Background : Tooth abnormalities are a deviation from the normal morphology and structure of the teeth due to growth and development disorders that will affect the tooth in the oral cavity. Mesiodens is an abnormality in the number of teeth, where these additional teeth usually observed are in the anterior maxilla. Fusion and gemination are one of the tooth shape anomalies. Purpose: The purpose of this study was to determine the prevalence of fusion, gemination, and mesiodens dental abnormalities in children in the RSGM UMY and its network. Material and methods: The method used in this study was descriptive observational, the total sample are 10,714 medical records of pediatric patients aged 0-18 years that visited RSGM UMY from 2013 – 2018 and patient of RSGM UMY network from 2017-2018. Data analysis in this study was a descriptive analysis in the form of frequency distribution and crosstabulation on SPSS. Results : The results of the prevalence study at the RSGM UMY and its network showed that the prevalence of mesiodens dental abnormalities was 0.14%, the prevalence of fusion dental abnormalities was 0.028%, and the gemination dental abnormalities were 0.009%.