Dental caries has been shown to be the most prevalent chronic disease in early childhood. Early childhood caries (ECC) has been linked to higher caries experience in adolescence. Common risk factors associated with dental caries – oral hygiene, diet, SES, and ethnicity – have also been associated with poorer oral health (dental erosion and periodontal health) and general health (adiposity and psychological health) conditions. Long-term studies suggest that behaviours established in early childhood are maintained into adulthood. The current study aimed to assess if children who had comprehensive dental treatment under general anaesthesia for early childhood caries had higher risk of poorer oral and general health in adolescence than children who had not. The specific objectives were to assess the effect of early childhood caries on oral and general health outcomes in adolescents, to assess the associations between oral and general health measures in adolescence, and to assess the impact of the common risk factors on health in adolescence. An in vivo matched case-control study was designed to assess the differences between children who had comprehensive dental treatment under general anaesthesia in early childhood and those who had minimal or no dental problems in early childhood. The case group was selected from Paediatric Dentistry records at the School of Dentistry. The control group was either volunteered by the case group or randomly identified from School Dental Service data. All children completed questionnaires to assess oral health behaviours, diet, self-esteem, dental anxiety, and oral-health-related-quality-of-life. They also received a clinical assessment that recorded dental caries status, erosion status, periodontal health status, and malocclusion status of the teeth. General health (adiposity) was clinically assessed through the child's height, weight, and waist circumference. Univariate and bivariate statistics were computed using SPSS version 19 and STATA version 10. The level of significance was set at p < 0.05. The current study had a low response rate with only 23 percent of invited case participants completing the study. The control group had similar sociodemographic characteristics to the case group, except for age. The control group was statistically significantly older (0.4 years), than the case group. The case group was found to be more likely to have severe erosion and more than four times more likely to have caries in the permanent dentition than the control group. Although not statistically significant, the case group also had a higher prevalence of moderate gingivitis and participants with a "handicapping" malocclusion. Dental caries experience was statistically significantly associated with obesity. A higher prevalence of Māori /Pacific children were identified as overweight, obese, and with excess central adiposity. A higher proportion of the case group was classified overweight, obese, with excess central adiposity, dentally anxious, and with poorer OHRQoL but these differences were not statistically significant. Dietary factors were not statistically associated with oral health or adiposity measures. Early childhood caries was associated with poorer oral health in adolescence. The poorer general health measures in the children with early childhood caries was not statistically significant. The dietary risk factors assessed were not conclusive in explaining the health outcomes in children with early childhood caries in this cross-sectional study. The findings do have clinical implications with early childhood caries being demonstrated as an indicator for increased risk of poorer oral health outcomes in adolescence.