The international standard ISO 22674 Dentistry – Metallic materials for fixed and removable restorations and appliances, has been revised and published in a second edition in 2016, after the first release in 2006.
The standard classifies metallic materials suitable for the fabrication of dental restorations and appliances. This includes metallic materials recommended for use either with or without a ceramic veneer, or recommended for both uses. The standard specifies requirements related to the properties of the materials, as well as for packing and marking of the products and to the instructions for use to be supplied with these materials.
Tests included in the standard are chemical analysis, mechanical testing, corrosion testing, thermal testing, formal requirements and sample preparation. The requirements for the mechanical properties shall be met by the metallic material after recommended processing techniques such as casting, bench-cooling, machining and after ceramic firing schedule, if appropriate, has been applied.
NIOM performs most of the tests specified in the standard, specifically chemical analysis, tensile testing, density, corrosion testing, tarnish testing, solidus and liquidus temperatures and thermal expansion coefficient.
The mechanical tests are performed at NIOM by two different universal test machines; one Zwick 10 kN machine with macro extensometer and one Lloyd LRX 2.5 kN table top machine. The Zwick machine is classified as class 0.5 and the Lloyd machine as class 1. This means that the accuracy of the test machines are better than ± 0.5% and ± 1%, respectively, which is according to the requirements of the standard.
The difference between the first and second edition of the standard include addition of lead as a hazardous element, and revision of the method for determination of the elastic modulus.