Surface Roughness
A quantitative measure of the microscopic texture of a material's surface, expressed as an average roughness value (Ra), relevant to plaque accumulation and aesthetic longevity.
Full Definition
Surface roughness in dental materials science quantifies the microscale topography of a restored or prosthetic surface, most commonly using profilometry to generate the arithmetical mean roughness (Ra, in µm). A threshold Ra of approximately 0.2 µm is widely cited as the level above which bacterial plaque accumulation on dental materials increases significantly. Surface roughness is influenced by material composition, finishing/polishing protocol, and in-service wear or chemical degradation. Editors must ensure that authors specify the measurement parameter used (Ra, Rz, Rq, etc.), as these are not interchangeable, and that the instrument and measurement conditions are reported in the methods section.
Usage
Usage note: Always specify the roughness parameter (Ra, Rz, Rq) and measurement conditions. Do not use 'roughness' generically without the associated parameter and unit (µm). Distinguish from surface energy, which is a thermodynamic rather than topographic property.
In Context
- "The study reported Ra values without specifying the cut-off wavelength (λc) used during profilometry, which the copy-editor queried as a methodological gap." — Research article copyediting query
- "Surface roughness values above 0.2 µm Ra are clinically significant because they promote bacterial adhesion and biofilm formation on the restoration surface." — Dental materials review article