What is ANSI/ADA Standard No. 134 about?This standard classifies metallic materials that are suitable for the fabrication of dental restorations and appliances, including metallic materials recommended for use either with or without a ceramic veneer, or recommended for both uses, and specifies their requirements. Furthermore, it specifies requirements with respect to packaging and marking the products and to the instructions to be supplied for the use of these materials.
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Standard No. 134
What are the requirements I should know for metallic materials?
This standard is important to the dentist because it classifies metallic materials according to 1 of 6 “Types” with respect to their mechanical behavior, and then provides examples of the applications for which these types are intended. For example, a Type 5 metallic material must have a minimum yield strength (0.2% proof stress) of 500 MPa, elongation after fracture of 2%, and “stiffness” of 150 GPa, and it is applicable for appliances in which parts require the combination of high stiffness and proof stress, such as thin removable partial dentures, parts with thin cross-sections, and clasps, as shown in the tables below. Therefore, when considering a metallic material for a certain procedure, the dentist may communicate with the dental laboratory that they would like a material that meets the requirements of the Type that fits their intended application. The standard also sets requirements for chemical composition, hazardous elements (cadmium, beryllium, and lead), thermal expansion, melt behavior, density, and corrosion and tarnish resistance. It also provides a definition for “nickel free.”
- Type 0
Intended for low stress bearing single-tooth fixed prostheses, e.g. small veneered one-surface inlays, veneered crowns
- Type 1
For low stress bearing single-tooth fixed prostheses, e.g. veneered or unveneered one-surface inlays, veneered crowns
- Type 2
For single tooth fixed prostheses, e.g. crowns or inlays without restriction on the number of surfaces
- Type 3
For multiple unit fixed prostheses
- Type 4
For appliances with thin sections that are subject to very high forces, e.g. removable partial dentures, clasps, thin veneered single crowns, full arch fixed dental prostheses or those with small cross-sections, bars, attachments, implant retained superstructures
- Type 5
For appliances in which parts require the combination of high stiffness and proof stress, e.g. thin removable partial dentures, parts with thin cross-sections, clasps
What’s the bottom line?
This standard can be used by a dentist to identify the “Type” of metallic material that meets the minimum requirements for the intended patient use. Therefore, when dealing with a dental laboratory, the dentist should make sure that they are using a metallic material that has packaging identifying it as being of the “Type” that meets the minimum mechanical behavior of the intended dental application. Furthermore, besides meeting the minimum mechanical requirements, it also means that the material meets minimum requirements for corrosion and tarnish resistance, deviation from the listed chemical composition, and freedom from hazardous elements, as well as the other listed requirements noted above.