Root canal tooth can get cavity if some portion of cavity has been left in the tooth while the treatment was done previously..crown should be given to avoid the tooth to fracture after root canal as it becomes brittle if left like that to bear the forces while eating..Brushing technique and type of brush used should be accurate..The cause of brittleness can be judged after a visit to dentist and further treatment can be done after that.

Hi Yes. Both with and without crown, rct treated teeth can get cavity if care not taken at home. Brittleness can be bcoz of systemayic lack of nutrients like ca etc.

If any decay is left behind or the filling is fractured then the tooth can get a decay. But generally after crown it is covered from all sides n is safe. If ur teeth are brittle use a soft brush n good calcium n fluoride toothpaste. Learn the technique of care of ur teeth from a dentist.

tooth canal treated tooth can get cavity if there any portion of decay left and If for brittle tooth you need to change your brushing technique and soft bristle brush should be used for the brushing You can also practo consult us regards