Before I tell you about filling you must know Why we require them. We need dental filling to fill the spaces created by caries . Now the question is What are Dental careis?

DENTAL CARIES :  Dental caries or dental cavity is the irreversible damage to the calcified part of the tooth. Tooth are not made of stones. They are just calcified structure in the body like bone but much harder then bone. Tooth are covered with enamel(Hardest material in a living body) which gives tooth a white appearance strength to your tooth. Our environment is full of bacteria and so our mouth. When bacteria start to colonize over the tooth surfaces they produces acids as by products which causes demineralization of enamel which is an irreversible damage to tooth. Our teeth contains grooves and flat surfaces. In these grooves bacteria finds shelter and increases their population. 

   Now as we know now that the Caries or decay of tooth is an irreversible damage we need to get rid of these bacteria and the decayed tooth before they reach the living portion of tooth and can cause major pain or damage to tooth or can  break itself . As the bacteria undermines the tooth structures they become prone to fracture. And if bacteria reaches to pulp(living part of tooth) it start degrading and form pus over the root inside the bone which stimulates sever pain and may cause swelling as well. 

  Hence to stop the bacteria from damaging Pulp we need to clean the tooth from bacteria and the decayed tooth portion. We clean the tooth untill healthy enamel or dentine surfaces are reached in all directions. If we leave the tooth in same condition the empty space will again give the bacteria a space to grow and further damage to tooth will occour. Because we dont want the bacteria to damage more tooth structure we fill this cavity will some hard material. These materials are called Dental fillings or Tooth Filling. 

How are fillings done?

A Small airturbine drill is used to clean the damaged portion of the tooth by bacteria. All bacteria along with decayed tooth part will be drilled out.
The hole created by drill in the tooth is filled by some hard, tooth-like material. The material used in fillings can be selected by yourself or your dentist.
This filling prevent  bacteria from re-entering the cavity again and restore the shap of the tooth.
You may or may not feel sensation or discomfort during drilling process. If you can’t bear the discomfort of drilling you can ask your dentist to do the same procedure under  Local Anesthesia.
After filling you may feel little discomfort for few days but if it persist talk to your dentist immediatly. The first time feeling is unusual, but not at all bad. If you’ve never experienced filling  before in your life, you’ll enjoy exploring that part of your mouth with your tongue and not feeling a thing.