Teeth whitening for a new year

October 22, 2020

Teeth whitening can be a wonderful way to bring in the new year. Gaining your confidence back with a new smile can make all the difference and one of the simplest ways is through teeth whitening.

Many people are interested in whitening their teeth for a brighter smile but are hesitant about the effects of whitening agents on their teeth. There are two ways that teeth can be whitened: externally or internally. What this means is that agents can be used to polish surface stains on the enamel off externally, or a chemical agent can be applied to the enamel which is absorbed internally to break down stains. So what is the difference? Read on and find out the benefits to both.

External Teeth Whitening

“Whitening” toothpastes, baking soda, bamboo/hard bristled toothbrushes and charcoal are examples of agents which can remove external stains on the surfaces of teeth caused by smoking, coffee, tea, and discoloured plaque and tartar. These substances are rough and abrasive, thus whiten by polishing off external stains. However after the surface stains have been removed, the underlying tooth colour itself is not lightened because the agents are not absorbed into the enamel.

External abrasive whitening agents must be used with caution, as they are erosive and can erode enamel and gum tissue away if used too often. Once the enamel and gums have been eroded, these tissues cannot grow back. Thinner, eroded enamel can appear to be more yellow as the darker dentin layer underneath the enamel begins to show through. Gum recession leads to the exposure of root surfaces which can lead to further problems such as sensitivity, loss of root structure through erosion, decay, periodontal disease and can cause aesthetic concerns.

Internal Teeth Whitening

Techniques that use hydrogen peroxide or carbamide peroxide, substances which can be found in whitening gels applied to teeth, can achieve whitening internally in the tooth. The enamel, which is the outside layer of the teeth, is porous, and as such absorbs the hydrogen peroxide (carbamide peroxide breaks down into hydrogen peroxide and urea) internally. When the hydrogen peroxide meets up with absorbed stains such as those caused by pigmented foods and drinks, it oxidizes and breaks down into water and oxygen which breaks apart the staining compounds. The hydrogen peroxide does NOT erode or etch the enamel itself. The stronger the hydrogen peroxide concentration, the quicker the whitening treatment is. Furthermore, the longer the hydrogen peroxide is in contact with the teeth, the more teeth will whiten.

Because the enamel pores are open after the hydrogen peroxide based whitening treatment, one can experience temporary sensitivity on the teeth because the open pores allow for stimuli to reach deeper into the teeth for a few days. However as the pores close over with the formation of a pellicle layer and the use of a fluoridated toothpaste, the sensitivity settles down. Internal whitening can be slight to drastic but won’t whiten anomalies in the structure of the enamel such as hypocalcified areas (white spots), fluorosis, mottling, cavities, and tetracycline stains. Composite fillings, crowns, veneers, and any other restorative materials will not whiten either.