If caries are present in Enamel or Dentine, the patient will feel no pain. This decay is removed and artificial tooth colored composite filling is applied.
Sometimes, when the proximal filling comes out due to masticatory forces, in that case, full crown is advisable.
Many times, improper brushing creates a gap in the area right in between the gums and teeth. This open gaps causes sensitivity, if kept untreated, can lead to a situation in which Root Canal Treatment becomes necessary. Plan of treatment: Tooth Coloured Filling.
If caries are deep into the tooth, the patient will feel the pain and occasional swelling. To remove this decay, Root Canal Treatment(link to RCT description) is done.
If infection is spread beyond the tooth, into the bones(periapical abscess), the tooth may not be able to survive for long time as it spreads the infection in bone and other teeth. In extreme cases, the tooth may need to be removed.