Lung Function Decline Among Nonsmoking Adults With Periodontitis in Pakistan: A Cross-Sectional Study

Periodontitis is increasingly recognized as a chronic inflammatory condition with systemic consequences beyond the oral cavity, including potential effects on respiratory health. This study aimed to evaluate the association between periodontitis and reduced lung function among nonsmoking adults and to assess whether systemic inflammation, indicated by high-sensitivity C-reactive protein (Hs-CRP), mediates this association.

This cross-sectional study included 120 nonsmoking adults aged 18-45 years, divided equally into a study group with periodontitis and a control group with clinically healthy periodontium. Periodontal status was assessed using the community periodontal index (CPI), probing pocket depth (PPD), and clinical attachment loss (CAL). Lung function was assessed using forced expiratory volume in 1 s (FEV₁), forced vital capacity (FVC), and the FEV₁/FVC ratio following ATS/ERS guidelines. High-sensitivity C-reactive protein (Hs-CRP) was measured as a marker of systemic inflammation. Data were analyzed using Spearman correlation, independent-samples t-tests, and mediation analysis with Hayes PROCESS Model 4 and bootstrapping.

Periodontal health variables (CPI, CAL, and PPD) were negatively associated with FEV₁ and the FEV₁/FVC ratio (p < 0.05), while weaker negative associations were observed for FVC. Hs-CRP showed a moderate positive correlation with periodontal measures and a weak negative correlation with FEV₁ and the FEV₁/FVC ratio. In the mediation models, periodontal measures remained significant predictors of FEV₁, while the indirect effects through Hs-CRP were not statistically significant for CPI (p = 0.12), CAL (p = 0.07), or PPD (p = 0.60).

Nonsmoking individuals with poorer periodontal health exhibited reduced pulmonary function, although the cross-sectional design limits causal inference. While systemic inflammation increased with worsening periodontal status, the findings did not support a mediating role of Hs-CRP in the association between periodontitis and lung function. Longitudinal studies are warranted to determine whether periodontal disease represents an independent risk factor for pulmonary function decline.