Malocclusion is the misalignment of teeth. One kind of malocclusion is crowding caused by dental factors, such as premature loss, retained teeth, supernumerary teeth, and tooth shape anomaly. The characteristics of crowding are rotation, overlapping, or displacement of teeth. We aimed to identify the prevalence of dental factors that cause crowding malocclusion in primary school students in Jakarta. We evaluated 81 students from randomly selected schools in the subdistrict of Johar Baru, Jakarta, for the presence of crowding malocclusion and the dental factor. Of the students with crowding malocclusion, 48.15% had premature loss, 58.02% had retained teeth, 9.88% had supernumerary teeth, and 9.88% had tooth shape anomalies. In some cases, crowding malocclusion was caused by more than one dental factor. Of the students with a combination of dental factors, 12% had premature loss with retained teeth, 0.67% had premature loss with tooth shape anomaly, 5% had retained teeth with supernumerary teeth, 4% had retained teeth with tooth shape anomaly, and 2% had supernumerary teeth with tooth shape anomaly. The most prevalent dental factors associated with crowding malocclusion were retained teeth and a combination of premature loss with retained teeth. © 2020, University of Dicle.