Early childhood caries (ECC) is tooth decay that effecting children 71 months or younger. It is the most common chronic disease of childhood. It is caused by the production of acid by bacteria naturally located in the mouth when the child consumes sugary foodstuffs. Genetic factors have been shown to be important in how likely a child is to develop ECC. this study will investigate whether any common changes in the genetic code are related to the development of this condition. Similar work has been conducted in ALSPAC previously however this project aims to use more detailed measures of tooth decay. This work is part of a larger group of work being conducted by a research group in Pittsburgh USA.