Orthodontist made a retainer nti. will this straighten teeth, or ruin front teeth. made of plastic. plastic feels too hard, retainer makes teeth hurt?

Mention concern: Probably will do neither. Retainers are meant to retain the teeth in place after orthodontics is completed, and nti appliance helps to reduce stress on muscles and tmjoints and harmful effects of bruxism. I would suggest that you discuss your concerns and discomfort with your orthodontist. Unfortunately, not being able to actually see the appliance i can only give you some generalizations.

Talk to them: Retainers are meant to "retain" not move teeth. However they may have developed a custom aligner for you (we do that all of the time for minor movements instead of invisalign). If you are in discomfort, call them-- maybe they simply need to reimpress for a new retainer.

TMJ appliance: The nti appliance is too help with grinding of your teeth at night. It keeps your teeth from coming together while sleeping. If your teeth hurt then the appliance needs to be adjusted. Your teeth will remain in the same position as they were before.

Not a retainer: An nti appliance brings the muscles of biting to bear on just the front teeth; the theory being that such a non-distributed force will prevent a patient from bruxing or grinding. It hurts because the ligaments surrounding those teeth are being assaulted. Pain indicates it is likely unhealthy. It is definitely not a retainer or a remote facsimile thereof. Ask for a consult again.

NTI not a retainer: An nti appliance is normally used in patients with symptoms of tmd, and by virtue of it preventing back tooth contact, can shut down facial muscle activity that is causing pain in many instances. It is not a long term appliance as it can lead to uncontrolled back tooth eruption that can create other problems. Ask your dental professional for clarification of its purpose in your case.

Not a fan: I don't care for nti appliances because they encourage changes in occlusion. Retainer, of any sort, should not hurt. Please seek review with your orthodontic specialist. An nti is an unusual post-orthodontic retention choice.