Oral-B Pro-Expert Bacteria Blast with anti-bacterial bristle protection helps keep bristles cleaner between brushing. It inhibits microbial growth that may affect the bristles for up to 90 days. The bristles do not kill bacteria in the mouth or protect you against disease. Always clean the product thoroughly after use. Bristles contain an antimicrobial to keep them cleaner. Does not kill bacteria in the mouth or protect against disease.