Sir, I have enjoyed reading the first of Dr Ahmad's series on Digital dental photography. The first dental image shown is a photograph of teeth and a shade guide together to assist a technician who is not present. This is an excellent, almost essential procedure for the majority of dentists who work with a distant technician.

Unfortunately, as Gordon Christensen illustrated in the CRA newsletter of May 2005, the method Dr Ahmad shows reflects a common error as the shade guide is not in the same plane as the teeth. A preferred method is for a single selected shade tab to be inside the oral cavity, so that the illumination for shade tab and teeth is the same.

When the technique Dr Ahmad shows is used, the shade guide will normally be significantly lighter than the teeth.