Gingivitis is the most common periodontal disease, affecting 90% of the population. It is an infection of the gums caused by bacteria that form plaque. Because early-stage gum disease is seldom painful, you can have gingivitis without even knowing it. Periodontal diseases are often classified according to their severity. They range from mild gingivitis, to more severe periodontitis, and finally acute necrotizing ulcerative gingivitis. 

Bacteria can cause inflammation of the gums. Although bacteria are normally found in our bodies and provide protective effects most of the time, bacteria can be harmful. The mouth is a great place for bacteria to live. The warm, moist environment and constant food supply are everything bacteria need to thrive. If not for a healthy immune system, bacteria in the mouth would rapidly reproduce out of control, overwhelming the body's defense system

Eventually, the plaque hardens and forms hard deposits called calculus or tartar. If not properly treated, gingivitis may progress to periodontitis, a periodontal disease in which there is loss of the bone that supports the teeth. An infection begins when the body's immune system is overwhelmed. 

Signs of Gingivitis 
Swelling, redness, pain, and bleeding of the gums are signs of gingivitis. The breath begins to take on a foul odor. Gums that bleed easily, even if they're not sore. Many people first detect a change in their gums when they notice that the bristles of their toothbrush are pink - a sign that gums are bleeding with just slight pressure.

The gums begin to lose their normal structure and color. The gums, which were once strong and pink, may begin to recede and take on a beefy red, inflamed color. 

Gingivitis begins with plaque. This invisible, sticky film, composed primarily of bacteria, forms on your teeth when starches and sugars in food interact with bacteria normally found in your mouth. Brushing your teeth removes plaque, but it re-forms quickly, usually starting within 2-4 hours.

Plaque that stays on your teeth longer than two or three days can harden into tartar (calculus), a white substance that makes plaque more difficult to remove and that acts as a reservoir for bacteria. What's more, you usually can't get rid of tartar by brushing and flossing - you'll need a professional cleaning to remove it.

The longer plaque and tartar remain on your teeth, the more they irritate the gingiva, the part of your gum around the base of your teeth. In time, your gums become swollen and bleed easily.

Periodontitis

You may not realize that persistent sore, swollen, red, or bleeding gums as well as tooth pain or sensitivity and bad breath are warning signs of periodontal disease (gum disease) - a serious infection that, left untreated, may lead to tooth loss as well as heart attack, stroke, diabetes, respiratory diseases, and premature/underweight babies. Here's what you can do to protect your health:

• Take a short quiz to determine if you are at risk for periodontal disease.
• Learn more about the health risks of periodontal disease.
• Contact a local periodontist who's an expert in the diagnosis and treatment of periodontal disease.

Periodontal disease can affect one tooth or many teeth. It begins when the bacteria in plaque (the sticky, colorless film that constantly forms on your teeth) causes the gums to become inflamed.

In the mildest form of the disease, gingivitis, the gums redden, swell and bleed easily. There is usually little or no discomfort. Gingivitis is often caused by inadequate oral hygiene. Gingivitis is reversible with professional treatment and good oral home care.

Untreated gingivitis can advance to periodontitis. With time, plaque can spread and grow below the gum line. Toxins produced by the bacteria in plaque irritate the gums. The toxins stimulate a chronic inflammatory response in which the body in essence turns on itself, and the tissues and bone that support the teeth are broken down and destroyed. Gums separate from the teeth, forming pockets (spaces between the teeth and gums) that become infected. As the disease progresses, the pockets deepen and more gum tissue and bone are destroyed. Often, this destructive process has very mild symptoms. Eventually, teeth can become loose and may have to be removed.

Although plaque is by far the most common cause of gingivitis, other factors can contribute to or aggravate the condition, including: 

Drugs. Hundreds of prescription and over-the-counter antidepressants and cold remedies contain ingredients that decrease your body's production of saliva. Because saliva has a cleansing effect on your teeth and helps inhibit bacterial growth, this means that plaque and tartar can build up more easily. Other drugs, especially anti-seizure medications, calcium channel blockers and drugs that suppress your immune system, sometimes cause an overgrowth of gum tissue (gingival hyperplasia), making plaque much tougher to remove.

Viral and fungal infections. Although bacteria are responsible for most cases of gingivitis, viral and fungal infections also can affect your gums. Acute herpetic gingivostomatitis, for instance, is an infection caused by the herpes virus that frequently leads to gum inflammation and to small, painful sores throughout your mouth. Oral thrush, which results when a fungus normally found in your mouth grows out of control, causes creamy white lesions on your tongue and inner cheeks. Sometimes these spread to the roof of your mouth, your tonsils and your gums.

Other diseases and conditions. Some health problems not directly associated with your mouth can still affect your gums. People with leukemia may develop gingivitis when leukemic cells invade their gum tissue, for example. Other conditions, such as oral lichus planus, a chronic inflammatory disease, and the rare, autoimmune skin diseases pemphigus and pemphigoid can cause gums to become so severely inflamed that they may peel away from the underlying tissue.

The swelling and redness of the gums may be disproportional to the amount of plaque present. To prevent further complications, meticulous plaque control is critical for people with these illnesses.

Hormonal changes. During pregnancy, your gums are more susceptible to the damaging effects of plaque. The problem is compounded if you have morning sickness - nausea and vomiting may make it hard to brush your teeth regularly.

Poor nutrition. A poor diet, especially one deficient in calcium, vitamin C and B vitamins, can contribute to periodontal disease. Calcium is important because it helps maintain the strength of your bones, including the bones that support your teeth. The recommended daily allowance for most adults is 1,200 milligrams a day - 1,500 milligrams if you are pregnant or are a postmenopausal woman not currently using HRT. Vitamin C helps maintain the integrity of connective tissue. It's also a powerful antioxidant that counters the tissue-destroying effects of free radicals - substances produced when oxygen is metabolized by your body. Although many fruits and vegetables are rich in vitamin C, you may have low levels of this vitamin if you smoke, you eat a limited diet, or you have an eating disorder such as anorexia nervosa. Infants fed only cow's milk or unfortified formulas are also likely to be deficient in vitamin C.

Risk factors 
Although anyone can develop gingivitis, many people first experience gum problems during puberty and then in varying degrees throughout life. The most common contributing factor is lack of proper oral hygiene, but other factors also can increase your risk, including:

Diabetes. If you have diabetes, elevated blood sugar levels can damage many parts of your body - and your mouth is no exception. Diabetes increases your risk of cavities, gingivitis, tooth loss and a variety of infections. It also makes it more likely that you'll have a dry mouth, which further increases your risk of gum disease.

Decreased immunity. If you have a weakened immune system, you're more susceptible to infections of all kinds, including gum infections.