title: Rheology of tissue conditioners.
abstract: BACKGROUND
  Tissue conditioners can be used to condition abused 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 rheology of the materials, manipulation, and suitability for various clinical applications.
  
  
  OBJECTIVE
  This study evaluated the gelation times, the viscoelastic properties after gelation of tissue conditioners, and the influence of the powder/liquid (P/L) ratio.
  
  
  METHODS
  Ten tissue conditioners were used and gelation times were obtained with an oscillating rheometer. A series of stress relaxation tests were also conducted to evaluate the viscoelastic properties after gelation and the changes with the passage of time by means of Maxwell model analogies.
  
  
  RESULTS
  Significant differences were found in the gelation times and flow properties after gelation among the materials mixed with the P/L ratios recommended by the manufacturers. The flow properties tended to increase with time of storage. Large differences in the limits of the clinically acceptable P/L ratios and the adjustable limits of elasticity and viscosity by altering P/L ratios were found among the materials.
  
  
  CONCLUSIONS
  The results suggested that each material should be selected according to each clinical purpose because of the wide ranges of viscoelastic properties and changes in viscoelasticity with time among the materials. Furthermore, gelation times and the viscoelastic properties after gelation can be controlled to improve handling and suit various applications by altering the P/L ratios within the acceptable limits.
authors.affiliation: Department of Prosthetic Dentistry, Hiroshima University, School of Dentistry, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Murata
authors.forename: T
authors.initials: T
authors.lastname: Hamada
authors.forename: E
authors.initials: E
authors.lastname: Djulaeha
authors.forename: H
authors.initials: H
authors.lastname: Nikawa
mesh_terms: D000704:Analysis of Variance; D003764:Dental Materials / Q000737:chemistry*; D003799:Dental Stress Analysis; D003822:Denture Liners; D004548:Elasticity; D005782:Gels / Q000737:chemistry*; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D008768:Methylmethacrylates / Q000737:chemistry*; D010795:Phthalic Acids / Q000737:chemistry; D011143:Polyvinyl Chloride / Q000737:chemistry*; D011208:Powders; D012212:Rheology; D013314:Stress, Mechanical; D013997:Time Factors; D014016:Tissue Conditioning, Dental; D014783:Viscosity
chemical_list: D003764:Dental Materials; D005782:Gels; D008689:Methacrylates; D008768:Methylmethacrylates; D010795:Phthalic Acids; D011208:Powders; D011143:Polyvinyl Chloride; C009931:poly(ethylmethacrylate)