Overweight and obesity are defined as abnormal or excessive fat accumulation that may impair health and as a health-care provider we must inform patients about oral health and specific periodontal health concerns. ¹ , ² The prevalence of obesity is increasing worldwide and the number of obese individuals has more than doubled since 1980. ³ In 2014, more than 1.9 billion adults were overweight. Of these, over 600 million were obese. For adults, WHO (World Health Organization) calculates BMI by dividing the person's weight in kilograms by the square of his height in meters (kg/m ²). Based on this calculation, BMI greater than or equal to 25 is categorized as overweight and a BMI greater than or equal to 30 ² , ³ , ⁴ is categorized as obesity.

Adipose tissue has been thoroughly studied in the recent years, and contrary to the assumption of it solely being a fat storage medium, it has been identified as a tissue responsible for metabolism and energy conversion. ⁵ This endocrine tissue is also associated with significant activity related to chemical substance secretion and inflammatory responses, much like an endocrine organ. Studies have also identified other organs besides adipose tissue which act as storage media of fat, such as the liver, and this could have important implications in measuring total body fat and composition, as these are means of determining weight imbalances and obesity. ⁶ By realizing the fact that obesity and weight imbalances stem from mechanisms which render energy intake and energy expenditure imbalances, many world health agencies have regarded obesity as a chronic disease. ⁷

Obesity has several negative implications on a person's systemic condition including hypertension, type II diabetes, coronary heart disease, stroke, osteoarthritis, and its presence significantly lowers a person's life expectancy. ⁸ Several studies have shown that it is also linked to reduced periodontal health. ⁹ The exact mechanism by which obesity predisposes to periodontitis is not fully understood; however, obese individuals have higher levels of circulating tumor necrosis factor-α (TNF-α) and interleukin (IL)-6, secreted by the adipose tissue, compared to nonobese individuals, and these have been implicated in the pathogenesis of periodontal disease. ¹⁰ , ¹¹ , ¹²

Nonsurgical periodontal therapy (NSPT) is the first step in the clinical management of chronic periodontitis. ⁷ , ⁸ , ⁹ It involves the mechanical removal of bacterial biofilm and deposits with scaling and root planing (SRP), creating a local environment favorable to better periodontal health. The efficacy of NSPT in the management of periodontitis is established, and clinical trials have shown a reduction of inflammation, pocket depth reduction, and clinical attachment gains following therapy. However, it is not clear if obesity affects the outcome of nonsurgical periodontal therapy. ¹⁰ , ¹¹ , ¹² , ¹³

The purpose of this systematic review was to determine whether there was a difference in response to NSPT between obese and nonobese individuals.

The literature search was structured according to the Population, Interventions, Comparisons, and Outcomes format Table 1. The population was composed of health subjects (>18 years old) obese and nonobese. The intervention was nonsurgical periodontal therapy. The comparator/control was nonobese subjects with nonsurgical periodontal therapy. The outcome is the response to NSPT between obese and nonobese individuals.{Table 1}

A search was conducted in the Medline, Embase, and Scopus databases using the keywords periodontal disease/periodontitis, overweight/obesity/obese, and treatment/outcome of therapy. Results in English language only up to December 31, 2020, were included. Results from all databases were combined and duplicates were removed. Studies were then subsequently excluded based on title, abstract, and finally full-text review for a final inclusion of 8 studies Figure 1. Figure 1

Search strategy studies.

The selected articles present different patient follow-up times, all eight articles present an evaluation after the baseline, four articles present a second evaluation, and only two articles present a third evaluation. As there were only two articles with the third evaluation, this result was not considered in this report.

The forest plot Figure 2and Figure 4, Figure 5is a graph that allows the visualization of the estimated measures and their confidence intervals. Each study is plotted on the graph and its representation has two elements, a box that represents the estimate for each study and a horizontal line, which represents the confidence interval for that estimate. Small horizontal lines indicate better accuracies of the study results. Figure 4

Forrest plot for estimating the mean of each group and evaluation time – Clinical Attachment Loss. BMI: Body mass index; CI: Confidence interval.

Despite decades of research and treatment, periodontitis remains one of the most common inflammatory conditions in humans. Often associated with systemic diseases such as cardiovascular disease and diabetes mellitus, there is mounting evidence that obesity may play a role in the immune response related to periodontal disease. ³ , ⁹ , ¹⁰ , ¹¹ , ¹² , ¹³ , ¹⁴ Considering that obesity affected 39.8% of adults in the U. S. in 2015–2016 (CDC NCHS data brief, No. 288, October 2017), the global health implications of periodontitis in obese individuals could be significant. ⁴ , ⁷

The relationship between periodontitis and obesity has been reported by several studies focusing on periodontal pathogens dissemination from epithelial through the circulation and consequently the immune system. ¹¹

Obesity as a chronic disease has been reported by recent studies to be associated with changes in many inflammatory mediators such as IL-6, TNF-α, monocyte chemoattractant protein-1 (MCP-1), and IL receptor agonists. Obesity has also been shown to be linked to changes in some adipose-related proteins such as leptin, adiponectin, resistin, and visfatin, suggesting systemic and immunological mechanisms by which obesity may be associated with other inflammatory or immunological-related disorders. ²⁶ , ³⁰ , ³¹ , ³² , ³³

Furthermore, it has been shown by experimental studies done on obese rats that periodontal disease markers, such as alveolar bone loss and periodontal inflammatory mediators linked to periodontitis, are significantly higher in these rats. ³¹ These results point toward a possible correlation between periodontitis and obesity.

Although a possible correlation exists between periodontitis and obesity, as with other oral-systemic disease implications, some controversy exists. While some studies have reported a distinct correlation between periodontitis and obesity, other papers have suggested only moderate or no association between the two conditions at all.

These results advise of a difference between response to NSPT in obese and nonobese individuals. However, with few quality studies and variable reported findings, there is limited evidence of any significant difference in clinical practice. However, it can serve as a positive warning that obesity is a risk factor toward the outcome of periodontal disease treatment.

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Conflicts of interest

The authors of this manuscript declare that they have no conflicts of interest, real or perceived, financial or non-financial in this article.