Comparison of the rheological properties of four root canal sealers.

The ability of root canal sealers to flow into and seal a root canal can best be measured with a strain-controlled rheometer. Researchers usually measure sealer viscosity using the simple press method, that is, by pressing the material between two glass plates and measuring the diameter of the resulting disc. Rheometers, however, can measure the viscosity of a complex fluid as it changes with strain, time and temperature. Kwang Shik Bae of the Seoul National University School of Dentistry, Korea, and colleagues tested four sealers (Capseal, AH Plus, Sealapex, and Pulp Canal Sealer EWT) using both methods. The rheometer measured sealer viscosity more sensitively than the simple press method. The rheometer data also showed how the viscosity of sealers changed as they set, indicating effective working times, and how increased temperature affected their chemical properties.