Excessive use of teeth whitening agents can be 'poison' to the teeth.

A teeth whitening agent that can make teeth appear whiter when applied or left on for about an hour. However, this is only a temporary effect and can potentially irritate the teeth and gums, so caution is advised.

Teeth whitening agents are mainly divided into gel formulations containing hydrogen peroxide or carbamide peroxide as the main ingredients and as adjuncts. Over-the-counter teeth whitening products contain hydrogen peroxide at levels of 3% or less. They are relatively safer and have fewer side effects because their concentration is lower than professional-grade products. However, it is important not to use them too frequently. Side effects such as tooth sensitivity, gum burns, inflammation, and tooth erosion can occur.

Professor Jeon Mi-jeong of the Department of Conservative Dentistry at Gangnam Severance Hospital said, "Even at low concentrations, frequent and prolonged use can irritate the teeth and gums," and added, "Since individual sensitivity of teeth and gums varies, some people may exhibit hypersensitive reactions even at low concentrations."

Therefore, teeth whitening agents should be used without touching the gums and the specified usage time and frequency must be followed. Additionally, they should not be used if you are undergoing orthodontic treatment, have an infection or wound in the mouth, or are pregnant or breastfeeding. In particular, products containing hydrogen peroxide and carbamide peroxide should not be used by children under 12 and 14 years old, respectively.

If the product comes into contact with the skin around the eyes or inside the mouth, rinse immediately and do not use it for ingestion or washing purposes. It is also important to check whether the product is classified as a quasi-drug by the Ministry of Food and Drug Safety's Drug Safety Korea or if it has been approved (reported) by the Ministry before purchasing.

Professor Jeon Mi-jeong emphasized, "It is advisable to consult experts for product recommendations and usage instructions suitable for your teeth and gum condition," and added, "If symptoms such as tooth sensitivity or gum irritation occur during use, you should stop immediately."

Meanwhile, there are cases where teeth whitening agents do not work well depending on the cause of discoloration. Extrinsic staining caused by coffee, tea, wine, etc., which results in staining, can be effectively treated with whitening therapy. On the other hand, intrinsic staining caused by tooth structure and defects often does not respond to whitening treatment.