Dental alloys

• A number of alloys are used in Dental technology to suit multiple applications

A typical high Gold (Au) alloy for ceramics ( BIOclus 4)

• • • • • • Typical Components Au 85.8% Platinum 11% Zinc 0.5% Indium 1.7% (Soluble with porcelain) Rhodium 0.7% •

Melting range 1040-1140°C

A typical white Au alloy for ceramics (Degudor)

• • • • • Will include Au 55.1% Palladium 34.5% Indium 9% Iridium 0.2% •

Melting range 1190-1275°C

A Non-precious bonding alloy (Matchmate NP10) contains…

• • • • • • • • Cobalt 61% Chromium 28% Tungsten 8.5% Silicon 1.6% Carbon 0.1% Manganese 0.25% Iron 0.5%

Melting range 1320-1420°C

• • • • • • • •

A high Au (Gold-coloured) crown & bridge alloy (Degulor C)… may contain

Au 74% Platinum 2.4% Palladium 2.0% Ag 13.5% Copper (Cu) 7.0% Zinc 1.0 % Iridium

Melting range 900-975°C

A reduced Au (silver-coloured) crown & bridge alloy (Stabilor IV plus)… will contain

• • • • • • Au 62.2% Platinum 4.4% Silver 22.5 % Copper 9.8% Zinc 1% Iridium 0.1% •

Melting range 870-925°C

A typical Chrome alloy for a denture (Biosil I) ..may include

• • • • • • • • Cobalt 62.5% Chrome 30.5% Molybdenum 5.0% Silicon (Si) 1.0% Manganese 0.4% Carbon 0.3% Nitrogen 0.3%

Melting range 1290-1390°C

An Orthodontic Stainless Steel wire for cold working will contain…

• • • • • • • • Containing a chemical range of… Iron 70.8% Nickel (Ni) 10% Chromium 16% Molybdenum 2% Silicon 1% Carbon 0.08% Phosphorous (P) 0.045

Sulphur 0.03%

Properties of constituents… Copper

• Increases alloy hardness and strength…increases the CTE (thermal co-efficiency) important for a ceramic bonding alloy.

Gold Au

• Main component of precious-metal dental alloys. Extremely stable intraorally, extremely resistant to corrosion

Indium

• Improves mechanical properties, increases the CTE, excellent flow characteristics

Iridium

• Decreases alloy grain size. Heat resistance, temperability (to alter properties) and melting range are all increased.

Manganese

• Decreases the grain size and increases the strength of the alloy

Palladium

• Homogenizes the alloy and increases its hardness, strength, corrosion resistance and overall intraoral stability, increases the melting range

Platinum

• Increases intraoral stability, hardness and heat resistance and decreases particle size, reduces the oxide layer.

Rhodium

• Decreases the grain size, increases hardness, improves flow characteristics and temperability

Silver

• Improves flow characteristics and increases hardness, improves soldering properties and increases the CTE.

Zinc

• Improves mechanical properties and flow characteristics, decreases the melting temperature

Cobalt

• Extremely hard element protected from oxidizing through a passive forming protective oxide.

Chromium

• Most abundant element, odourless and tasteless extremely hard and corrosion resistant

Molybendum

• Hard and stable, often a key component in high strength alloys.

Steel

• Formed from Iron & carbon