Light Transmittance and Polymerization of Bulk-Fill Composite Materials Doped with Bioactive Micro-Fillers.

Phoebe Dieckmann,Tobias T Tauböck,Matthias Zehnder,Dirk Mohn,Thomas Attin

doi:10.3390/ma12244087

Abstract

This study investigated the effect of bioactive micro-fillers on the light transmittance and polymerization of three commercially available bulk-fill resin composites. These were mixed with 20 wt% bioactive glass 45S5, Portland cement, inert dental barium glass, or nothing (controls). Composites were photo-activated and light transmittance through 4 mm thick specimens was measured in real time. Moreover, degree of conversion (DC) and Knoop hardness (KHN) were assessed. Light transmittance of all bulk-fill composites significantly decreased (p < 0.05) with addition of 20 wt% bioactive glass 45S5 but not when inert barium glass was added. For bulk-fill composites modified with Portland cement, light irradiance dropped below the detection limit at 4 mm depth. The DC at the top surface of the specimens was not affected by addition of bioactive or inert micro-fillers. The bottom-to-top ratio of both DC and KHN surpassed 80% for bulk-fill composites modified with 20 wt% bioactive or inert glass fillers but fell below 20% when the composites were modified with Portland cement. In contrast to Portland cement, the addition of 20 wt% bioactive glass maintains adequate polymerization of bulk-fill composites placed at 4 mm thickness, despite a decrease in light transmittance compared to the unmodified materials.

Highlights

IntroductionBioactive glasses have been successfully incorporated as fillers into resin-based restorative composites [1,2]
The functionalization of resin composites has opened new paths in dental material research.Recently, bioactive glasses have been successfully incorporated as fillers into resin-based restorative composites [1,2]
Scanning electron electronmicroscopy microscopyimages imagesofofthe the micro-filler particles used as additional fillers micro-filler particles used as additional fillers for for bulk-fill the bulk-fill composite materials

Summary

Introduction

Bioactive glasses have been successfully incorporated as fillers into resin-based restorative composites [1,2]. Composites functionalized with bioactive glasses have been shown to release ions (e.g., calcium and phosphate) [3,4] into the dentin matrix which might prevent formation of secondary caries lesions [5,6]. Another promising property of bioactive glasses of the 45S5 type is their ability as alkaline biomaterials to create a high pH environment that inhibits bacterial growth [7,8]. Khvostenko and co-workers [11] found that the mechanical properties of composites containing up to 15% bioactive glasses were comparable, or even

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Discussion

Conclusion