Why Dental Fillings Turn Yellow: Causes and Solutions

Dental fillings are a great defense against tooth decay. They can help repair cavities in your teeth, restoring structure and sealing off weak areas to prevent further damage by bacteria. However, many will notice that their fillings will begin to lose their natural color over time. This can cause yellow, brown or gray spots around the edges.

Understanding why dental fillings can go yellow can help protect your investment and improve your overall oral health. This comprehensive guide looks at what causes fillings to discolor.

What Are the Different Types of Dental Filling Materials?

The type of filling you have will play the biggest factor in how your dental restoration will react to environmental factors. Dentists will use different types of material, each with their own characteristics.

Composite Resin – This is made by mixing liquid plastic resins with very fine glass/quartz particles. They are color matched to your natural enamel. However, they have small pores which will absorb dark pigments from food and drink over time.
Amalgam – Made from a range of elemental metals such as silver, tin, copper and mercury in liquid form. These will not match your enamel and overtime will oxidize causing them to go dark. Often causing a gray/black stain around the area.
Porcelain/Ceramic – This has been made in a specialized lab and uses very dense non-porous minerals. They will rarely cause a surface stain.
Glass Ionomer – These have been made from a combination of acrylic and particular types of glass powder that contain fluoride. They will release fluoride to protect your teeth however they are prone to quick staining because they are porous.

How Do Food and Drinks Cause Dental Fillings to Turn Yellow?

The foods and drinks you eat and drink everyday will cause your tooth colored fillings to stain. Just like your enamel, your resin fillings will absorb the colors from highly pigmented foods and drinks.

Dark Drinks – Coffee, black tea, dark wines and cola all have high levels of chromogens. This is a strong pigment which will stick to your fillings causing them to become yellow/brown.
Pigmented Foods – Dark berries, soy sauce, tomato sauces, curry and beetroot will leave a stubborn stain on your resin and glass-ionomer fillings.
Acidic Drinks & Fruit – Acidic drinks such as lemon juice, sports drinks and fizzy drinks will cause your fillings to go soft. This happens because the acidic liquid will cause the thin resin to go soft and will make it easier to absorb darker pigments.

How Does Smoking Affect the Color of Dental Fillings?

Tobacco products will cause harsh chemicals in your mouth causing your clear/tooth colored fillings to go bad quickly.

Tar & Nicotine – Cigarettes, cigars, vaping liquids and chewing tobacco will all leave thick layers of yellow and brown stains on your teeth. Nicotine is colorless but will turn yellow when mixed with oxygen in your mouth.
Porosity – The tar particles will seep into the tiny pores in your fillings. Once they have gone deep into the fillings, standard brushing will not remove the dark stains.
Alcohol Based Mouthwash – Using alcohol based mouthwashes daily will cause the outer layer of your resin to go soft. When this goes soft it will lose its shiny finish and will absorb more of the dark pigments.

What Natural Chemical Reactions Cause Dental Fillings to Discolor?

Even if you follow a strict diet and do not smoke, your fillings will still change color as they will naturally break down overtime.

Resin Breakdown – Resins in your fillings have organic molecular bonds. These will break down over many years when exposed to moisture, enzymes in saliva and chewing pressure. This will cause your filling to darken/lighten slightly.
Metal Oxidation – Amalgam fillings have metal elements in them which will chemically react with the oxygen and sulfur in your saliva. This causes the filling to oxidize leaving dark marks and causing the filling to go black. Dark silver will also show in your natural enamel.
Not Fully Cured – Your dentist will use a special blue light to cure your filling. If it is not fully cured the inner layers will go discolored quickly (within a few months).

How Does Micro-leakage Cause Dental Fillings to Discolor?

Sometimes fillings can go discolored at the edges.

Bond Breakdown – Over time and lots of chewing pressure the tiny bonding glue will start to break down.
Micro-leakage – As the glue starts to break down tiny gaps will begin to form around the edges of your filling. This will allow saliva, food and damaging bacteria to go into the gaps causing dark stains around your fillings.
Secondary Decay – This will allow bacteria to grow underneath your current filling. This will cause your teeth to go rotten underneath your filling causing the dark rotten dentin to show through the clear filling.

How Does Natural Teeth Discoloration Affect the Appearance of Fillings?

As you age your natural teeth will begin to change color.

Thin Enamel – Over many years your natural enamel will become thinner. This will cause the yellow dentin to show through your white enamel causing your teeth to look darker.
Fillings Color – Whilst your enamel will go yellow with age, fillings such as porcelain will remain bright. This will cause a clear difference in color.
Whitening – Whitening your teeth will whiten your natural enamel however it will not whiten your composite or porcelain fillings. Your fillings will look much darker.

How Can You Prevent Dental Fillings From Turning Yellow?

Following good oral hygiene can help your fillings last longer.

Brush Twice A Day – Brush your teeth for 2 minutes twice a day with a soft bristled brush and non-abrasive fluoridated toothpaste. Using abrasive toothpastes such as charcoal or whitening will cause tiny scratches on your fillings causing them to stain quicker.
Floss Daily – Floss between all your teeth to remove any hidden plaque or food build-up around the edges of your fillings.
Drink Water – After having a dark drink such as coffee/tea/red wine brush your teeth with water to remove any dark pigments.
Drink Through A Straw – Drinking iced tea/coffee through a straw will help reduce any staining on your front tooth fillings.
Regular Cleanings – Visit your pediatric/dentist every 6 months to have a professional clean. The hygienists will use special pastes to polish away any surface stains.

What Professional Treatments Can Restore Discolored Dental Fillings?

If your fillings have gone dark/yellow you can have professional treatments to return them to their original beautiful color.

Surface Polish – If your fillings have just gone yellow on the surface your dentist can polish them using fine diamond pastes.
Repair – Your dentist can carefully remove the outer layer of your fillings and place a new layer on top. This will match your teeth.
Replace – If there is micro-leakage or secondary decay under your old fillings your dentist will need to remove the whole filling. Then remove any decay and replace with a new composite or porcelain filling.
Porcelain Veneer/Crown – If there is a lot of decay or on your front teeth, you can replace large fillings with strong porcelain crowns/veneers. This will prevent them from going yellow in the future.

What Are the Frequently Asked Questions About Yellow Dental Fillings?

Can I Whiten My Discolored Filling?

No. You cannot whiten composite, porcelain or amalgam fillings with professional whitening gels or over the counter whitening strips. They will only whiten your natural enamel. If you want to whiten your teeth then do this first and ask your dentist to match your new filling to your brighter enamel.

How Long Should a Composite Filling Last?

With a high quality composite filling they will generally stay the same color and strong for 5-7 years. With excellent oral hygiene, minimal dark drinks and regular check-ups they can last up to 10 years.

Why Is There a Dark Ring Around My Old Filling?

This means there is micro-leakage. The bonding glue between your filling and tooth has worn away causing food staining, fluid and bacteria to build up in the tiny gaps. Get this checked by your dentist.

Overall, fillings can go yellow due to various factors such as the material used, foods and drinks consumed, natural chemical reaction and micro-leakage. Non-porous fillings such as porcelain are very resistant to staining however composite fillings will absorb the colors. Following strict oral hygiene, drinking less dark drinks, avoiding smoking and having regular professional cleans will help your fillings stay strong and beautiful. If you notice any dark spots or color changes around your fillings see your dentist.