Everyone is born with natural variations in our hair colour, skin tone, height and so on. Our teeth are the same—there are up to 29 shades of teeth! Most of our natural teeth colour fall in the middle range of B4–A3.
Dentists commonly use a tool known as a shade guide to determine our tooth colour, and above is a shade guide commonly used. We use this to match fillings to your tooth colour to ensure that tooth fillings appear “invisible”. Dentists also use it to gauge what shade your teeth currently are, and what shade can be achieved after whitening.
The guide classifies teeth colour as follows:
- A: Reddish-brown
- B: Reddish-yellow
- C: Grey
- D: Reddish-grey
The numbers (1–4) denote the intensity of the colour, and “1” is the lightest shade. B1 is the whitest shade that natural teeth can achieve. Usually, natural teeth still have a tinge of yellow even at the lightest shade.
What Causes Teeth Discolouration?
Some of our patients ask us, “Why are my teeth still so yellow even though I keep brushing them?” That is because yellow teeth can be caused by factors that are not related to dental hygiene. Tooth discolouration can be divided into 3 different causes: extrinsic, intrinsic, and age-related.
1. Extrinsic (External) Causes For Discoloured Teeth
Extrinsic stains are external stains. These stains are caused by:
- Frequent ingestion of dark-coloured beverages like coffee, tea and red wine.
- Smoking: Cigarettes contain tar, which is dark brown and can stain teeth
- Poor brushing habits can result in your teeth becoming yellow or dark due to a layer of yellow plaque, or a build-up of dark-brown calculus (hardened plaque).
These stains can be removed during your regular cleaning visits at your dentist. They can also be controlled with the proper use of whitening toothpaste. Whitening toothpaste contains abrasive particles that help to rub away external stains. However, they do not change the base colour of your teeth. Good oral hygiene reduces the occurrence of extrinsic stains, but it also cannot alter the natural shade of our teeth.
2. Intrinsic (Internal) Causes For Discoloured Teeth
Intrinsic or internal stains are stains that cannot be removed with cleaning or abrasives. Here are 5 common causes of internal teeth stains:
I. Tetracycline – If a mother took the antibiotic during her pregnancy, or if a child took it below age 8, the child’s teeth will appear dark-brown or grey. These discolourations tend to be in bands as they reflect the time period the antibiotic was taken as the tooth germ was forming.
II. Fluoride – Excessive use of fluoride below the age of 8 can also cause white to brown spots.
III. Root canal treatment or a non-vital tooth – Teeth can discolour when it dies or after a root canal treatment. They tend to appear dark-grey or brown.
IV. Traumatic injury to a tooth – The injured tooth tends to appear reddish brown or pink.
V. Heavy smoking – Tar can seep into the tubules and permanently stain teeth black especially, at the cervical region (near the gumline).
3. Ageing Can Be A Cause Of Discoloured Teeth
The outer layer of our tooth is enamel, which is a translucent bluish layer. The inner layer, known as dentine, is what imparts the tooth its yellow colour. The thicker or more opaque the enamel, the whiter the tooth. As we age, enamel thins due to wear, acid erosion or parafunction (teeth grinding). This thinning of enamel makes the teeth appear yellow and sometimes brown.
Is Teeth Whitening Worthwhile?
For some people, first impressions are important. Humans are visual creatures and tend to make assumptions based on looks. They may feel that a white smile makes a better impression than having badly-stained teeth.
Studies also show that when a person is confident with their smile, they tend to smile more. Smiling creates positive emotions, which in turn boosts your confidence. It also helps put others at ease. Whitening has a feel-good factor that helps with self-esteem for some people.
We have many patients who whiten their teeth before a big event, such as a wedding photo shoot or an interview. They tell us it is a great confidence booster. We have a lady who comes in once a year before Christmas to whiten her teeth as a present to herself. It helps her feel her best for all the year-end parties.
What Are My Teeth Whitening Options?
You can get your teeth whitened with (1) chairside teeth whitening or (2) with a take-home teeth whitening kit.
1) Chairside (In-clinic) Teeth Whitening
Chairside teeth whitening refers to teeth whitening that is done by a dentist in the clinic.
Common FAQs About Teeth Whitening
Most of our patients enjoy a movie or sleep during the procedure. There is some post-operative sensitivity that lasts for 24 hours, as the teeth are dehydrated during the procedure. This is because all soft tissue and gum are covered to ensure the patient’s safety, leaving only the teeth exposed. Once the teeth are rehydrated over 24 hours, the sensitivity naturally disappears.
A trained dental professional will check for pre-existing conditions such as tooth decay or gum disease before whitening. The teeth whitening process can be painful or have harmful effects if you have active disease.
Teeth whitening is the safest and most non-invasive way to have a beautiful smile.
- All products used are safe and non-acidic
- There is no damage to the tooth structure
- The by-products of peroxide are just oxygen and water
The process can be slightly sensitising, thus we advise our patients to use a desensitising toothpaste for a week before teeth whitening. The Zoom whitening kit also comes with Pro-relief ACP gel, which contains nitrates to help desensitise teeth after the whitening.
For more information on the process and whether it is safe, read our post “I am scared to try teeth whitening as I heard whitening destroys teeth!” But is this even true at all?
- Do not take any acidic food after Zoom chairside whitening or during your take-home teeth whitening period of 7–10 days. Avoid vinegar, lime, or any other citrus fruits as it can trigger sensitivity.
- Avoid any dark-coloured food or beverages during whitening and at least 3 days after. The main culprits would be coffee, dark tea, red wine, ketchup, berries, soy sauce and curry. Some of our patients get by with sipping their coffee with a straw.
- Avoid smoking.
- SMILE, SMILE, SMILE. Do show off your brand new smile. People will know you look better even if they cannot tell why!
It really depends on the thickness and opacity of your enamel. It also depends on the colour that you start with. Most of the time, our patients will see an improvement of 6–7 shades.
- If your teeth are very dark, you might need (1) more than 1 session of Zoom teeth whitening, or (2) a session of Zoom chairside whitening plus a take-home teeth whitening kit to achieve B1 (the lightest shade for natural teeth)
- Thin and translucent teeth do not whiten well
- Yellow, brown teeth whiten better than grey teeth
- Teeth whitening cannot even out the difference in teeth colour. The curved area of a tooth near the gum is yellower as the enamel thins out there
- Whitening cannot completely even out bands or spots as the whitening gel is not a smart gel
- In cases of tetracycline stains, we might follow up with porcelain veneers
- For fluorosis stains, we can use a system that involves resin infiltration to remove the brown and white spots
Some patients have teeth at B1 or A1, which are at the whitest end of our natural teeth colour. They come in asking for teeth whitening, and we often tell them that repeated whitening cannot whiten them further than a B1. If they are at A1, getting their teeth to B1 may not be discernible to the eye without a shade guide comparison.
On the other hand, dentists call super white teeth “toilet-bowl white”, because it resembles the porcelain of a toilet bowl. That’s because extremely white teeth is bluish and will appear fake. Teeth should have a warm hue to it, just like our skin. Therefore, paper-white is not a recommended result. For teeth already at A1 or B1, we would recommend a take-home teeth whitening kit for maintenance instead.
The results of your teeth whitening can last about 8–12 months depending on your social and dietary habits. If you are particular and keen to have white teeth all the time, you can maintain it with a take-home teeth whitening kit. You can use it every 3 months over 3 days, either 15 minutes a day or wear it to sleep overnight.
Some people might say if the results don’t last, what’s the point? This is up to personal preference. Yellow teeth will remain yellow without teeth whitening. On the other hand, a small change, such as 2–3 shades lighter, can make a noticeable difference to a smile.
The dentist is trained to examine your teeth and advise if you are suitable for teeth whitening. Gum disease and tooth decay have to be treated prior to whitening. The dentist would also advise on the effectiveness of whitening for you, and if other treatment options such as porcelain veneers might be more suitable. Over-the-counter whitening kits that are not approved by the Health Science Authority (HSA) can cause more harm than good.
Teeth whitening is an aesthetic procedure, much like getting a hairstyle cut. Although it does not last, it can help boost confidence for those who wish to have a whitened smile. If you’re exploring your teeth whitening options or wish to learn more, you can contact our friendly dentists today or book an appointment.