Evaluation of Irradiance and Composite Depth of Cure with a Laser Curing Light over Distance: An In Vitro Study

This study compared the irradiance and depth of cure (DOC) of two resin-based composites (RBCs) polymerized using a novel laser diode (LD) light-curing unit (LCU) vs single-spectrum (SS) and multispectrum (MS) light-emitting diode (LED) LCUs across clinically relevant distances.

Irradiance was measured for each LCU using a spectrometer over six tested distances (0, 2, 4, 6, 8, and 10 mm). For DOC assessment, two RBC materials were polymerized in standardized cylindrical metal molds (4 mm diameter × 6 mm height). Five RBC specimens were fabricated per group based on four LCU and curing time combinations (LD: 1 and 3 seconds; SS: 10 seconds; and MS: 10 seconds) and six distances (0, 2, 4, 6, 8, and 10 mm) resulting in 120 specimens per RBC type and 240 total specimens. Depth of cure was determined using the scraping technique. Data were analyzed using analysis of variance with Tukey's post-hoc tests (α = 0.05).

From 0 to 10 mm, the LD LCU exhibited a 6.6% increase in irradiance, while the SS and MS LED LCUs showed substantial decreases of 63.7% and 49.4%, respectively. Significant differences in DOC were observed among LCUs, influenced by curing distance and RBC type (p < 0.05). Specifically, the LD LCU with a 3-second exposure yielded the highest DOC for both RBCs across all distances. In contrast, the LD with a 1-second exposure generally resulted in the lowest DOC.

Compared with SS and MS operating at 10 seconds, the LD LCU maintained irradiance more effectively and achieved the highest DOC at distances up to 10 mm using only 3-second exposures with both RBCs.

This study aimed to evaluate the irradiance and DOC of a novel LD LCU compared with traditional LED units, especially over varying distances relevant to clinical practice. The clinical translational value lies in the potential for the LD unit to offer more effective and consistent polymerization of RBCs in challenging intraoral situations where maintaining close proximity to the restoration is difficult. This could lead to more durable and successful dental restorations by ensuring adequate material curing even at increased working distances. How to cite this article: Sanabria O, Gedge JL, Mitchell TM, et al. Evaluation of Irradiance and Composite Depth of Cure with a Laser Curing Light over Distance: An In Vitro Study. J Contemp Dent Pract 2025;26(5):462-467.