Glass fibre dental ceramic. Coloured scanning electron micrograph (SEM) of a dental ceramic reinforced with glass fibres. This ceramic is used to make artificial teeth such as those used in dental bridges. Previously, artificial teeth were made from a metal base to give strength covered by a white dental ceramic. However the metal expands differently to the ceramic in heat, conducts electricity, can cause allergies and gives teeth an ugly, dark appearance. The use of a single non-conducting, white material is therefore preferable. Magnification: x40 at 6x6cm size.