Meera,

It is not that uncommon to have post op numbness or odd sensations in the tongue, lip, cheek, chin... for several days or weeks after having a dental injection in the posterior region of the lower jaw. This problem can also result from the extraction of a lower posterior tooth... especially a root canaled or infected tooth.

The fact that it has gone away is a good sign that the affected nerves have healed. There is no guarantee that it won't come back if another tooth in that area were to become infected or be extracted. But hopefully you will never have to worry about any of that again.

Bryanna