Cavities and gum diseases such as periodontitis are among the most common infections in humans worldwide. This often has far-reaching consequences, as even heart attacks and other cardiovascular diseases can be triggered by infections in the oral cavity. However, even the regular use of antibacterial mouthwash, toothpaste, and dental floss often cannot prevent these infections. The reason: they only combat the symptoms and destroy both harmful and beneficial bacteria alike. Every mouth is densely populated with bacteria, fungi, and viruses—harmful microorganisms that attack teeth and gums and constantly reinfect them. But there are also good, health-promoting bacteria that provide protection in the oral cavity. Studies have shown that so-called probiotics can already exert their effects in the mouth, not just in the gut.