you'll probably find that it's mainly eating carbohydrates - potatoes, pasta, sweets, etc. People eating the caveman diet are less likely to get plaque and less likely to suffer dental caries too. You can help prevent or lessen it by chewing sugar free gum after meals and by drinking plenty of water.
Its accumulation of minerals from saliva on plaque on the teeth and you will find it most on lower anterior teeth where salivary ducts open. Prevent it by: 1. brushing twice daily 2. Flossing daily 3. professional cleaning by dentist every 3-6 month.