RHEOLOGY OF TISSUE CONDITIONERS

Statement of problem. Tissue conditioners can be used to condition abu sed tissues, record functional impressions, make temporary relinings, and for other clinical applications, mainly because of their specific viscoelasticity. However, little information is available on the rheol ogy of the materials, manipulation, and suitability for various clinic al applications. Purpose. This study evaluated the gelation times, the viscoelastic properties after gelation of tissue conditioners, and th e influence of the powder/liquid (P/L) ratio. Material and methods. Te n tissues conditioners were used and gelation times were obtained with an oscillating rheometer. A series of stress relaxation tests were al so conducted to evaluate the viscoelastic properties after gelation an d the changes with the passage of time by means of Maxwell model analo gies. Results. Significant differences were found in the gelation time s and flow properties after gelation among the materials mixed with th e P/L ratios recommended by the manufacturers. The flow properties ten ded to increase with time of storage. Large differences in the limits of the clinically acceptable P/L ratios and the adjustable limits of e lasticity and viscosity by altering P/L ratios were found among the ma terials. Conclusions. The results suggested that each material should be selected according to each clinical purpose because of the wide ran ges of viscoelastic properties and changes in viscoelasticity with tim e among the materials. Furthermore, gelation times and the viscoelasti c properties after gelation can be controlled to improve handling and suit various applications by altering the P/L ratios within the accept able limits.