Why is it done to treat fissure or piles? Is it useful to cure anal fissure?any side effects?how much time it takes to recover after surgery to become normal.

Never heard of dilation as a cure. Who is saying this?
Fissures:
Home treatment, including soaking in a shallow tub of warm water (sitz bath) 2 or 3 times a day, increasing fiber in the diet, and taking stool softeners or laxatives. Although your pain may go away, it may take several weeks for the fissure to heal completely.

Try to prevent constipation, because it can keep a fissure from healing. The pain of a fissure may make you anxious about having bowel movements. But trying not to have bowel movements will only increase constipation and create a cycle that keeps the fissure open and painful.

Drinking lots of water or other fluids also will make stools softer and easier to pass.

Try zinc oxide, Preparation H, Anusol, or 1% hydrocortisone to soothe anal tissues. But evidence suggests that fiber and sitz baths help symptoms better than creams.

Prescription medicine may help if those don't, such as nitroglycerin, high blood pressure medicines, and Botox.

You may need to consider surgery as a last resort. The most commonly used surgery is lateral internal sphincterotomy. In this procedure, a doctor cuts into part of the internal sphincter to relax the spasm that is causing the fissure.

Hemorrhoids can be easily removed in a day surgery clinic if OTC preparations don't work well enough.