In-Depth Evaluation of the Impact of Different Light Curing Techniques on Orthodontic Adhesive Performance: An Elaborate Study of Mechanical Strength, Bond Durability, and Surface Morphology in Vitro

Abstract

Background
Light curing techniques are pivotal in orthodontics for achieving optimal adhesive performance. Different curing methods, such as halogen, LED, and plasma arc, offer distinct advantages and challenges. Understanding the impact of these techniques on mechanical strength, bond durability, and surface morphology is crucial for clinical practice.

Objective: This study aims to assess and compare the effectiveness of halogen, LED, and plasma arc curing techniques on the mechanical strength, bond durability, and surface morphology of orthodontic adhesives.

Materials and Methods: In this in vitro study, 60 human premolar teeth were allocated into three groups (20 each) for halogen, LED, and plasma arc curing. Orthodontic brackets were bonded, and the specimens were subjected to shear bond strength (SBS) testing, thermocycling, and scanning electron microscopy (SEM). Statistical analysis included one-way ANOVA, Tukey’s post hoc test, and paired t-tests with significance set at p < 0.05.

Results: Plasma arc curing achieved the highest mean SBS before (21.5 MPa) and after thermocycling (19.0 MPa), outperforming LED (18.3 MPa and 15.1 MPa) and halogen (15.2 MPa and 12.4 MPa). The plasma arc group exhibited the smallest reduction in SBS (11.6%), indicating superior bond durability. Additionally, plasma arc curing resulted in fewer adhesive failures (50%) and a smoother surface with fewer voids and cracks. It was also the quickest method (6 seconds) and produced the thinnest adhesive layer (40 µm).

Conclusion: Plasma arc curing demonstrated superior performance in bond strength, durability, and surface quality with reduced curing time compared to LED and halogen methods. This suggests that plasma arc curing is the most effective choice for orthodontic adhesive bonding