Are Commercially Available Orthodontic Adhesive Systems Suitable for Rapid (3 s) High-Intensity Light Curing?

With the growing use of high-intensity LED units in orthodontics, the effect of ultra-fast curing protocols on polymerization efficiency remains unclear. This study aimed to evaluate the influence of conventional and rapid high-intensity light curing protocols on the degree of conversion (DC) of ort...

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Main Authors: Ivona Profeta Krznar, Senka Meštrović, Helena Miler, Danijela Marovic, Zrinka Tarle, Matej Par
Format: Article
Language:English
Published: MDPI AG 2025-07-01
Series:Applied Sciences
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Online Access:https://www.mdpi.com/2076-3417/15/14/7641
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Summary:With the growing use of high-intensity LED units in orthodontics, the effect of ultra-fast curing protocols on polymerization efficiency remains unclear. This study aimed to evaluate the influence of conventional and rapid high-intensity light curing protocols on the degree of conversion (DC) of orthodontic adhesive systems. Three commercially available materials were tested under two conditions, without bracket interference (control group, CG) and with a metal bracket present during curing (metal bracket group, MBG). Two light-curing protocols were employed: conventional curing, using two consecutive 10 s exposures at 1100 mW/cm<sup>2</sup>, and rapid curing, with two consecutive 3 s exposures at 2900 mW/cm<sup>2</sup>. The DC was assessed via Fourier-transform infrared (FTIR) spectroscopy at short-term intervals (2, 6, and 10 min) and after 24 h. The results showed that rapid high-intensity curing yielded significantly lower DC values at both the short term and 24 h period compared to the conventional protocol. Short-term DC values ranged from 44.4% to 64.4% for conventional curing and from 43.0% to 60.0% for rapid curing. At 24 h, DC values increased for all materials, reaching 54.4–82.8% in the conventional group and 49.7–81.4% in the rapid curing group. The largest difference in DC values between curing protocols was observed in the MBG, with reductions of up to 5.9% (short-term) and 4.7% (24 h). The 24 h DC values were mostly material-dependent, while external factors (curing protocol and the presence of a bracket) had more impact on the short-term DC values.
ISSN:2076-3417