A research report submitted to the Faculty of Health Sciences, University of the Witwatersrand, in partial fulfillment of the requirements for the degree of Master of Science in Dentistry. School of Oral Health Sciences, Faculty of Health Sciences University of the Witwatersrand, South Africa Johannesburg, 2017. / Introduction Although the prevalence of dental caries experience among the children in the world has decreased significantly in the last fifty years, dental caries is one of the most predominant chronic childhood diseases worldwide, and it is a public health problem, both for individual children and families who choose to deal with young children suffering from a toothache. Aims and objectives The purpose of this study was to determine caries experience and associated factors contributing to the condition among preschool children in Johannesburg. The objectives were to determine the dmft status, the pufa index of the children and to compare the prevalence of caries between age-groups. Furthermore, the association between demographic characteristics and the caries experience was assessed. Methodology A cross-sectional study was carried out at six sites in Johannesburg on children aged 2-5 years. Data was collected by means of a parental questionnaire covering demographic information and oral dietary habits. This was followed by an oral examination using two indices: Decayed Missing Filled Teeth (dmft) and Pulp Exposure Ulceration Fistula Abscess (pufa). Results Two hundred and twenty-two preschool children aged 2- 5 years participated in this study (n= 222): girls (n= 125) (56%), slightly outnumbering boys (n= 97) (44%). The mean dmft at 2, 3, 4 and 5 years was 0.96, 1.93, 3.44 and 3.38 respectively. The prevalence of dental caries of the children was 47.74% with a mean dmft of 2.41 (SD ± 3.60). The mean age of the children in the study was 3.5 years (SD ± 1.01 years). The results showed statistically significant difference among the age groups. The 4 and 5-year olds had higher levels of dmft than the 2 and 3 year olds (P < 0.001). There were no significant differences (P = 0.3566) in the mean dmft between the boys and girls in the study. There were negligible pufa scores, only 2.2% of the children had pufa scores. The largest contribution was the abscesses. The average dmft value for the children in Berea/Yeoville area was significantly higher (3.8; SD± 4.2) than the one for the children in OR Tambo Diepsloot immunization clinic (1.5; SD± 2.8), (P < 0.001). Household size and parental education had no significant influence on the dmft. Conclusion The prevalence of dental caries was found to be high among 2 to 5-year-old preschool children in Johannesburg, and the mean dmft was directly proportional to the age. / MT2018