[Bond strength of multilayer-cured composites]

Area of Science:

• Dental Materials Science
• Polymer Chemistry
• Biomaterials Engineering

Background:

• Visible light-cured composites are widely used in restorative dentistry.
• The surface layer of these composites can be oxygen-inhibited, affecting material properties.
• Understanding the impact of this inhibited layer is crucial for clinical success.

Purpose of the Study:

• To investigate the morphological and mechanical effects of removing the oxygen-inhibited layer from visible light-cured composites.
• To compare the properties of composites with and without the inhibited layer.
• To determine the influence of the inhibited layer on the transverse strength of dental composites.

Main Methods:

• Scanning Electron Microscopy (SEM) was used to examine the morphology of composite surfaces.
• Transverse strength testing was performed on composite specimens.
• Comparisons were made between specimens with and without the removed inhibited layer.
• The effect of reirradiation on the inhibited layer was also studied.

Main Results:

• Removing the inhibited layer in some materials led to increased air bubbles and a porous interface.
• Transverse strength decreased by an average of 26% after inhibited layer removal.
• Specimens with the inhibited layer retained showed significantly less reduction in transverse strength (average <13%).
• The inhibited layer demonstrated potential for secondary polymerization upon reirradiation.

Conclusions:

• The oxygen-inhibited layer plays a significant role in the integrity and strength of visible light-cured composites.
• Removing this layer can compromise mechanical properties and introduce defects.
• Retaining the inhibited layer is beneficial for maintaining composite strength, likely due to its capacity for further polymerization.