fractured, chipped & Cracked Tooth

Decay and large filling cause a weakening in the remaining tooth structure over time. A hairline fracture often develops at the bottom corner of the filling. The molar and premolar teeth are most commonly affected. Grinding your teeth will cause a large increase in the stress and strain on your premolar and molar teeth increasing the risk of this condition. The reason it hurts to bite when you have a cracked tooth is that your tooth is flexing, which stimulates the nerve in the tooth. These hairline (microscopic) cracks open and close causing fluid to move inside the tiny tubules that make up the dentin of the tooth causing pressure on the tooth’s pulp (nerve) resulting in pain. The pulp in the cracked tooth may also be exposed to bacteria and their toxins become inflamed making it sensitive. If the crack goes untreated it can spread and deepen and a part of tooth may break off causing a need for root canal therapy or extraction.
Symptoms and Sings of Cracked tooth Syndrome 
The tooth may be very sensitive to hot, cold and sweet stimulus .
The pain may occur upon release of biting pressure because the crack will close quickly causing pain.
There may be gum pocket beside the tooth root surface of the crack extending below the gum margin.
Diagnosis of Cracked Tooth Syndrome 
Your dentist may use the following processes for the diagnosis of your cracked tooth.
Questioning about your dental history and present problem.
Testing individual teeth with hot or cold items to identify the tooth producing the symptoms.
Looking for signs of teeth wear, cracks of the surface of teeth, large filling with weakened cups (the cup is the pointed or raised part of the tooth).
Bite test can be helpful in locating the pain. Your dentist will use an object to direct your biting pressure into an individual cusp.
X-ray examination may be used, however the tooth crack will rarely be seen on an x-ray film.
The removal of a filling in a suspect tooth may help your dentist identify the position of the crack, and sometimes be used in this situation to highlight the crack .
Probing below the gum line may help identify an extensive crack.
Treatment for a cracked tooth 
Early detection and treatment is important as developing cracks can be slowed down or stopped, increasing the chances that the tooth can be saved. The treatment required depends on the extent and position of the crack. The treatment for most cracked teeth involves removing the weakened cups and placing a large filling or crown on the tooth. If more than one cup is cracked or weakened, a crown or overlay is the treatment of choice as this will help protect the other weakened cups. Treatment for a cracked tooth If the crack is a complex one that has led to involvement and inflammation of the pulp (nerve) then root canal treatment will be required prior to crowning of the tooth. This may involve two or three additional appointments, and as with any treatment in complex situations, there is always a possibility that the treatment will not succeed.
Sometimes your dentist will suggest that a referral to a specialist is required for treatment of a particular tooth If the crack is terminal (unable to be treated) then your dentist will recommend that removal of the tooth is the best treatment option. Please remember that diagnosis and management of the cracked tooth is not always a simple task, and that sometimes a number of visits and tests are required before treatment options can be offered.