Abstract
Data from the Dunedin (New Zealand) Multidisciplinary Health and Development Study were used to examine continuity and discontinuity in digit sucking between 5 and 11 years. The data were also used to examine the relationship between digit sucking and behaviour problems at 5, 7, 9, 11 and 15 years. Cross-sectional analyses showed a relationship between digit sucking and behaviour problems at all ages, except 5 years. Longitudinal analysis by multiple regression showed that digit sucking at 5 and 7 years predicted behaviour problems at 7, 9 and 11 years. This effect was most apparent at 7 years. Children who sucked their digits at 11 years were more likely to have overjets of 6mm or more between their upper and lower dental arches. The behavioural and dental evidence suggest that it would be better for children to stop sucking their digits before they started school and acquired their permanent dentition.