This can be many things but the most common 3 include:

  1. Throbbing without trigger – past the point of no return, the tooth needs a root canal
  2. Only hurts when chewing – bite may be high and just need an adjustment, cracked tooth or need a crown. Does not necessarily mean it needs a root canal.
  3. Hot and cold sensitivity – if cold only, early stages and may just needs a filling or adjustment. If it is heat sensitive too it means it is a later stage and likely needs a root canal.