Flexural Properties, Wear Resistance, and Microstructural Analysis of Highly Filled Flowable Resin Composites and Packable Composites

Abstract

Background: This study was conducted to assess the flexural properties, wear resistance, and for microstructural analysis of highly filled flowable resin composites and packable composites.

Material and methods: For each group of resin composites (n=10), a total of 10 specimen bars were produced utilizing a silicon mold to facilitate the assessment of flexural strength (FS), flexural modulus (E), flexural toughness (FT), Weibull modulus (m), and scanning electron microscopy (SEM) microstructural analysis. Within each group, 8 bars underwent testing via a three-point flexural test on a universal testing machine, while the remaining 2 bars were embedded in acrylic resin for subsequent SEM examination to analyze their structural characteristics. In the two-body wear test conducted with a chewing simulator, 6 specimens from each resin composite group were created using a designated mold and subjected to 120,000 wear cycles against a steatite ball, with the depth of material loss being recorded. To evaluate the differences in flexural and wear properties across the various groups, three one-way ANOVA tests were performed, followed by Tukey's post hoc tests.

Results: In this study, the mean flexural strength of packable composites (128.26±47.6 Mpa) was higher than that of flowable composites (106.56±89.5 Mpa). The flexural modulus of flowable composites (4.63 Gpa) was lower than that of packable composites (11.65 Gpa). It was observed that flowable composites showed 20.3 µm wear while the packable composites showed 9.7 µm wear, indicating that packable composites have better wear resistance as compared to flowable composites.

Conclusion: From the results of this study, it can be concluded that packable composites have superior wear resistance, flexural modulus and flexural strength as compared to highly filled flowable composites. Even though the filler content is high in flowable composites, packable composites are still better than flowable composites and can also be used for posterior restorations.