Rising tooth decay in young children. The number of preschoolers with serious dental tooth decay is on the rise, across all income levels. Some young children have six to ten cavities. Some of the reasons for the increased rise in tooth decay among young children, is mainly snacking and juices or other sweet drinks t bedtime. But other reasons includes children drinking bottled water instead of fluoridated tap water. As well as parents who have simply grown lax about making their kids have proper dental care habits such as brushing and flossing daily.