Obesity and Periodontal Outcomes: A Population-Based Cohort Study in Brazil

• Autores: Gustavo G. Nascimento, Karen G. Peres, Murthy N. Mittinty, Gloria C. Mejia, Diego A. Silva, David Gonzalez Chica, Marco A. Peres
• Localización: Journal of periodontology, ISSN 0022-3492, Vol. 88, Nº. 1, 2017, págs. 50-58
• Idioma: inglés
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• Resumen

  • Background: The aim of this study is to investigate the effects of abdominal and general obesity on periodontal outcomes in a population-based cohort of Brazilian adults.

    Methods: Abdominal and general obesity were assessed in the years 2009 (n = 1,720) and 2012 (n = 1,222). For abdominal obesity, a dichotomous variable was created: 1) eutrophic/lost weight or 2) obese/gained weight. For general obesity, a categorical variable was created: 1) eutrophic/lost weight; 2) gained weight; or 3) obese. Periodontal outcomes were percentage of teeth with bleeding on probing (BOP) and combination of BOP and attachment loss (AL). Hypertension was set as the mediator. Marginal structural models (MSMs) were used to estimate the controlled direct effect of obesity on periodontal outcomes.

    Results: Periodontal data were presented from 1,066 participants. The total effect model showed those with general obesity in the cohort period presented higher risk of unfavorable periodontal outcomes (rate ratio [RR]: 1.45 for AL and BOP in different teeth; RR: 1.84 for AL and BOP in the same tooth). Estimates from MSMs revealed an effect of general obesity on AL and BOP in different teeth (RR: 1.44). No effect of general obesity was noted on the percentage of BOP. Total effect of abdominal obesity increased risk of AL and BOP in different teeth (RR: 1.47), AL and BOP in the same tooth (RR: 2.77), and percentage of BOP (RR: 1.49). In a MSM, those with abdominal obesity presented greater risk of AL and BOP in the same tooth (RR: 2.16) and percentage of BOP (RR: 1.37).

    Conclusion: Abdominal obesity has a direct effect on unfavorable periodontal outcomes in MSMs.

    Obesity is an emerging chronic disease associated with relevant morbidity and mortality, not only in high-income but also in medium- and low-income countries.1 This condition has been associated with adverse effects on chronic health conditions, such as diabetes mellitus (DM), hypertension, depression, infectious diseases, and all-cause mortality.2-5 Furthermore, systematic reviews have supported evidence that an association between obesity status and periodontal disease may exist.6,7 Periodontal disease is a chronic inflammatory condition affecting supporting structures of the teeth, mainly induced by the presence of a specific microbial biofilm.8 Its establishment and progression also depend on the quality of the host immune response, which is impacted by systemic conditions such as DM, hypertension, and obesity.8,9 Given the cyclic nature of periodontal disease, when an imbalance in the relationship between periodontopathogens and host immune response occurs, a greater susceptibility for active destruction of the periodontal tissues is expected.9 Some mechanisms were proposed to explain the relationship between obesity and periodontal disease.10 It is suggested that lipopolysaccharide of Gram-negative periodontal bacteria could lead to hepatic dyslipidemia.10 In addition, white adipose tissue is responsible for secreting proinflammatory cytokines, working as an endocrine organ.11 Furthermore, expansion of adipose tissue during weight gain constrains blood vessels, causing macrophage migration into this tissue.12 The combination of the aforementioned situations may induce a generalized chronic low-grade inflammation. Hypertension is among the systemic conditions that seem to exacerbate the inflammatory load induced by obesity.13 Increased blood pressure affects collagen metabolism and, consequently, bone loss progression at the site-specific level.14 It also impacts the gingival arteriolar wall thickening, leading to a precarious local immune response.14,15 There are few longitudinal studies regarding the topic and a lack of information from low- and middle-income countries.16 Considering that behaviors, dietary habits, and patterns of socioeconomic inequality are different between high-income and lower-middle-income countries, effects of obesity on periodontal disease may substantially vary.17 Additionally, all prospective cohort studies found in the literature used conventional analytical methods.18-22 This might be a concern, as conventional regression methods cannot deal with mediation properly. Given that a mediator is a variable underlying the relationship between exposure and outcome, conventional regression methods conditioning on a mediator will create collider bias.23 Robins et al.24 proposed an approach to analyze longitudinal data with time-varying confounders and mediators. Marginal structural models (MSMs) are a new class of causal models that distinguish between confounder and mediators in the analysis, reducing the gap left by conventional regression methods to assess mediation.25,26 This technique is also considerably relevant for observational studies when exposures cannot be randomly allocated in an intervention, such as obesity.

    Considering the aforementioned, this study investigated the controlled direct effect (CDE) of general and abdominal obesity on periodontal outcomes, not mediated by hypertension, in a population-based cohort of Brazilian adults. It was hypothesized that obesity has a direct effect on periodontal outcomes independently of the mediator.