Effects of fibers on the color change and stability of resin composites after accelerated aging

An experimental teeth bleaching agent containing casein phosphopeptide-amorphous calcium phosphate

OBJECTIVES

This study was aimed to obtain an experimental bleaching agent by adding casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) in order to eliminate the mineral loss on the tooth surface after bleaching and to evaluate the bleaching effectiveness.

MATERIALS AND METHODS

In this study, experimental bleaching agents containing 1%, 3% CPP-ACP and without CPP-ACP were obtained. Bleaching effectiveness (color change), the effect of bleaching agents on mineral content (energy dispersive x-ray spectroscopy), surface morphology (scanning electron microscope), and surface hardness of enamel (Vicker's microhardness) before and after bleaching were evaluated. The obtained data were statistically analyzed.

RESULTS

When the bleaching levels of the groups were compared, no statistically significant difference was observed between the control and 1% CPP-ACP groups (p > 0.05) while the addition of 3% CPP-ACP decreased significantly the effectiveness of the bleaching agent (p < 0.05). When the effects of experimental bleaching agents on surface hardness were examined, while the enamel surface hardness decreased statistically significantly after application in the control group (p < 0.05), no statistically significant change was observed in surface hardness after the application of 1% CPP-ACP containing bleaching agent (p > 0.05). However, a statistically significant increase was observed in surface hardness after the application of 3% CPP-ACP containing bleaching agent (p < 0.05). When the Ca and P ratio of the groups were compared, no statistically significant difference was observed between the control and 1% CPP-ACP groups (p > 0.05), while they increased significantly in 3% CPP-ACP group (p < 0.05).

CONCLUSIONS

The addition of 1% CPP-ACP to the bleaching agent had positive effects on the mineral content and surface hardness of the enamel, and did not negatively affect the whitening effectiveness.

CLINICAL SIGNIFICANCE

Adding CPP-ACP to the bleaching agent at appropriate concentrations can eliminate possible negative effects without compromising the effectiveness of the bleaching agent.

Effect of aging and fiber-reinforcement on color stability, translucency, and microhardness of single-shade resin composites versus multi-shade resin composite

OBJECTIVE

The purpose of this study was to evaluate the effect of aging and fiber-reinforcement on the color stability, translucency, and microhardness of single-shade resin composites versus multi-shade resin composite.

MATERIALS AND METHODS

Four resin composites (Filtek Z250, Omnichroma, Vittra APS Unique, Zenchroma) were tested. Three subgroups of specimens were prepared for each of the composites: control, polyethylene fiber-reinforcement, and glass fiber-reinforcement- groups (n = 10/per group). The samples were subjected to aging for 10,000 thermal cycles. Color differences (ΔE00 ) were calculated after aging. Relative translucency parameter (RTP00 ) and microhardness values were calculated before and after aging. A two-way analysis of variance and the generalized linear model was used (p < 0.05).

RESULTS

The lowest and highest ΔE00 values were found for Filtek Z250 (0.6 ± 0.2) and Omnichroma resin composites (1.6 ± 0.4), respectively. The ΔE00 value of the polyethylene fiber-reinforcement group (1.2 ± 0.6) was significantly higher than the ΔE00 value of the glass fiber-reinforcement group (1.0 ± 0.4, p < 0.001). The RTP00 value of the glass fiber-reinforcement group (1.92 ± 0.78) was significantly higher than the RTP00 value of the polyethylene fiber-reinforcement group (1.72 ± 0.77, p < 0.001). The highest microhardness values were found in glass fiber-reinforcement group (76.48 ± 17.07, p < 0.001).

CONCLUSION

Single-shade resin composites were more translucent, had higher color change, and lower hardness than multi-shade resin composite. For relative translucency and microhardness, statistical significance was found in the material and fiber type interaction. The glass fiber-reinforcement provided higher translucency, lower color change and higher microhardness values than polyethylene fiber-reinforcement group after aging. Thermocycling had a significant impact on the color stability, translucency parameter, and microhardness of the tested resin composite materials.

CLINICAL SIGNIFICANCE

Single-shade resin composite materials have greater color-changing potential. The glass fiber-reinforcement optimize resin material mechanical properties and color stability more than polyethylene fiber-reinforcement.

Effect of orthodontics combined with fibre-reinforced composite resin-bonded fixed partial denture on anterior dentition defects with minimal vertical intermaxillary space

BACKGROUND

Prosthodontics are often performed to treat patients with malocclusion and dentition defects. However, single prosthodontics cannot properly correct the disharmony of teeth, dental arch and other parts affected by malocclusion, and some patients may have difficulty in recovering the occlusal function due to poor prosthodontics.

OBJECTIVE

This study aims to investigate the effect of orthodontics combined with fibre-reinforced composite resin-bonded fixed partial denture (FRC-RBFPD) on anterior dentition defects with minimal vertical intermaxillary space.

METHODS

Sixty-two patients with anterior dentition defects with minimal vertical mandibular space admitted to our hospital between March 2021 and May 2023 were enrolled in this study. The participants were divided into the observation group (31 cases) and the control group (31 cases), according to the treatment plan. The control group was treated with traditional therapy, and the observation group was treated with orthodontic combined FRC-RBFPD therapy. Periodontal conditions (periodontal pocket depth [PD], the plaque index [PLI], the sulcus bleeding index [SBI]), levels of inflammatory factors in gingival crevicular fluid (high mobility group box 1 [HMGB1]), myeloid cell triggering receptor-1 (TREM-1), monocyte chemoattractant protein-1 (MCP-1), pain (visual analogue scale [VAS]), the clinical response rate and the incidence of adverse reactions were collected and compared.

RESULTS

After 1, 3, 5 and 9 months following treatment, the scores of the PD, PLI, SBI, HMGB1, VAS, TREM-1 and MCP-1 in the observation group were found to be lower than those in the control group (FPD treatment= 352.532, FPLI score treatment= 112.341, FSBI score treatment= 79.479, FVAS score treatment= 96.132, FHMGB1 treatment= 52.532, FTREM-1 score treatment= 64.593, FMCP-1 score treatment= 53.582, and they were all statistically significant P< 0.05). There was a statistically significant difference in the response rate between the two groups (97.77% vs. 80.65%, χ2= 4.026, P= 0.045). No statistically significant difference was observed in the incidence of adverse reactions between the two groups (6.45% vs. 16.13%, χ2= 1.449, P= 0.229).

CONCLUSION

Orthodontics combined with FRC-RBFPD shows an ideal restorative effect on patients with anterior dentition defects and minimal vertical intermaxillary space.

Effects of UV sensitivity and accelerated photo-aging on stab resistance of ρ-aramid fabrics impregnated with shear thickening fluids (STFs)

The use of Kevlar in the field of ballistic and stabbing protection has been studied by researchers in polymeric composites for this purpose. This study presents complementary knowledge on energy absorption and dissipation in ρ-aramid fabric impregnated with shear thickening fluids (STFs), especially aiming to obtain better protection against impacts that are deeply associated with STFs, as well as color change, accelerated aging (QUV), and penetration depth (drop tower test). In addition, Scanning Electron Microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) was performed. The research shows that there was a good distribution of STF particles on the ρ-Aramid fabric surface, promoting increased friction between the interfilament and the yarns, further increasing performance and, consequently, improving the energy absorption and dissipation mechanism and, also, the penetration effectiveness in relation to non-impregnated ρ-Aramid fabric. Regarding the protection efficiency against UV exposure (250-400 nm region), there was a significantly decreased compared to those non-impregnated Kevlar® woven with STFs. The FTIR analysis showed that the conditions of aging, after exposure to UV, did not produce new functional groups, that is, there was no chemical modification. Finally, Kevlar fabric impregnated with STFs improved penetration depth performance with the blades independent of the blade type with up to 81% increase in resistance. This result was improved due to interactions between the nanoparticles present in STFs, yarns, and even high-performance woven impregnated with shear-thickening fluids.

Discoloration of fiber-reinforced composite resin disc for computer-aided design/computer-aided manufacturing after immersion in coffee and curry solutions

The purpose of this study was to clarify the discoloration of fiber-reinforced composite resin (FRC) disc materials. The color differences (ΔEs) of three CAD/CAM disc materials, FRC with different fiber orientations, composite resin, and polyether-ether-ketones were evaluated after month-long immersion in water, coffee, and curry. The ΔEs of all materials after coffee and curry immersion increased with increasing immersion periods, while those after water immersion barely increased. FRC exhibited a smaller color difference and water sorption value than composite resin and a greater color difference and water sorption value than polyether-ether-ketones. The ΔEs after coffee immersion were significantly correlated with the water sorption value. The ΔE of FRC with fiber orientations perpendicular to the surface was greater than that of FRC with fiber orientations parallel to the surface, likely due to greater exposure of the matrix-fiber interface. This result suggested that the fiber orientations of FRC affected the discoloration.

The effect of bleaching applications on stained bulk-fill resin composites

Background

The structure of bulk-fill resin composites differs from that of their conventional counterparts, but how this difference affects the color stability of the former after staining and bleaching is unclear. Accordingly, this study was aimed at investigating color change in nine bulk-fill resin composites and one nanohybrid resin composite treated with hydrogen peroxide and carbamide peroxide after staining with tea, coffee, and red wine.

Methods

Eighty specimens were prepared from each resins [Clearfil Majesty Posterior (CMP), SDR flow⁺ (SDR), Filtek^TMBulk-Fill Flowable Restorative (FBF), Reveal HD Bulk (RHD), Beautifil-Bulk Restorative (BBR), Tetric EvoCeram® Bulk Fill (TEC), SonicFill™2 (SF2), everX Posterior™ (eXP), X-tra base (XB), and Venus® Bulk Fill (VBF)]. Following baseline color measurements, the specimens were randomly divided into 4 groups according to immersion solutions and distilled water as the control. At the end of a 30-day test period, color measurements were repeated, and color change values (∆E₀₀) were calculated. Each resin group was then divided into 2 subgroups (with 10 specimens per group) on the basis of bleaching agent (Opalescence Boost 40%, Opalescence PF 16%). Following bleaching application, ∆E₀₀ and changes of whiteness (∆WI_D1 = WI_Dbleaching-WI_Dbaseline, ΔWI_D2 = WI_Dbleaching-WI_Dstaining) values were recorded. Two- and three-way analyses of variance and Tukey’s post hoc test were performed, with a P < 0.05 regarded as indicative of significance.

Results

After immersion in distilled water, tea, and red wine, the highest ΔE₀₀ values were observed in eXP (P < 0.05). Resin materials immersed in coffee and tea exhibited statistically higher ∆E₀₀ values than those immersed in red wine except for eXP, TEC, and FBF (P < 0.05). For eXP, the highest ∆E₀₀ values were recorded in distilled water. For TEC and FBF, there was no statistically significant difference among the immersion solutions and distilled water (P > 0.05). For all the resins and staining beverages, no statistically significant difference in ∆WI_D1 and ∆WI_D2 values were detected between bleaching agents (P > 0.05). All the ΔWI_D1 values were above the whiteness perceptibility threshold.

Conclusion

The bulk-fill materials were more resistant to discoloration and bleaching procedures than the conventional resin composites. Coffee and tea caused more staining than distilled water and red wine generally. The type of bleaching procedure had no effect on the whiteness of the tested materials.

Color Change Evaluation of Three Universal Resin Composites after Storage in Water: An In Vitro Study

Aim:

The aim of this in vitro study was to evaluate the color changes of three different universal resin composites after immersion in distilled water for one month.

Materials and Methods:

Omnichroma, Estelite Σ Quick, and Filtek Universal Restorative were investigated. Ten disk shaped specimens (6 mm diameter, 2 mm thickness) were prepared according to the manufacturers’ instructions for each material. After polishing, initial color measurements were taken followed by individual storage of the specimens in distilled water at 37 °C for one month when color measurements were repeated. The change in the color of each resin composites (Δ E00) was calculated with a digital method, using the CIEDE2000 color difference formula. The data were analyzed using one-way ANOVA followed by Tukey post-hoc test ( P < .05).

Results:

All resin composites exhibited acceptable color change after one month. Omnichroma exhibited the highest color change (2.26 ± 0.48) value while Filtek Universal Restorative showed the lowest (1.14 ± 0.38) value. All color parameters influenced the Δ E00 values in all groups except Filtek Universal for Δ L* and Δ b values.

Conclusion:

When performing composite resin restorations, especially for esthetic purposes, polymerization may lead to change in the color of restorative material over time, but it should be considered whether this is within acceptable limits.

Effect of Different Solutions on the Colour Stability of Nanoparticles or Fibre Reinforced PMMA

This study aimed to evaluate the colour stability of polymethyl methacrylate (PMMA) denture base reinforced with ZrO2 nanoparticles, E-glass fibres, and TiO2 nanoparticles at various concentrations over 180-day storage in Steradent™ (STD) denture cleaner or coffee (CF). A total of 130 disc-shaped specimens were fabricated at various filler concentrations and divided into four main groups to measure the colour changes. Groups Z, T, and E consisted of PMMA reinforced with ZrO2 nanoparticles, TiO2 nanoparticles, or E-glass fibre, respectively, while Group C consisted of PMMA specimens without filler served as the control group (n = 10). The three reinforced groups were further subdivided according to the filler content (n = 10) added to the PMMA (1.5%, 3.0%, 5.0%, and 7.0% wt.%). Half of the specimens were stored in STD, while the other half was stored in CF for 180 days. A Minolta Chroma Meter was used to measure the colour changes (ΔE) at 7, 30, 90 and then 180 days. The results were assessed using two-way repeated-measures analysis of variance (RM-ANOVA) along with Bonferroni post hoc tests at a p ≤ 0.05 significance level. Significant different colour changes (ΔΕ) were observed between all tested groups and across different time points. TiO2-reinforced PMMA in coffee showed the lowest colour stability, while the E-glass fibre-reinforced PMMA in STD/CF showed the highest colour stability. Furthermore, coffee appeared to have the greatest impact on the CF change in comparison to the STD/CF. The results indicated that the filler type and concentration, type of solution, and length of storage all affected the colour stability of the tested specimens.

Effect of Polishing Systems on the Color and Surface Properties of Resin Composites in the Process of Accelerated Artificial Aging

Objective: This study aimed to investigate the effects of polishing system on the color stability, surface roughness, and hardness of resin composites in the presence and absence of accelerated artificial aging (AAA). Methods: Six resin composites (Universal Restorative 200, G-Aenial Anterior, Ceram-X Duo, Admira, IPS Empress Direct, Clearfil Majesty Esthetic) were evaluated. Thirty disc-shaped samples were prepared for each composite group. Resin composite groups were divided into three subgroups: control (Mylar strip), disc (Optidisc), and rubber (Dimanto) (n=10). Color change (ΔE00) was calculated using the CIEDE 2000 formula. Before and after AAA, the surface roughness (Ra, μm) and hardness (VHN) values were measured. Data were analysed using ANOVA, the Bonferroni test, and Pearson correlation (p

Evaluation of the Repolished Surface Properties of a Resin Composite Employing Structural Coloration Technology

Resin composites employing structural coloration have recently been developed. These resins match to various tooth shades despite being a single paste. To accomplish this, the filler and base resin are tightly bonded, which is thought to provide excellent discoloration resistance. Here, we investigated the surface properties of one of these resins, including the discoloration of the repolished surface. We developed an innovative in vitro method to adjust the repolished surface, in which structural degradation is removed according to scanning electron microscopy (SEM) observation rather than by the naked eye. The resin samples (20 mm (length) × 10 mm (width) × 4 mm (depth)) were manufactured using this resin material. After accelerated aging of the resin by alkaline degradation, the resin was repolished and the discoloration (ΔE*ab), surface roughness (the arithmetic mean roughness (Ra)), and glossiness (the 60° specular) were measured. SEM observation showed that the appearance of the bond between the organic composite filler and base resin on the repolished surface was different from that on the mirror-polished surface. This revealed that according to our in vitro method it was difficult to make the repolished surface structurally identical to the mirror-polished surface. Among the properties of the repolished surface, the degree of discoloration did not change despite the rougher and less glossy surface. It can be concluded that the factors that induce discoloration in this resin composite are independent of the surface roughness and glossiness.

Influence of Different Beverages on the Color Stability of Nanocomposite Denture Base Materials

BACKGROUND

The effect of beverages on nanocomposite denture base materials is neglected. Therefore, this study aimed to investigate the influence of different beverages (coffee, tea, cola, and mineral water) on the color stability of nanoparticles-modified denture base materials (DBMs).

MATERIALS AND METHODS

A total of 280 specimens (n = 10/group) were prepared from heat-polymerized acrylic resin modified with different concentrations (3% and 7%) of zirconium dioxide (nano-ZrO2), titanium dioxide (nano-TiO2), and silicon dioxide (nano-SiO2) nanoparticles, while 0% was taken as a control. Color change (∆E) of the specimens was evaluated after simulating 6-month immersion time in four commonly used beverages, coffee, tea, cola, and mineral water, as experimental groups. Color stability was measured using a spectrophotometer, and then values were converted to National Bureau of Standards units (NBS units). The one-way ANOVA test was applied to compare color change (ΔE) results followed by Bonferroni's post hoc test (α = 0.05).

RESULTS

The results showed that the heat-polymerized acrylic resin modified with different types of nanoparticles showed lower color changes after being immersed in beverage solutions compared to the unmodified group (P < 0.001), so the color stability of heat-polymerized acrylic resin was significantly enhanced by the addition of several nanoparticles; nano-ZrO2 showed the lowest ΔE followed by nano-TiO2 and then nano-SiO2. Regardless of the filler type, 3% concentration showed lower mean ΔE than 7% concentration. Regarding the beverage solutions, the greatest color change was found in the coffee group followed by tea and cola, while water showed the least changes.

CONCLUSION

Modification of heat-polymerized acrylic resin with certain amounts of nano-ZrO2, nano-TiO2, and nano-SiO2 may be useful in improving color stability.

Accelerated Aging Effects on Color Stability of Potentially Color Adjusting Resin-based Composites

The aim of this study was to compare the effects of accelerated aging on the overall color stability of potentially color adjusting commercial resin-based composite resins. Thirty specimens (10 mm diameter and 2.5 mm thick; n=6) were fabricated using five different materials: Estelite Omega, GC Kalore, Venus Pearl, Harmonize, and Omnichroma. Color measurements were taken for each sample using a spectrophotometer before and after submitting samples through the artificial aging process (Q-sun Xenon Test Chamber, 102 min light at 63°C black panel temperature; 18 min light and water spray per ASTM G155) for a total of 300 hours (12.5 days). The total color difference (ΔE*ab) was calculated using SpectraMagic NX software and analyzed using one-way analysis of variance and Tukey test. The results for color change (ΔE*ab) were statistically significant. Omnichroma and Venus Pearl presented superior color stability and the lowest overall color change, whereas GC Kalore and Harmonize presented significant color change that would be considered clinically unacceptable (ΔE*ab > 3.3).

Structure Property Investigation of Glass-Carbon Prepreg Waste-Polymer Hybrid Composites Degradation in Water Condition

The limited shelf life of carbon prepreg waste (CPW) from component manufacturing restricts its use as a composite reinforcement fibre on its own. However, CPW can be recycled with glass fibre (GF) reinforcement to develop a unique remediate material. Therefore, this study fabricated (1) a glass fibre-carbon prepreg waste reinforced polymer hybrid composite (GF-CPW-PP), (2) a polypropylene composite (PP), (3) a carbon prepreg waste reinforced composite (CPW-PP), and (4) a glass fibre reinforced composite (GF-PP) and reported their degradation and residual tension properties after immersion in water. The polymer hybrid composites were fabricated via extrusion technique with minimum reinforce glass-carbon prepreg waste content of 10 wt%. The immersion test was conducted at room temperature using distilled water. Moisture content and diffusion coefficient (DC) were determined based on water adsorption values recorded at 24-h intervals over a one-week period. The results indicated that GF-PP reinforced composites retained the most moisture post-168 h of immersion. However, hardness and tensile strength were found to decrease with increased water adsorption. Tensile strength was found to be compromised since pores produced during hydrolysis reduced interfacial bonding between glass fibre and prepreg carbon reinforcements and the PP matrix.

The effect of artificial accelerated aging on the color stability, microhardness, and surface roughness of different dental laminate veneer materials

OBJECTIVE

This study aimed to evaluate the effect of artificial accelerated aging (AAA) on color stability, surface roughness, and microhardness of three laminate veneer (LV) materials.

MATERIALS AND METHODS

Specimens of ceramic LV (CLV-IPS E.max Press), hand-layered composite LV (hand-layered laminate veneer [HLV]-Tetric N-Ceram), and prefabricated composite LV (prefabricated laminate veneer [PLV]-Componeer Coltene) were prepared as discs (n = 10). CIE L*, a*, and b* color coordinates, the Vickers microhardness, and surface roughness were measured 24 hours after preparation and reevaluated after aging for 300 hours in an ultraviolet (UV)-AAA system (Ci35 Weather-Ometer). Color difference (CIEDE2000 [ΔE₀₀ ]) was calculated. Data were statistically analyzed with the Shapiro-Wilk test and the Kruskall-Wallis test followed by the Mann-Whitney U tests (α = .05).

RESULTS

All of the LV groups showed significant differences in ΔE₀₀ after AAA (P < .001). Comparing the color changes of the HLVs with the PLVs, no significant difference could be found (P = .705). There was a statistically significant difference in the means of changes in microhardness among the LVs materials (P < .001). The changes in surface roughness results showed a significant difference after AAA in all the LVs (P < .001).

CONCLUSIONS

Within the limitations of this in vitro study, the color stability, the microhardness, and surface roughness of tested LVs were influenced by AAA.

CLINICAL SIGNIFICANCE

The prefabricated composite LV system does not replace the individualized ceramic LV technique, but rather offers an alternative to hand-layered LVs, which is delicate and time-consuming technique.

Effects of Fibers on Color and Translucency Changes of Bulk-Fill and Anterior Composites after Accelerated Aging

The aim of this study was to determine the effects of glass and polyethylene fibers on the color and translucency change of bulk-fill and anterior composites before and after artificial accelerated aging (AAA). Two types of teflon molds were used to fabricate samples which were 13 mm in diameter and, respectively, 2 mm and 4 mm in height. Polyethylene fiber (PF) and glass fiber (GF) were incorporated in the middle of the composite samples. Color and translucency changes of each composite were evaluated before and after AAA with spectrophotometer. ANOVA and Tukey's HSD post hoc statistical analysis were used at a significance level of 0.05. Before AAA (for anterior composites), there were no significant differences in L^* and b^* parameters among the three groups (p > 0.05); there were no significant differences in L^* parameter between PF and GF groups or in TP between GF and control groups (p > 0.05) (for bulk-fill composites). After AAA, there were no significant differences in L^* parameter between GF and control groups, in a^* parameter between PF and control groups, in b^* parameter among all groups, or in TP parameter between GF and control groups (p > 0.05). Fiber reinforcement led to color and TP change in both anterior and bulk-fill resin composites.

Comparative evaluation between glass and polyethylene fiber reinforced composites: A review of the current literature

BACKGROUND

Fiber reinforced composite (FRC) is a promising class of material that gives clinicians alternative treatment options. There are many FRC products available in the market based on either glass or polyethylene fiber type. The aim of this study was to present a comparison between glass and polyethylene fiber reinforced composites based on available literature review.

MATERIAL AND METHODS

A thorough literature search, with no limitation, was done up to June 2017. The range of relevant publications was surveyed using PubMed and Google Scholar. From the search results, articles related to our search terms were only considered. An assessment of these articles was done by two individuals in order to include only articles directly compare between glass and polyethylene FRCs. The search terms used were "fiber reinforced dental composites" and "glass and polyethylene fibers in dentistry".

RESULTS

The search provided 276 titles. Full-text analysis was performed for 29 articles that met the inclusion criteria. Most were laboratory-based research with various test specimen designs prepared according to ISO standard or with extracted teeth and only three articles were clinical studies. Most of studies (n=23) found superior characteristics of glass FRCs over polyethylene FRCs.

CONCLUSIONS

Significant reinforcement differences between commercial glass and polyethylene fiber reinforced composites were found. Key words:Fiber reinforced composite, glass fiber, polyethylene fiber.