Which direct composite has the best polishability and color stability?

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/).

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/).

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/).

4. Discussion

Regarding the composite resins reported in the different studies, it should be noted that although Filtek Supreme XT (transparent shade and dentin shade) and Tetric EvoCeram resin obtained the best results, the results obtained were averaged considering only 30 samples for each composite resin and these were obtained only from the study of Senawongse et al. [29], the results obtained after the composite resins with nanoparticles were subjected to the different polishing systems are highlighted in this study, with average values of Ra (µm) from 0.016 to 0.088 obtained. Therefore, it is evident that this study is one of the lowest reported surface roughness values, which suggests that Filtek Supreme XT and Tetric EvoCeram resins are not necessarily the best polished composite resins.

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/).

CONCLUSION AND CLINICAL SIGNIFICANCE

The findings of this study may not be directly applied to the clinical situation because of the continuous staining procedure, absence of the effects of the complex oral environment, and habitual oral hygiene effects; nonetheless, they provide an indication of the effect of these staining solutions on the color stability of dental resin composites. Within the limitations of this study, we concluded that, overall, Soflex discs finish resulted in better color stability compared to White polishing stone and Mylar finish for both the nanofill and the microhybrid composites; therefore, clinicians may accomplish best results if they complete these restorations using the Soflex discs. All staining solutions caused clinically unacceptable discolouration of all specimens finished with mylar and white stone. For Soflex finish, red wine produced clinically unacceptable color difference beyond 48 h; therefore, the effect of the staining solution was found to be dependent on the polishing protocol, which ideally should be determined by the type of filler system. Patients should be advised to consume potentially staining foods or beverages in moderation.

Effect of finishing protocols and staining solutions on color stability of dental resin composites. © 2022 The Authors. Clinical and Experimental Dental Research published by John Wiley & Sons Ltd. 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/).