Are Dyslipidemia Following Obesity and Hyperglycemia as an Indicator of Diabetes Involved in Dental Caries Development in Zucker Rats?

Several studies indicated that both obesity and diabetes are related to dental caries development, but their involvement remains unclear. Thus, we investigated the effect of obesity and diabetes on dental caries development using obese Zucker fatty (ZF) rats, obese Zucker diabetic fatty (ZDF) rats, and Zucker lean (Lean) rats as controls. Eight ZF, 6 ZDF, and 7 Lean male rats were studied. We macroscopically examined the mandibular and maxillary molars and evaluated soft X-ray photographs for caries development. From each group, 5 mandibles and maxillae were examined histologically. The ZF rats' average body weight was more than twice that of the other 2 groups, but the ZDF and Lean rats had comparable body weights. The average triglyceride and total cholesterol levels were elevated in the ZF and ZDF rats, but the ZF rats' average triglyceride and total cholesterol levels were three times and twice, respectively, those of the ZDF rats. The ZDF rats became diabetic after 13 weeks of age and demonstrated a high blood glucose level (> 500 mg/dL) after 23 weeks of age. The ZF rats had a significantly higher blood glucose level than that of Lean rats after 23 weeks of age but had about one-half that of the ZDF rats. The ZDF rats had significantly more molar caries and greater alveolar bone resorption than the other two groups; the ZF rats' caries and bone resorption were moderately higher than those of the Lean rats. Histopathologically, crown caries progressed to apical periodontitis in 20% and 50% of the ZF and ZDF rats' molars, respectively, corresponding to the alveolar bone resorption on the soft X-ray film. Dyslipidemia and hyperglycemia may involve dental caries development and obesity or diabetes could enable lesion progression to apical periodontitis in Zucker rats; diabetes enhances dental caries to a greater extent than obesity.