Lower molar tooth hurts when biting down. had root canal several years ago have filling. no crown. no sensitivity to head or cold. thought?

Two: Recurrent infection in your bone or a fractured tooth. Only educated guesses, so see your dentist for a complete evaluation.

Cracked Tooth: Teeth that have root canals are more brittle. If the tooth is not adequately restored with a crown the remaining tooth structure will be very prone to crack. Visit a dentist to diagnose the problem before the pain worsens.