Electronic Thesis and Dissertation Repository

Thesis Format

Monograph

Degree

Doctor of Philosophy

Program

Medical Biophysics

Supervisor

Dr. Sharat C. Pani.

2nd Supervisor

Dr. Dixon, Jeffrey S.

Abstract

Oral health disparities are influenced by socioeconomic and demographic factors. Recent research suggests that stressors can contribute to these disparities. Adolescents and young adults are particularly vulnerable to these stressors, which can affect hypothalamic-pituitary-adrenal (HPA) axis reactivity. This thesis aimed to enhance understanding of the relationships among stress, geographic and sociodemographic factors, and oral health outcomes in adolescents and young adults. Additionally, salivary levels of mRNA encoding the glucocorticoid receptor (GR) were assessed and their relationship to stress and oral health outcomes investigated.

In the first study, the association between neighborhood-level socioeconomic status and dental care outcomes was explored in 2915 patients split into two groups: adolescents (15-17 years) and young adults (18-24 years). Young adults showed significantly worse preventive and treatment outcomes compared to adolescents. Individuals from neighborhoods with lower household income showed a significantly higher cost of dental care, yet worse treatment outcomes.

The second study assessed the association between perceived stress, cortisol levels (hair and saliva), and caries experience in 93 adolescents and young adults without periodontal disease. Results revealed a significant association of dental caries experience with hair cortisol level (a marker of chronic stress) and perceived stress scale score. These associations remained significant even after adjusting for sociodemographic variables.

The third study involved 78 individuals who had also participated in the second study. RNA was isolated from saliva, followed by quantitative real-time polymerase chain reaction to evaluate levels of GR mRNA. mRNA encoding GRα was identified in saliva. Its levels were inversely associated with hair cortisol levels, however there was no significant association with dental caries experience. Thus, additional factors likely contribute to the connection between stress and caries experience. Chronic stress has been associated with reduced expression of GRα and this association appears to hold for GRα mRNA in saliva.

Incorporating individual and community stressors into the analysis of oral health outcomes provides insights into the complex pathophysiological pathways underlying dental disorders. Establishing the association of biomarkers, such as hair cortisol and GRα mRNA levels, with oral disease may encourage further research and open new avenues for focused preventive strategies, diagnostics, and interventions.

Summary for Lay Audience

Social and economic position in society is known to influence an individual's oral health. In addition, stress can profoundly impact our mental and physical health, especially during adolescence and young adulthood. We studied whether dental treatments are associated with social and financial status, and the relationships of stress and molecules related to stress with tooth decay in teenagers and young adults.

First, we analyzed how the income of the neighborhood they reside in is associated with dental care in teens (aged 15-17) and young adults (aged 18-24). Young adults seem to experience more challenges in keeping their teeth healthy than do teens. Also, people from poorer neighborhoods paid more for dental care and had worse treatment results.

Second, we checked stress hormone levels, stress scores, and the number of cavities, missing teeth, and filled teeth in teens and young adults. We found that having cavities was linked to feeling stressed and having high levels of the stress hormone cortisol in hair, which reflects long-term stress. This link stayed strong even after considering things like age, income, and parental education.

Third, we looked at participants from our previous research in more detail. We collected their saliva and used a special method called RT-PCR to measure levels of RNA that codes for the protein that functions as a receptor for cortisol. This receptor is known as GRα. We found that RNA for GRα was present in saliva. Moreover, GRα levels were lower in people with higher levels of cortisol in their hair. When people experience chronic stress, they produce more cortisol, which can decrease levels of GRα, as we observed in saliva. In contrast, GRα levels were not associated with whether or not participants had experienced dental cavities.

These findings emphasize the interaction between social and psychosocial factors and the oral health of adolescents and young adults. The results help us understand how mental and social well-being affects oral health and how this may contribute to inequalities in oral health.

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Creative Commons Attribution-Noncommercial 4.0 License
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