My gums around my crown is swelling and its spreading near gums . what is the reason and how can it be solved?

From what you are describing you may have a cracked tooth underneath your crown.  You should not be able to get your finger caught under the margin of the crown nor should you be able to move it.  Did you have a large metal (amalgam) filling in the tooth prior to having the crown...

Based on your photo, I would highly recommend that you replace your veneer.  Dental bonding (also known as composite) does not work well on with porcelain veneers.  Good luck and I hope this helps. Follow me if you have more questions.Sarah Thompson, DMD

Based on your photos and your description, it sounds like you are having some bacteria accumulation around your gum margins.  This is most often due to poor oral hygiene or a non dental friendly diet.  I would suggest getting regular teeth cleaning by a dental hygienist every 6 months,...

Based on your description, it sounds like you have only a crown prep remaining, in which looks like a short tooth.  If this is the case, it is not difficult at all to re-prep the tooth and place another crown.  It would be in your best interest to take care of this tooth very soon,...

If you have a dark line around your crown, it sounds like you have a metal crown that is coated with porcelain.  If this is the case, it is impossible to remove that line without replacing the crown.  I would recommend getting a full porcelain emax crown on this tooth to get rid of...

In general, most dentist do not guarantee crowns for more than a few months, so I would not expect your dentist to cover crowns that are 4 years old.  However, at my office, we guaranty our crowns will not crack, chip or full off for at least 10 years, but we expect our crowns to last 20-30...