Periodontitis, Oral Helicobacter pylori Reservoirs, and Gastric Cancer: Implications for Adjunctive Periodontal...

In this review study, we address the epidemiological, causal, and clinical associations between the oral and gastric occurrence of Helicobacter pylori and its role in the etiopathogenesis of gastric cancer, gastritis, as well as peptic ulcer disease and dyspeptic disorders of the stomach and duodenum. We summarize and critically analyze numerous meta-analytical studies addressing the oral occurrence of H. pylori and its eradication from the stomach and oral cavity using conventional pharmacological eradication therapy. In the process of analysis, we examine whether the oral cavity can serve as a reservoir of H. pylori during reinfections of the gastric mucosa, while not all studies confirm the survival of H. pylori in the oral cavity. However, the majority of studies, including their meta-analytical outputs, conclude that H. pylori may survive in saliva and potentially persists in the oral cavity by exploiting the microaerophilic to anaerobic environment of periodontal pockets, as well as the structures of supra- and subgingival dental calculus and various locations of oral biofilms, which are inaccessible to both innate and adaptive immune defense mechanisms of the patient. While a minority of studies regard oral H. pylori as transient (Al-Ahmad, 2012), the weight of current evidence - particularly from PCR-based and co-culture studies (Scholz et al., 2025) - supports a biologically plausible reservoir role. The structures of periodontal pockets, oral biofilms, and dental calculi lack effective blood supply, moreover, these sites are not routinely accessible to home oral hygiene measures. For the removal and elimination of the mentioned structures, targeted periodontological treatment combined with various methodologies of professional oral hygiene is required. The elimination of H. pylori using these approaches has been confirmed by many studies, from which several clinically relevant therapeutic implications for clinical practice in dentistry and periodontology arise. These findings support a strong recommendation that dental practitioners provide thorough periodontal treatment and eliminate the environment of periodontal pockets through comprehensive periodontal therapy combined with the removal of oral biofilms and dental calculi in patients with a diagnosed finding of H. pylori in the GIT who are undergoing pharmacological eradication treatment. In line with the observed improvement in gastric H. pylori eradication when periodontal therapy is added - with odds ratios of 2.15 (95% CI: 1.47-3.14) and 2.64-4.11 across independent meta-analyses - gastroenterologists, internists, and oncologists should systematically consider referring H. pylori‑positive patients to dentists for periodontological and hygiene procedures, accompanied by regular recall appointments.