Fillings are done to restore a decayed tooth. The dentist removes the decayed part from the tooth and fills the tooth surface with a resin material, usually tooth-colored.
After filling, a tooth is safe from carries and decay. Another use of tooth-colored filling material is to correct cracked or worn off teeth. Teeth can wear off by night grinding or nail-biting.
There are silver fillings as well, but we use solely tooth-colored material for fillings.
Signs of the requirement of fillings:
Decay, visible hole on any tooth
Sensation in any particular tooth after having anything cold