Micro-sized erosions in a nanofilled composite after repeated acidic beverage exposures: consequences of clusters dislodgments

Effects of Detox Juices on Color Stability and Surface Roughness of Universal Chromatic Resin Composites

This study investigated the color stability and surface roughness of universal chromatic resin-based composites (RBCs) after immersion in detox juices. One hundred seventy-six disc-shaped specimens (8 mm in diameter and 2 mm in thickness) were prepared using four universal chromatic RBCs: NeoSpectra ST (NS), Omnichroma (OM), Charisma Topaz One (CO), and G-ænial Universal Injectable (GI). Specimens of each material were randomly divided into four subgroups (n=11) and immersed in either the assigned detox juices (red, green, or yellow) or distilled water (control). Color and surface roughness measurements were taken at baseline, 15 and 30 days of immersion. Scanning electron microscopy (SEM) was used to evaluate the surface topography of the composites. The color change [CIEDE2000 (ΔE00)] and surface roughness (Ra) values were analyzed using generalized linear models and multiple comparison tests with Bonferroni correction. Correlation analysis was performed using Spearman rank correlation test. The main variable effects of "composite and immersion media" were significant for both color change and surface roughness parameters (p<0.001). Additionally, the main effect of the "evaluation period" was significant only for surface roughness (p=0.001). The highest discoloration occurred in the GI group immersed in a red beverage, while the CO group immersed in yellow beverage had the highest Ra values. In SEM analysis, OM demonstrated a more homogeneous filler structure with clearly visible nano-spherical fillers and nanoclusters, contributing to its superior smoothness. Conversely, a significant increase in rough areas was observed, especially in NS exposed to the green beverage and CO exposed to the yellow beverage, after 30 days. While the immersion of resin composites in detox juices induced an acceptable color alteration except for OM and GI groups immersed in the red beverage, all tested materials exhibited clinically admissible results regarding surface roughness.

Analysis of color stability and degree of conversion of different types of resin composites

Resin composites containing surface pre-reacted glass (S-PRG) have been introduced to reduce demineralization and improve remineralization of the tooth structure. However, water diffusion within the material is necessary for its action, which can impair its overall physicomechanical properties over time, including color stability. This study aimed to evaluate the color stability and related degree of conversion (DC) of four resin composites. Discs (6 x 4 mm, n = 5/group) of microhybrid (MH), nanofilled (NF), nanohybrid (NH), and S-PRG-based nanohybrid (S-PRG-NH) composites with two opacities (A2/A2E and A2O/A2D) were prepared. Color (CIELab and CIEDE2000) was evaluated with a spectrophotometer after aging in grape juice (2 x 10 min/10mL/7days). The DC was analyzed by using Fourier transform infrared spectroscopy before and after light-curing. Data were statistically analyzed by using two-way analysis of variance and post-hoc least significant difference tests (p<0.05). In the color stability analysis, the interaction between filler type and opacity was significant (CIELab, p = 0.0015; CIEDE2000, p = 0.0026). NH presented the highest color stability, which did not differ from that of MH. The greatest color alteration was observed for S-PRG-NH. S-PRG fillers also influenced DC (p < 0.05). The nanohybrid resin composite presented favorable overall performance, which is likely related to its more stable organic content. Notwithstanding the benefits of using S-PRG-based nanohybrid resins, mostly in aesthetic procedures, professionals should consider the susceptibility of such resins to color alteration, probably due to the water-based bioactive mechanism of action.

The Use of Composite Layering Technique to Mask a Discolored Background: Color Analysis of Masking Ability After Aging—Part II

The aim of this study was to evaluate the effectiveness of the layering technique to mask a discolored background (C4) after one year of water aging. The technique was used with three resin composite restorative systems (IPS Empress Direct, Charisma Diamond, and Filtek Z350XT). Ninety 1.5-mm-thick specimens were divided into groups and subgroups according to the restorative system and resin composite shade combination used in the layering technique (enamel, body, and dentin). The color measurements were made by reflection spectrophotometer (SP60, EX-Rite) over the C4 substrate at two time points: after 24-hour water immersion (T0) and after one-year water aging (T1). The masking ability was evaluated by calculating the ΔE between an inherent color background and a C4 background at T0 and T1. CIELAB and CIEDE2000 formulas were used for comparative analysis between T0 and T1 color measurements. Analysis of variance and Turkey's post hoc test (a=0.05) were performed to analyze ΔEab and ΔE00 mean values. The Z350XT restorative system presented adequate masking ability in the combinations of 0.5 mm body + 1.0 mm dentin, 0.5 mm enamel + 1.0 mm dentin, and 1.5 mm dentin after 24-hour water immersion. The masking ability was affected negatively by water aging in most of the combinations. The IPS Empress Direct was the only system that remained stable after aging in the combinations of 0.5 mm enamel + 1.0 mm dentin and + 1.5 mm dentin (p=0.05 and p=0.47 for CIELAB; p=0.15 and p=0.51 for CIEDE2000), although it did not present adequate masking ability in both time points. None of the combinations of any system presented adequate masking ability after prolonged water aging.

Degradation Potential of Bulk Versus Incrementally Applied and Indirect Composites: Color, Microhardness, and Surface Deterioration

This study investigated the color stability and microhardness of five composites exposed to four beverages with different pH values. Composite discs were produced (n=10); Filtek Z250 (3M ESPE) and Filtek P90 (3M ESPE) were applied in two layers (2 mm, 20 seconds), and Tetric N-Ceram Bulk Fill (TetricBF, Ivoclar Vivadent) and SonicFill (Kerr) were applied in bulk (4 mm) and then light cured (40 seconds, Ortholux-LED, 1600 mW/cm²). Indirect composite Sinfony (3M ESPE) was applied in two layers (2 mm) and cured (Visio system, 3M ESPE). The specimens were polished and tested for color stability; ΔE was calculated using spectrophotometer readings. Vickers microhardness (50 g, dwell time=45 seconds) was assessed on the top and bottom surfaces at baseline, 40 days of storage, subsequent repolishing, and 60 days of immersion in distilled water (pH=7.0), Coca-Cola (pH=2.3), orange juice (pH=3.75), or anise (pH=8.5) using scanning electron microscopy (SEM). The materials had similar ΔE values (40 days, p>0.05), but TetricBF had a significantly greater ΔE than P90 or SF (40 days). The ΔE was less for P90 and TetricBF than for Z250, SonicFill, and Sinfony (60 days). Repolishing and further immersion significantly affected the ΔE (p<0.05) except for P90. All composites had significantly different top vs bottom baseline microhardnesses. This was insignificant for the Z250/water, P90/orange juice (40 days), and Sinfony groups (40 and 60 days). Immersion produced variable time-dependent deterioration of microhardness in all groups. Multivariate repeated measures analysis of variance with post hoc Bonferroni tests were used to compare the results. ΔE and microhardness changes were significantly inversely correlated at 40 days, but this relationship was insignificant at 60 days (Pearson test). SEM showed degradation (40 days) that worsened (60 days). Bulk-fill composites differ regarding color-stability and top-to-bottom microhardness changes compared with those of other composites. P90 showed better surface degradation resistance. In conclusion, bulk-fill composites are not promising alternatives to incremental and indirect composites regarding biodegradation.

Comparative Evaluation of Colour Stability and Surface Hardness of Methacrylate Based Flowable and Packable Composite -In vitro Study

INTRODUCTION

With the advent of new technology in material sciences in recent years, the quality of composite resin restorations has improved; however, discolouration and wear of composite resin materials remains to be a major problem in long-term clinical studies.

AIM

The aim of the present study was to compare the colour stability and surface hardness of methacrylate based flowable nano composite with methacrylate based packable nano composite.

MATERIALS AND METHODS

The difference in colour stability and microhardness of the three composites: G aenial Universal Flo (GC India), Filtek Z350XT (3MESPE) and Tetric N Ceram (Ivoclar Vivadent) were evaluated. Forty eight disc shaped specimens were made out of three different resin composite materials which were subdivided into two groups of Colour Stability (CS) and Vicker's Hardness (VH). For colour stability, specimens were immersed in staining solution consisting instant coffee for 72 hours, and then specimens were rinsed thoroughly under tap water and subjected to 10 strokes of brushing with a soft-grade toothbrush. The colour measurements were obtained using spectrophotometer and the process was repeated every 72 hours for three weeks. VH was evaluated using microhardness tester (Zwick/Roell Vicker's Microhardness Tester). Vicker's Hardness Numbers (VHN) were determined from indentations made under 10 N load for 15 seconds by the arithmetic mean of three indentation values randomly performed. One-way ANOVA and Tukey's post-hoc analysis were applied.

RESULTS

Statistically significant difference was found in comparison of colour stability at different time interval in study groups (p<0.001). Filtek Z350XT group showed least discolouration followed by Tetric N Ceram group and highest colour change in G aenial Universal Flo group after immersion for 21 days. Mean microhardness value of Filtek Z350XT (101.62) group was found to be significantly different from Tetric N Ceram group (63.74) (p<0.001*) and G aenial Universal Flo group (56.75) (p<0.001*).

CONCLUSION

Greatest CS and VH was seen in Filtek Z350XT followed by Tetric N Ceram and least values were seen in G aenial Universal Flo.

Effect of Energy Drinks on Discoloration of Silorane and Dimethacrylate-Based Composite Resins

OBJECTIVES

This study aimed to assess the effects of two energy drinks on color change (ΔE) of two methacrylate-based and a silorane-based composite resin after one week and one month.

MATERIALS AND METHODS

Thirty cubic samples were fabricated from Filtek P90, Filtek Z250 and Filtek Z350XT composite resins. All the specimens were stored in distilled water at 37°C for 24 hours. Baseline color values (L*a*b*) of each specimen were measured using a spectrophotometer according to the CIEL*a*b* color system. Ten randomly selected specimens from each composite were then immersed in the two energy drinks (Hype, Red Bull) and artificial saliva (control) for one week and one month. Color was re-assessed after each storage period and ΔE values were calculated. The data were analyzed using the Kruskal Wallis and Mann-Whitney U tests.

RESULTS

Filtek Z250 composite showed the highest ΔE irrespective of the solutions at both time points. After seven days and one month, the lowest ΔE values were observed in Filtek Z350XT and Filtek P90 composites immersed in artificial saliva, respectively. The ΔE values of Filtek Z250 and Z350XT composites induced by Red Bull and Hype energy drinks were not significantly different. Discoloration of Filtek P90 was higher in Red Bull energy drink at both time points.

CONCLUSIONS

Prolonged immersion time in all three solutions increased ΔE values of all composites. However, the ΔE values were within the clinically acceptable range (<3.3) at both time points.