Gum inflammation is caused by the buildup of bacterial plaque along and below the gumline, which triggers your immune system to attack the infection and damages surrounding tissue in the process. About 4 in 10 U.S. adults aged 30 and older have some level of periodontal disease, and the earliest stage, gingivitis, is even more common. While plaque is the primary trigger, several other factors, from hormonal shifts to certain medications, can make your gums more vulnerable or make inflammation worse.
How Bacterial Plaque Triggers Inflammation
Your mouth naturally hosts hundreds of bacterial species, and in a healthy state, these organisms live in balance with your immune system. Problems start when plaque, a sticky film of bacteria, accumulates on teeth and isn’t removed. The bacterial community shifts from mostly harmless species to more aggressive ones, a transition researchers call dysbiosis. Once that shift happens, certain bacteria begin producing toxins and enzymes that penetrate gum tissue and provoke a strong immune reaction.
One of the most destructive species involved is Porphyromonas gingivalis, which produces powerful protein-cutting enzymes called gingipains. These enzymes account for roughly 85% of the bacterium’s tissue-destroying activity at the site of infection. They break down the connective fibers that hold your gums to your teeth, degrade proteins involved in blood clotting (increasing bleeding), and even disable your immune cells’ ability to fight back by destroying their surface receptors and neutralizing natural antibacterial compounds. The bacterium also coats itself in a capsule that helps it resist being engulfed by white blood cells, essentially hiding in plain sight while continuing to cause damage.
Your immune system responds by flooding the area with inflammatory chemicals and white blood cells. This response is what actually produces the redness, swelling, and bleeding you notice. In other words, much of the visible damage comes not from the bacteria themselves but from your own immune system’s aggressive attempt to clear the infection.
Poor Oral Hygiene Is the Starting Point
Plaque begins forming on teeth within hours of brushing. If it isn’t removed daily through brushing and flossing, it hardens into tarite (calculus) within about 24 to 72 hours. Once hardite forms, you can’t remove it at home; it requires professional cleaning. Tartar creates a rough surface that attracts even more plaque, and it sits right at the gumline where it continuously irritates the tissue.
The good news is that gingivitis, the earliest form of gum inflammation, is fully reversible. After the irritant is removed through professional cleaning and consistent home care, healthy gum tissue typically returns within days to weeks.
Smoking and Tobacco Use
About 62% of U.S. adults aged 30 and older who currently smoke have periodontitis, compared to roughly 40% of adults overall. Smoking is one of the strongest risk factors for gum disease, and it works through a deceptive mechanism.
Nicotine suppresses some of the visible signs of inflammation, such as bleeding, by dampening certain immune signals in the short term. This means smokers often don’t notice the early warning signs of gum disease. Meanwhile, nicotine accelerates the underlying destruction. It disables natural antibacterial proteins in the gums, allowing harmful bacteria to flourish, and it triggers the self-destruction of the very immune cells responsible for fighting infection. The result is faster bone loss around the teeth, often without the obvious bleeding that would prompt someone to seek care.
Hormonal Changes During Pregnancy and Puberty
Rising levels of estrogen and progesterone during pregnancy increase the permeability of blood vessels in the gums and cause capillaries to widen. This leads to fluid accumulating in gum tissue, making it puffy, tender, and more likely to bleed. The same plaque that might cause mild irritation in a non-pregnant person can trigger a much more pronounced inflammatory response during pregnancy. This condition, often called pregnancy gingivitis, is common in the second trimester and typically resolves after delivery when hormone levels normalize. Similar hormonal effects can occur during puberty and with certain hormonal contraceptives.
Diabetes and Blood Sugar
Diabetes and gum disease have a two-way relationship: each one makes the other worse. Chronically elevated blood sugar disrupts the immune system at multiple levels. White blood cells become hyperactivated, causing more tissue damage than necessary, while simultaneously becoming less effective at actually clearing bacteria. The balance between cells that break down bone and cells that rebuild it shifts in favor of destruction, accelerating the loss of the bone that supports your teeth.
High blood sugar also impairs the gum tissue’s ability to heal. It slows the migration of skin cells needed to repair wounds, increases the production of enzymes that break down collagen (the structural protein in gums), and reduces growth factors essential for tissue repair. People with poorly controlled diabetes don’t just get gum inflammation more easily; they also recover from it more slowly.
Medications That Cause Gum Overgrowth
Certain medications can cause the gums to grow over the teeth, a condition called gingival overgrowth. The overgrown tissue traps plaque and bacteria, creating a cycle of chronic inflammation. Three drug classes are most commonly responsible:
- Anti-seizure medications, especially phenytoin, which is the anticonvulsant most strongly linked to gum enlargement
- Immunosuppressants used after organ transplants, particularly cyclosporine
- Blood pressure medications in the calcium channel blocker family, including nifedipine and amlodipine
If you take any of these and notice your gums becoming thick or growing over your teeth, talk to your prescribing doctor. In some cases, switching to an alternative medication can help. Meticulous oral hygiene and more frequent dental cleanings are especially important for people on these drugs.
Vitamin C Deficiency
Vitamin C is essential for collagen production, and collagen is the main structural component of your gums. When intake drops below about 10 mg per day (the amount in a single strawberry), scurvy can develop, and one of its hallmark symptoms is swollen, bleeding gums that may eventually lead to tooth loss. While full-blown scurvy is rare in developed countries, chronically low vitamin C intake can still weaken gum tissue and slow healing. Getting adequate vitamin C through fruits and vegetables helps maintain the structural integrity of the gums.
How Gingivitis Progresses to Periodontitis
Gingivitis that goes untreated can advance to periodontitis, where inflammation spreads below the gumline and begins destroying the bone and connective tissue anchoring your teeth. Dentists classify periodontitis in four stages based on how much attachment has been lost between the gum and tooth. In Stage I, the loss is minimal (1 to 2 mm) and pockets between the gum and tooth measure 4 mm or less. By Stage III, attachment loss reaches 5 mm or more and pockets deepen to 6 mm or beyond. Stage IV involves the same level of tissue loss plus functional problems like loose teeth, bite collapse, or fewer than 20 teeth remaining.
The critical difference between gingivitis and periodontitis is reversibility. Gingivitis causes no permanent damage. Once plaque is removed and good habits resume, the gums heal. Periodontitis, however, destroys bone that doesn’t grow back on its own. The progression isn’t inevitable, though. Consistent brushing, daily flossing, and regular professional cleanings interrupt the process at the earliest stage, before permanent damage occurs.