Evaluation of microhardness, sorption, solubility, and color stability of bulk fill resins: A comparative study

Abstract

Background Due to the increasing popularity of bulk fill resins, there is a concern that their components can be leached; this is because these are inserted in a single 4-5 mm increment. This in vitro study evaluated the microhardness, sorption, solubility, and color stability of three restorative bulk fill resins, namely: Filtek Bulk Fill (FBF), Tetric N-Ceram Bulk Fill (TNC), and Opus Bulk Fill (OBF). Material and Methods Cylindrical samples were fabricated to be 15 mm in diameter and 1 mm thick (n = 10). For the microhardness test, three random indentations were formulated on the samples using a micro-durometer with a load of 300 gf for 15 s. Sorption and solubility were then evaluated (ISO 4049: 2009). Color stability was analyzed with a digital spectrophotometer three times (initially, after 24 h, and after 7 d) during immersion in coffee and distilled water (control). The Shapiro-Wilk test was applied to analyze normality. The Mann-Whitney and Kruskal-Wallis tests were used to compare the groups and the immersion solution, with a significance level of 5%. Results There were a significant difference in microhardness ( p <0.001), with the FBF group showing a higher value compared to the other groups (56.38). The highest average of sorption scores was observed in the OBF group (16.9 µg / mm3), followed by FBF (16.8 µg / mm3) and TNC (11.3 µg / mm3). Solubility was lowest in the OBF group (-2.83 µg / mm3), with a significant difference ( p = 0.031). There was also a significant difference after 24 h in the mean ∆E score of all groups ( p <0.005). After one week of immersion, the group that pigmented most was OBF ( p = 0.008). Conclusions The three bulk fill resins had acceptable hardness, sorption, and solubility values. However, all groups showed a high pigmentation rate after 7 d of immersion in coffee. Key words: Bulk fill, color stability, composite resins, microhardness, solubility, sorption.

The Microhardness and Surface Roughness Assessment of Bulk-Fill Resin Composites Treated with and without the Application of an Oxygen-Inhibited Layer and a Polishing System: An In Vitro Study

“…This could contribute to improving the survival rate of restorations since it has been reported that having poor surface properties can lead to pigment retention, plaque, the possibility of fracture, and secondary caries formation [ 9 , 10 , 11 , 30 ]. As a strength of the present study, it should be mentioned that several authors such as Wheeler et al [ 12 ], Paravina et al [ 21 ], Espindola et al [ 51 ], and Bouschlicher et al [ 53 ] have assessed only one surface property of resin composites, while in the present study, two surface properties could be assessed in the same sample unit, reducing the bias that would be obtained by assessing surface microhardness and surface roughness in different study units. Furthermore, according to the obtained results, it is evident that the Tetric N-Ceram Bulk Fill and Filtek Bulk Fill resin composites with OIL control and after polishing improved their surface properties, which could favor a better esthetic and functional performance under masticatory forces [ 25 , 39 , 40 , 46 ], while in the case of Opus Bulk Fill, only its surface roughness was significantly improved, which could allow a better esthetic performance but not necessarily an improvement in its resistance to masticatory forces.…”

“…Previous studies have shown that ivocerin acts as a polymerization enhancer, allowing it to be efficient [ 2 , 3 , 49 ]. Filtek Bulk Fill is a composite resin that has camphorquinone as a photoinitiator, with an absorption peak of approximately 470 nm that matches the wavelength emitted by most LED-curing lights on the market [ 51 ], which could improve the conversion degree of the resin composite by increasing its surface microhardness, as it has been shown with a variety of different composite resins that 80% of maximum hardness is associated with 90% of maximum polymerization [ 52 , 53 , 54 ].…”

Color stability of resin‐based composites: Staining procedures with liquids—A narrative review

“…Any disagreement was resolved by discussion. After full text reading 178 studies 11,13–189 were included in the review (Figure 1).…”

Characterization of whitening toothpastes and their effect on the physical properties of bulk-fill composites

“…9 These alterations promote a change in surface smoothness, loss of gloss, and color change because the surface roughness also interferes directly with the intensity and rate of pigmentation. 13 - 14 This is why it is imperative to assess the characteristics of these toothpastes and their effect on restorative materials.…”

“… 5 , 13 Intrinsic factors are associated with material degradation due to components such as organic matrix composition and the initiator system, whereas the size, content, and hardness of the filler particles are directly influenced by photopolymerization. 14 - 15 Extrinsic factors are associated with pigment adsorption and absorption derived from sources such as nicotine, medications, and the patient’s diet. 14 - 15 Color stability can be compromised by chromogenic beverages, depending on the pH, and the frequency and duration of contact of these beverages with the material.…”