Silorane- and high filled-based"low-shrinkage" resin composites: shrinkage, flexural strength and modulus

Cesar Augusto Galvão Arrais,Frederick Allen Rueggeberg,Donald Mettenburg,Marcelo Giannini,Marcelo Tavares De Oliveira

doi:10.1590/s1806-83242013005000001

Cesar Augusto Galvão Arrais, Frederick Allen Rueggeberg + Show 3 more

Open Access

https://doi.org/10.1590/s1806-83242013005000001

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Abstract

This study compared the volumetric shrinkage (VS), flexural strength (FS) and flexural modulus (FM) properties of the low-shrinkage resin composite Aelite LS (Bisco) to those of Filtek LS (3M ESPE) and two regular dimethacrylate-based resin composites, the microfilled Heliomolar (Ivoclar Vivadent) and the microhybrid Aelite Universal (Bisco). The composites (n = 5) were placed on the Teflon pedestal of a video-imaging device, and VS was recorded every minute for 5 min after 40 s of light exposure. For the FS and FM tests, resin discs (0.6 mm in thickness and 6.0 mm in diameter) were obtained (n = 12) and submitted to a piston-ring biaxial test in a universal testing machine. VS, FS, and FM data were submitted to two-way repeated measures and one-way ANOVA, respectively, followed by Tukey's post-hoc test (a = 5%). Filtek LS showed lower VS than did Aelite LS, which in turn showed lower shrinkage than did the other composites. Aelite Universal and Filtek LS exhibited higher FS than did Heliomolar and Aelite LS, both of which exhibited the highest FM. No significant difference in FM was noted between Filtek LS and Aelite Universal, while Heliomolar exhibited the lowest values. Aelite LS was not as effective as Filtek LS regarding shrinkage, although both low-shrinkage composites showed lower VS than did the other composites. Only Filtek LS exhibited FS and FM comparable to those of the regular microhybrid dimethacrylate-based resin composite.

Highlights

Despite improvements in the mechanical properties of resin composites (RCs), polymerization shrinkage still remains a challenge and imposes limitations on the clinical use of RCs.[1]
Shrinkage is caused by an exchange of van der Waals spaces for shorter covalent bond spaces when monomer molecules are converted into a polymer network.[2]
Since the microhybrid dimethacrylate-based RC is recommended for posterior teeth, its mechanical properties were used as a reference for comparison with the mechanical properties of both LSRCs

Summary

Introduction

Despite improvements in the mechanical properties of resin composites (RCs), polymerization shrinkage still remains a challenge and imposes limitations on the clinical use of RCs.[1] Shrinkage is caused by an exchange of van der Waals spaces for shorter covalent bond spaces when monomer molecules are converted into a polymer network.[2] The resulting composite shrinkage of 2%–5%3,4 generates stress at the dentin/adhesive interface,[5,6] causing cusp deflection[7,8] or de-bonding, marginal staining, enamel cracking, and/or post-operative sensitivity.[9]. Many strategies have been proposed to reduce the shrinkage stress created during the polymerization of RCs into the prepared tooth cavity. Some of these techniques include the use of liners and the incremental placement of composites to allow them to shrink freely toward the adhesive interface.[10] Other strategies focus on slowing down the polymer-

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