Eight days ago I had the remains of a root canal extracted (#18). The site of the tooth seems to be healing well; however, in the last 2-3 days I have been experiencing tightness in my jaw and having difficulty opening my mouth fully. What is going on?
This sounds a lot like symptoms of TMJ. Your root canal and tooth healing may be causing you to unconsciously clench your jaw during the day or while you're sleeping. Warm compresses of moist heat, soft foods, and OTC pain medications may help ease your pain. If the pain continues you should talk to your doctor, but in the meantime here's a great list of home treatments for TMJ.
Here are some other links that might be useful:
Using Tylenol Responsibly
Let’s Talk Pain Meds
What You Didn’t Know About Pain Meds
your jaw muscles are probably in spasm. You can put warm compress on your face and it will help. The muscles are not happy they had to stretch and stay open for the root canal so not they are fighting back. As long as ther is no pain at the root canal site, that's probably what it is. You can massage your face gently after you put the warm compresses on it. Leave them on for about 5 min. and gently open your mouth too. If it continues to get worse or this doesn't help I would call your dentist.