A radiant smile isn’t just about straight, white teeth—it’s a reflection of your overall oral health. Yet, many people notice their teeth darkening over time or find unexpected patches of discoloration along the gums. While tooth staining is fairly common, gum discoloration often catches people off guard and can be a sign of something more serious.
One question dentists hear often is, “What’s that black line on my gums, and how do I get rid of it?” In many cases, it’s linked to old dental work, gum disease, or staining from everyday habits. We break down the most common causes here, and for a complete look at treatments and prevention.
1. Food and Drinks That Leave a Mark
Our diets are one of the most common reasons teeth lose their natural whiteness. Certain foods and drinks contain strong pigments or tannins that cling to the enamel and can also affect the gumline. Common culprits include:
- Coffee and tea – Both are rich in tannins that bind to teeth and cause gradual staining.
- Red wine – Contains chromogens and acids that soften enamel, making it easier for stains to stick.
- Dark berries – Blueberries, blackberries, and cherries have deep pigments that can leave behind color.
- Tomato and soy-based sauces – Their rich color and acidity can contribute to surface staining.
Pro tip: Rinse your mouth with water after eating or drinking dark-colored items to reduce stain buildup.
2. Tobacco Use
Smoking and chewing tobacco are notorious for their effect on oral aesthetics. Nicotine and tar settle into the tiny pores of enamel, causing yellow or brown discoloration. Over time, these stains become harder to remove with regular brushing.
Tobacco can also affect gum tissue, sometimes leading to darker patches caused by excess melanin production—known as smoker’s melanosis. In more severe cases, tobacco use contributes to gum disease, which can cause further discoloration and gum recession.
3. Poor Oral Hygiene
When brushing and flossing aren’t part of your daily routine, plaque quickly builds up on teeth. Left unchecked, it hardens into tartar—a rough, porous substance that traps stains and makes them harder to remove.
Tartar can form not just on teeth, but also along the gumline, leading to visible discoloration. This yellow or brown buildup can make gums appear unhealthy and inflamed, increasing the risk of gum disease.
4. Dental Restorations
Dental crowns, bridges, and fillings can sometimes contribute to gum staining—especially older restorations made with metal. A black line along the gum can occur when the metal from a crown base becomes visible as gums recede or when the porcelain covering wears away.
This discoloration is not typically harmful on its own, but it can be an aesthetic concern. It’s also a sign you may need to replace or upgrade older dental work. (For detailed solutions, see our complete guide: How to Get Rid of Black Line on Gums.)
5. Medications
Certain medications can change the color of your teeth or gums:
- Tetracycline antibiotics – When taken during childhood tooth development, they can cause permanent gray or brown bands.
- Chlorhexidine mouth rinses – Often prescribed for gum disease, these can darken enamel with prolonged use.
- Iron supplements – Liquid forms can temporarily stain teeth unless taken with a straw or followed by rinsing.
If your medication is causing staining, talk to your dentist about preventive measures.
6. Excess Fluoride
Fluoride strengthens enamel and prevents cavities, but too much during childhood can lead to dental fluorosis. This condition causes white streaks or brown spots on teeth that are often permanent, though they can be minimized with cosmetic dental treatments.
7. Gum Pigmentation and Other Conditions
Some gum discoloration is natural. People with more melanin in their skin may also have naturally darker gums. However, certain conditions can cause unusual gum pigmentation, such as:
- Amalgam tattoos – Tiny fragments from silver fillings that lodge in gum tissue.
- Oral melanoma – Rare but serious, presenting as dark spots that require immediate medical evaluation.
- Gum disease – Can cause redness, swelling, and darker gum tissue due to inflammation and tissue breakdown.
How to Prevent Teeth and Gum Stains
While not all staining is avoidable, you can greatly reduce your risk with good oral habits:
- Brush at least twice daily with a fluoride toothpaste.
- Floss once a day to remove plaque between teeth.
- Use a straw for dark beverages like coffee, tea, and soda.
- Limit stain-causing foods and drinks.
- Quit smoking and avoid tobacco products.
- Visit your dentist every 6 months for professional cleaning and early detection.
When to See a Dentist
If you notice sudden discoloration, especially on the gums, don’t ignore it. Stains that appear quickly, are spreading, or are accompanied by symptoms like bleeding, pain, or swelling may indicate gum disease or other oral health problems.
A dental professional can determine the cause and recommend treatments—from whitening procedures and professional cleanings to replacing old dental restorations.
Bottom Line
Teeth and gum staining can result from lifestyle habits, dental materials, medications, or health conditions. While some stains are purely cosmetic, others are a sign that something needs attention. The sooner you identify the cause, the easier it is to restore your smile’s health and appearance.
And if your concern is specifically about a dark or black line along the gums, understanding the underlying cause and exploring treatment options is essential—our guide on How to Get Rid of Black Line on Gums is a great place to start.
