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9 Main Reasons You Have Black Lines On Your Teeth

It is a matter of concern if you have black lines on your teeth. The lines may be around the tooth base or near the gums. They may appear without pain and despite having excellent brushing and flossing habits. Removing them can be a struggle.

In this article, we discuss the following:

  • What causes black lines on teeth?
  • Can you DIY to remove them?
  • What are the professional steps you can take to remove black lines?

Let’s look at the matter closely.

9 Main Reasons You Have Black Lines On Your Teeth

1. The presence of chromogenic bacteria

You may notice a thin black line, or a dotted line, on your teeth, mostly near your gumline. That black line may result from having stain-forming bacteria in your mouth.

These bacteria create a brownish film on your teeth, which turns black with time. The stain is extrinsic and removable.

Two types of bacteria may cause this black line:

  1. Actinomyces: A genus of the Actinomycetia class of bacteria. They are gram-positive. That means they give a positive result in the Gram stain test
  2. Prevotella Melaninogenica: Gram-negative bacteria that are commonly found in oral cavities

These black lines are classified based on their formation and the location of their occurrence.

  1. Score 1: the lines are incomplete (dots) and parallel to the gum line
  2. Score 2: the black lines are limited to half of the cervical third of the tooth surface
  3. Score 3: the black lines extend beyond half of the cervical third of the tooth surface

2. A reaction between hydrogen sulfide and iron

You may have black lines on your teeth when bacteria in your mouth produce hydrogen sulfide and that reacts to the iron content of your saliva.

The iron content of the saliva may come from the following:

  1. Iron-rich vegetables, such as spinach, peas, broccoli, string beans, and collards
  2. Dairy products, such as cheese and yogurt
  3. Certain fruits, such as strawberries, watermelons, dates, and figs

It may also come from the fluid that leaks out of the blood vessels and spreads to the gum tissues.

The fluid is also called pus. It contains proteins and solid materials.

The process of leakage is called an exudate, and when it happens in your gums, it is called a gingival exudate.

3. Use of chlorhexidine mouthwashes

You may use chlorhexidine mouthwashes to treat the following:

  • Inflammation of the gums
  • Swelling
  • Bleeding

But chlorhexidine mouthwashes come with some noticeable side effects, such as the following:

  • Black lines on the teeth
  • Change in taste
  • Formation of hard plaque or tartar

According to the National Institute for Health and Care Research (NIHR), using chlorhexidine mouthwash for longer than four weeks may lead to tooth staining. That is why they are licensed for only 30 days’ use in the UK and are not recommended for routine use.

4. Intake of iron supplements

Iron supplements are used to prevent different types of anemia. Anemia is a condition when your body does not produce enough healthy red blood cells.

According to Penn Medicine, iron deficiency is the most common type of anemia.

The iron supplements are also known as the following:

  • Iron pills
  • Iron salts
  • Ferrous salts
  • Ferric sulfide
  • Ferric salts

Although called by different names, the truth remains that they stain your teeth.

An article published in the Journal of Pharmacy Practice and Community Medicine in 2020 documents how a 16-year-old female patient’s teeth discoloration was developed by her liquid iron supplements (iron salts).

5. Below-standard oral hygiene

You must take iron supplements if your body does not produce enough red blood cells. There is no way around it. That means you may have black lines on your teeth.

But there are things you can do to prevent those black lines. That is where optimal oral hygiene comes in.

You can prevent the bacterial population from forming plaque on your teeth by brushing and flossing your teeth regularly, as instructed by your dentist.

By doing that, you won’t only prevent black lines but also gum inflammation and bleeding.

According to Crest, the average individual performs 45-70 seconds of toothbrushing daily, despite being instructed to brush for two minutes twice daily. In addition, only 2% of dental patients floss their teeth daily.

As you understand, below-standard oral hygiene can damage your oral health and push you into dental complications, including black lines on your teeth.

How to optimize your oral hygiene:

  • Drink fluoridated water
  • Reduce the consumption of sugary food and beverage
  • Brush and floss your teeth effectively as instructed by your dentist.

6. The black line is the result of an internal staining

Tooth discoloration, hence the black lines on your teeth, often results from external stains entering the body of the tooth.

The stains may enter as deep as the pulp chamber requiring sophisticated cosmetic dental treatments such as root canals. If not treated, the pulp can die, killing the tooth.

The stains can enter the tooth’s interior through cavities and cracks on the tooth surface. If that happens, you need the help of a dental professional to remove them. Your dental professional has the tools required to treat your teeth without causing trauma to your gums.

7. Drinking coffee, tea, or red wine and the use of tobacco products

We have placed them together simply because they communicate our habits or lifestyles.

The use of pigmented food and beverages is supposed to stain your teeth. We are not talking about a black line on the teeth here. Tea, coffee, or tobacco may compromise your entire oral ecosystem.

Avoid them, reduce them or quit them. You cannot expect great teeth if you are into coffee or tobacco.

8. Exposure to polyvalent metal salts

If you are professionally exposed to metallic salts, you may have black lines on your teeth. However, the staining may not always appear as lines, and the color of the lines may not be entirely black. Let us call it simply tooth discoloration.

An article published in the British Dental Journal in 2001 discusses several metals and the discoloration they may cause to your teeth.

  • Copper salts cause green stains on teeth
  • Potassium permanganate produces a violet-to-black color
  • Silver nitrate salts cause a grey color
  • Stannous fluoride (an anti-bacterial agent: different from sodium fluoride) results in a golden-brown discoloration. Colgate Renewal Gum Revitalize has Stannous Fluoride (0.454%).

You need to develop a health and safety management system that includes both your respiratory protection and the protection of your teeth and oral health.

9. Balck lines on the teeth may result from the teeth’s developmental defects

Several developmental defects can influence how your teeth will look.

  • Light transmission through the enamel and dentine partially dictates the color of your teeth
  • Defects in enamel may let extrinsic stains enter your teeth and cause black lines. You may have underdeveloped teeth or teeth without sufficient calcium deposition in them
  • Your teeth tissues may suffer from regular wear and tear. They may experience enamel loss or thinning. A thinner enamel makes a tooth darker
  • Melanin can cause tooth discoloration
  • If your teeth do not possess the required proportion of mineralization, they may look black

Can you remove the black lines on your teeth at home?

Brush your teeth as recommended by your dentist or by American Dental Association. If that does not remove the black lines on your teeth, you may require a thorough examination of the teeth to identify the underlying reasons for the discoloration.

Do not DIY your teeth to get rid of the black lines. You will cause trauma to your gums or teeth. That may complicate the matter for you, as you can understand your dental health is highly connected to your facial structure and overall health.

What are the professional steps you can take to remove black lines?

Whether it is exposure to metallic salt or enamel loss, your dentist will come up with a treatment plan for your teeth.

Sometimes, you may get rid of the black lines by whitening your teeth in-office. We have written extensively about how much teeth whitening will cost you based on your location in a separate post.

Sometimes, you may need what is called deep cleaning. Learn all about deep-cleaning teeth therapy.

Your dentist may even refer you to an external service provider for an opinion or for treatment.

In addition, you may need the involvement of more than one specialist in your case, if other dental complications must be taken care of.


What to do if you have black stains on your teeth?

Brush your teeth with non-abrasive toothpaste. If that does not bring results, consult your dentist for an oral examination. Your dentist will come up with a treatment plan for you.

Is an oral examination necessary for the removal of black lines?

A correct diagnosis of the black lines is required to identify the cause appropriately so that your dentist can provide you with the best dental advice and treatment possible.

How important is flossing in maintaining good dental hygiene?

Flossing is of optimal significance when considering good dental health. According to the European Federation of Periodontology, flossing has enormous therapeutic value in patients with periodontal and peri-implant diseases. It is highly important for the primary prevention of gum inflammation.

Black lines on teeth treatment planning: A doctor’s flowchart

  1. The treatment begins with a diagnosis of the black lines
  2. The dentist explains to the patient the reasons for the black lines
  3. Time for some preventative advice
  4. Recommendation for removing black lines, which may include scaling and polishing
  5. The dentist will explain if and why all black lines may not be removed
  6. For future reference, the dentist will explain why the black lines may return to your teeth
  7. The dentist will recommend a post-treatment assessment meeting to see if everything is all right – that the treatment has worked as expected.

Ref: British Dental Journal volume 232, pages 857–860 (2022)


Janjua, U. et al. Black staining: an overview for the general dental practitioner. British Dental Journal. 232, pages 857–860 (2022).

National Institute for Health and Care Research (NIHR). Chlorhexidine mouthwash is useful short-term for people with mild gum disease. Accessed on 12 December 2022.

Healthline. The Advantages and Disadvantages of Chlorhexidine Mouthwash. Accessed on 12 December 2022.

Penn Medicine. What is Anemia? Accessed on 12 December 2022.

Rawal KB, Girish HN, Andrew GJ, Anusha S, Luhar MB. Ferrous Sulphate-Induced Black Color Discoloration of Teeth: A Case Report. Journal of Pharmacy Practice and Community Medicine. 2020, 6(2):29-30.

Sulieman M. An overview of tooth discoloration: extrinsic, intrinsic and internalized stains. Dental Update. 2005 Oct;32(8):463-4, 466-8, 471. 

A. Watts, and M. Addy. Tooth discolouration and staining: a review of the literature. British Dental Journal. Vol 190 No.6 March 24, 2001.

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