In-office whitening is a professional dental procedure designed to lighten the color of teeth. During the treatment, a dentist applies a whitening gel containing hydrogen peroxide or carbamide peroxide to the teeth. A special light or laser may be used to enhance the whitening effect, allowing for quicker and more effective results compared to at-home methods. The procedure typically takes about one to two hours and can brighten teeth several shades in a single visit. It is considered safe when performed by a qualified dental professional and can help improve the overall appearance of a person's smile.