Gastric pH seems to be a key factor for the development of Equine Gastric Ulcer Syndrome (EGUS). It is influenced by the amount and duration of roughage uptake, as chewing increases the production of alkaline saliva. The protone-pump-inhibitor omeprazole is currently recommended by the American College of Veterinary Internal Medicine/European College of Equine Internal Medicine (ACVIM/ECEIM) consensus statement for therapy of both Equine Squamous Gastric Disease (ESGD) and Equine Glandular Gastric Disease (EGGD). We hypothesized that dental disorders decrease saliva production due to altered chewing and in consequence gastric pH, therefore predisposing horses to EGUS. In 54 horses, a gastroscopy with measurement of the intragastric pH after 12 hours of fasting and an examination of the oral cavity were carried out. Omeprazole therapy was recommended (n=32), dental disorders were corrected (n=22) and gastroscopy was repeated 4 weeks later (n=9). No influence of moderate-severe dental disorders on ESGD (grade ≥2/4) (p = 0.394) and EGGD (grade ≥2/3) (p = 0.857) could be determined. Nevertheless, there was a trend that moderate- severe dental disorders were associated with a low gastric pH (1-4) (p = 0.100). In conclusion, we found no evidence that gastroscopy should be recommend in horses with dental disorders and vice versa.