Gum decay is caused by bacterial buildup along and below the gum line, which triggers an inflammatory immune response that gradually destroys the soft tissue and bone supporting your teeth. About 42% of American adults over 30 have some form of periodontal disease, and that number climbs to nearly 60% for adults 65 and older. The process starts slowly and painlessly, which is why many people don’t realize it’s happening until significant damage is done.
How Bacteria Break Down Gum Tissue
Your mouth contains hundreds of bacterial species. When plaque, a sticky film of bacteria, accumulates on teeth near the gum line, certain disease-causing species begin to invade the surrounding tissue. Your immune system responds with inflammation to fight off these bacteria, and that response is what actually does most of the damage.
In the short term, this inflammation causes red, swollen, bleeding gums, a condition called gingivitis. If the bacterial infection persists, the immune response escalates. Your body releases inflammatory signaling molecules that activate specialized cells called osteoclasts, whose job is to break down bone. Normally, bone breakdown and bone rebuilding stay in balance. In gum disease, the scale tips heavily toward destruction: osteoclasts dissolve the jawbone faster than it can be rebuilt. Over time, pockets form between the teeth and gums, teeth loosen, and without treatment, tooth loss follows.
The critical detail is that gum decay isn’t simply bacteria eating away at your gums. It’s your own immune system, overstimulated by chronic bacterial infection, that tears down the supporting structures. This is why people with compromised or dysregulated immune systems are especially vulnerable.
Stages of Gum Disease
Gum disease progresses through distinct stages, measured partly by how deep the pockets between your gums and teeth have become.
Gingivitis is the earliest stage. Gums are inflamed and may bleed when you brush or floss, but no bone loss has occurred yet. This stage is fully reversible. With proper brushing, flossing, and a professional cleaning, healthy gum tissue can return within days to weeks.
Once bone loss begins, the condition becomes periodontitis, which is classified in four stages:
- Stage I: Pocket depths up to 4 mm, with early bone loss. You likely won’t feel much at this point.
- Stage II: Pocket depths up to 5 mm, with moderate bone loss. You may notice persistent bad breath or gums that bleed easily.
- Stage III: Pocket depths of 6 mm or more, with significant bone loss. Teeth may start to shift or feel loose.
- Stage IV: Severe bone loss with deep pockets, often requiring complex treatment. Tooth loss becomes likely without intervention.
Unlike gingivitis, periodontitis cannot be fully reversed. The bone that’s been lost doesn’t grow back on its own. Treatment focuses on stopping further destruction and, in some cases, surgically rebuilding lost tissue.
Smoking and Tobacco Use
Smokers have twice the risk of developing gum disease compared to nonsmokers. Nicotine constricts blood vessels in gum tissue, reducing the flow of oxygen and immune cells to the area. This does two things: it makes your gums less capable of fighting off bacterial infection, and it slows healing after any tissue damage occurs. Smoking also masks early warning signs because reduced blood flow means your gums may not bleed as noticeably, even when disease is present. Many smokers don’t realize they have gum problems until the disease has advanced significantly.
Diabetes and Blood Sugar
The relationship between diabetes and gum disease runs in both directions. High blood sugar creates conditions that accelerate gum tissue destruction through several pathways. It suppresses the production of collagen, the structural protein that holds gum tissue together, while simultaneously increasing the activity of enzymes that break collagen down. High glucose levels also enhance bone-destroying cell activity and reduce new bone formation.
Research has shown that in people with diabetes, gum tissue fibroblasts (the cells responsible for building and maintaining connective tissue) produce less collagen and break down more of it. Meanwhile, advanced glycation end products, compounds that form when sugars react with proteins in your blood, directly interfere with collagen production in the gums. The result is gum tissue that deteriorates faster and repairs itself more slowly. Poorly controlled diabetes makes gum disease harder to treat, and gum disease in turn makes blood sugar harder to control.
Nutritional Deficiencies
Vitamin C plays a direct role in gum health. A large analysis combining 15 studies and data from over 8,000 people found that low blood levels of vitamin C were associated with increased gum bleeding, even with gentle probing. Vitamin C is essential for collagen synthesis, so when levels drop, the connective tissue in your gums weakens and becomes more prone to breakdown. You don’t need to be severely deficient to see effects. Even moderately low intake can compromise your gums’ ability to maintain and repair themselves.
Vitamin D deficiency has also been linked to gum disease, primarily because of its role in calcium absorption and immune regulation. People who don’t get enough vitamin D tend to have weaker bone density overall, including in the jaw.
Medications That Affect Gum Tissue
Certain medications cause gum overgrowth, a condition where gum tissue swells and grows over the teeth. This overgrowth creates deep pockets that trap bacteria and make cleaning nearly impossible, setting the stage for decay underneath.
The most common culprits are anti-seizure medications, immune-suppressing drugs used after organ transplants, and blood pressure medications in the calcium channel blocker family. Among people taking phenytoin for seizures, an estimated 15 to 50% develop gum overgrowth. For transplant recipients on cyclosporine, the rate is around 27%. Calcium channel blockers like nifedipine and amlodipine cause gum overgrowth in 10 to 20% of users. When cyclosporine and nifedipine are used together, as sometimes happens in transplant patients with high blood pressure, the effect compounds.
If you’re on any of these medications and notice your gums looking puffy or growing over your teeth, talk to your prescriber. In some cases, switching to an alternative medication can resolve the overgrowth.
Other Contributing Factors
Hormonal changes during pregnancy, puberty, and menopause increase blood flow to gum tissue and alter how the immune system responds to plaque bacteria. Pregnant women are particularly susceptible to gingivitis, sometimes called “pregnancy gingivitis,” which typically develops in the second trimester.
Genetics also play a meaningful role. Some people are simply more prone to aggressive immune responses against oral bacteria, which accelerates tissue destruction even with reasonable hygiene habits. If your parents lost teeth to gum disease, you may need to be more vigilant about prevention.
Chronic stress raises levels of the hormone cortisol, which dampens immune function and makes it harder for your body to fight gum infections. Teeth grinding, often stress-related, adds mechanical force that can worsen bone loss in areas already weakened by inflammation. The research on periodontitis confirms that mechanical stress activates the same bone-destroying cells that bacterial infection does, meaning the two forces work together.
Poor oral hygiene remains the most fundamental cause. Plaque hardens into tarite (calculus) within 24 to 72 hours if not removed, and once it hardens, brushing alone can’t get rid of it. Only professional cleaning can remove calculus below the gum line, which is why people who skip dental visits for years often discover significant gum damage by the time they return.