This updated systematic review and meta-analysis examined the association between oral hygiene and gastric cancer risk. It included twelve studies searched through April 2024 in PubMed, Embase, Web of Science, Scopus and Cochrane Library databases. Infrequent tooth brushing was associated with a 55% increased risk of gastric cancer (OR 1.55, 95% CI: 1.17–2.05). Tooth loss significantly increased the risk of gastric cancer (OR 1.25, 95% CI: 1.12–1.39). Heterogeneity was high, mainly due to study design, but associations were robust in sensitivity analyses. Subgroup analyzes showed a stronger association of tooth loss with risk in Europe and America (OR 1.68) versus Asia (OR 1.19). The study confirms poor oral hygiene as a risk factor for stomach cancer and recommends integrating oral health into prevention. Registration: CRD42024546658.