Faculty Bibliography

INTRODUCTION/BACKGROUND:The oral microbiome may influence brain health and contribute to cognitive decline. However, little evidence exists on the potential modifying role of the oral microbiome in the relationship between tooth loss and cognitive performance. This study aimed to investigate the interaction effects between tooth loss and oral dysbiotic status on cognitive performance. METHODS:Data were from the 2011-2012 National Health and Nutrition Examination Survey. The sample included 677 adults aged 60 to 69 y. Cognitive performance was assessed by the Consortium to Establish a Registry for Alzheimer's Disease, the Animal Fluency Test (AFT), and the Digit Symbol Substitution Test. Significant tooth loss was defined as a loss of ≥10 permanent teeth out of 28. A high dysbiotic index was defined as being in the upper tertile of the ratio of periodontal disease-associated bacteria (Treponema, Porphyromonas, and Tannerella) to healthy bacteria (Rothia and Corynebacterium). RESULTS:A multivariable linear regression model showed a significant interaction effect between tooth loss and dysbiotic index on the AFT (b = -1.87, P = 0.03), indicating that participants with a higher dysbiosis index and fewer missing teeth scored lower on the AFT. CONCLUSIONS:The effect of tooth loss on verbal fluency depends on oral bacterial imbalances: if there is significant tooth loss, bacterial imbalances may not be important. However, when fewer teeth are lost, high bacterial imbalances may account for lower verbal fluency. These findings suggest that maintaining periodontal health aimed at decreasing oral dysbiosis should be promoted among older adults in the community.Knowledge Transfer Statement:Our findings highlight the importance of preserving the health of the teeth and not just retaining the teeth. Oral health awareness and good oral hygiene practice should be further promoted among older adults in the community.

OBJECTIVES/OBJECTIVE:Edentulism and diabetes mellitus (DM) are frequently seen among older adults. However, the joint effect of edentulism and DM on mortality was understudied. We aim to examine the joint effect of edentulism and DM on all-cause mortality and to what extent the joint effect varies by race/ethnicity. METHODS:Analysis of US Health and Retirement Study (HRS) data (2006-2018) included 11,813 non-Hispanic Whites, 2216 non-Hispanic Blacks, and 1337 Hispanics aged ≥ 50 years old. Mortality data came from the National Death Index or HRS surveys. Edentulism was self-reported and DM was determined by self-reported diagnosis, medication use, or glycosylated hemoglobin. Cox proportional-hazard models with inverse probability treatment weighting were applied. RESULTS:During mean follow-up of 9.6 years, 2874 Whites, 703 Blacks, and 441 Hispanics died. DM was associated with higher mortality across all groups (Whites: HR = 1.43, 95% CI = 1.25-1.64; Blacks: HR = 1.62, 95% CI = 1.28-2.04; Hispanics: HR = 1.46, 95% CI = 1.07-1.99). However, edentulism predicted higher mortality only in Whites (HR = 1.65, 95% CI = 1.51-1.80). Having both conditions showed highest mortality risk in all groups (Whites: HR = 2.31, 95% CI = 1.56-3.42; Blacks: HR = 1.94, 95% CI = 1.45-2.59; Hispanics: HR = 1.77, 95% CI = 1.16-2.70), with a significant additive interaction observed only in Whites (relative excess risk due to interaction = 0.22, p < 0.05). CONCLUSIONS:DM and edentulism pose an additive risk for mortality in Whites, and there are racial/ethnic differences in edentulism-related mortality.

Periodontal disease (PerioD) is a chronic inflammatory disease of dysbiotic etiology. Animal models and few human data showed a relationship between oral bacteria and gut dysbiosis. However, the effect of periodontal inflammation and subgingival dysbiosis on the gut is unknown. We hypothesized that periodontal inflammation and its associated subgingival dysbiosis contribute to gut dysbiosis even in subjects free of known gut disorders. We evaluated and compared elderly subjects with Low and High periodontal inflammation (assessed by Periodontal Inflamed Surface Area (PISA)) for stool and subgingival derived bacteria (assayed by 16S rRNA sequencing). The associations between PISA/subgingival dysbiosis and gut dysbiosis and bacteria known to produce short-chain fatty acid (SCFA) were assessed. LEfSe analysis showed that, in Low PISA, species belonging to Lactobacillus, Roseburia, and Ruminococcus taxa and Lactobacillus zeae were enriched, while species belonging to Coprococcus, Clostridiales, and Atopobium were enriched in High PISA. Regression analyses showed that PISA associated with indicators of dysbiosis in the gut mainly reduced abundance of SCFA producing bacteria (Radj = -0.38, p = 0.03). Subgingival bacterial dysbiosis also associated with reduced levels of gut SCFA producing bacteria (Radj = -0.58, p = 0.002). These results suggest that periodontal inflammation and subgingival microbiota contribute to gut bacterial changes.

Diabetes mellitus (DM) is a recognized risk factor for dementia, and increasing evidence shows that tooth loss is associated with cognitive impairment and dementia. However, the effect of the co-occurrence of DM and edentulism on cognitive decline is understudied. This 12-y cohort study aimed to assess the effect of the co-occurrence of DM and edentulism on cognitive decline and examine whether the effect differs by age group. Data were drawn from the 2006 to 2018 Health and Retirement Study. The study sample included 5,440 older adults aged 65 to 74 y, 3,300 aged 75 to 84 y, and 1,208 aged 85 y or older. Linear mixed-effect regression was employed to model the rates of cognitive decline stratified by age cohorts. Compared with their counterparts with neither DM nor edentulism at baseline, older adults aged 65 to 74 y (β = -1.12; 95% confidence interval [CI], -1.56 to -0.65; P < 0.001) and those aged 75 to 84 y with both conditions (β = -1.35; 95% CI, -2.09 to -0.61; P < 0.001) had a worse cognitive function. For the rate of cognitive decline, compared to those with neither condition from the same age cohort, older adults aged 65 to 74 y with both conditions declined at a higher rate (β = -0.15; 95% CI, -0.20 to -0.10; P < 0.001). Having DM alone led to an accelerated cognitive decline in older adults aged 65 to 74 y (β = -0.09; 95% CI, -0.13 to -0.05; P < 0.001); having edentulism alone led to an accelerated decline in older adults aged 65 to 74 y (β = -0.13; 95% CI, -0.17 to -0.08; P < 0.001) and older adults aged 75 to 84 (β = -0.10; 95% CI, -0.17 to -0.03; P < 0.01). Our study finds the co-occurrence of DM and edentulism led to a worse cognitive function and a faster cognitive decline in older adults aged 65 to 74 y.

BACKGROUND:Periodontal disease (PerioD) is a chronic, complex inflammatory condition resulting from the interaction between subgingival dysbiotic bacteria and the host immune response leading to local inflammation. Since periodontal inflammation is characterized by multiple cytokines effects we investigated whether Periodontal Inflamed Surface Area (PISA), a continuous measure of clinical periodontal inflammation is a predictor of composite indexes of salivary cytokines. METHODS AND FINDINGS/RESULTS:In a cross-sectional study of 67 healthy, well-educated individuals, we evaluated PISA and several cytokines expressed in whole stimulated saliva. Two salivary cytokine indexes were constructed using weighted and unweighted approaches based on a Principal Component Analysis [named Cytokine Component Index (CCI)] or averaging the (standardized) level of all cytokines [named Composite Inflammatory Index (CII)]. In regression analysis we found that PISA scores were significantly associated with both salivary cytokine constructs, (CCI: part R = 0.51, p<0.001; CII: part R = 0.40, p = 0.001) independent of age, gender and BMI showing that single scores summarizing salivary cytokines correlated with severity of clinical periodontal inflammation. CONCLUSIONS:Clinical periodontal inflammation may be reflected by a single score encompassing several salivary cytokines. These results are consistent with the complexity of interactions characterizing periodontal disease. In addition, Type I error is likely to be avoided.

Periodontal disease (PD) is one of the most common inflammatory diseases in humans and is initiated by an oral microbial dysbiosis that stimulates inflammation and bone loss. Here, we report an abnormal elevation of succinate in the subgingival plaque of subjects with severe PD. Succinate activates succinate receptor-1 (SUCNR1) and stimulates inflammation. We detected SUCNR1 expression in the human and mouse periodontium and hypothesize that succinate activates SUCNR1 to accelerate periodontitis through the inflammatory response. Administration of exogenous succinate enhanced periodontal disease, whereas SUCNR1 knockout mice were protected from inflammation, oral dysbiosis, and subsequent periodontal bone loss in two different models of periodontitis. Therapeutic studies demonstrated that a SUCNR1 antagonist inhibited inflammatory events and osteoclastogenesis in vitro and reduced periodontal bone loss in vivo. Our study reveals succinate's effect on periodontitis pathogenesis and provides a topical treatment for this disease.

Inflammation plays a significant role in Alzheimer's disease (AD) pathogenesis. Studies have shown that systemic, peripheral infections affect AD patients. Cognitive dysfunction is a consistent finding in AD and periodontal disease is a chronic, peripheral infection often resulting in tooth loss. We hypothesized that older adults with periodontal inflammation (PI) or many missing teeth would show impaired cognition compared to subjects without PI or with few missing teeth, and among subjects with PI, those with many missing teeth would show impaired cognition compared to those with few missing teeth. The effect of PI/tooth loss on cognitive function [measured by Digit Symbol (DST) and Block Design (BDT) tests] was assessed in 70-year old Danish subjects. We found: 1) subjects with PI obtained lower mean DST scores compared to subjects without PI (p < 0.05); 2) subjects with many missing teeth had lower mean DST and BDT scores compared to subjects with few missing teeth (p < 0.05); 3) the association of PI with DST and BDT scores was dependant on the number of missing teeth (interaction: p = 0.03 and p = 0.06); and 4) education and previous cognitive scores (age 50) were important covariates. Subjects with PI had significantly lower adjusted mean DST scores compared to subjects without PI. However for adjusted BDT, the significance held only for subjects with few missing teeth. No difference in the adjusted DST and BDT scores was seen between subjects with many missing teeth compared to those with few missing teeth. These results support the hypothesis that PI may affect cognition.
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INTRODUCTION:Individuals with mild dementia are at high risk of poor oral health outcomes. To address this issue, we describe an intervention to teach care partners skills to guide individuals with mild dementia in proper oral hygiene techniques and provide reminders to practice oral hygiene care. By providing support to perform these tasks successfully, we aim to delay oral health decline among this vulnerable population. METHODS AND ANALYSIS:This multisite study is a three-arm randomised controlled trial. The primary objective is to evaluate the efficacy of an intervention to improve oral hygiene outcomes by promoting positive oral hygiene behaviours and skills among individuals with mild dementia. Care partners' behaviour factors, such as oral care self-efficacy and implementation of the care plan, serve as mediators of the intervention. Participant-care partner dyads will be randomly assigned to either Treatment Group 1, Treatment Group 2 or the Control Group. All groups will receive an educational booklet. Treatment Group 1 and Treatment Group 2 will receive a smart electronic toothbrush. Treatment Group 2 (the intervention group) will also receive an oral hygiene care skill assessment, personalised oral hygiene instruction and treatment plan; and care partners will receive in-home and telephone coaching on behaviour change. Oral health outcomes will be compared across the three groups. The duration of the active intervention is 3 months, with an additional 3-month maintenance phase. Data collection will involve three home visits: baseline, 3 months and 6 months. The study enrollment started in November 2021, and the data collection will end in Spring 2024. ETHICS AND DISSEMINATION:The study has been approved by the Institutional Review Board of the NYU Grossman School of Medicine and Duke University, and is registered at Clinicaltrials.gov. A Data Safety Monitoring Board has been constituted. The study findings will be disseminated via peer-reviewed publications, conference presentations and social media. TRIAL REGISTRATION NUMBER:NCT04390750.

Electronic cigarettes (e-cigs) have become prevalent as an alternative to conventional cigarette smoking, particularly in youth. E-cig aerosols contain unique chemicals which alter the oral microbiome and promote dysbiosis in ways we are just beginning to investigate. We conducted a 6-month longitudinal study involving 84 subjects who were either e-cig users, conventional smokers, or nonsmokers. Periodontal condition, cytokine levels, and subgingival microbial community composition were assessed, with periodontal, clinical, and cytokine measures reflecting cohort habit and positively correlating with pathogenic taxa (e.g., Treponema, Saccharibacteria, and Porphyromonas). α-Diversity increased similarly across cohorts longitudinally, yet each cohort maintained a unique microbiome. The e-cig microbiome shared many characteristics with the microbiome of conventional smokers and some with nonsmokers, yet it maintained a unique subgingival microbial community enriched in Fusobacterium and Bacteroidales (G-2). Our data suggest that e-cig use promotes a unique periodontal microbiome, existing as a stable heterogeneous state between those of conventional smokers and nonsmokers and presenting unique oral health challenges. IMPORTANCE Electronic cigarette (e-cig) use is gaining in popularity and is often perceived as a healthier alternative to conventional smoking. Yet there is little evidence of the effects of long-term use of e-cigs on oral health. Conventional cigarette smoking is a prominent risk factor for the development of periodontitis, an oral disease affecting nearly half of adults over 30 years of age in the United States. Periodontitis is initiated through a disturbance in the microbial biofilm communities inhabiting the unique space between teeth and gingival tissues. This disturbance instigates host inflammatory and immune responses and, if left untreated, leads to tooth and bone loss and systemic diseases. We found that the e-cig user's periodontal microbiome is unique, eliciting unique host responses. Yet some similarities to the microbiomes of both conventional smokers and nonsmokers exist, with strikingly more in common with that of cigarette smokers, suggesting that there is a unique periodontal risk associated with e-cig use.