Smoking and Depth-Related Anaerobic Bacteria in Endodontic–Periodontal Lesions: A Pilot Study

Endodontic–periodontal lesions are complex conditions in which endodontic infection and periodontal breakdown coexist and may create anaerobic microbial niches along the root surface. Although smoking is a well-established modifier of periodontal disease progression and subgingival microbial ecology, its influence on the depth-related distribution of anaerobic periodontal bacteria in teeth affected by endodontic–periodontal lesions remains incompletely understood. This cross-sectional study investigated the distribution patterns and co-occurrence of selected anaerobic periodontal bacteria in smokers and non-smokers with endodontic–periodontal lesions, considering periodontal pocket depth and anatomical site. Subgingival samples were collected from periodontal pockets of different probing depths (3–4 mm, 5–6 mm, and ≥7 mm), as well as from healthy gingival sulci and oral mucosa, in 26 patients with endodontic–periodontal lesions. The presence of Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia, Prevotella nigrescens, and Aggregatibacter actinomycetemcomitans was assessed. Detection was performed using polymerase chain reaction (PCR). Qualitative detection frequencies and microbial co-occurrence patterns were compared between smokers and non-smokers across sites and pocket depths. Non-smokers showed higher detection of Tannerella forsythia in pockets ≥7 mm (p<0,05). Overall microbial co-occurrence was lower in smokers in deeper periodontal pockets, whereas detection patterns in healthy gingival sulci and oral mucosa were broadly comparable between groups. Our findings suggest that smoking may be associated with an attenuated depth-related detection pattern and reduced co-occurrence of selected anaerobic periodontal bacteria in endodontic–periodontal lesions.