Micro‐computed tomography evaluation of internal void formation of bulk‐fill resin composites in Class II restorations

Abstract

The aim of this study was to quantify the internal void volume formation in bulk‐fill resin composites with using 3D micro‐computed tomography (μCT). Class II box cavities in 4‐mm depth were prepared and treated with Clearfil S3 Bond Plus (Kuraray Medical). Five resin composites were evaluated: one conventional paste‐like (Filtek Ultimate Universal Restorative‐as the control), one conventional flowable (Filtek Ultimate Flowable Restorative), two flowable bulk‐fill (Voco Extrabase, SDR), one paste‐like bulk‐fill (Filtek One BulkFill Restorative). Resin composites were light cured using a light‐emitting diode light‐curing unit (SDI Radii Plus, SDI Limited, Australia). Samples were evaluated by μCT, and data were imported into software The NRecon (ver. 1.6.10.4, SkyScan) and CTAn (ver. 1.16.1.0, SkyScan) for 3D reconstruction, from which the percentage of void volume was calculated. Data were analyzed using the Kruskal‐Wallis test and the Mann–Whitney U‐test at a significance level of 5%. All restorative tested materials showed different levels of voids. Filtek One BulkFill Restorative showed the least void formation, which was statistically less than that of the conventional flowable composite group (p < 0.05). All other restorative materials showed similar void formation. POLYM. COMPOS., 40:2984–2992, 2019. © 2018 Society of Plastics Engineers

Micro-computed tomographic evaluation of the effects of pre-heating and sonic delivery on the internal void formation of bulk-fill composites

“…Moreover, they can lead to increased water sorption and contribute to the anisotropic behavior of the composite 8) . Several studies have used micro-CT 1,23,28) , optical coherence tomography 24,29) or classical sectioning method 30,31) to evaluate the internal and marginal adaptation or void formation of restorative materials. Specimen sectioning is damaging and labor-intensive process and cannot provide 3D quantification of the entire restoration mass.…”

“…Insertion method may lead to varying amounts of internal voids depending on the material brand since their viscosities may differ with respect to insertion techniques. Despite the few studies that have examined the internal void formation of dental resin composites 1,[22][23][24] , there are no studies that have compared the effects of different insertion techniques on internal void formation of different bulk-fill composites.…”

“…Besides these inherent factors, operator related factors could also influence the overall mechanical behavior of the resin composite. During the placement of the resin composite into the cavity, operator could lead to void formation in between the layers of the composites 1) . Moreover, viscosity of the composite material could also affect the void formation incidence [2][3][4] .…”

Quantification of porosity in composite resins delivered by injectable syringes using X-ray microtomography

“…Estimates of the amount of porosity in CPRs varies between studies and falls mostly within the range of 0.5-4 vol% [10][11][12][13]. The inconsistency may be explained by material handling factors in the laboratory or clinic, as well as the inherent properties of the material itself as a function of qualities and quantities of oligomers and fillers.…”

“…The method is non-invasive, three-dimensional and can be used to appraise the amount of porosity both in polymerised and in unpolymerised specimens. While many studies have measured the amount of porosity in polymerised CPRs [10][11][12][13], nobody hasto the knowledge of the authorsundertaken studies of whether the unpolymerised material within CPR compules may include pores. Quantifying and characterising such pores can provide knowledge about potential sources of pores in dental restorations.…”