Visco-elastic properties of dental elastomeric impression materials

Area of Science:

• Materials Science
• Polymer Science
• Biomaterials Engineering

Background:

• Elastomeric impression materials are crucial in dentistry for accurate prosthodontic restorations.
• Understanding their long-term mechanical behavior, specifically permanent deformation (set), is essential for clinical success.
• Viscoelastic properties influence the dimensional stability and recovery of these materials after deformation.

Purpose of the Study:

• To investigate the relationship between the viscoelastic properties of elastomeric impression materials and their permanent set behavior.
• To compare the correlation of mechanical loss tangent with tension set and compression set.
• To evaluate the applicability of linear viscoelasticity theory to permanent set tests.

Main Methods:

• Determination of complex shear modulus (G1 and G2) and mechanical loss tangent (Tan delta) using a torsional pendulum apparatus.
• Comparison of viscoelastic data with published tension and compression set data for various elastomeric impression materials.
• Application of Fourier integral analysis based on linear viscoelasticity theory.

Main Results:

• A significant positive correlation ( >99%) was observed between the mechanical loss tangent (Tan delta) and compression set.
• No significant correlation was found between Tan delta and tension set.
• Theoretical predictions based on linear viscoelasticity showed qualitative agreement with compression set but significant quantitative discrepancies.

Conclusions:

• The mechanical loss tangent is a reliable indicator of compression set in elastomeric impression materials.
• Tension set behavior deviates from linear viscoelastic predictions due to nonlinear deformation.
• Further investigation is needed to explain the quantitative differences between theoretical models and experimental results for compression set.