Dynamic and static mechanical analysis of resin luting cements

Area of Science:

• Dental Materials Science
• Biomaterials Engineering
• Polymer Chemistry

Background:

• Resin cements are widely used as luting agents for indirect dental restorations.
• Understanding their mechanical properties under oral conditions is crucial for clinical success.
• Contemporary resin cements require thorough evaluation of their performance.

Purpose of the Study:

• To assess the mechanical properties of four contemporary resin luting agents.
• To investigate the influence of temperature and moisture on these properties.
• To evaluate the creep behavior and permanent deformation of the tested cements.

Main Methods:

• Four resin cements (Choice 2, Clearfil Esthetic Cement, Resicem, RelyX Unicem) were tested.
• Dynamic and static testing evaluated shear and flexural modulus, loss tangent, viscosity, and Poisson's ratio at 21°C (dry/wet), 37°C, and 50°C.
• Creep testing was performed under constant loads for 3 hours with a 50-hour recovery period.

Main Results:

• Choice 2 exhibited the highest modulus, while RelyX Unicem had the lowest.
• Water presence affected all cements, with RelyX Unicem being least affected.
• Increased temperature impacted properties, with Resicem showing the least susceptibility.
• Permanent deformation after creep testing ranged from 0.43% to 5.53%; no full recovery was observed.
• No significant transitions were noted under tested conditions.

Conclusions:

• The tested resin cements demonstrate satisfactory mechanical behavior for restorations not subjected to significant mechanical stress.
• Oral cavity conditions, including moisture and temperature fluctuations, can influence the performance of these materials.
• Clinical performance in stress-bearing restorations may be compromised due to environmental factors affecting mechanical properties.