Abstract
Four reversible hydrocolloid impression materials were studied by nuclear magnetic resonance (NMR).
Temperature hysteresis was observed in spin-lattice relaxation (T1) and spin-spin relaxation (T2), which corresponded to that of the sol-gel transition. It was found that the sensitivity of T2 values were greater than that of T1 values. T1 and T2 values were reduced with increasing concentration of agar.
It was suggested that the differences of T1 and T2 values in those impression materials were affected by their viscosity and the paramagnetic ion (Fe2+) contained within them.
This study demonstrated that the T2 values could be one index of gelation in reversible hydrocolloid impression materials.
