Teeth Whitening: How It Works, Professional vs. At-Home Whitening, Sensitivity, and Maintenance

How does teeth whitening work?

Teeth whitening is a procedure in which hydrogen peroxide or carbamide peroxide oxidizes and breaks down pigment molecules deposited in the teeth, lightening their shade [1]. Its defining feature is that it breaks down pigment rather than grinding the teeth down or painting them white [1].

Teeth can look yellow for many reasons. Besides staining from food and smoking, thinning enamel can let the yellowish dentin underneath show through, so cleanliness alone does not explain it [1]. When DentStat analyzed 4,388 patient comments (1,580 of them questions) on teeth whitening in YouTube dental content, the most common questions concerned cost, number of sessions, and clinic information (169), whitening toothpaste and home remedies (127), and pain and sensitivity (109) [4].

What is the difference between professional whitening at the dentist and at-home whitening?

The key differences are the concentration of the agent and who supervises it. Professional whitening at a dental clinic uses relatively higher concentrations under a dentist’s supervision, while at-home whitening with custom-made trays uses lower concentrations [1]. At-home whitening products sold in Korea as quasi-drugs are limited to low hydrogen peroxide concentrations for safety [3].

The comment analysis found 72 questions about DIY and over-the-counter products, and cases of people visiting a dentist after sensitivity worsened during at-home use came up repeatedly [4]. Cases of products bought directly from overseas whose labeled concentration differs from the actual active concentration were also mentioned, so it is important to check that a product is approved [3].

Is it covered by National Health Insurance? Why do prices differ?

Teeth whitening is a cosmetic procedure and is non-covered (not paid by Korea’s National Health Insurance) [2]. Fees for non-covered care are set by each clinic, so prices differ from clinic to clinic [2].

Even under the same name, “whitening,” the package differs by agent concentration, number of sessions, method (professional, at-home, or internal whitening for non-vital teeth), and whether trays and agents are included [1]. In the comment analysis, questions saying it was hard to compare by total price alone were a main thread of the top theme, cost and number of sessions (169), showing demand for comparisons based on sessions and what is included [4]. Prices at individual clinics vary, so this guide does not cover them.

Is it normal for teeth to feel sensitive during whitening?

Sensitivity after whitening can occur and is often temporary [1]. However, pain is not a measure of effectiveness, and continuing despite severe or prolonged sensitivity is not safe [1].

Pain and sensitivity was the third most common question theme in the comment analysis (109), with repeated questions about “what is normal and when to stop” [4]. If sensitivity continues, stop using the product and consult a dentist about whether there are other causes, such as cracks in the tooth surface or wear near the gumline [1].

How long do whitening results last?

Whitening results are not permanent [1]. Strongly pigmented foods such as coffee, tea, and curry, and smoking, are known causes of restaining, and how long results last varies widely with diet and care [1]. Touch-up treatments are sometimes done later to restore brightness, and how often depends on the individual [1].

Questions about how long results last and restaining were the fourth theme in the comment analysis at 91, centered on maintenance questions such as “Isn’t it pointless if they get darker again?” [4].

Can crowns or root-canal-treated teeth be whitened?

Artificial materials such as crowns, veneers, resin, and implant restorations do not change color with whitening agents [1]. If only the natural teeth get lighter, a color mismatch with existing restorations can appear, so when restorations are present, the order of whitening and remaking restorations is sometimes planned together [1].

For a tooth discolored after root canal treatment (a non-vital tooth), surface whitening is not used. Instead, a separate internal whitening that places the agent inside the tooth is considered [1]. The comment analysis found 73 questions about restorations and special cases, many asking “Will it work on my teeth?” [4].

Are there limits based on age or the condition of the teeth?

Whether whitening is suitable can depend on age, tooth development, and the cause and degree of discoloration [1]. The comment analysis found questions about suitability for minors, older adults, and timing before or after orthodontic treatment, but little content addressed them [4].

As with any cosmetic procedure, results cannot be stated uniformly and vary widely between individuals, so discuss it with a dentist along with an examination of your own teeth [1].