This is done in the very initial stage of developing a Gum Disease. Your dentist will remove the plaque or tartar (which hardens the tooth surface) from below and above the gum line. It is a preventive measure which helps you to save from getting gum disease.
This is also a deep cleaning process. The only difference is that your dentist will give local anesthesia to start the process. Plaque and tartar are removed from above and below the gum line and after that, the rough spots are made smooth. The process of smoothing helps to remove the bacteria. This is done only if your dentist finds that you have calculus deposits under the gum.
In this, incision is made on the gums to remove the tartar. Sometimes the irregular surface of the bone is smoothened so that there are no areas for bacteria which cause this disease can hide. This method is used to remove the gap between gums and tooth.