Macrophotograph of an extracted molar (male,upper,number 7),a top view showing three 20 year old amalgam fillings. The filling is a powdered alloy consisting of silver,tin,copper & zinc mixed with mercury. The decayed area is removed & the cavity lined with a white filler,protecting the base from the effects of the filling itself. The source of tooth decay (dental caries),is complex. It is linked to the build up of plaque,a mixture of saliva,bacteria & carbohydrate on the tooth's surface. Acid produced during the breakdown of carbohydrates by the bacterium Streptoccocus etches into the enamel & deeper if not treated. Magnification: X1.6 (at 35mm size) |