Gingivitis is the inflammation of the gums around the teeth due to improper cleaning of teeth. Gingivitis may be caused by a build up of plaque and tartar. If not treated, gingivitis can progress to more-serious gum diseases, such as periodontitis, and eventually to the destruction of bone and to tooth loss.

Causes

If you don't brush and floss your teeth every day, this food can big problem for you. The rotten bits of food cause a bad smell in your mouth. Rotten food also helps bacteria to grow in your mouth. This bacterium can cause gum disease, or gingivitis. Gingivitis also causes bad breath.
In addition to causing tooth decay, some of these bacteria contribute to gum disease. One type in particular, Fusobacterium nucleatum, assists other bacteria in adhering to the teeth and penetrating beneath the gum line.
Other things increase the risk of it developing, including:
Injury to the gum
Pregnancy
Uncontrolled diabetes
Smoking
Stress
Poor nutrition
The side effects of certain drugs
Problems such as rough or misaligned teeth

Symptoms

The common symptoms are-
Swollen, soft, red gums.
Gums that bleed easily.
A change in the color of your gums from a healthy pink to dusky red.
A complex system by which bacteria-fighting cells of the body are recruited to an area of bacterial infection plays a major role in gingivitis
When bacteria first begin to invade the gums, proteins present in the saliva and soft tissues called antibodies coat the bacteria and weaken it, making it an easy target for the body's immune system.
One particular cell called a macrophage is responsible for ingesting the bacteria and dissolving it with chemicals. This system works nicely, but it is not terribly efficient.
The body sees this inflammation as a small price to pay for stopping the bacteria. This process will continue until the source of the infection is removed.

Treatment

Take some clove oil and rub it on your gums. Or else, keep a clove in your mouth and chew slowly. Brush your teeth with toothpaste that contains sage oil, peppermint oil etc. In 1 glass of lukewarm water, add a pinch of salt and prepare a homemade saline solution. Using this solution, gargle two times in a day. It will help a great deal in reducing the swelling in your mouth.
Treatment of pericoronitis consists of removal of debris from under the gingival flap; irrigation with saline, 1.5% hydrogen peroxide, or 0.12% chlorhexidine; and, particularly when episodes recur, extraction. If severe infection develops, antibiotics may be given for a day before extraction and continued during healing.