The main objective of a 2012-2013 clinical study on the oral health of Quebec elementary school students was to assess the oral health status of Grade 2 and Grade 6 students. We assessed various stages of caries and created caries indicators for primary and permanent dentitions combined.Oral health examination of 2875 Grade 2 students and 2788 Grade 6 students, enrolled in public and private, French- and English-language schools, was carried out at schools. The examinations were performed by 16 trained and calibrated dentists using International Caries Detection and Assessment System (ICDAS) II criteria. A 3-level sampling design ensured that the study was representative for the province of Quebec.Mean indexes for decayed, missing, filled primary teeth (dmft) and secondary teeth (DMFT) or surfaces (dmfs and DMFS) for all stages of caries were as follows. Grade 2 students: dmft 3.96, DMFT 1.88, dmft + DMFT 5.84, dmfs 8.33, DMFS 2.96 and dmfs + DMFS 11.28. Grade 6 students: dmft 1.94, DMFT 4.98, dmft + DMFT 5.98, dmfs 4.04, DMFS 7.86 and dmfs + DMFS 9.96. Most students (90% for Grade 2 and 92% for Grade 6) had a dmfs + DMFS > 0.Tooth decay remains a public health problem in Quebec. The findings testify to the importance of reinforcing preventive measures to better control dental caries among youth. It is advantageous to use ICDAS II in the context of oral health surveillance at a population level and to present the results as a combination of primary and permanent dentitions.