Effect of preheating on polymerization shrinkage strain of BIS-GMA free and containing resin composite restorative materials (in vitro study)

Abstract

Background This study investigated the effect of preheating of bulk-fill BIS-GMA free and containing resin composite on post-gel shrinkage strain. In a split Teflon mold, sixty resin composite specimens were prepared with dimensions 7 mm length × 4 mm width × 4 mm height. Thirty specimens of each tested restorative materials were prepared, ten specimens for each selected temperature used in the study (room temperature 23 °C, 50 °C and 65 °C). The resin composite was monitored for post-gel shrinkage strain for 3 min after light irradiation using strain gauges. For pairwise comparisons, Duncan’s multiple range test was used to analyze the data after two-way ANOVA. The p ≤ 0.05 significance level was chosen. Results Viscalor thermoviscous bulk-fill composite Bis-GMA containing had the lowest polymerization shrinkage strain values in the three different temperatures. There was a statistically significant difference between groups according to material used at different temperatures. Both tested materials showed the highest shrinkage strain when preheated at 65 °C. Conclusions While the technology of thermoviscous is introduced to deliver the viscosity of a flowable resin composite so reducing the polymerization strain, it actually had adverse effect on it. Preheating of bulk-fill BIS-GMA free resin composite either to 50 °C or 65 °C had no effect on decreasing the polymerization shrinkage strain. Polymerization shrinkage strain of bulk-fill BIS-GMA contains resin composite either without or with preheating far superior to that of BIS-GMA free resin composite.

Effect of preheating of bulk-fill resin dental composite on polymerization shrinkage strain

“…The results of this study were in disagreement with Kampanas in 2018 (42) who found higher polymerization shrinkage in preheated resin composites since polymerization shrinkage is directly proportional to the degree of conversion. These results were in agreement with Lotfy et al in 2022 (43) who found that VisCalor thermo-viscous bulk-fill composite has a lower polymerizing shrinkage strain values than Admira fusion X-tra and also in agreement with Deb et al in 2011 (25) where they found that the preheating of dental composites significantly improves the linear polymerization shrinkage and degree of conversion, also with Lohbaurer et al in 2009 (44) as they found that preheating composite resins didn't significantly increase the polymerization shrinkage strain. These results were also in disagreement with ElKorshy in 2010 (45) where preheating of resin composite enhanced its degree of conversion and also increased post-gel shrinkage strain, and this was attributed to three reasons: first preheating resulted in a higher rate of polymerization where a rapid stress built-up was created within the composite resin.…”

“…To evaluate the effect of different resin composites on polymerization shrinkage, an independent t-test or an equivalent non-parametric test is applied for comparison between two groups. Based on Lotfy et al in 2022 (43) , polymerization shrinkage varied from 635±54.77 to 569±51.16.…”

Surface Roughness of Bis-GMA Free Resin Composite in Comparison With Bis-GMA Containing Resin Composite (In-vitro Study)

“…Admira Fusion-Ormocer, a nano-hybrid bulk fill Ormocer-based resin composite, is the only brand of the most recent generation of pure Ormocer-based composite resin. 15,16,17 Admira Fusion (VOCO), in comparison to other resins that have dimethacrylate monomer matrix, has low shrinkage (1,25%) ceramic polysiloxane. This type of ormocer improves biocompatibility, aesthetics, caries protection, abrasion resistance, and decreases surface roughness as well as polymerization shrinkage, with absence of cytotoxicity found in classic monomers, such as TEGDMA and BisGMA.…”

“…The resin composite could shrink easily that's because the mold was made of Teflon material, which doesn't adhere to it. 16 The system of choice for polishing discs was the Sof-lex polishing discs. Because of its ability to make polished surfaces that are smooth, non-destructive, and less susceptible to chemical dissolution, aluminium oxide discs have been recommended as a standard approach.…”

In Vitro Evaluation of the Strength of Dentin Replacement in Complex Posterior Tooth Restoration

“…Direct composite resin restorations exhibit certain limitations, such as resistance to fracture and polymerization shrinkage [8][9][10][11][12][13][14]. However, the mechanical properties and longevity of composite resin restorations are affected by their composition and viscosity [7,8,15,16].…”