Delayed onset of Local Anaesthesia.

This young person of 30 years undergone dental treatment sometime back and had complained of unbearable  pain during the procedure.
When another dental treatment was needed , it was referred to me for possible anaesthesia support with adminstration of Gen Anaesthetic during dental treatment ( root canaling )
Before that the patient was called to the hospital  anaesthesia department.
He was adminstered local anaesthetic subcutaneously in various concentrations of  Lignocaine 1 %, Lignocaine 2 % , Sesorcaine 0.5%  in the forearm of both hands they were marked. After an interval of  of 5 mins  touch and pin prick test  and thermal response with ice cube was done on all injection sites and compared to non injection sites. There was hardly no change in  perception of above sensations.
The  tests were repeated after 15 mins and 20 mins and 30 mins when about 20-25 % pain
differentiation was observed. Thinking that most probably he will need Gen Anaesth for the procedure later, I let him go home.
As he was an educated person,  he was sent home and was asked to do the test on himself with a needle  Lo... the person called from home after  4 hours to say that after about 1 and 1/2 hrrs from the injectiopn,   he felt obliteration of touch sensation and no pain  on needle prick . So the onset was very very delayed.
With counselling and assurance and discussion with dental surgeon. the procedure was done under local anaesthesia using 1 % lignocaine  but after an waiting period of about more 1 hour. He felt no pain and  the procedure was uneventful. Other routine investigations were within normal limit.
Later on we had suggested a nerve conduction test but he did not report.