Common Causes of Tooth Discolouration

Have you noticed your teeth losing their brightness over time? You are not alone — and brushing more vigorously is not the answer. Tooth discolouration has many causes, some within your control and others determined by biology. Understanding the difference between extrinsic (surface) and intrinsic (internal) staining is essential for choosing the right treatment.

At Orion Dental in Scarborough and Milton, we help patients identify the cause of their discolouration and recommend appropriate treatments — from professional whitening to veneers and bonding.

Two Types of Tooth Staining

Before exploring specific causes, it helps to understand the two broad categories of discolouration:

Extrinsic stains sit on the surface of your enamel. They are caused by pigmented substances that adhere to the tooth surface over time. These stains are typically the easiest to address — professional cleaning and whitening can often restore brightness effectively.

Intrinsic stains occur within the tooth itself, often at the dentin level beneath the enamel. These are caused by factors like medications taken during tooth development, trauma to a tooth, or the natural aging process. Intrinsic discolouration is more challenging to treat and may require cosmetic solutions beyond whitening alone.

Genetics and Natural Tooth Colour

Your genetic makeup plays a significant role in the natural shade of your teeth. The formation of your enamel — including its thickness, translucency, and the size of its pores — is largely determined by your DNA. Enamel is naturally porous, and the size of those pores affects how easily your teeth absorb staining compounds from food and drink.

Some people are born with thicker, whiter enamel that resists staining naturally. Others have thinner enamel that allows the yellowish dentin underneath to show through more prominently. This is why two people with identical dietary habits can have noticeably different tooth shades. While you cannot change your genetics, understanding your natural baseline helps set realistic expectations for whitening treatments.

How Your Diet Affects Tooth Colour

Your daily food and beverage choices have a direct and cumulative impacton the colour of your teeth. Certain substances contain chromogens — intensely pigmented molecules that bond to tooth enamel — as well as tannins that enhance the chromogens' ability to stick.

While solid foods certainly contribute, beverages tend to be the primary culprits because of how frequently they come into contact with teeth throughout the day. A cup of morning coffee followed by afternoon tea creates hours of exposure to staining compounds.

The acidity of certain foods and drinks also plays a role — acidic substances temporarily soften enamel, making it more porous and susceptible to absorbing pigments. This is why the combination of acid and colour (as in red wine or cola) is particularly potent.

The Role of Aging

Even with impeccable oral hygiene, teeth naturally darken with age. There are two key reasons for this: first, enamel gradually wears thinner over decades of use, allowing the naturally yellower dentin layer beneath to show through more prominently. Second, the dentin itself darkens over time as it produces additional layers in response to daily wear.

This process typically becomes noticeable in your 30s and progresses gradually. It is one of the most common reasons patients in their 40s and 50s seek professional whitening — not because their habits have changed, but because the natural aging of their tooth structure has shifted the overall shade.

Tobacco Use

Tobacco is one of the most aggressive causes of tooth discolouration. Tar and nicotine in cigarettes, cigars, and chewing tobacco create stubborn stains that penetrate enamel deeply. Tar is naturally dark, while nicotine, though colourless on its own, turns yellow when it reacts with oxygen.

Tobacco staining is often concentrated along the gum line and between teeth, creating a particularly noticeable pattern. Long-term tobacco users may find that even professional whitening has limited effect without first quitting the habit. Beyond discolouration, tobacco use significantly increases the risk of gum disease and oral cancer.

Medications and Fluorosis

Certain medications can cause intrinsic discolouration that does not respond to conventional whitening:

Fluorosis is another form of intrinsic discolouration. It occurs when a child is exposed to excessive fluoride during tooth development — typically from a combination of fluoridated water, toothpaste, and supplements. Mild fluorosis appears as faint white spots, while moderate to severe cases may cause brown patches or pitting. Normal fluoride exposure from toothpaste and municipal water is considered safe.

What You Can Do to Address Discolouration

The right approach depends on the type and cause of your discolouration. Here is a practical framework:

Professional Treatment Options

When home care and dietary changes are not enough, your dentist can recommend targeted treatments:

Get a Professional Assessment

Tooth discolouration has many causes, and the right treatment depends on understanding yours. Whether your staining is caused by your morning coffee, a medication you take, or simply the passage of time, your dental team can help you find a solution that works.

Schedule a consultation at our Scarborough or Milton office. Book an appointment or call 416-291-0306 (Scarborough) / 905-636-9770 (Milton).