Influence of Preheating Procedure and Polymerization Modes on Degree of Conversion of Contemporary Resin Composites

Year 2025, Volume: 35 Issue: 1, 65 - 70, 20.01.2025

Özge Gizem Yenidünya Ahmet Erdem Nilgün Akgül , Başak Yazkan Mutlu Özcan

https://doi.org/10.17567/currresdentsci.1617446

Abstract

Objective: To evaluate the effects of preheating procedure and polymerization modes on degree of conversion (DC) of resin composites.
Methods: Three different types of composites - a conventional (GrandioSO - [GSO]), a bulkfill (GrandioSO x-tra - [GSX]), and a thermoviscous bulkfill (VisCalor bulk - [VCB]) - were investigated. Three specimens were prepared for each combination of the variables (composite type*preheating procedure*polymerization mode). Photo-polymerization was performed using an LED operated in standard (SM), high power plus (HM), and x-tra power (XM) modes. DC was measured with Fourier Transform Infrared Spectroscopy after 5 min and 24 h post-irradiation. Furthermore, three-way analysis of variance followed by a Tukey test at a significance level of P <.05 were performed to compare the DC values.
Results: Considering the DC values at two post-irradiation time, preheated VCB group polymerized with HM gave the highest DC value, while GSX cured with XM, regardless of the preheating exhibited the lowest one. Preheating application caused a statistically significant increase in the DC values of the VCB*SM, VCB*HM, and GSO*HM groups at both evaluation periods, and the GSX*SM group at 24h post-irradiation. Regarding the polymerization mode, the ranking depending on the significant differences among all preheated composites tested at both time intervals was HM > SM > XM.
Conclusion: Preheating generally exhibited favorable effects on the DC of all tested composites, with the most significant impact observed in VCB. Additionally, polymerization with x-tra power mode is not recommended to achieve a sufficient DC required for clinically acceptable restorations.
Keywords: bulk fill composite; degree of conversion; FTIR; polymerization mode; preheating; thermoviscousity

Keywords

bulk fill composite, degree of conversion, FTIR, polymerization mode, preheating

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