How successful are steroidal injections in treating tmj?

Depends: If the cause of the TMJ problem is due to arthritis/inflammation, then steroid injections are effective. Consult with your doctor to determine the cause of the TMJ problem.

Will help: Just for a period of time. Usually the best way to help with tmd is the uses of mouthgards, muscle relaxants , nsad's and warm moist compresses.

Depends: As others have mentioned, the cause and symptoms will often dictate whether injections can or will be successful.

May be helpful: I've had many patients helped with steroid injections to TMJ. With careful patient selection and technique, can be very effective.