Once your teeth are damaged, no medicine can bring back them to
  their natural healthy state. Your dental health depends on what
  and how you eat and drink. Some foods are healthy for teeth,
  they fight bacteria naturally, remove plaque on teeth,
  strengthen the enamel, and freshen breath when you eat them.
  Certain foods are especially harmful causing enamel erosion that
  could lead to increased teeth sensitivity to hot, cold, sour and
  sweet.

   1. Drink plenty of water daily.
   2. After eating acidic foods like citrus fruits or juices,
      tomatoes and lemons rinse your mouth with water thoroughly,
      as the acids present in them can weaken enamel. Or these
      foods should be a part of a larger meal. Don't brush
      immediately, otherwise the enamel erodes away faster.
   3. Eat beat sprouts.
   4. Don't eat all the times. Leave at least 2-3 hours between
      meals or snacks. This allows the acid level in the mouth to
      fall and also gives saliva a chance to counteract the effect
      of acid and repair tooth enamel.
   5. Brush your teeth after you eat foods that are not good for
      teeth. Or eat such foods at times when you can brush your
      teeth soon afterwards.

  Best Foods For Teeth

   1. Calcium rich foods such as milk, yogurt, cheese, chicken or
      other meats and nuts are good. These foods may protect tooth
      enamel by providing the calcium and phosphorus and
      remineralize teeth.
   2. Eating high protein foods are good for teeth health.
   3. Eat fiber-rich raw foods (high fiber foods), which massage
      the gums and clean the teeth.

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   4. Eat some raw food after every meals. This will help clean
      your teeth and gums due to high water content. Raw foods
      increase salivation, which neutralizes acids and alkalis
      within the mouth. You may grate, dice, ground, blend, or
      juice raw foods. Good raw foods for teeth to eat are apple,
      carrot, radish, cucumber, orange, pear, beetroot,
      watermelon, etc.
   5. Nuts: Nuts are rich in calcium, magnesium and phosphate,
      which are important nutrients for dental health. Nuts good
      for teeth are cashews (stimulates saliva) , peanuts (calcium
      that helps both teeth and gums and vitamin D), almonds (
      high calcium) and walnuts (fiber, iron, folic acid,
      thiamine, magnesium, niacin, potassium, zinc, vitamin E,
      vitamin B6,).
   6. Fruits, vegetables, wholegrains and cereal products.
   7. A glass of milk, yogurt or fresh fruits are healthy snacks.
   8. The best drink choices are water, milk, and unsweetened tea.
   9. Meat Eaters

      Meat eaters require to take better care of their teeth. If
      the stuck meat fibres are left overnight without cleaning,
      the fibres may petrify and release an acid which acts on the
      tooth causing it to decay.

  10. Chewing sugarless gum is beneficial to your teeth as chewing
      increases saliva flow to neutralize mouth acids. Some gums
      contain ingredients that can reduce cavities. Saliva in our
      mouth helps to wash away food particles and protect against
      acidic foods.

     Ideas For Snacks

  Sweets and other sticky carbohydrate foods are not suitable as
  snacks, especially when you can not brush soon after. Following
  are healthy and good snacks for teeth.

   1. Fresh fruit
   2. Glass of milk, soy milk or buttermilk
   3. Natural yogurt with fresh fruit
   4. Smoothies made with milk, yogurt and fruits
   5. Whole wheat breakfast biscuits with milk
   6. Cheese or cheese sticks
   7. Hot soups in winter

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     Worst Foods For Teeth

   1. Foods with Sugar

         * When you eat sugary or starchy foods, the bacteria in
           plaque gets chance to form decay-causing acid so they
           should be avoided. To protect your teeth, it is
           important that sugar should stay in your mouth as
           briefly as possible. So it is essential that you should
           at least rinse mouth thoroughly after eating them.
         * Note that It is not the amount of sugar taken is
           important but how often and how long the teeth are
           exposed to sugar.
         * Sugars are not good for teeth. Minimize foods that
           contain sugars. It is better if you have all your sugar
           at once, than to distribute it throughout the day.
         * If you wish to eat 5 lollipops, eating all in one
           sitting is safer than having one lollipops each hour
           for 5 hours! One acid attack is less damaging than
           frequent attacks.
         * Sticky sweets & lollipops: Sugary sweets, hard candies
           and lollipops and caramels stick are very bad as they
           cling to tooth surfaces and crevices. Chewable vitamin
           tablets are worse, because they contain a concentrated
           acid.
         * Cough drops should be used only when necessary as they,
           like sugary candy, contribute to tooth decay because
           they coat the teeth with sugar.
         * Dried fruits like raisins, prunes, figs and apricots,
           are similar to caramels. Their sugars are highly
           concentrated as the water is dried away, and their
           sticky texture can cling to teeth. These can easily
           stick to teeth so the sugar in them encourage bacteria
           in the mouth, weakening tooth enamel. Regular fruits
           are less harmful, because they are not as sticky.

   2. Carbonated soft drinks, Health & Sports drinks

         * Soft drinks and sports are loaded with sugar and
           acidic; and most artificially sweetened soft drinks
           contain phosphoric and citric acids that erode tooth
           enamel. Even bottles iced teas may contain
           flavor-enhancing organic acids that can erode tooth
           enamel.
         * Drinks (normal or diet) such as coke, pepsi, sport
           drinks and fruit juices though don't stick in the teeth
           but they are highly acidic.
         * The diet drinks are not high risk for dental cavities,
           but the tooth enamel may be affected due to their high
           acid levels.
         * Acidic foods and drinks like citrus (oranges, lemons
           and grapefruit) juices contain powerful acid.
         * Sipping a soft drink or a sports drink or acidic juices
           every few minutes is hazardous, it is best to finish
           the whole drink in one go, then rinse your mouth
           thoroughly with plain water to remove the acid. Don't
           brush your teeth immediately after a soft drink, as it
           can damage the tooth enamel due to etching.
         * The impact of sweet or acidic drinks can be lowered by
           drinking through a straw.

   3. Drinking frequent cups of tea or coffee with sugar added
      will increase the risk of teeth decay.
   4. Starchy foods like white bread, potato chips, burgers,
      pizza, pasta and French fries can easily get lodged between
      teeth and in the crevices between two teeth. The starches in
      these foods can convert to sugar almost immediately, both by
      the bacteria and the predigestive process that begins in the
      mouth through the saliva.
   5. Cookies, potato chips, lollipops, sweet breakfast cereals
      (eaten dry), granola bars, cakes and other sweet foods are
      not suitable as snacks because most people don't clean their
      teeth after every snack. These may be eaten at mealtimes.
   6. Mouth-drying eatables
      A dry mouth is harmful for teeth and gums. Alcohol and wine,
      psychiatric medications and mouth washes with alcohol are
      among the worst for causing dry mouth as they suppresses the
      production of saliva. If taken in excess, these may dissolve
      enamel, making teeth porous.

      Source: fatfreekitchen.com