Dental metals and alloys for casting, cobalt-chromium, silver-palladium

Metallic materials are used in almost every industry, dentistry is no exception.

Suitable metals and alloys are used to manufacture prostheses and frameworks, because they have important properties.

Differences

Metal is a set of elements that have features of this nature:

• electrical conductivity;
• plastic;
• temperature resistance.

Almost all chemical elements are metals, the most popular of which are:

• aluminum;
• vanadium;
• iron;
• magnesium;
• sodium;
• chromium.

Non-metals - that part of the elements that do not have the above features. Distinctive black is the presence of electrons, which makes it more likely to oxidize.

There are several features that will help to distinguish metals from non-metals, even for an ordinary person:

1. The color range of metals is much poorer.
2. Non-metals are always softer, with the exception of mercury and iodine.
3. Metallic luster found in metals.

Requirements for materials used in dentistry

Not only dental instruments are made of metals and alloys, but also:

• crowns;
• implants;
• fillings.

Once it was only allowed to use gold and silver, but later this list was replenished with tin, copper, lead.

Requirements that metals must meet for use in dentistry:

1. Compatible with fabrics where application is required.
2. The presence of mechanical properties: hardness, high resistance.
3. The shape and volume must remain unchanged under the influence of certain factors.
4. Must have technological properties.
5. The inability to bring local and general harm.
6. Persistence.

Important properties

Basic properties of metals:

1. Technological. This group implies fluidity, liquation. Fluidity is essential for optimal filling of the model and obtaining the correct shape. Elimination (from lat. liquatio - liquefaction, melting) is called the property of alloys to decompose during the transition from liquid to solid state into component parts or individual joints that have different points melting. Also, malleability can be attributed to the technological group. Malleability is one of the metallic properties of being workable. It is due to plasticity, accordingly, under the influence of pressure, the appearance can take any shape.
2. Physical properties, these include color and structure.
3. Chemical. The group includes oxidizability, solubility and corrosion resistance. Corrosion is usually called the destruction of the appearance under the influence of the external environment. The alloys used in dentistry must necessarily be resistant to corrosion, as it has a negative effect on the oral cavity.
4. Mechanical properties: viscosity, strength.

When overflowing from a liquid, a crystal lattice is formed, and isolated crystals appear, and the process itself is called crystallization.

The crystal lattice of metals is:

• volumetric;
• cubic;
• hexagonal.

Classification of metals

Metals can be classified into groups such as:

• light and heavy;
• colored and black;
• noble and ignoble.

Ferrous and non-ferrous

Ferrous metals - iron and alloys that are formed on its basis. They account for more than 90% of the total volume used in the economy. The most popular variety is:

1. Cast iron - not used in dentistry, not only because of the color, but also because of the lack of the ability to polish.
2. Steel - used in orthopedics.

All other metals are classified as non-ferrous, such as gold, silver - they are used as material for crowns.

Noble and ignoble

The noble elements include elements that are not subject to corrosion and oxidation - silver, gold and platinum. Precious metals have the following features in their use in dentistry:

1. The absence of corrosion, accordingly, such materials are not harmful to the oral cavity.
2. Does not affect saliva production.
3. Not allergenic.

Often this category is the priority for people who suffer from allergies.

Precious metals are used as:

• bridge prosthetics;
• crowns.

The durability of the material is also a positive point in the application: the crown and bridge can perform their functions for 50–70 years.

The only drawback is the high price in comparison with other materials.

Non-noble materials have a cost several times less than noble ones, and are used for the production of:

• prostheses;
• crowns;
• facets;
• dental systems;
• filling matrices.

They include those safe substances that can reduce the cost of the structure, but the disadvantages include:

• high weight in contrast to noble materials;
• high risk of developing allergies;
• high likelihood of development galvanose (a disease in which the presence of galvanic currents in the oral cavity is combined with the simultaneous presence of single or multiple symptoms of alloy intolerance).

Light and heavy

There are about 40 different definitions of the term heavy metals. Accordingly, the list of heavy metals according to different definitions includes different elements.

The criterion used can be an atomic weight of over 50, and then all metals, starting with vanadium, are included in the list, regardless of density. Another commonly used criterion is a density that is approximately equal to or greater than that of iron (8 g / cm³), then the list includes elements such as lead, mercury, copper, cadmium, cobalt, and, for example, lighter tin drops out of the list. There are classifications based on other values ​​of the threshold density (for example, a density of 5 g / cm³) or atomic weight. Some classifications make exceptions for noble and rare metals, not classifying them as heavy, some exclude non-colored metals (iron, manganese).

The term heavy metals is most often viewed not from a chemical, but from a medical and environmental point of view and, therefore, when included in this category not only the chemical and physical properties of the element are taken into account, but also its biological activity and toxicity, as well as the volume of use in the economic activities.

For medicine, heavy metals are those substances that have high toxicity and environmental significance. However, gold with a density of 19.32 g / cm³ and an atomic weight of 197 amu. not classified as heavy, due to its inertness and excellent biocompatibility, due to which it is used in dentistry.

Alloys, classification

Alloys - a collection of several metals or metals with additives.

By appointment

By appointment, dental alloys are divided into:

• alloys intended for sealing - amalgams;
• constructional - they are used for making prostheses;
• auxiliary - used for other purposes;
• for instrumentation;
• by chemical composition:

Alloys of noble metals are highly valued in medicine, not only because of their cost, but also because of their quality.

Alloys of base materials are used in restoring the condition of teeth (orthopedic dentistry). The most popular are cobalt-chrome and nickel-chrome.

Some types of alloys:

• bronze is used for ligatures;
• magnalium in the manufacture of cuvettes;
• brass - for pins.

Most popular types

Steel

Steel is the most popular metal alloy in the world. Dental steel is divided into:

• alloyed - an alloy of iron, to which other materials are added that affect properties, for example, ductility and ductility;
• stainless - used in conjunction with chromium, which, in turn, increases resistance to rust.

Steel is cheap but can cause allergies.

Cobalt chromium alloy

Cobalt chromium alloy in dentistry is a base material with excellent physical and mechanical properties. Due to its fluidity, it allows you to make the required products with high strength. This alloy consists of:

• cobalt - strong metal;
• iron - increases casting;
• manganese - increases the temperature, which promotes rapid melting;
• chromium - reduces the possibility of corrosion.

Materials made from this category of metal alloys remain shiny for a long time and are practically indestructible, except for mechanical injuries.

Silver-palladium

According to its properties, the silver-palladium alloy is as close as possible to gold, but the resistance to rusting is less. Connects with gold solder. Refers to the noble.

Nickel chrome

The structure is closest to chrome. Used to create wireframes and removable dentures.