Check your teeth before starting
Tooth decay, gum problems, exposed roots and cracks can contribute to sensitivity or affect a whitening plan. A tooth that has suddenly changed color should be evaluated rather than simply covered up with a whitening product.
Crowns, veneers, fillings and implant restorations do not bleach like natural enamel. Ask how your existing dental work will look beside whitened teeth and whether treatment should be sequenced differently.
Choose products and instructions carefully
Ask about the differences between over-the-counter products and a dentist-provided home plan. Follow the recommended amount, frequency and duration. Combining products or leaving them on longer is not a reliable way to improve the result.
Avoid improvised mixtures made with household chemicals, acidic fruit or abrasive powders. A product described as natural is not automatically safe for enamel or gums. Ask which products have suitable evidence and instructions for your situation.
Respond to sensitivity and set realistic expectations
Sensitivity or gum irritation can occur. If a product causes discomfort, stop using it and contact your dentist for guidance rather than pushing through symptoms. Do not apply more product to a painful or discolored tooth.
The result depends on the starting shade, cause of staining and product used. Ask how long a course is expected to take, whether touch-ups are appropriate and how to maintain the result. Regular cleaning remains important even when teeth look brighter.
Further reading
American Dental Association: Whitening ↗
General education, not a diagnosis or an individual treatment recommendation. Ask your dental professional about your own care.