For better hygiene patented Thermoweld technology fuses together every bristle filament inside the base of Terradents Replaceable Toothbrush Head. Thermowelding eliminates microscopic spaces between and around Terradents bristles-spaces which in conventional toothbrushes provide the ideal breeding grounds for millions of harmful bacteria! Thanks to Thermowelding Terradent has the lowest bacteria count of any toothbrush tested in research conducted at a leading Dental School. Brushing with an oridinary bran can spread harmful bacteria throughout your mouth every time you brush- and to nieghboring toothbrushes between brushings! Suggested Use: Use as you would any quality toothbrush. To replace head. Remove worn head as shown. Clean handle. Insert Replacement Head. Press in Head until you hear Click. Head is now safely and securely inplace.