Mechanisms linking periodontitis and diabetes

Background + Aims

• Persistent high blood glucose can damage small blood vessels, potentially impairing the periodontal tissues’ response to infection and capacity for repair. Green tea contains polyphenols with antioxidant and anti-inflammatory properties that may help limit these changes.
• This study aimed to:
  • Evaluate the effects of daily green tea consumption on periodontal vascular changes and the progression of spontaneous periodontal disease in rats with prolonged diabetes-related hyperglycaemia.

Materials + Methods

• Male Wistar rats were allocated to 4 groups:
  • Normal blood glucose with water
  • Normal blood glucose with green tea
  • Type 1 diabetes with water
  • Type 1 diabetes with green tea.
• Diabetes was induced using streptozotocin. Green tea or water was then provided freely as the animals’ drinking fluid.
• Assessments were performed at baseline and after 15, 30, 60 and 90 days. Periodontal disease developed spontaneously rather than being induced using ligatures or bacterial inoculation.
• Researchers measured fasting glucose, body weight, fluid intake, dental plaque and tooth decay.
• Micro-CT and tissue microscopy assessed periodontal bone loss and tissue damage.
• Vascular assessments focused on the periodontal ligament, which connects teeth to surrounding bone. These measured small blood vessel density, CD31 (a marker found on blood vessel lining cells) and vascular endothelial growth factor (VEGF), a protein regulating blood vessel growth and permeability.

Results

• Diabetic rats drinking water developed progressive plaque accumulation, inflammation and substantial periodontal bone loss. Green tea reduced plaque accumulation and delayed and lessened tissue destruction.
• Micro-CT showed significantly less periodontal bone height loss in diabetic rats receiving green tea from the later stages of the experiment. Nevertheless, their periodontal tissues remained more affected than those of rats with normal glucose.
• By approximately 60 days, diabetic rats drinking water showed about a 36% reduction in microvessel density, a 33% reduction in CD31-positive cells and a 53% increase in VEGF-positive cells, as reported by the authors. In diabetic rats receiving green tea, these measurements generally remained similar to those in the normal-glucose groups.
• Reported mean glucose levels were lower in diabetic rats receiving green tea than water (approximately 284 versus 357 mg/dL) but remained elevated.
• Green tea also delayed and reduced caries severity, without preventing it completely.

Limitations