Chapters 13 and 14 have dealt with materials which are used to form the denture base and to line the fitting surface of the denture base. The other main components of a denture are the artificial teeth themselves. The materials most widely used for manufacturing artificial teeth are acrylic resin and porcelain.
The most important requirement of artificial teeth is good appearance. They should, ideally, be indistinguishable from natural teeth in shape, colour and translucency. Good matching often requires that the shade and translucency of the artificial tooth should vary from the tip of the crown to the gingival area.
There should be good attachment between the artificial teeth and the denture base. The introduction of artificial teeth into the base should not adversely affect the base material. That is, the artificial tooth and base materials should be compatible.
It is an advantage for the artificial teeth to be of low density in order that they do not increase the weight of the denture unduly. The artificial teeth should be strong and tough in order to resist fracture. They should be hard enough to resist abrasive forces in the mouth and during cleaning, but should allow grinding with a dental bur so that adjustments to the occlusion can be made by the dentist at the chairside.
15.3 Available materials
The two materials which are commonly used for the production of artificial teeth are acrylic resins and porcelain.
Acrylic resin artificial teeth are produced in reusable metal moulds using either the dough moulding technique, described for denture base construction (Chapter 13), or by injection moulding in which the acrylic powder is softened by heating and forced into the mould under pressure.
The resins used are highly cross-linked in order to produce artificial teeth which are resistant to crazing. The main difference between the materials and those used for denture base construction is the incorporation of tooth-coloured pigments rather than pink ones.
The composition and manipulation of porcelain are dealt with in Chapter 11. Artificial porcelain teeth are produced to standard shapes and sizes by using moulds which are approximately 30% larger than required, in order to allow for shrinkage during firing. Small holes or metal pins are incorporated in the base of the porcelain teeth during their production. These are used to give mechanical attachment to the denture base.
Both acrylic and porcelain teeth can be made to give a realistic appearance. The slightly greater translucency and depth of colour achieved with porcelain possibly gives this material a slight advantage in terms of aesthetics. Both materials are produced to a variety of shapes, sizes, colours and shades which enable selection of teeth to suit most individuals.
One aspect of porcelain teeth which is sometimes unpopular with patients is the ‘clicking’ sound which is made when two porcelain teeth come into contac/>