Teeth whitening products generally contain either hydrogen peroxide or carbamide peroxide, which break down stains on the teeth, making them appear lighter.

When used as directed, teeth whitening is generally considered safe. However, overuse or improper use of whitening products can lead to tooth sensitivity or damage to the enamel. It's essential to follow instructions carefully and consult with a dentist if you have concerns.

The duration of whitening results varies depending on factors such as diet, oral hygiene habits, and lifestyle choices. Generally, results can last from a few months to a couple of years.

Teeth whitening is most effective on stains caused by food, drinks, and smoking. It may not be as effective for intrinsic stains, which are stains that occur within the tooth structure, such as those caused by certain medications or tooth trauma.

The most common side effects of teeth whitening include tooth sensitivity and gum irritation. These are usually temporary and subside after treatment.

While teeth whitening is generally safe for most people, it may not be suitable for individuals with certain dental conditions or those who are pregnant or breastfeeding. It's best to consult with a dentist before starting any whitening treatment.

To maintain whitened teeth, it's important to practice good oral hygiene, avoid foods and beverages that can stain teeth (such as coffee, tea, and red wine), and schedule regular dental cleanings.