Denture base materials are used to
contact the oral tissues and support artificial teeth
(Powers and Wataha, 2014). Since the 18th century, a wide
variety of denture materials have been introduced to replace missing teeth and
their associated structures. Wax was the first material used for intra-oral
impressions and models; then ivory was used by carving it into the required
denture shape. However, ivory’s hygienic prospect limited its use, and in 1728
Fauchard suggested making dentures from porcelain (Fauchard, 1728), assuming
that it could be more attractive and coloured as required as well as more
hygienic (Young, 2010). In 1744, Duchateau produced the first recorded
porcelain denture (Murray and Darvell, 1993).
In the 1850s, a cheap and easy to handle vulcanite material was
identified, and this was used to replace unhygienic costly ivory and porcelain
dentures. Vulcanite produced accurately fitting prostheses at reasonable cost,
making it accessible to a large number of consumers (Khindria et al.,
2009). Vulcanite denture bases were fitted with porcelain teeth requiring
mechanical retention due to lack of chemical bonding between the vulcanite
denture base material and the porcelain teeth. Techniques were established to
improve this bonding by making undercut holes in posterior porcelain teeth and
placing pins in anterior teeth (Engelmeier, 2003; Young, 2010). Nonetheless,
this material became less satisfactory due to its lack of translucency which
affected the aesthetic results; additionally, its porosity had the potential to
increase the accumulation of
plaque and oral fluids which consequently made the denture base unhygienic (Young,
2010). Many synthetic polymers such as polyamides, epoxy resin, polystyrene,
polyvinyl acrylic, rubber graft copolymers, polycarbonate and
polymethylmethacrylate have been developed and tested as potential alternative
denture base materials (Stafford et al., 1980; Stafford et al.,
1986). These are organic molecules of many repeating segments (Powers and
Wataha, 2014), but may not generally prove successful since many of them are
susceptible to distortion due to water sorption as well as being soluble in
most solvents, including chloroform (Van Noort, 2013), although some
rubber-reinforced polymers of higher impact strength have been used to reduce
the risk of fracture (Powers and Wataha, 2014).
Metals and alloys have been introduced for dental application and used
in a number of restorations in dentistry by means of casting techniques (Van
Noort, 2013; Powers and Wataha, 2014). Great improvements have been made in the
physical and mechanical properties of these base metal alloys and their
application could outstrip that of the rarely and costly pure metals (Luthy et
al., 1996; Powers and Wataha, 2014). However, for the last two decades
their uses have been limited due to their performance or biocompatible risks.