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Updated: Jul 18, 2026

Evaluation of the Curing of Adhesive Systems by Rheological and Thermal Testing
Published on: July 3, 2020
Polymerization kinetics of dental adhesives cured with LED: correlation between extent of conversion and permeability
Lorenzo Breschi1, Milena Cadenaro, Francesca Antoniolli
1Department of Biomedicine, Unit of Dental Sciences and Biomaterials, University of Trieste, Via Stuparich 1, I-34129 Trieste, Italy. lbreschi@units.it
Objectives:
The aim of this study was to analyze the polymerization kinetics of different adhesive films in relation to their permeability after exposure to different LED curing units.
Methods:
One adhesive from each class was analyzed: a three-step etch-and-rinse (OptiBond FL; Sybron-Kerr), a two-step etch-and-rinse (One-Step, Bisco), a two-step self-etch (Clearfil Protect Bond, Kuraray) and a one-step self-etch adhesive (Xeno III; Dentsply DeTrey). Adhesive films were prepared and cured with SmartLite IQ (Dentsply) or L.E. Demetron I (Demetron Kerr) up to complete curing. Polymerization kinetic curves of the tested adhesives were obtained with differential scanning calorimetry (DSC). In particular, total reaction time and extent of polymerization (Ep) at 20, 40 or 60s were compared. Permeability of the adhesive films was evaluated on flat dentin surfaces of human extracted teeth connected to a permeability device and statistically analyzed.
Results:
Total reaction time differed among the adhesives tested: OptiBond FL
Significance:
This study supports the hypothesis that, longer curing times than those recommended by the respective manufacturer decrease permeability of the bonded interfaces.
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