By Dr. Heering, Jun 21 2016 10:07PM
Personally, I've used both light-accelerated whitening in the office and take home gels on myself and on my patients. Results will vary but I've seen shade improvements of up to 8 shades (see image below).
The improvements last up to 1 year and will require touch-ups. Your mileage will vary depending upon what you consume (For example, wine, coffee, tobacco will re-stain your teeth). For more lasting solutions, cosmetic dentistry offers veneers and other procedures.
Some people have stains that have traditionally been very difficult to remove and recent advancements can help even these patients. For patients with tetracycline and other hard to whiten stains, there are special treatments that make dramatic improvements. Some patients will have a tooth that is darker than others because of trauma and even these teeth can be lightened in a variety of ways.