The temperature changes, chemical agents, and brushing activity that resin composite restorations are exposed to in the oral environment can cause changes in surface roughness. In this study, the aim was to investigate in vitro the clinical one-year surface roughness changes of different types of composites (flowable or conventional) from the same companies by subjecting them to immersion in solutions, brushing, and thermal cycling procedures to simulate intraoral conditions. Four different resin composite brands were included in the study using both their conventional (Charisma Smart, 3M Filtek Ultimate Universal, Omnichroma, Beautifil II) and flowable resin composites (Charisma Flow, 3M Filtek Ultimate Flowable, Omnichroma Flow, Beautifil Flow Plus F00), giving 4 groups with 2 types of resin composite in each. 40 samples were prepared for each group/resin type, for a total of 320 samples. After initial surface roughness measurements by a mechanical profilometer, the samples were divided into 4 subgroups (n = 10) and immersed in solutions (distilled water, tea, coffee, or wine) for 12 days. The samples were then subjected to 10,000 cycles of brushing simulation and 10,000 cycles of thermal aging. Surface roughness measurements were repeated after the procedures. For statistical analysis, the 3-way analysis of variance and the Tukey test were used (p < 0.05). It was concluded that composite groups and types had an effect on surface roughness at time t0 (p < 0.001). At time t1, the highest surface roughness value was obtained in the Beautifil-conventional interaction. When the surface roughness values between time t0 and t1 were compared, an increase was observed in the Beautifil II and Beautifil Flow Plus F00, while a decrease was observed in the other composite groups. Composite groups, types, and solutions had an effect on the surface roughness of resin composites. After aging procedures, it was concluded that the Beautifil group could not maintain the surface structure as it exceeded the threshold value of 0.2 μm for bacterial adhesion.

Background: This study aimed to evaluate the long-term color stability of single-shade composite resins when exposed to simulated intraoral conditions, including staining, brushing, and thermal cycling. Additionally, the study compared the performance of spectrophotometry and cross-polarized (CP) photography in detecting color changes, focusing on their applicability for both clinical and research purposes. Materials and methods: The study employed five single-shade composite resins (Omnichroma; OMN, Zenchroma; ZNC, Vittra APS Unique; VTR, Charisma One; CHR, and Essentia Universal; ESU) and one multi-shade composite resin (Filtek Z550: FLT) for testing. The specimens were subjected to thermal cycling, staining, and brushing to simulate intraoral conditions. Color measurements were conducted using a spectrophotometer and CP photography at the initial baseline (t₀) and following each subsequent procedure 10-day (t₁) and 1-year simulated staining, brushing and thermal cycling (t₂). Color differences (ΔE₁, ΔE₂) were calculated using the CIEDE2000 formula. Statistical analyses included Shapiro-Wilk for normality, ANOVA and paired t-tests for parametric data, and Kruskal-Wallis and Wilcoxon tests for non-parametric data. Method consistency was evaluated with the Intra-Class Correlation Coefficient (ICC) (p < 0.05). Results: All composite groups demonstrated statistically significant color changes following the simulated conditions (p < 0.001). The CHR group exhibited the highest values for both ΔE₁ and ΔE₂, indicating the greatest degree of discoloration. The FLT and ZNC groups exhibited the lowest ΔE values across methods at various time points. A positive correlation was identified between spectrophotometer and CP photography measurements for all parameters (p < 0.001), although the correlation for ΔE₁ and ΔE₂ was less robust. Conclusions: Single-shade composites display a high susceptibility to significant discoloration when subjected to simulated intraoral conditions, with CHR exhibiting the most pronounced alterations. Both spectrophotometry and CP photography were effective in assessing color stability, with CP photography offering a practical alternative for clinical settings. These findings offer insight into the aesthetic durability of single-shade composites and underscore the importance of long-term evaluations.

The aim of this study was to evaluate the effect of rotation frequency (rpm) of different polishing discs on the surface roughness of a nanohybrid resin composite material. 126 specimens were prepared in metal molds of 10 mm diameter and 2 mm depth using a nanohybrid resin composite material. The prepared specimens were kept in distilled water for 24 hours. Polishing treatments at 5k, 10k, 15k, and 20k rpm were applied to the nanohybrid resin composite material by grouping different brand polishing discs: Sof-Lex Contouring and Polishing Discs (3M Espe, USA) (3M Group), Optidisc (Kerr Corporation, USA) (Kerr Group), Super-Snap Rainbow Technique Kit (Shofu Dental, Japan) (Shofu Group), Finishing Disc (Bisco Dental, USA) (Bisco Group). The surface roughness was evaluated at three different points by atomic force microscopy for all specimens and scanning electron microscopy was used for visual assessment. Data were evaluated by Two Way ANOVA and Tukey’s HSD Test. The mean surface roughness (Ra, μm) of all prepared samples showed significant differences (α = 0.05). According to Two-Way ANOVA, there is a statistically significant relationship between the rpm values and the discs. The 3M group showed the highest roughness value at all rpm speeds. Shofu group at 15k, 20k rpm, Bisco group at 10k, 15k, 20k rpm, the Kerr group at 15k, 20k rpm showed the lowest roughness value and had roughness close to the surfaces finished with a mylar strip. The smoothest surfaces were obtained at 15k rpm, even though polishing discs from different brands were used. It was also observed that 5k and 20k rpm polishing speeds can increase the surface roughness of the nanohybrid resin composite material.