- The property of a dental material that describes its ability to resist surface deformation such as scratching or indentation is known as hardness.

- Hardness measures a material's resistance to localized plastic deformation, which means how well it can withstand forces that might cause surface damage like scratches, dents, or permanent indentations.
- This property is crucial in dentistry because materials used for restorations, crowns, or fillings must endure constant mechanical forces without wearing down quickly.

In contrast:
- Ductility refers to a material's ability to deform under tensile stress, often characterized by the ability to be stretched into a wire.
- Toughness is the ability of a material to absorb energy and plastically deform without fracturing; it reflects resistance to fracture rather than surface deformation.
- Elasticity is the ability to return to its original shape after deformation when the applied stress is removed.

Understanding these properties allows dental professionals to select appropriate materials that will perform well under oral conditions.

Reference: Craig's Restorative Dental Materials, 13th Edition, Chapter 2, Page 45