Hi.as you told you had Dental treatment done in that region ,so you have got rct done with crowns on it ,while doing rct ,we need to give anaesthesia  or nerve block in that region,which sometimes leads to numbness in half jaw and also the muscles get in tension ,and sometimes it also leads to inability of opening of jaw muscles ,due to the LA that was given to you.you need to take muscle relaxants,warm saline rinses and hot fomentation on the outer side of jaw,and also get an OPG done to check any problems with the rct done to you.

Hi..you have a condition called oral submucous fibrosis, it happens because of gutkha chewing. Visit a oral surgeon. You might need surgery to correct it. Regards

Hello..As you are giving a history of dental treatment recently..when was this treatment done..as sometimes the local anesthetic injection given to numb the tooth can cause spasm in the muscles of the jaw..