Inclusion Criteria:  obesity in case group (having a BMI above the 97th percentile + 2.17 to+2.18 SDS), normal weight in the control group (BMI between the 10th and 90th percentile -1.64 to +1.64 SDS). Obese and normal weight groups were defined using the BMI according to the European Childhood Obesity Group (ECOG) and the growth curves for Flemish boys and girls (2-20years).  Exclusion Criteria:  smoking chronic disease receive treatment with antibiotics three months prior to the study consume medications with side effects on the gums wearing orthodontic appliances other ethnicity (not Belgian) were excluded as ethnicity is an influential factor in the relation between caries and obesity.