Helicobacter pylori (H. pylori), a bacteria transmitted from human to human through upper digestive tract as well as fecal-oral transmission, had infected more than half of people around the world. However, the quantity of H. pylori in oral cavity and its influence on oral microbiota remains to be unclear. The aim of the present study was to examine the effects of H. pylori infection as well as its eradication on oral microbiota.

Inclusion Criteria:

• Participants with non-ulcer functional dyspepsia or peptic ulcer disease
• Ability and willingness to participate in the study and to sign and give informed consent
• Received both endoscopy and 13C urea breath test (13C-UBT) before enrolled

Exclusion Criteria:

• Less than 18 years old
• With previous gastric surgery
• Major systemic diseases
• Pregnancy or lactation
• Allergy to any of the study drugs Administration of antibiotics, bismuth, antisecretory drugs in 8 weeks prior to inclusion
• The use of antibiotics or PPI within 2 months before the study
• The presence of dental carious or any untreated cavitated carious lesions and oral abscesses