Every night you watch your child brush their teeth, toothpaste foaming, timer running, doing everything right by the book. So when the dentist finds a new cavity at the next checkup, it can feel almost personal—like something must have gone wrong on your end. Is brushing really enough, or is there more to cavity prevention than what happens at the bathroom sink? Could there be sneaky culprits hiding in their diet or daily routine? If this scenario sounds familiar, there's usually a logical explanation once…