Background and aimMercury exposure is encountered most commonly in individuals with amalgam fillings. The toxic, bactericidal, and immunosuppressive effects of mercury are well known. Furthermore, multiple antibiotic resistance can be transferred, together with mercury resistance. The aim of this study was to investigate the frequency of Helicobacter pylori infection in dyspeptic patients with amalgam fillings and the effect of the amalgam fillings on H. pylori eradication rates in these patients.Patients and methodsFour hundred and seventy-five patients who presented with dyspeptic complaints and underwent upper gastrointestinal endoscopy and gastric biopsy were included in this study. One hundred and sixty-nine (35.6%) patients were negative and 306 (64.4%) patients were positive for H. pylori. All of the participants underwent dental examinations in a blinded manner. The participants were divided into two groups on the basis of the presence of amalgam fillings. The H. pylori-positive patients were divided randomly into three subgroups: patients who received concomitant therapy (CT) (rabeprazole-amoxicillin-clarithromycin-metronidazole for 14 days; n=122); patients who received quadruple therapy (QT) (rabeprazole-tetracycline-metronidazole-colloidal bismuth subcitrate for 10 days; n=97); and patients who received levofloxacin-based therapy (LT) (rabeprazole-amoxicillin-levofloxacin for 10 days; n=87). Eradication success was detected by a urea breath test 6 weeks after the end of treatment.ResultsThe frequency of H. pylori infection was significantly lower in the filling group compared with the nonfilling group (53.7 and 78.8%, respectively; P<0.001). The eradication rates in the CT, QT, and LT groups were 65.5, 67.0, and 58.6%, respectively, in the intention-to-treat (ITT) analysis and 69.6, 70.7, and 62.2%, respectively, in the per-protocol (PP) analysis. In all of the H. pylori-positive patients and separately in the CT and LT groups, the eradication rates were significantly lower in the filling group compared with the nonfilling group. However, in the QT group, there was no significant difference between the patients with and without fillings (P=0.001, 0.003, 0.012, 0.14, respectively). Logistic regression analysis showed that the absence of amalgam filling exerts independent effects on the increased frequency of H. pylori infection and increased rate of H. pylori eradication.ConclusionThis is the first study to show a lower frequency of H. pylori colonization in patients with amalgam fillings than without and that H. pylori eradication rates are lower in patients with amalgam fillings compared to those without.