I had labial frenectomy 3days ago.but my front teeth do not have gaps.doc performed this to prevent relapse.was this necessary?am still in pain

Most Likely: Without seeing you before any treatment it is impossible to tell for certain here but frenectomies are frequently required for just the reasons stated. 3 days is not an uncommon time for recovery. If it is not better after about a week or you develop fever or it gets worse, see the doctor that performed the procedure to be sure you have no infection. Ice on the area may help it feel better.

Frenectomy- yes: Yes it is necessary to do the frenectomy to prevent relapse of the gap that was closed between the front teeth. The labial frenulum if attached too low on the ridge can pull the teeth apart. So your dentist did the right thing. Pain is only a part of the procedure and should go away in 2-3 days. If it worsens then you should contact your dentist otherwise painkillers like advil (ibuprofen) or morton can help.

Likely unnecessary: At 21, when no space exists, it is not necessary to preform a frenectomy. Another dr. Said it was done to prevent relapse: relapse to what? It (space) never existed. A good reason would/could have been for vertical pull on tissue for perio health. It will heal in a few more days, no worries, but i think it was done without sufficient reason, if relapse was the issue.

Frenectomies: There are cases when a frenectomy is absolutely warranted and others when it is totally unnecessary and then there are those cases where it becomes a judgment call. Without knowing the details of your specific circumstances and being unable to clinically examine you, we can't possible know what was best for you. The pain should subside soon. Best to discuss all your concerns with your dentist.