Surface Energy
Also written as: SFE — Surface Free Energy
The excess energy at the surface of a dental material compared to its bulk, expressed in millijoules per square metre (mJ/m²), which governs adhesion, wettability, plaque accumulation, and bonding agent spreading.
Full Definition
Surface energy (also referred to as surface free energy, SFE) quantifies the disruption of intermolecular bonds that occurs when a new surface is created. In dental materials, it is a determinant of wettability (the ability of a liquid adhesive or cement to spread over a substrate), with higher surface energy substrates generally exhibiting better adhesive bonding. It is measured by contact angle goniometry using a series of probe liquids, and components are resolved into dispersive (Lifshitz–van der Waals) and polar (Lewis acid–base) contributions using established models (Owens–Wendt, van Oss–Chaudhury–Good). Editors should note that surface energy values are always expressed as mJ/m², not J/m² or dyne/cm, in dental materials literature. Surface energy should not be conflated with wettability, which is a contact-angle measurement rather than a material property.
Usage
Usage note: Express surface energy values in mJ/m². The shorthand SFE is acceptable after first expansion. Do not conflate with 'surface tension', which applies to liquids, or 'wettability', which is a macroscopic contact-angle result.
In Context
- "Air abrasion with alumina particles significantly increased the surface energy of the zirconia specimens, improving subsequent silane coupling efficiency." — Surface treatment research article
- "The manuscript reported surface energy in dyne/cm; the editor standardised these values to mJ/m² for consistency with the target journal's style." — Copyediting unit-conversion note