Obesity and dental decay: inference on the role of dietary sugar

To evaluate the relationship of children's obesity and dental decay.

We measured parameters related to obesity and dental decay in 8,275 4(th) and 5(th) grade Kuwaiti children (average age = 11.36 years) in a cross-sectional study. First to determine body weight, height, age for computation of BMI . Second, to determine numbers of teeth, numbers of fillings and numbers of untreated decayed teeth to determine extent and severity of dental disease. From these measurements, we computed measures of dental decay in children from four body weight categories; obese, overweight, normal healthy weight and underweight children.

The percentage of children with decayed or filled teeth varied inversely with the body weight category. The percentage of decayed or filled teeth decreased from 15.61% (n=193) in underweight children, to 13.03% (n=4,094) in normal healthy weight children, to 9.73% (n=1,786) in overweight children to 7.87% (n=2,202) in obese children. Differences between all groups were statistically significant. Male children in this population had more dental decay than female children but the reduction of tooth decay as a function of BMI was greater in male children.

The finding of an inverse obesity-dental decay relationship contradicts the obesity-sugar and the obesity-dental decay relationship hypotheses. Sugar is well recognized as necessary and sufficient for dental decay. Sugar is also hypothesized to be a leading co-factor in obesity. If the later hypothesis is true, one would expect dental decay to increase with obesity. This was not found. The reasons for this inverse relationship are not currently clear.