Floss once or twice a day, just before you brush your teeth. This removes plaque from between your teeth, preventing a build up of yellow or off-white plaque. If you have braces, ask your orthodontist for "threaders: you can use to floss in between the wires. For clean, healthy teeth, brush twice a day for at least two or three minutes. Use a toothpaste that contains fluoride for best results. Brush gently, especially around the gum line. Rough brushing won't make your teeth cleaner, and may even damage your gums. Whitening toothpastes are abrasive, so long-term use may damage your teeth enamel. Consider using one every other day, or only until obvious surface stains are removed. If a simple flossing and brushing regimen isn't enough to whiten your teeth, you may want to try a whitening treatment. These home remedies are a good first step, since they are much cheaper than drugstore options.  Add a small amount of baking soda to your toothpaste and brush for two minutes. Do this only once a week, since overuse can damage your teeth. Swish a small spoonful of coconut oil in your mouth for a few minutes, then spit it into the trash. Dentists are divided on whether this "oil pulling" works, but it shouldn't cause any harm and has plenty of fans.  Do not use home remedies involving strawberries, vinegar, or other acidic foods. While these can remove some stains, they can rapidly eat into your tooth enamel. All of the following can be very painful for people with cavities or sensitive gums, or anyone who overuses them. That said, they can be very effective at hiding stains on teeth. Here are a few options:   Dental whitening strips: Available at drugstores, these can help with surface and deeper stains, but may have limited effect on darker stains. They may cause temporary tooth sensitivity.  Dental whitening trays: These use a more powerful whitening gel than the strips. For best results, ask your dentist for a tray custom-fit to your teeth.  Dental whitening procedure: Your dentist can provide ultra-strong...

TL;DR in Vietnamese:
Dùng chỉ nha khoa mỗi ngày. Đánh răng hai lần mỗi ngày. Hãy thử phương pháp làm trắng tại nhà. Hãy cẩn thận với các phương pháp làm trắng chuyên nghiệp. Hạn chế tiếp xúc với các chất gây xỉn màu. Giữ cho đôi môi mềm mại. Cân nhắc việc chữa răng.