: Mentally retarded children experience higher dental and oral health problems compared to normal children due their ability to carry out independent activities, especially in dental and oral health maintenance behaviours. The right behaviour change strategy is to provide dental health education using learning methods and media tailored to the needs of mentally retarded children. Model of the 3D Gosgi modification puzzle was made specifically for learning carried out by mentally retarded children in group and been assisted by teachers. Aims: Find effect of application media puzzle modified 3D Gosgi as an effort to improve the skills of brushing teeth for mentally retarded children. Research design is quasy experimental and research location at Special Need School at Semarang, Indonesia. The subjects were 30 mentally retarded children divided into two groups, intervention group was given education with a modified 3D puzzle model for 5 d and control group with video media and brushing teeth demonstrations. Measurement of index debris and tooth brushing skills of mentally retarded children were carried out before and after intervention. Statistical analysis used is Wilcoxon and Mann Whitney test. Puzzle modified 3D gosgi are effective to decrease debris index (p < 0.001) and improve tooth brushing skill (p < 0.001) compared to group with video and demonstration. Application of puzzle modification 3D Gosgi by teacher for effective in improving the brushing skills of mentally retarded children.