Had 4 shots to numb before partial crown and next day chin/lip became numb. root canal followed & 12 days later my lip/chin still numb. paraesthesia?

Contact dentist!: You have waited a long time and it seems unlikely that this is clearing up on its' own. Definitely call the dentist to describe the situation and ask him to correct whatever went wrong. Don't try to self diagnose, it will not help you in any way. I hope the dentist will discover the cause and make it right as soon as possible. This followup should be part of the procedure done. Best wishes!

Unfortunately: Unfortunately nerve damage is an occasional vexing complication of Dental treatment. Parasthesia is usually transient but sometimes permanent. Recovery can take days to many months. Please return to your Dentist for an evaluation.

Nerve injury: Yes it could be paresthesia. could have been caused by physical trauma during the injection, or by the solutions. the vast majority of these resolve on their own most within 2-4 weeks although some take up to a year.