Clinical
Figures 7 and 8: Prepared teeth are isolated with rubber dam and tried-in
Fig 7 Continued »
and do not harden by heat treatment. Their application is limited in that they are appro- priate only in areas not under occlusal stress. • Type II alloys are considered to have intermediate hardness values and are used commonly for gold restorations where burnishability of margins is more important than high strength. • Type III alloys are often used to provide gold castings
Fig 8
“Advancements in adhesive dentistry have provided clinicians with more options”
in higher-stress applications where restoration design makes burnishability less important than strength. • Type IV alloys are strong, hard and non-ductile and are intended for high stress applications such as partial dentures. They are rarely used.
The main incentive for
the use of low gold alloys is cost. Alloys in this group are susceptible to tarnish and corrosion and have mechanical properties similar to ADA type III alloys. With only moderate ductility, their use is limited to full veneer crownsı4,ı5.
Restoration design Traditionally cast gold restorations have been clas- sified as being intracoronal or extracoronal. Advance- ments in adhesive dentistry have provided clinicians with more options, helping them to restore teeth without destruc- tive preparations and this has led to the development of adhesively retained cast gold restorations. Chana et alı6 demonstrated the use of alumina blasted resin bonded type III gold alloy cement for
44 Scottish Dental magazine
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