In Indonesia town people are being increase almost twofold. Than many people have to stay in the slum areas. The health of teeth and mouth service in health centres (puskesmas) is given toothache for low income people and specially for anxious people to toothache. The percentage of the toothache, pulpitis and periapical membrane diseases for people took the fourth rank from nine non contagious diseases at Kecamatan Penjaringan are 2.9% in 1999. The objectives of the research were to determine the relations of knowledge, attitude, and behavior aspect about dental caries with DMF-T index. The other objecllves were to determine the classification of slum and non slum areas regarding the knowledge, attitude, and behavtor about caries on the elementary school students 6th class. Results by simple linear regression showed that DMF-T index were influenced by variables of knowledge (p = 0.041). Results by multiple linear regression showed that DMF-T index is influenced by variable of knowledge and attitude about dental (p knowledge = 0.010 and p attitude = 0.046). Results by t test proved there were the significant differences in the knowledge and attitude between elementary school students 6th class in the slum and non-slum area (p knowledge= 0.001 and p attitude= 0.029). Dental healthy of elementary school students 6th class were mfluenced by knowledge. If the variables of knowledge, attitude, and behavior were analyzed together, just variables of knowledge and attitude that influenced caries dentis (DMF-T index). The classification slum and non-slum areas influenced the knowledge and attitude of the students about dental caries.