Tooth decay is the most common, chronic childhood ailment, according to the Centers for Disease Control and Prevention. In Massachusetts, where one in four kindergartners have dental disease, the state has added teeth brushing to the daily routine at day-care centers throughout the state. Massachusetts is the first state to require all children who attend day care for more than four hours, or eat a meal while at day care, to brush their teeth to help stem dental disease. Most day care providers are choosing to apply so little toothpaste that it is safe for children to swallow, a practice used in Head Start programs, which mandated tooth brushing in 2006. The regulations, which went into effect last month and are overseen by the state Department of Early Education and Care, also require that children be educated about oral health. Parents who feel strongly about the regulation can opt out. (Photo: makelessnoise on Flickr)