This study evaluated the effects of light‑curing source and time on shear bond strength (SBS) and degree of conversion (DC%) of an orthodontic resin‑composite adhesive. Brackets were bonded to bovine incisors using Transbond XT and cured with either a quartz‑tungsten halogen or a second‑generation LED light. SBS was measured at 5 minutes, 60 minutes, and 24 hours, and DC% was assessed using FTIR spectroscopy. Light source type had no significant effect on SBS or DC%. SBS increased significantly over time, while DC% remained unchanged. These findings support the clinical use of second‑generation LED curing units due to comparable performance with reduced curing time.
