Rheological properties of elastomeric impression materials for selective pressure impression technique

Area of Science:

• Dental Materials Science
• Rheology
• Removable Prosthodontics

Background:

• The selective impression technique is vital for removable prosthodontics.
• Understanding the time-dependent viscoelastic properties of impression materials post-tray seating is currently limited.

Purpose of the Study:

• To investigate the viscoelastic rheological properties of dental impression materials.
• To focus on time-dependent changes immediately after tray seating.

Main Methods:

• Evaluated eight polyvinylsiloxane (PVS), two polyether, and two alginate impression materials.
• Measured storage modulus (G') and loss tangent (tanδ) using a rheometer from 0 to 360 seconds post-mixing.
• Compared G' and tanδ values at 0s and 20s.

Main Results:

• Significant variation in stiffness (G') was observed among PVS, polyether, and alginate materials immediately after mixing.
• Stiffness ranged from 4.49-0.26 × 10(4)Pa for PVS, 1.55-0.5 × 10(4)Pa for polyethers, and 0.64-0.21 × 10(4)Pa for alginates.
• All materials exhibited continued hardening beyond 20 seconds post-mixing.

Conclusions:

• Impression material stiffness (G') varies significantly even immediately after mixing.
• Accurate impression-taking time can be determined using loss tangent (tanδ) results.
• These findings offer valuable insights for refining the selective impression technique.