There are two main methods for bleaching teeth: in office or at-home. In an office setting, a rubber-like substance is painted on the gums and then light cured. An extremely strong solution of hydrogen peroxide, usually 35%, is applied to the front teeth surfaces. The solution is left on the teeth for long enough to leach into the enamel and oxidizing the stains. This usually takes about 15 minutes. Some dentists employ the use of lights to accelerate the process. The lights can cause overheating of the dental pulp which contains the nerve and can greatly increase the sensitivity to temperatures. Studies have shown that the use of lights or “lasers” makes no difference in the final results. If there is an increased lightening right after the appointment with the use of lights, it has been shown that that is due to dehydration of the tooth surface and the color will return once the teeth have rehydrated. There are some desensitizing that the dentist can apply afterwards. These contain potassium nitrate. There are also toothpastes that are specially made for sensitive teeth that can help make an in-office bleaching procedure much easier to tolerate.