Consistency and softness of soft liners

Area of Science:

• Dental Materials Science
• Biomaterials Engineering

Background:

• Relining procedures require materials with predictable consistency and softness.
• Autopolymerized soft liners are commonly used, but their long-term properties require evaluation.
• Heat-cured silicone soft liners offer known long-term softness stability.

Purpose of the Study:

• To assess the consistency and softness of four autopolymerized soft liners.
• To compare their properties against International Standards Organization (ISO) 10139-1 specifications.
• To evaluate their performance relative to heat-cured silicone soft liners.

Main Methods:

• Consistency testing using an initial flow test.
• Softness assessment with a Shore A durometer.
• Comparison of autopolymerized soft liners with heat-cured silicone soft liners.

Main Results:

• All four autopolymerized soft liners met ISO specifications for consistency, with disk diameters between 41.3 and 72.2 mm.
• The softness of the autopolymerized soft liners varied significantly over time.
• In contrast, the heat-cured silicone soft liners exhibited consistent softness.
• Softness readings were significantly influenced by sample thickness.

Conclusions:

• Autopolymerized soft liners meet current ISO consistency standards but lack long-term softness stability compared to silicones.
• Further research is needed to establish standardized criteria for measuring softness and determining optimal thickness for clinical use.
• Material selection for relining should consider the dynamic nature of autopolymerized soft liner softness over time.