Which direct composite has the best polishability and color stability compared with OMNICHROMA?

4. Discussion

Thus, standardizing the curing protocol with adequate light irradiation and exposure time, visible light irradiance and wavelengths, and the correct distance between LCU tips are essential to avoid variations in attachment accuracy. The color stability of composite resins is a fundamental parameter in material selection, especially for esthetic areas. In general, studies indicate that coffee and red wine are the most aggressive staining agents, inducing color changes beyond clinically perceptible thresholds [17,20,23]. In clinical trials, ref. [28] confirmed that G-ænial Universal Injectable showed less color change after exposure to staining substances, a result attributed to its high inorganic filler density, filler distribution, particle shape and size, and low content of aromatic monomers. These findings reinforce that chemical composition and surface finishing are determining factors for esthetic performance, with the use of nanoparticulate composites being recommended in anterior regions [20,23]. The study by Erçin, ref. [25] demonstrated that Omnichroma (Tokuyama) showed the best performance in terms of color stability, followed by GC Aligner Connect, while Tetric PowerFlow exhibited the highest color change after immersion in coffee. These results corroborate previous findings by Feinberg et al. [24], who identified the direct influence of the matrix composition and the amount of nanometric particles on stain resistance.

Material Properties of Composite Resins Used for Orthodontic Attachments in Clear Aligner Therapy: A Systematic Review. © 2026 by the authors. Creative Commons Attribution 4.0 International (https://creativecommons.org/licenses/by/4.0/).

Tables and figures

Table 3 — Comparison of performances of composite resins according to evaluated outcomes. Outcome | Best-Performing Materials | Lower-Performing Materials | Main Findings/Trends Surface Roughness | Composite resins with high filler loads and increased viscosity: 3M: Bis-GMA, UDMA, Bis-EMA, silica, zirconia nanoparticles (20 μm) (72.5 wt%) | Flowable composite resins (e.g., Aligner Connect under high irradiance) Aligner Connect, GC: Octahydro-4,7-methano-1H-(indenediyl) bis(methylene) bismethacrylate,1,3,5-triazine-2,4,6-triamine, polymer with formaldehyde, 2,2′-ethylene- dioxydiethyl dimethacrylate, 2-(H-benzotriazol-2-yl)-p-cresol, UDMA. Inorganic filler content not disclosed. | Higher-viscosity materials show smoother surfaces; flowable composite resins may increase roughness. Microhardness (VHN) | Optimized flowables (e.g., Clearfil Majesty Flow) and composite resins with high inorganic filler contents and increased viscosity. Clear fill Majesty Flow: TEGDMA, hydrophobic aromatic dimeth- Acrylate, dl-Camphorquinone · accelera- tors · | Variable depending on composition | Depends on filler type and polymerization; no consistent superiority. Color Stability | Nanohybrid/high-filler composite resins (e.g., Omnichroma, G-ænial Universal Injectable) | Flowable composite resins, e.g., Tetric PowerFlow: Bis-GMA, Bis-EMA, UDMA, DCP, barium aluminum silicate glass, iso-filler copolymer mix, ytterbium fluoride (71 wt%) | Coffee and wine cause highest discoloration; higher filler improves stability. Accuracy of Attachment Reproduction | High-viscosity composite resins with PET-G molds | Flowable composite resins | High-viscosity resins show better shape fidelity; flowable composites may cause excess.

Material Properties of Composite Resins Used for Orthodontic Attachments in Clear Aligner Therapy: A Systematic Review. © 2026 by the authors. Creative Commons Attribution 4.0 International (https://creativecommons.org/licenses/by/4.0/).

1. Introduction

Polishability is an important characteristic of composite resins: a smooth surface gives the restoration better aesthetics and comfort to the patient, reduces discoloration, facilitates hygiene [9,10,11,12], decreases bacterial adhesion [10], and reduces tissue inflammation, secondary caries, biofilm retention [9,10,13,14] and the risk of fracture [11]. Similarly, the use of composites is relevant in other clinical fields, such as orthodontics, where polishing systems play an important role after the treatment to ensure aesthetics and to reduce associated dental or periodontal complications [15,16,17,18]. A polished surface reduces initial bacterial adhesion and the development of biofilm in the restoration and the adjacent dental surfaces [19]. The surface roughness threshold for bacterial retention is 0.2 μm; below this, a reduction in plaque accumulation could be expected [20]. Changes of even 0.3 μm in the surface finish can be easily detected by the tongue [8,12]. Finishing procedures remove excess material with particles larger than 25 μm, while polishing procedures remove particles smaller than 25 μm [12]. At present, it is believed that composite resins with nano-filled particles obtain a better polish and shine after being subjected to different polishing processes. However, in a systematic review carried out by Kaizera et al. [21], it was concluded that there are no statistically significant differences in the polishing and brightness of composite resins with nano-filled particles vs composite resins with hybrid or nano-hybrid particles.

Effect of Polishing Systems on the Surface Roughness of Nano-Hybrid and Nano-Filling Composite Resins: A Systematic Review. © 2021 by the authors. Creative Commons Attribution 4.0 International (https://creativecommons.org/licenses/by/4.0/).

3.1.1. Optical Properties and Color Stability of Highly Filled Flowable Composite Resins

The findings on optical properties indicate that highly filled flowable composite resins exhibit an acceptable color stability, supporting their potential use in esthetically demanding restorations. Initially, Nair et al. demonstrated that a highly filled flowable composite resin performed inferiorly compared to nanofilled and nanohybrid conventional composites [55]. Owing to recent developments in highly filled flowable composites, no statistically significant differences were found in color stability among highly filled flowable composite resins, a bulk-fill flowable composite, and a conventional nanofilled composite resin [56]. Interestingly, Tüter Bayrakrat et al. reported that conventional composite resins had lower fluorescence (ΔEFI) and color adjustment (ΔECP) levels compared to highly filled flowables in class V cavities [62]. Color changes due to toothbrushing abrasion remained within acceptable thresholds when highly filled flowables were compared with traditional and self-adhesive flowables [69].

Highly Filled Flowable Composite Resins as Sole Restorative Materials: A Systematic Review. © 2025 by the authors. Creative Commons Attribution 4.0 International (https://creativecommons.org/licenses/by/4.0/).

4. Discussion

It is important to highlight that long-term color stability is also influenced by the staining capability of the restorative material when it is in contact with foods and beverages containing dyes. The scoping review conducted by Paolone et al. [34] presented conflicting in vitro studies regarding the single-shade bulk-fill resin Admira Fusion X-tra. One study revealed that this single-shade resin exhibited a higher discoloration rate than conventional bulk-fill resin did, while another study revealed that it had less pigmentation after artificial aging. The negative behavior was likely attributed to insufficient integration between the resin matrix and the siloxane particles, allowing greater dye diffusion [34]. In contrast, the positive behavior was due to the conventional bulk-fill resin comparator having a higher organic matrix content [34]. In an in vitro study, Omnichroma resin also showed a high staining potential after storage challenges in tea and red wine, especially compared to a multi-shade resin. Omnichroma contains low molecular weight monomers, increasing water sorption [35]. Resins with pigments tend to have better color matching after staining, which also explains the behavior of the Filtek universal resin, which shows a greater predisposition to color changes compared to other studied multi-shade resins [36].

Color Stability of Single-Shade Resin Composites in Direct Restorations: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. © 2024 by the authors. Creative Commons Attribution 4.0 International (https://creativecommons.org/licenses/by/4.0/).

Tables and figures

Table 3 — In vitro studies incorporating conventional composite resins into their methodological framework. Author/Year | Dental Materials and Procedures | Tested Parameters and Key Findings Francois et al., 2024 [67] | Nine highly filled flowable resin composites + viscous composites + traditional flowable composites | Flexural strength/wear resistance: Most highly filled composites exhibited-similar flexural strength-superior wear resistancecompared to viscous composites. Elastic modulus: Conventional composite resins > highly filled flowables > traditional flowables Jrady et al., 2024 [68] | (1)Microhybrid composite resin (Gradia Direct Anterior, GC Corp., Tokyo, Japan)(2)Nanohybrid composite resin (Palfique LX5, Tokuyama Dental Corp, Tokyo, Japan)(3)Nanofilled composite resin (Filtek Universal, 3M ESPE, St. Paul, MN, USA)(4)Highly filled flowable composite resin (G-aenial Universal Injectable, GC)Polishing procedures:(1)No polishing (control group)(2)4-step polishing using aluminum oxide discs (Sof-Lex polishing discs, 3M ESPE)(3)3-step polishing using silicon rubber diamond discs (Astropol, Ivoclar Vivadent, Schaan, Lichtenstein)(4)1-step polishing (Charisma Easyshine, Kulzer Dental, Hanau, Germany)+ immersion in water or coffee | Color stability: Material type, polishing technique, storage media, and their interaction influence ΔΕ values. The lowest color change is present inHighly filled flowable composite resin compared to other materials3-step polishing diamond discs compared to other polishing proceduresWater compared to coffeeHighly filled flowable composite resin is more resistant to staining

Highly Filled Flowable Composite Resins as Sole Restorative Materials: A Systematic Review. © 2025 by the authors. Creative Commons Attribution 4.0 International (https://creativecommons.org/licenses/by/4.0/).

4. Discussion

The vast majority of studies reported a control group, with the application of a pressure Mylar band on the composite resin being the most popular, with a total of 328 samples and an average of Ra 0.1281. However, Alawjali and Lui in 2013 published an in vitro study in which they demonstrate that Mylar groups generate greater color change after being subjected to different substances with pigments, and mention that the increase in discoloration can be explained by the presence of a layer rich in the composite resin matrix that is formed on the surface of the restoration [44]. It has also been shown that the polishing achieved with the Mylar strip results in surfaces with less hardness (versus abrasive polishing systems) and, consequently, greater discoloration [44]. Therefore, the removal of the composite resin matrix by finishing and polishing will allow the harder filler particles to remain in contact with the surface during polishing, producing a harder and pigment resistant surface [20].

Effect of Polishing Systems on the Surface Roughness of Nano-Hybrid and Nano-Filling Composite Resins: A Systematic Review. © 2021 by the authors. Creative Commons Attribution 4.0 International (https://creativecommons.org/licenses/by/4.0/).

Discussion

Different composite materials may have distinct resin compositions as well as filler particles with varying sizes and compositions. The sensitivity of the surface to damage may therefore vary [17]. For example, although the better polishability and aesthetic appearance of nanofill resin-based composites are considered superior to nano- or micro-hybrid resin-based composites, due to the larger surface area/volume ratio of the filler particle system, nanofill resin-based composites may undergo a higher degree of degradation during function in the oral cavity [26]. Nemeth et al. reported that the effect of air polishing on micro-hybrid resin-based composite was more than three times, while it was less aggressive on nano-filler resin-based composite [27]. Crea-lign, which contains only nanoparticles and no glass filler, and Gradia, which contains prepolymer and glass particles as filler, showed similar mechanical and optical properties after air-polishing. However, the fact that C-e is the only group that does not show a significant difference in hardness measurements depending on time can be explained by the higher durability of Crea-lign due to its filler content.

Effects of types of air polishing powders on roughness, microhardness, color, and gloss of gingiva-colored resin-based composites. © The Author(s) 2025. Creative Commons Attribution 4.0 International (https://creativecommons.org/licenses/by/4.0/).