Hydrated silica in toothpaste is a common abrasive ingredient that helps remove plaque and surface stains from teeth. However, excessive use of toothpaste containing hydrated silica can lead to tooth enamel erosion and gum irritation. Additionally, some people may experience sensitivity or allergic reactions to hydrated silica. It is important to use toothpaste containing hydrated silica in moderation and consult with a dentist if you experience any adverse effects.