Gum disease is caused by the buildup of dental plaque, a sticky film of bacteria that forms on your teeth every day. About 42% of American adults aged 30 and older have some form of periodontitis, the more advanced stage of gum disease, making it one of the most common chronic conditions in the country. While plaque is the primary trigger, several other factors determine whether a mild case of gum inflammation progresses into something that threatens your teeth and jawbone.
How Plaque Starts the Problem
Your mouth naturally hosts hundreds of species of bacteria. When these bacteria mix with food particles and saliva, they form plaque, a soft, colorless film that clings to your teeth along and below the gumline. If you brush and floss regularly, most of this plaque gets removed before it causes harm. But when plaque is left undisturbed, the bacteria it contains release toxins that irritate your gum tissue and trigger an inflammatory response.
This inflammation is your immune system’s attempt to fight off the bacterial invasion, but it ends up damaging your own tissue in the process. Your gums become red, swollen, and prone to bleeding. At this early stage, the condition is called gingivitis, and the damage is still reversible with a professional cleaning and better brushing habits at home.
When Plaque Hardens Into Tartar
If plaque stays on your teeth long enough, minerals from your saliva begin depositing into it. Calcium and phosphate ions crystallize within the plaque’s deeper layers, eventually forming a rock-hard substance called tartar (or calculus). This process can happen in as little as two weeks for some people, while others may take months. The buildup typically levels off after two to three months of undisturbed growth.
Tartar is firmly cemented to the tooth surface. The mineral crystals fill every pit and irregularity in the enamel, creating a bond that no toothbrush or floss can break. Only a dental professional with specialized instruments can remove it. Tartar also creates a rough surface that makes it even easier for new plaque to accumulate, setting up a cycle that accelerates gum damage.
How Gingivitis Progresses to Periodontitis
Gingivitis is the earliest and mildest form of gum disease. The signs include swollen gums, redness, discomfort when probing, and bleeding when you brush or floss. At this stage, the underlying bone and connective tissue that hold your teeth in place are still intact. A good dental cleaning combined with consistent home care can resolve gingivitis, though it will come back if hygiene habits slip.
When gingivitis goes untreated, bacteria seep deeper beneath the gumline and begin destroying the bone and tissue that support your teeth. This is periodontitis, and it is not reversible. Your gums start pulling away from your teeth, forming pockets that trap more bacteria in spaces your toothbrush can’t reach. As the disease advances, teeth may become loose or shift position. Severe periodontitis affects nearly 8% of adults over 30, while another 34% have a milder form.
Smoking and Gum Disease
Smoking is one of the strongest modifiable risk factors for gum disease. A large meta-analysis found that smokers have an 85% higher risk of developing periodontitis compared to nonsmokers. Smoking impairs both your immune response and the blood supply to your gums, which means your body is less able to fight off bacterial infection and slower to heal from any damage that occurs. Smokers also tend to respond less well to gum disease treatment, making the condition harder to manage even after diagnosis.
The Diabetes Connection
Diabetes and gum disease have a two-way relationship. High blood sugar creates conditions that allow gum infections to worsen more quickly, through mechanisms involving chronic inflammation, elevated blood fats, and impaired insulin signaling. People with diabetes consistently develop more severe periodontitis than those without it.
The relationship works in reverse too. Severe gum disease generates low-grade inflammation throughout the body, which interferes with how your cells respond to insulin. This can make blood sugar harder to control. Treating gum disease in people with diabetes often helps improve their glycemic management, which is one reason dentists and physicians increasingly coordinate care for these patients.
Medications That Affect Your Gums
Certain medications create conditions in your mouth that make gum disease more likely, even if your brushing habits are solid. There are two main ways this happens.
Some drugs cause gum tissue to overgrow, a condition called gingival enlargement. The swollen tissue creates deep folds around the teeth where bacteria can hide. Blood pressure medications like amlodipine, nifedipine, and diltiazem are common culprits. Anti-seizure medications, particularly phenytoin, are also well known for this side effect. If you take any of these and notice your gums thickening or growing over your teeth, bring it up with your prescriber.
The second pathway is dry mouth. Saliva plays a critical role in washing away food particles and neutralizing bacterial acids. More than 500 medications list dry mouth as a side effect, including antihistamines, antidepressants, decongestants, diuretics, and anxiety medications. When saliva production drops, plaque builds up faster and your gums lose one of their most important natural defenses.
Genetics and Immune Response
Not everyone with the same brushing habits develops the same level of gum disease, and genetics are a significant reason why. Your genes influence how aggressively your immune system responds to the bacteria in plaque. Some people mount an exaggerated inflammatory response that ends up doing more harm than good, destroying gum tissue and bone faster than others with the same bacterial load.
Research has identified several genes involved in immune signaling that are more active in people with periodontitis. These genes regulate how inflammatory molecules are released, how immune cells are recruited to infection sites, and how the body handles bacterial toxins. If you have a family history of gum disease or tooth loss, you may be genetically predisposed to more aggressive progression, which makes consistent preventive care especially important.
Other Contributing Factors
- Hormonal changes: Pregnancy, puberty, and menopause increase blood flow to the gums and heighten their sensitivity to plaque bacteria, making gum inflammation more likely during these periods.
- Poor nutrition: A diet low in vitamin C impairs your body’s ability to repair gum tissue. Diets high in sugar feed the bacteria that produce plaque.
- Teeth grinding (bruxism): Chronic clenching or grinding puts excess force on the tissues supporting your teeth, which can accelerate the breakdown caused by existing gum disease.
- Crooked or crowded teeth: Misalignment creates hard-to-clean areas where plaque accumulates more easily.
Gum disease is ultimately driven by bacteria, but how far it progresses depends on the full picture: your hygiene habits, your genetics, your overall health, and the medications you take. The plaque that starts the process forms every single day, which is why the condition is so common and why daily removal is the most effective thing you can do to prevent it.