What metals are surgical instruments made from? Are they heat treated?

Just as each industry has its own requirements, there are also issues to consider when choosing materials in the medical world. After all, the wrong choice of material leads to undesirable consequences. In this article, we will look at which metals are used for surgical instruments.

Tools such as forceps, retractors, forceps, scissors and scalpel handles used in operating rooms are important equipment used by doctors when performing vital operations. They differ from other medical instruments and are therefore usually made of special materials that will not cause negative health consequences when in contact with the body.

Every material used in their production must be specially produced and subjected to heat treatment.

First of all, the metal from which the surgical instrument will be made must be easily shaped, but it must also be resistant to losing its geometry under usage conditions. Since most of them are thin and long in geometry, they will need some stiffness.

Deteriorations such as scratches and dents on the tool prepare the ground for biofilm formation. For this reason, they should have a shiny and scratch-resistant surface that will facilitate sterilization and prevent bacteria from nesting.

To sort them according to their usage rates and prices:

· Stainless steel

· Titanium

· Tantalum

· Platinum and Palladium

1. Stainless steels

It is the most commonly used material group in the production of surgical instruments. Although austenitic stainless steels are used more frequently, martensitic stainless steels are also used.

AISI 316L is the best known surgical instrument material. Its high corrosion resistance and the fact that it does not lose its form at temperatures exceeded for sterilization make it frequently chosen. This intensive use has given it the name "surgical steel".

AISI 301 is used as springs in surgical instruments due to its increased hardness when cold formed, despite its relatively low corrosion resistance.

Austenitic stainless steels do not harden due to their chemical structure, but they are stress relieved after production. With the development of nitriding technologies in recent years, they can be hardened to a depth of 30-50µm without losing their corrosion resistance.

Precipitation hardening stainless steel 17-4 PH is widely used in surgical instruments where hardness is required. Maraging steels, such as 1.6358 (C300), are chosen as surgical needle materials due to their high flexibility.

These two groups of materials require solution and aging .

In dentistry, milling cutters and drills that open holes to place implants are made of martentisic stainless steel because they require high hardness and wear resistance. These materials are hardened and tempered in vacuum furnaces.

2. Titanium

Its most distinctive feature is its high strength and low weight. While it has the same strength values as carbon steels, unlike carbon steels, it is 100% corrosion resistant and 40% lighter.

Thanks to their superior properties, they are also used as surgical instruments and implants.

Since they have good biocompatibility, they bond well with bone structures. Pins, plates and dental implants are areas of use in orthopedics.

Sample material Titan Grade 1 (3.7025) and Titan Grade 2 (3.7035). Titaniums are also hardened by solution and aging .

3. Tantalum

Due to their very good corrosion resistance and biocompatibility, they are used both in the production of surgical instruments and as implants.

Due to their high strength and ductility, they can be used as thin wires in surgery without causing negative effects within the body.

The most commonly used material, referred to as medical tantalum, is UNS R05200.

After being sintered or drawn into wire, they can be subjected to stress relief annealing.

4. Platinum and palladium

Although platinum and palladium are expensive, precious metals, they have similar properties that make them uniquely suited to certain surgical applications.

Since both are easily shaped and ductile, they can be easily manufactured into a variety of shapes.

Both platinum and palladium are highly corrosion resistant and inert, so they do not cause problems when in contact with the body or internal organs.

One of the most important uses in recent years is to create ultra-thin wires that surgeons use to guide and position implants such as catheters and stents.

Since both metals are radiopaque (impermeable to x-rays), it is placed as a marking tape on implants and catheters that are not visible on x-rays.

After they are shaped, they undergo annealing heat treatment.

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Conclusion:

Surgical instruments are made of 5 different metals: stainless steel, titanium, tantalum, palladium and platinum. They are heat treated to provide the desired mechanical properties.

I hope this article has given you an idea about the different types of metals used to make surgical instruments and their properties.