Uncertainty about optimal sonic toothbrush brushing duration causing compliance confusion

Users are confused about how long they actually need to brush with sonic toothbrushes, leading to either under-brushing (poor oral health) or over-brushing (gum damage and wasted time). Current toothbrush instructions are unclear or contradictory, and users lack personalized guidance on optimal brushing duration for their specific needs. This creates anxiety about whether they're doing it right and potentially damaging their teeth.