Obsah: 1. úvod: porozumění významu zubní péče 2. 3. how does an ultrasonic toothbrush work? 4. benefits of using an ultrasonic toothbrush 4.1 superior plaque removal 4.2 gum health improvement 4.3 stain and discoloration reduction 4.4 gentle and comfortable cleaning 4.5 convenient and time-saving 4.6 ideal for se