economic conditions.
Observing such oral health inequalities gives rise to important questions around why social plight makes individuals more prone to oral diseases, and on the other hand, what makes fantastic teeth a trait of social advantage. The answer is a multi-factorial one in which several forces are at play. Good oral health has occasionally been attributed to one’s “good genes” that can be protective against acquiring some of the most common yet preventable oral diseases, such as dental cavities/caries and gum inflammation. However, genetic studies do not, on their own, fully justify the variation in oral disease risk, and are certainly unable to explain any oral (or non-oral) health inequalities. Along with the other determinants of health, an individual’s social and economic conditions can impact their access to resources such as quality dental care, adequate nutrition, and fresh produce, while deterring their consumption of sticky and starchy foods that are known to cause oral diseases. Variations in health-compromising behaviours such as oral hygiene practices and smoking have also long been considered as some of the main drivers of oral disease risk that are largely determined by one’s social stance. Earlier studies have however suggested that aiming to enhance oral health behaviours by educating patients about brushing and flossing, while definitely important, may arguably fail to yield the anticipated sustainable results—at least not for those with less resources.
Here, the role of psychosocial stress emerges. Chronic stress can result from the low-grade yet persistent exposures to adverse social and living conditions on a daily basis. Studies in psychoneuroimmunology have demonstrated the pivotal role of chronic stress in several health conditions. Stress acts on various biological responses, putting the hypothalamic-pituitary-adrenal axis in a constant activation mode. This in turn triggers a cascade of multi-system stress responses that contribute to the increased vulnerability to a multitude of diseases, including those of the mouth. Our team at Western University has been diving deeper into how the psychosocial environment and related chronic stress can “get under the skin and in between teeth” to become biologically embedded. In our previous clinical studies, we found that a higher accumulation of the stress biomarker cortisol in hair and saliva was linked to an increased risk of periodontal disease (inflammation of the tooth-supporting structures) in individuals of lower income. These patients also exhibited oral innate immune cells (neutrophils) that were primed to be more conducive of oral inflammation. In a large study of American children and adolescents, we found the risk of untreated dental cavities to increase with the multi-system cumulative biological toll of chronic stress, known as allostatic load. We noted this as being more evident in children from minority racial/ethnic backgrounds. More recently, we started investigating how social disadvantage and related chronic stress may increase oral disease risk by getting down to the level of the genes involved in oral disease initiation and progression. We anticipate providing insight into how oral health inequalities occur over the life-course, and why socially disadvantaged individuals become more susceptible to oral diseases than their more advantaged counterparts.
To this end, we can conclude that fantastic teeth may not just be found with good genes or oral hygiene. For many, they are a prerogative of affluence and access to enabling resources that can determine whether one becomes susceptible or resilient to oral diseases. Consequently, concerted multi-level solutions that target social and living conditions, curb psychosocial stressors (and their biological toll), and enable equitable access to quality oral health care, will continue to be key.