Whitening gels primarily contain bleaching agents, most commonly hydrogen peroxide or carbamide peroxide. These substances work by breaking down the chromogens (color-causing molecules) in tooth stains.
Hydrogen peroxide is a strong oxidizing agent. In lower concentrations (around 3 – 10% for over-the-counter products), it can effectively remove surface stains from coffee, tea, and smoking. However, when the concentration goes up, its oxidizing power increases. High concentrations (above 15%) can start to not only break down stains but also etch away at the tooth enamel if used improperly.
Carbamide peroxide is a derivative of hydrogen peroxide. It gradually releases hydrogen peroxide when it comes into contact with saliva. This makes it a bit more stable and less likely to cause immediate harsh reactions compared to pure hydrogen peroxide. But again, depending on the concentration (ranging from 10 – 35% in various products), it can still pose risks.
Tooth Enamel and Sensitivity
The outer layer of our teeth, the enamel, is crucial for protecting the softer dentin and the nerve inside. Whitening gels can impact the enamel. When the bleaching agents in the gels penetrate the tiny pores in the enamel, they can cause the enamel to become more porous over time.
If used as directed for short periods and at appropriate concentrations, the enamel can usually recover. But if the gel is left on for too long, or if high-concentration gels are used frequently, the enamel can start to thin. Thinner enamel means that the dentin underneath becomes more exposed. Dentin has tiny tubules that lead to the nerve of the tooth. As a result, when the dentin is exposed, people often experience increased tooth sensitivity. This sensitivity can be in the form of sharp pains when eating or drinking hot or cold substances.
Gum Health
Gums are very sensitive tissues. Even a small amount of the bleaching gel coming into contact with the gums for an extended period can cause irritation. The gel can make the gums red, swollen, and sore. In some cases, if the irritation is repeated or severe, it can lead to gingivitis, which is the early stage of gum disease.
When using whitening gels, proper tray fit is essential. If the tray is too big or doesn’t conform well to the teeth, the gel can leak out and onto the gums. Disposable trays, which may not always fit perfectly, are more prone to causing this kind of leakage. Custom trays, on the other hand, can reduce the risk of the gel reaching the gums but are not completely foolproof.
Risks Associated with Overuse
Overusing whitening gels is a common problem. Some people think that using more gel or leaving it on for longer than recommended will give them faster or better results. In reality, this can lead to serious issues.
Over time, excessive use can cause irreversible damage to the enamel. Once the enamel is severely thinned, it can’t be regenerated naturally. The teeth may start to look more translucent, yellow, or even gray. Also, the increased sensitivity can become a long-term problem that affects a person’s quality of life, making it difficult to enjoy certain foods and drinks.
For those with pre-existing gum problems like periodontitis, overusing whitening gels can exacerbate the condition. The irritation from the gel can cause the gums to pull away from the teeth even more, creating deeper pockets where bacteria can accumulate.
Professional vs. Over-the-Counter Gels
Professional whitening gels used in a dentist’s office usually have higher concentrations of the bleaching agents. But they are also applied under the supervision of a trained professional. The dentist will take steps to protect the gums, often using a barrier gel or a rubber dam. They also carefully monitor the treatment time to ensure that the gel doesn’t cause excessive damage.
Over-the-counter gels, on the other hand, are designed for self-use at home. They have lower concentrations to reduce the risk of misuse. However, many people don’t read or follow the instructions properly. This lack of proper guidance can lead to problems that might not occur with professional application.
Long-Term Effects
The long-term effects of using whitening gels depend on how they are used. If used occasionally and as directed, the impact on oral health may be minimal. But consistent improper use can lead to a variety of issues.
As mentioned earlier, enamel damage can lead to permanent changes in the appearance and function of the teeth. The increased sensitivity can also become chronic. And if gum problems develop due to gel irritation, they can progress to more serious gum diseases that can eventually result in tooth loss.
