Unpolymerized layer on autopolymerizing, hard reline materials.

Area of Science:

• Materials Science
• Polymer Chemistry
• Dental Materials

Background:

• Autopolymerizing reline resins are crucial for denture repair.
• The unpolymerized surface layer can affect resin properties and biocompatibility.
• Understanding factors influencing this layer is essential for material development.

Purpose of the Study:

• To characterize the unpolymerized surface layer of six hard, autopolymerizing reline resins.
• To evaluate the impact of polymerization conditions on this layer.
• To assess the susceptibility of the surface layer to contamination.

Main Methods:

• Examined conventional and cross-linked reline resins.
• Polymerized materials in air and distilled water at 24°C and 37°C.
• Varied powder-to-liquid ratios and measured inhibition depth.
• Assessed surface contamination using methylene blue staining.

Main Results:

• Higher temperatures, lower oxygen, and lower powder-to-liquid ratios reduced the unpolymerized layer on cross-linked resins (P < 0.01).
• All materials exhibited staining of the unpolymerized layer.
• Conventional resins showed stained voids in the polymerized region, unlike cross-linked resins.

Conclusions:

• Inhibition depth is significantly influenced by temperature, air presence, and viscosity.
• The unpolymerized layer is prone to contamination across all tested materials.
• Cross-linked reline resins demonstrate superior resistance to contamination compared to conventional types.