Errors in light-emitting diodes positioning when curing bulk fill and incremental composites: impact on properties...

Area of Science:

• Dental Materials Science
• Polymer Chemistry
• Biomaterials Engineering

Background:

• Dental composite polymerization relies on light-curing devices.
• Inconsistent curing light positioning can compromise restoration integrity.
• Bulk fill and incremental composites have distinct handling and curing characteristics.

Purpose of the Study:

• To assess the impact of improper light-emitting diode (LED) positioning on dental composites.
• To compare single-peak and multi-peak LED curing efficacy.
• To evaluate effects on color stability, microhardness, and surface topography after aging.

Main Methods:

• Bulk fill and incremental composites were cured under optimal and varied angulation/displacement conditions.
• Curing was performed using single-peak and multi-peak LED devices.
• Specimens underwent 1-year water aging followed by analysis of color change (ΔE), Vickers hardness, and surface topography (Ra, Rt, Rv).

Main Results:

• Single-peak LED curing with improper positioning significantly increased color change (p < 0.001).
• Multi-peak LED curing showed significant effects of composite type and condition on color change (p < 0.001).
• Both LEDs demonstrated that composite type and curing conditions affected Vickers hardness and bottom/top hardness ratios (p < 0.01).

Conclusions:

• Bulk fill composites exhibited superior wear resistance, color stability, and microhardness compared to incremental composites under improper curing.
• Multi-peak LEDs provided improved polymerization under suboptimal conditions versus single-peak LEDs.
• Appropriate light-curing technique is crucial for reliable, long-term clinical outcomes in dental restorations.