In order to fully address all the questions about how to whiten teeth, let’s look at some definitions and differences between current common whitening techniques.
Let’s dive right into understanding how whitening works, the difference between intrinsic and extrinsic tooth discolouration, and common whitening strategies.
The Two Types of Stains
There are two main categories of stains that cause our teeth to be discoloured.
Intrinsic:
Intrinsic stains occur when the deeper layer of tissue, the dentin, becomes discolored.
Common causes of intrinsic stains are:
- Dental fluorosis – when a person is exposed to too much fluoride while the teeth were forming
- Antibiotic exposure – exposure to tetracycline early in life can cause intrinsic stains
- Tooth trauma – if you injure a tooth badly, it can permanently discolour
Extrinsic:
Extrinsic stains are what most of us think of when we want to whiten our teeth. Extrinsic stains are on/in the surface enamel layer of tissue on our teeth.
To help stop causing extrinsic stains on your teeth, avoid common staining foods, the first step to having naturally whiter teeth.
Age-related:
Honourable mention goes to age-related discolouration.
Teeth tend to yellow as we age. The main reasons for this are accumulated stains and a thinning of enamel. You see, dentin (the layer of tissue in each of our teeth just under the outer enamel layer) naturally has an ‘off white’ colour. So if we wear through our enamel more quickly, our teeth will seem more discoloured.
After a handful of decades drinking coffee and brushing unconsciously, you can see why teeth yellow with age. If we allow stains to accumulate while we brush our teeth like we were scrubbing a grout line, the combination of extrinsic stains and thinning enamel will hasten results in ‘age related’ discoloration.
Let’s continue to establish some definitions to base our discussion on
What’s the difference between ‘whitening’ and ‘bleaching’?
While both terms whitening and bleaching are used for making our teeth whiter, our culture definitely has leaned toward using the term whitening, at least in part because industry realised that using the term bleaching is bad for marketing such products.
Why Do Teeth Turn Yellow?
Teeth become discoloured, turning yellow or even a beige or brown colour, due to stains that develop on both the surface of teeth (the enamel) as well as deeper in the teeth’s structure. Tooth enamel is the hard, white surface of your teeth.
Underneath enamel is a pale brown substance called dentin, which can become more visible when enamel gets thinner – a very common occurrence for many adults. Dental erosion (erosive tooth wear) results from chronic loss of dental hard tissue that is chemically etched away from the tooth surface by acid and/or chelation (without bacterial involvement). Some of the reasons enamel thins? Risk factors include ageing, genetics and intake of foods that promote erosion and/or staining. Many of these same unhealthy habits also increase your risk for gum disease.
While it’s unrealistic to expect that your teeth will remain shiny and very white into older age, many factors that accelerate the rate of teeth discolouration can be avoided.
Some of the reasons teeth turn yellow, beige or brown include:
- Drinking coffee or tea
- Smoking cigarettes
- Thinning tooth enamel due to aging
- Suffering from dry mouth (since lack of saliva means less protection for enamel)
- Breathing through your mouths and having blocked nasal passages. These lower saliva and prevent the teeth/mouth from remoisturising
- Antibiotic use
- Excessive fluoride intake, especially if this habit starts when you’re a child
- Genetic factors
- Eating a poor diet. This includes consuming lots of processed foods high in acid, including soft drinks/soda, candies or sometimes certain fruits.
Even some supplements can worsen enamel thinning due to containing acids.
