Oral Health Issue	Evidence Level	What We Know
Dry mouth (xerostomia)	HIGH	PG in e-liquid absorbs moisture; well-documented effect
Tooth staining	MODERATE	Less than smoking but more than non-vaping; nicotine oxidation + dry mouth contribute
Gum disease (gingivitis/periodontitis)	MODERATE	Consistent association in studies; multiple biological mechanisms explain it
Cavities (tooth decay)	MODERATE	Plausible mechanisms + early clinical evidence; more research needed
Oral microbiome changes	MODERATE	Vaping clearly changes mouth bacteria; health implications still being studied
Bad breath	HIGH	Dry mouth + flavorings + gum changes = common complaint
Oral cancer	INSUFFICIENT	Likely much lower than smoking, but long-term data doesn't exist yet
Tooth loss	LOW	Plausible through gum disease pathway, but no direct long-term data