THE RELATIONSHIP BETWEEN DENTAL PLAQUE AND THE SEVERITY OF DENTAL CARIES AMONG PRESCHOOL CHILDREN Sri Utami School of Dentistry, Faculty of Medicine and Health Sciences Universitas Muhammadiyah Yogyakarta Abstract Background: Dental caries is a major dental and oral health problem worldwide with a very high prevalence of morbidity. Dental caries in preschool children is a disease which is extremely destructive; thus, this impacts on the growth and development of the permanent teeth. The prevalence of caries in children aged 2-4 years in countries has reached 18%, while the prevalence of ECC in children aged 3-6 years in the city of Yogyakarta has reached 84.1%. Oral hygiene factors such as the accumulation of plaque were a risk factor for dental caries in children, there was a relationship between dental caries and plaque index. Objective: The objective of this study was to determine the relationship between dental plaque and the severity of dental caries among preschool children. Methods: This was an observational using a cross-sectional design. Subjects were 618 children aged 4-6 years who attended kindergarten (TK) in Sleman, and selected using simple random sampling. The severity of dental caries was measured using the dmf-s index, while dental plaque was measured using the O’Leary plaque index. Data analysis used logistic regression. Result: The result showed that children aged 5 years were the most suffering from severe dental caries (52,3%), and most of them were boys (50,8%). The Odds Ratio value (OR) was 3,3 (p=0,000, 95% CI=2,134-4,824). Conclusions: Dental plaque is a risk factor of dental caries severity among preschool children (OR=3,3). It conclude that children with higher dental plaque index have 3,3 times greater risk of suffering severe dental caries than children with low dental plaque index. Key words: dental caries, dental plaque, preschool children