Here's an interesting article found in AGD magazine, October 2010 regarding childhood obesity and cavities:
Decay Linked to Nutrition
"A preliminary study of children being treated for cavities in their primary teeth found that nearly 28 percent had a body mass index (BMI) in the 85th percentile or above, indicating obesity. That percentage is more than 5 percent higher than the estimated national average, suggesting that poor food and nutritional choices--particularly sugary sodas and fruit juices--are contributing not just to obesity but to childhood tooth decay as well. The findings were presented in June at the 2010 annual meeting of the Endocrine Society by researchers from the University at Buffalo. The study involves 65 children ages 2 to 5, all of whom required anesthesia during treatment due to the severity of their dental problems. Approximately 71 percent of the group had a calorie intake above the 1,200 calories per day considered normal for their age group. The researchers concluded that, because cavities are the most common chronic childhood disease, [it is important] to educate families on both nutrition and the risks of obesity and tooth decay."