Thixotropy
Pronunciation: thik-SOT-roh-pee
A property of certain dental materials whereby viscosity decreases under mechanical stress (such as mixing or syringing) and recovers upon removal of that stress.
Full Definition
Thixotropy is a time-dependent rheological property in which a material becomes less viscous (thinner) when agitated or sheared and returns to a higher viscosity at rest. In dental materials, thixotropic behaviour is clinically desirable in impression materials and cements: the material flows easily when injected or manipulated, then becomes viscous enough to resist slumping once placed. Editors must distinguish 'thixotropic' from 'pseudoplastic' (shear-thinning without time-dependence). The adjective is 'thixotropic'; the noun form 'thixotropy' refers to the property itself.
Usage
Usage note: Do not conflate with 'pseudoplastic'. Both involve shear-thinning, but thixotropy specifically implies a time-dependent recovery of viscosity. Flag 'thixotropic' when used loosely to mean simply 'thick' or 'viscous'.
In Context
- "The thixotropic nature of the light-body silicone allowed easy syringing into the sulcus before the material regained its resting viscosity." — Clinical technique article
- "Thixotropy should not be confused with pseudoplasticity; the former is time-dependent whereas the latter is purely rate-dependent." — Dental materials textbook