It is possible that H. pylori and periodontitis are related. H. pylori is a conditionally pathogenic bacteria, mainly resides in the human stomach at the pylorus, a small amount may also reside in the oral cavity, and may also be related to periodontitis, stomatitis, mouth ulcers, gastritis, gastric ulcers, etc. Patients can do a breath test such as carbon 13 and carbon 14 to determine the diagnosis. If they have H. pylori infection, they can apply sensitive antibiotics such as amoxicillin and clarithromycin with gastric medicine for treatment.