Brushing teeth is a means of maintaining dental and oral hygiene which aims to prevent dental caries. Primary school age is the appropriate time to train and to lay on correct habit and behaviour in brushing teeth. The behaviour and habit of brushing teeth will affect the occurrence of dental plaque accumulation. The accumulation of plaque that attach to the teeth for a long period of time, and is not immediately cleaned, will increase the maturity level of dental plaque, and may potentially grow into dental caries. This study aims to identify the relationship between the behaviour of brushing teeth with the level of dental plaque maturity.An analytical study with cross-sectional design, with the number of samples as many as 83 children and is determined by purposive sampling. Completion of questionnaires to assess knowledge, attitude, action, and habit of teeth brushing and using the Tri Plaque ID Gel to measure the maturity level of dental plaque. Using the Spearmen test acquired p=0,000 (p<0,005) and r=0,632. It shows that there is a relationship between good behaviour in brushing teeth and the decrease on the level of maturity of dental plaque. There is a relationship between the behaviour and habit of brushing teeth with the maturity level of dental plaque. The better the behaviour is and the habit in brushing teeth, the lower level of dental plaque maturity.