What are these Black Lines on Teeth and How to Remove them

What are these black line stains?

Black line stains, or simply black lines, are a type of buildup that forms on the outer layer of your teeth (enamel). They’re most common in children and often disappear on their own with age.



They usually show up as blackish dots, lines, or stripes that follow the contour of your gum line. While their exact cause isn’t fully clear, many agree that certain chromogenic (pigment-producing) bacteria are involved.

These stains are extremely sticky — no matter how good your brushing is, they can’t be removed at home and tend to reappear after professional cleaning.

What sets black line stains apart from regular plaque and tartar is that they aren’t harmful to your teeth and gums. In fact, studies have shown that people with these stains often have a lower risk of cavities.

Black lines can be classified into different categories based on their appearance and severity. Here’s one common classification:

What causes black line stains to appear?

While there’s no single answer, certain chromogenic bacteria seem to be the main culprits behind these black lines.

The most common species involved is Actinomyces. These bacteria interact with the iron in saliva and release compounds that stick to the teeth, creating the typical black discoloration.

This results from the hydrogen sulfide they produce, which reacts with iron in saliva to form black compounds called ferric sulfide.

Over time, these compounds mix with plaque and other minerals in the mouth—such as calcium and phosphorus—resulting in black deposits that stick firmly to the tooth surface.

Who is most at risk?

These black lines are commonly seen in children.

One possible reason is that Actinomyces are among the first bacteria to colonize a baby’s mouth—often within the first five months of life. At this early stage, the oral microbiome is still immature, meaning there’s little competition to prevent certain bacteria from thriving.

Add to this the fact that children are usually not consistent with their oral hygiene and may not brush their teeth properly, which can allow stains to develop quickly.

As children grow and their oral microbiome settles and stabilizes, these black lines often fade on their own.

Other factors that may increase the risk include diet and certain medications:

• Diet: Diets rich in iron and staining foods or drinks—such as tea, coffee, and chocolate—can contribute.
• Medication: Iron supplements or certain medications can also interact with chromogenic bacteria and speed up the staining process.

Do black line stains mean a higher risk of cavities?

Not at all. Black lines are completely different from plaque buildup, which is the main culprit behind cavities and gum disease.

In fact, studies show that people who develop this type of staining often have a lower risk of cavities.

The plaque buildup we typically see in people with poor oral hygiene is mostly made up of acid-producing bacteria—the ones that cause cavities. These bacteria release acids that erode the tooth’s minerals, creating the perfect conditions for decay.

Black line stains, on the other hand, contain very few of these acid-producing bacteria.

Interestingly, for black lines to form and build up, they require an alkaline (not acidic) environment and saliva rich in minerals such as calcium and phosphorus. All of these factors are actually protective against cavities.

This is why people prone to black line stains usually also have mineral-rich saliva and a less acidic mouth.

So, apart from their unsightly appearance, these stains are harmless to your teeth.

How to remove these black line stains for good?

These types of stains are extremely sticky and can’t be removed at home with simple brushing or flossing. Only your dentist or dental hygienist can remove them.

Here are some tools and techniques they may use:

• Scaling: Using special instruments that vibrate at high speeds to break up and remove the buildup.
• Air abrasion: A tool that sprays tiny abrasive particles to clean the tooth surface.
• Polishing: Rotating, gentle abrasive tools that smooth the tooth surface, making it less prone to future stains.

The main challenge with these black lines is their tendency to come back quickly after treatment.

Having frequent professional cleanings is an option, but it's not the best idea, because repeated cleanings can weaken and damage your enamel over time.

The best approach is to maintain good oral hygiene at home to prevent them from coming back.

Here are some tips:

• Switch to an electric toothbrush: Electric toothbrushes clean more effectively than manual ones and are easier to use.


• Use toothpaste with whitening and tartar-control ingredients: Toothpaste with tartar-control formulas can help, but they tend to be more abrasive. Alternate them with a gentler toothpaste to get benefits without harming your teeth.


• Use baking soda: Baking soda helps remove plaque and buildup from your teeth thanks to its mild abrasiveness. It’s gentler than most abrasives found in toothpastes, so it’s safe to use once a day. Just make sure to use it along with your regular toothpaste, not on its own.


• Consistency is key: Brush at least twice daily for two minutes and floss once a day to remove plaque and debris from between your teeth. Plaque constantly forms on our teeth, so a regular oral hygiene routine is key.


• Limit staining foods and drinks: Reduce intake of pigmented foods and drinks like tea, coffee, red wine, and sodas, which can stain your teeth quickly. Rinse your mouth with water if you do consume them.


• Chew sugar-free gum between meals: Chewing gum stimulates saliva production, which helps wash away bacteria, plaque, and food particles.

Other dental conditions that cause black staining:

Before assuming black line stains come from chromogenic bacteria, you should know that other dental issues can also cause black staining. Some of these can be harmful, so it’s important to rule them out.

These include:

• Cavities: Caused by acid-producing bacteria that eat away at tooth minerals, forming holes. As decay progresses, teeth may become sensitive and painful. If untreated, it can advance and lead to serious complications.


• Tooth staining from foods or smoking: Extrinsic stains from pigmented foods like tea, coffee, red wine, or from smoking can look like black stains. These discolorations penetrate the enamel and usually require professional whitening treatments.


• Other forms of tartar buildup: Chromogenic black lines can be mistaken for black tartar, which is a hardened form of plaque. Tartar usually starts yellow and may darken over time when exposed to foods, turning brown or black.
  If left untreated, tartar can irritate gums, causing redness, swelling, and bleeding, and can be a major risk factor for gum disease.