Dental Restorations

Colour is the property possessed by an object of producing different sensations on the eye as a result of the way it reflects or emits light. Sir Isaac Newton made an observation which was that sunlight separates into bands of bright colours when projected through a prism in other words a prism could reassemble or disassemble white light. The white light however was being separated into the different colours of the spectrum. Newton divided the spectrum into seven colours: red, yellow, orange, blue, green, violet and indigo. Although the spectrum does not contain all colours, other colours can be made from a mix of wavelengths for example red and blue make the colour purple. In dental technology matching natural dentition with an artificial

Translucency is described as the medium between being transparent and being opaque. It is the transmission and diffusion of light through an item so that a specific image beyond the object is unseen. 96% of translucency comes from Enamel and the remaining percentage comes from the dentin. Areas in a tooth or a restoration that are higher in translucency will have lower value because light passes through the tooth and away from the observer. When translucent material is added into porcelain it gets scattered around the porcelain body. Light then enters the enamel and gets spread around the enamel to that any of the translucent material can catch light and spread it throughout the whole crown. Translucency is so powerful that if one side of a tooth is illuminated with a curing light, then the whole tooth will get lit up. When assessing enamel translucency, the observer will also focus on the opalescence. Opalescence is the ability of a translucent material to appear one colour in light that is reflected from it and a different colour in a light that is transmitted through it. This is because opals (aquatic object) breaks trans-illuminated light down into its particular spectrum by bending the light. It is able to do this because Opals act like prisms which allows them to bend varying wavelengths. Wavelengths of light have different amounts of translucency through teeth and dental materials. When Enamel and opals are illuminated the red colour of the spectrum will trans illuminate and the blue colours of the spectrum will scatter within the enamel body. This is why many incisal edges may appear blue even though it may be