Effects of polishing procedures on color stability of composite resins

Evaluation of Long-term colour resistance of composite materials used in aligner treatments: A comparative study

AIM

The aim of this study is to evaluate the discolouration resistance of attachments made of composites having different physical properties, filler ratios and viscosity through the simulated environment and conditions.

MATERIALS AND METHODS

Seventy-two extracted human teeth were aligned to simulate upper and lower dental arches. The attachments were prepared according to the guides determined by ClearCorrect. Three different composite groups were used for attachments preparation: Aligner Connect, G-Aenial Universal Injectable, and Tetric Prime and Tetric Evoflow combination. Dental models and aligners were kept in artificial saliva throughout the experiment of 96 weeks. The aligners were also subjected to 2308 thermal cycles and insertion and removing procedures 840 times for each period of 12 weeks. Afterwards, the models were kept in coffee and red wine solutions. Colour measurements were made with Vita Easy Shade 4.0 at 12th, 24th, 48th and 96th simulated weeks.

RESULTS

No significant difference in discolouration was observed during thermal cycle application of 12th and 24th week experimental periods. In the later periods, discolouration was observed in the composite materials, and G-Aenial Universal Injectable was less coloured than the other samples. The composite samples were more coloured in proportion to their residence time. The G-Aenial Universal Injectable was more affected by wine solution, and Tetric Prime and Tetric Evoflow combination were more affected by coffee solution.

CONCLUSIONS

Viscosity, resin matrix content and nature of inorganic filler particles of the composite materials significantly affect the colour changing properties of them due to the long-term ageing and exposure to colouring agents.

Color Stability Assessment of Single- and Multi-Shade Composites Following Immersion in Staining Food Substances

Composite resins are the material of choice for direct restorations, and their success depends mainly on their color stability, since discoloration causes color mismatch, and consequent patient dissatisfaction. A single- and a multi-shade resin were compared in order to evaluate their pigmentation after immersion in staining substances and to investigate the effect of the polymerization time on their color stability. Two-hundred-and-forty composite specimens were created, half made of a single-shade (Group ONE, n = 120) and half of a multi-shade composite (Group OXP, n = 120). Each group was further divided into ONE30 (n = 60) and OXP30 (n = 60), polymerized for 30″, and ONE80 (n = 60) and OXP80 (n = 60), polymerized for 80″. Randomly, the specimens were immersed in turmeric solution, soy sauce, energy drink, or artificial saliva. By means of a spectrophotometer, ΔE00 and WId were calculated at 24 h (T0), at 7 (T1), and 30 (T2) days. Single-shade composites showed statistically significant differences in color change from the turmeric solution, energy drink, and soy sauce than the multi-shade composites (p < 0.005), showing a higher discoloration potential. The polymerization time did not have significative effects on color stability. Single-shade composites showed more color change than multi-shade systems after immersion in staining substances, and the curing time did not influence color variations.

Can discolored dental composites be bleached in depth?

Objectives

Previous in vitro studies determined the whitening effects of bleaching products on stained resin composite surfaces. This in vitro study aimed to verify the effectiveness of a whitening system on composite resin previously subjected to pigmentation, specifically examining the depth of whitening effectiveness within the material structure.

Materials and Methods

A commercially available nano-filled composite resin was used. Specimens were stained using a coffee-based solution and a 10% carbamide peroxide-based gel was employed as the whitening agent. The pigment's penetration and the effect of the bleaching gel were evaluated by measuring color (CieLab values) from the outer edge to the inner part of the specimens. Color measurements were taken at 14 points, starting from 0.1 mm from the external perimeter up to 3.0 mm.

Results

Analysis of variance tests showed a statistically significant difference between the Control Group (CG), Pigmentation Group, and Whitening Group. The whitening agent was effective up to 1.5 mm in depth, with Whiteness index (W) values not statistically different from those of CG up to 0.5 mm in depth.

Conclusions

Whitening agents on nano-filled resin composite previously pigmented appear effective in restoring the W to values similar to the original, particularly in the superficial layers of the sample.

The effects of monomer type, filler size, and filler content of three resin cements on the color stability of laminate veneers exposed to accelerated aging

STATEMENT OF PROBLEM

Commercially available resin cements consist of various filler sizes, filler content and monomers, and it is unclear which of these factors have the greatest effect on the color stability of laminate veneers.

OBJECTIVES

To evaluate the color stability of lithium disilicate-reinforced laminate veneers inserted with three commercial resin cements with various filler sizes/contents and monomers upon accelerated aging.

METHODS

Veneers were fabricated and cemented on resin abutments using three commercially available resin cements comprised of two different monomers and varying filler sizes/contents: 1) triethylene glycol dimethacrylate, TEGDMA (RelyX™ Veneer = 0.6 µm/66 %, Calibra® Esthetic Light Cure =1.2 µm/65 %); and 2) urethane dimethacrylate, UDMA (Variolink Esthetic LC = 0.1 µm/38 %). A total of 60 specimens were fabricated (n = 20 for each cement). The relative number of particles (N) and relative surface area (A) were calculated for each filler size/content. Color coordinates (L*, a*, b*) were measured, and color change (ΔE00) was calculated after cementation and following aging at 150, 300, 450, and 600 h using xenon light. Differences in color coordinates and color change were determined using repeated measures ANOVA followed by Tukey's post hoc test (α = .05). A post-hoc power analysis was performed to confirm reliability of the results.

RESULTS

Based on a post-hoc power analysis of a repeated measures ANOVA with two between-factors and 1 within-factor, we had 89 % power to detect a difference of effect by cement type, 10 % power to detect a difference by shade, and 100 % power to detect a difference of effect by aging. The UDMA-based cement (0.1 µm/38 %) was least affected by aging, despite having the largest number of particles (N = 1010) and largest particle surface area (A = 7.02). The TEGDMA-based cements exhibited a significant color change, with 0.6 µm/66 % (A = 2.03, N = 8.12) producing a larger ΔE00 than 1.2 µm/65 % (A = 1.00, N = 1.00).

CONCLUSIONS

Among the commercial cements tested, UDMA-based resin (0.1 µm/38 %) provided better color stability than TEGDMA-based resin cements. The color change after aging was affected by the relative surface area and relative number of particles for the TEGDMA-based resin cement (0.6 µm/66 % and 1.2 µm/65 %), with a larger surface area and a higher relative number of particles, accelerated color change with aging. The present study demonstrates a novel approach to determine color stability for any resin cement with particulate filler.

CLINICAL IMPLICATIONS

The dental practitioner should be selective in choosing a commercial light cure cementation product for laminate veneers, as UDMA containing resin cement is more resistant to color changes over time than TEGDMA, regardless of the filler size/content.

Effect of surface sealant on the color stability and whiteness index of single-shade resin composites after staining and bleaching

Objectives

The aim of the current study was to evaluate the effect of polishing systems and surface sealant on the color stability and whiteness index of single-shade resin composites after staining and bleaching.

Materials and Methods

Three single-shade (Omnichroma, Charisma Diamond One, Zenchroma) and one multi-shade (Filtek Z250) materials were tested. From each resin composite, 40 specimens were prepared. The specimens were divided into 4 subgroups (n = 10) according to the surface treatments: 1-step polishing, 1-step + Biscover LV, 2-step polishing, and 2-step polishing + Biscover LV. Color differences (ΔE00) were calculated after being immersed in the coffee solution for 12 days. After the staining, the specimens were immersed in a whitening mouthrinse (Crest-3D White) for 12 hours. Whiteness index differences (∆WID = WID after staining - WID after bleaching) values were recorded. The generalized linear model was used for analysis (p < 0.05).

Results

The lowest and highest ΔE00 values were found for Zenchroma and Charisma Diamond One respectively. Sealed groups indicated higher ΔE00 values than nonsealed groups with significant differences (p = 0.008). The lowest and highest ΔWID values were found for Zenchroma and Charisma Diamond One respectively. Sealed groups indicated lower ΔWID values than nonsealed groups with significant differences (p = 0.022).

Conclusions

The use of surface sealant increased the discoloration and showed less whiteness change in resin materials. When the 1-step was compared with the 2-step polishing, the effects on the color stability and whiteness index values of the resin materials were similar.

Surface treatment, liquid, and aging effects on color and surface properties of monolithic ceramics

PURPOSE

The purpose of this study was to investigate the effects of surface treatments, liquids, and aging on color, translucency, and surface properties of monolithic ceramics.

MATERIALS AND METHODS

Lithium disilicate (LDS) and zirconia-reinforced lithium silicate (ZLS) ceramics (n = 135 each) were cut and divided into three groups [crystallization+glaze (single stage), crystallization-glaze (two stages), and crystallization-polish (two stages)]. One sample from each group was examined using scanning electron microscopy (SEM). Remaining samples were divided into four subgroups (distilled water, coffee, grape juice, and smoothie) (n = 11 each), stored for 12 d in the respective liquids, and thermally aged. One sample from each subgroup was analyzed using SEM. The color, gloss, and roughness values of the samples were analyzed after surface treatment (initial) and storage under different liquids+aging conditions. The initial data and both the aged data and data change values were analyzed using robust two- and three-way analyses of variance.

RESULTS

The glazed groups exhibited smoother surfaces. Ceramic type and ceramic-surface treatment interactions affected the initial translucency parameter (TP) (P < .001) and the initial and aged roughness values (P ≤ .001). Surface treatment type affected the color change (P < .001), and ceramic type affected the aged TP values (P < .001). Type of ceramic, surface treatment, and their interactions affected both the initial and aged gloss (P ≤ .001) and TP change values (P ≤ .015). Surface treatment type and ceramic-surface treatment interactions affected the gloss change values (P ≤ .001).

CONCLUSION

Although both ceramics and all surface treatments are clinically applicable, crystallization-glaze is recommended. When gloss and smoothness are important or when translucency is important, ZLS or LDS may be preferred, respectively.

Bleaching versus color change resistant adhesive in the discoloration of bracket-bonded tooth surfaces: an in vitro study

OBJECTIVES

The aim of this study was to compare the effect of office bleaching of teeth bonded with Transbond XTTM (3M Unitek, Monrovia, CA, USA) (TRXT) and the use of color change resistant Orthocem (FGM, Joinville, Brazil) in bracket bonding on coffee-induced enamel discoloration.

MATERIALS AND METHODS

Eighty premolars were distributed in equal numbers (n = 20) to group 1 (TRXT + distilled water), group 2 (TRXT + coffee solution), group 3 (TRXT + coffee solution + bleaching), and group 4 (Orthocem + coffee solution). Color was measured using a SpectroShade Micro (MHT, International, Verona, Italy) device at the beginning (T0), after coloring (T1), after bleaching (T1B), and after debonding (T2). ΔE color change values were calculated as T1-T0, T1B-T0 and T2-T0 differences. The conformity of the data to the normal distribution was examined with the Shapiro-Wilk test. Multiple comparisons were made with Tamhane's T2 test and Tukey's HSD test using one-way analysis of variance in the comparison of normally distributed data, and multiple comparisons were made with Dunn's test using the Kruskal-Wallis H test for comparison of non-normally distributed data. The significance level was set at p < 0.050.

RESULTS

A statistically significant (p < 0.001) difference was found between the T1-T0 and T2-T0 stages for group 1-4 ΔE values. A statistically significant (p < 0.001) difference was also found when the T1B-T0 ΔE values of group 3 were compared with the T1-T0 ΔE values of groups 1, 2, and 4.

CONCLUSIONS

After coffee-induced enamel discoloration, bleaching of teeth bonded with TRXT produced acceptable color difference of the incisal, middle, and gingival regions of the crown. In teeth bonded with Orthocem, acceptable color difference was seen only in the middle of the crown.

CLINICAL RELEVANCE

The presented study will guide the clinician on how enamel discoloration side effect of fixed orthodontic appliance can reduce.

The Impact of Simulated Bruxism Forces and Surface Aging Treatments on Two Dental Nano-Biocomposites-A Radiographic and Tomographic Analysis

Background and Objectives: Nowadays, indication of composite materials for various clinical situations has increased significantly. However, in the oral environment, these biomaterials are subjected (abnormal occlusal forces, external bleaching, consumption of carbonated beverages, etc.) to changes in their functional and mechanical behavior when indicated primarily for patients with masticatory habits. The study aimed to recreate in our lab one of the most common situations nowadays-in-office activity of a young patient suffering from specific parafunctional occlusal stress (bruxism) who consumes acidic beverages and is using at-home dental bleaching. Materials and Methods: Sixty standardized class II cavities were restored with two nanohybrid biocomposite materials (Filtek Z550, 3M ESPE, and Evetric, Ivoclar Vivadent); the restored teeth were immersed in sports drinks and carbonated beverages and exposed to an at-home teeth bleaching agent. The samples were subjected to parafunctional mechanical loads using a dual-axis chewing simulator. A grading evaluation system was conducted to assess the defects of the restorations using different examination devices: a CBCT, a high-resolution digital camera, and periapical X-rays. Results: Before mechanical loading, the CBCT analysis revealed substantially fewer interfacial defects between the two resin-based composites (p > 0.05), whereas, after bruxism forces simulation, significantly more defects were identified (p < 0.05). Qualitative examination of the restorations showed more occlusal defects for the Evetric than the other nanohybrid composite. Conclusions: There were different behaviors observed regarding the studied nanocomposites when simulation of parafunctional masticatory forces was associated with aging treatments.

Stain Susceptibility of Composite Resins: Pigment Penetration Analysis

Composite resins are considered the material of choice for esthetic direct restorations, considering both their satisfying esthetic and mechanical properties. The success of composite resin restorations depends highly on their color stability. Discoloration causes color mismatch, consequent patient dissatisfaction, and eventually additional costs for correction/replacement of the restoration. The purpose of this study was to evaluate the degree of pigment penetration within the composite resins, in order to understand how discoloration can be treated properly. Two different commercially available composite resins were compared in the study: a nano-filled composite resin and a non-homogeneous micro-hybrid composite resin. A coffee solution was used to induce staining of the materials. Subsequently, the penetration of the pigments was measured by analyzing the color from the outside to the inside of the specimen. 14 levels were analyzed starting from 0.1 mm to 3.0 mm in depth. The ANOVA test demonstrated a statistically significant difference (p < 0.0001) between test and control groups up to a depth of 1.0 mm for the nano-filled composite and up to a depth of 2.0 mm for the non-homogeneous micro-hybrid composite. The two composite resin materials, subjected to pigmenting treatment, underwent a color variation with different patterns.

Color stability of hybrid ceramics exposed to beverages in different combinations

Background

The aim of this study is to evaluate the color stability of hybrid ceramics stored in different combinations of beverages that are routinely consumed.

Methods

The specimens were prepared with resin nano-ceramic (Lava Ultimate, 3M Espe, USA) and hybrid ceramic (Vita Enamic, Vita Zahnfabrik, Germany). The specimens were aged in a thermocycler machine for 10,000 cycles. They were stored in different combinations of beverages (water, tea, coke, coffee, red wine, pomegranate juice, and turnip juice) for 12 + 12 h. Surface roughness measurements were performed using a profilometer. The specimen colors were measured using a spectrophotometer. The color values (L-a-b) of the specimens and mean surface roughness values (Ra) were recorded at the end of the 1st (D1), 7th (D7), 14th (D14) and 28th (D28) d.

Results

When the solution groups were examined, significant color changes were observed in the Lava coffee-tea, Enamic coffee-tea, Lava coffee-wine, and Enamic coffee-wine groups compared with the other groups (p < 0.01). Except for the samples in the Lava coffee-wine 28th day (D28) and Enamic coffee-wine 28th day (D28) groups, more color changes were observed in the Lava samples than in the Enamic samples across all groups and periods.

Conclusion

Greater color changes (except for the samples stored in coffee-wine) were observed in the Lava samples than in the Enamic samples across all groups and periods. It was observed that the coffee-tea and coffee-wine beverage combinations produced the greatest color change in hybrid ceramics within the limitations of this study.

Color Match of Composite Resin and Remaining Tooth Structure over a Period of 28 Days Using Spectrophotometer-A Randomized Clinical Trial

OBJECTIVES

The tooth and the composite restoration can undergo a change in color after the restorative procedure over time. The purpose of this randomized clinical trial was to evaluate the color difference (ΔE) of two types of composite resins and remaining tooth structure over a period of 28 days.

METHODS AND MATERIALS

A total of 40 teeth in 30 patients with Class IV caries or EllisClass II fracture in maxillary incisors were randomized into two groups based on the type of composite resin used for restoration: IPS Empress (n=20 teeth) and Filtek Z250 (n=20 teeth). Shade selection was done using a spectrophotometer. Restorations were performed using an anatomical layering technique, and finishing and polishing was done after 48 hours. Baseline spectrophotometer color values for the remaining tooth structure were measured before isolation and for composite restorations, 10 minutes after light cure. Further color evaluations using a spectrophotometer for the remaining tooth structure and composite restorations were done at 48 hours (both before and immediately after finishing and polishing), 7days, 14 days, and 28 days, and color difference (ΔE) from baseline values for remaining tooth structure and restorations and ΔE between remaining tooth structure and restorations were calculated. Descriptive statistics including mean, standard deviation, and frequencies were computed. Mann-Whitney U test was done to compare spectrophotometer values.

RESULTS

There was a significant reduction in mean color difference (ΔE) from baseline values for both tooth (p<0.05) and composite restoration (p<0.05) at all evaluation periods in both groups. Filtek Z250 showed significantly lower mean ΔE between the tooth and the composite resin restoration than IPS Empress at 48 hours (before and after finishing and polishing), 7 days and 14 days (p<0.05). At the 28 day recall, mean ΔE value of IPS Empress restorations to tooth structure was 3.5, while the mean ΔE value of Filtek Z250 restorations to tooth structure was 3.6, which was not statistically different (p>0.05).

CONCLUSION

The remaining tooth structure as well as the composite restorations showed color changes at all evaluation periods, compared to baseline values in both the composite resin groups. Filtek Z250 exhibited less ΔE with remaining tooth structure at 48 hours, 7 days, and 14 days, when compared to IPS Empress. The composite restorations of both the groups reached clinically acceptable color match (mean ΔE<3.7) with the remaining tooth structure 28 days after the procedure.

Effect of finishing and polishing systems on the surface roughness and color change of composite resins

Background

This study is to examine the surface roughness and color changes occurring on composite resins following the application of different finishing and polishing systems.

Material and Methods

In our study, a total of 200 samples were prepared from composites resin (6×2 mm) containing supra-nano, submicron hybrid, nanohybrid, nano-ceramic and microhybrid filler. They were polished with diamond, aluminum oxide, silicon carbide finishing and polishing systems. The initial color values of composite samples were measured with a spectrophotometer and surface roughness values with a profilometer. After that, samples were immersed of coffee solution and color measurements were repeated on the 1st and 7th day. The differences between surface roughness (Ra) and color change values (∆Eab) were evaluated using two-way analysis of variance (ANOVA) test (p<0.05).

Results

Finishing and polishing systems produced a statistically significant difference between the surface roughness values of nano-ceramic, submicron hybrid and microhybrid composite resin samples (p<0.05). Supra nano composite, which showed the lowest surface roughness after all finishing and polishing systems, showed the least color change after 7 days compared to other composite groups (p<0.05). The microhybrid composite with the highest surface roughness was the most color changing composite group (p<0.5).

Conclusions

The spiral finishing and polishing system containing diamond particles was the system to provide the least color difference on all composite groups. However, color differences of all composite resin groups were found to exceed the perceptibility threshold (PT) and acceptability threshold (AT).

Key words:Composite resin, color stability, surface roughness.

Varying the Polishing Protocol Influences the Color Stability and Surface Roughness of Bulk-Fill Resin-Based Composites

Surface properties of composites such as roughness and color impact periodontal health and aesthetic outcomes. Novel bulk-fill composites with improved functionality are being introduced and, in light of the existing variety of finishing/polishing procedures, research of their surface properties is warranted. Sixty discs were prepared from bulk-fill composites (Filtek™ Bulk Fill Posterior Restorative and Fill-Up™) and incremental-fill Filtek™ Z250. They were further divided according to different polishing procedures (n = 5): three multi-step polishing procedures or finishing with a bur (control). Surface roughness (Ra) was measured using an atomic force microscope (The AFM Workshop TT-AFM). A spectrophotometer (Spectroshade Micro Optic) was used to determine color stability, after exposure to a coffee solution. Data were analyzed using two-way MANOVA (significance level of 5%). Resin composite type, polishing procedure, and their interaction had a statistically significant effect on surface roughness (p < 0.001) and color change (p < 0.001). Fill-Up™ exhibited the highest surface roughness and greatest color change. Differences in color change were statistically significant (p < 0.001). Filtek™ Bulk Fill registered the lowest surface roughness and color change, after the three-step polishing procedure. Both parameters were significantly correlated (ρ = 0.754, p < 0.001) and found to be material dependent and polishing-procedure dependent. Higher surface roughness relates to greater color changes.

Physical and surface properties of a 3D-printed composite resin for a digital workflow

STATEMENT OF PROBLEM

Information related to the optical and surface properties, including health compatibility, surface roughness, and esthetics, of 3D-printed dental materials is scarce.

PURPOSE

The purpose of this in vitro study was to compare the physical and surface properties of a 3D-printed resin with those of materials used for interim restorations.

MATERIAL AND METHODS

A 3D-printed resin (PR) (NextDent C&B MFH; 3D Systems), an autopolymerizing interim material (BA) (Protemp 4; 3M ESPE), and a composite resin (Z350) (Filtek Z350XT; 3M ESPE) were tested for degree of color change (ΔE) (n=7) at different timepoints-24 hours after polishing/baseline (P0), 8 days after polishing (P1), and after artificial aging in water at 60 °C for 24 hours (P2)-by using a CIELab-based colorimeter; flexural strength (σ) (n=10) with a 3-point bend test; Knoop hardness (H) (n=8); and surface roughness (Ra) (n=7) with a profilometer. All specimens were polished 24 hours after polymerization, except for the additional group for surface roughness (BA) without polishing (BANP). A statistical analysis was performed by using 2-way repeated-measures ANOVA followed by the Fischer test for ΔE and 1-way ANOVA followed by the Fisher test for microhardness and surface roughness (α=.05).

RESULTS

The Z350 showed the highest values for σ and H, followed by PR. BA showed the lowest results for both tests (P<.05). Considering roughness, the Z350 showed similar values to those of BA but lower than PR; PR showed similar roughness when compared with BA. PR showed the highest color variation among the groups at all timepoints, followed by BA. The Z350 was the most color stable material at all timepoints.

CONCLUSIONS

The 3D-printed composite resin had adequate mechanical and surface properties for an interim restorative material. It has the potential to be a low-cost workflow in dentistry, although its color stability could be a concern for long-term use.

Avaliação do manchamento e da rugosidade superficial de materiais restauradores diretos após diferentes sistemas de polimento: estudo in vitro

Resumo Introdução Com o avanço estético e tecnológico dos compósitos restauradores diretos, a procura pela Odontologia Éstética tem aumentado. Objetivo Avaliar o manchamento e a rugosidade superficial dos compósitos Filtek Z350 (3M ESPE) e Filtek Bulk Fill (3M ESPE), polidos por diferentes sistemas: Disco SofLex e Disco SofLex diamantado espiral (ambos da 3M ESPE), após exposição repetitiva ao café. Material e método Neste estudo in vitro, um total de 80 discos de resina foi confeccionado, com 40 espécimes para cada compósito avaliado. Os espécimes foram ainda subdivididos em grupos (n=10) de acordo com o método de polimento ‒ SofLex e SofLex diamantado ‒ e a solução de armazenamento ‒ água deionizada (controle) e café (experimental). Após 24 horas de armazenamento em água deionizada, foi realizada a avaliação de cor e rugosidade inicial, bem como a execução dos protocolos de polimento testados. Posteriormente, os espécimes foram expostos ao processo de manchamento em café e água deionizada durante 42 dias. Após esse período, a cor e a rugosidade foram reavaliadas. Resultado A análise estatística paramétrica evidenciou que o manchamento superficial foi influenciado significativamente pelos fatores compósito e solução, mas não pelo fator polidor ou ainda por qualquer interação entre os fatores. Para o fator compósito, Filtek Z350 exibiu maior manchamento, e para o fator solução, foi observado maior manchamento para o café. Já na análise de rugosidade, não houve diferenças significativas. Conclusão Independentemente do sistema de polimento, a solução experimental de café alterou a cor de ambos os compósitos avaliados e verificou-se que a rugosidade não foi alterada.

Surface Sealant Effect on the Color Stability of a Composite Resin Following Ultraviolet Light Artificial Aging

OBJECTIVE

To examine how exposure to accelerated artificial aging (AAA) stimuli (ultraviolet [UV] light) affects the color stability of a composite resin following surface sealant (SS) application.

METHODS AND MATERIALS

A total of 30 cylindrical composite resin (Esthet-X) discs were prepared using Teflon-coated rings. The treatment groups, defined by different SS (Seal-N-Sine, PermaSeal, OptiGuard, Biscover LV, and DuraFinish) use, were divided into five groups of six discs each. The discs were subjected to baseline color measurements followed by measurements after surface sealant application (specular included component [SCI] and specular excluded component [SCE]) using a spectrophotometer. Three measurements (SCI and SCE) were performed for a total of 18 readings (test surface) per specimen group. All specimens were then exposed to a UV light source for a total of 382 hours. Color readings of the specimens were again recorded for each group. Quantitative color measurements were executed using Commission Internationale de l'Eclairage L*a*b* calculations.

RESULTS

Baseline color measurements of the composite resin discs, following the AAA exposure protocol, revealed no significant differences. A comparison of the composite resin discs before and after SS application (without UV light exposure) showed statistically significant differences using both SCI and SCE measurement criteria. Although significant differences were encountered between the ΔL*, Δa*, Δb*, and ΔE parameters, all specimens (groups) were within the clinically acceptable range (1.0<ΔE≤ 3.3). Again, statistically significant differences were noted (ΔL*, Δa*, Δb*, and ΔE parameters) for all specimen groups receiving SS application, utilizing both SCI and SCE measurements, following exposure to UV light. All groups were within the clinically acceptable range (1.0<ΔE≤ 3.3), except the Durafinish group. The Durafinish SS group experienced significantly greater (p<0.001) overall color change (SCI and SCE) following UV light exposure. An intergroup comparison following UV exposure revealed that the Permaseal, OptiGuard, and Seal-n-Shine SS groups displayed the least amount of color change statistically but not necessarily always perceptibly significant, while the Durafinish group exhibited the greatest color change statistically and perceptibly.

CONCLUSIONS

The color stability of a composite resin, including the addition of most SSs, was not affected perceptibly by UV light exposure.

Avaliação do efeito cromático em resinas compostas nanoparticuladas submetidas a solução café

Resumo Introdução Em uma sociedade de alta competitividade social, os padrões estéticos estão cada vez mais refinados e, dentro destes, a concepção e o desejo de se ter o sorriso perfeito aumentaram consideravelmente a busca pelos tratamentos dentários e, consequentemente, o desenvolvimento de materiais que possam propiciar tais resultados. O sucesso clínico de uma restauração engloba sua longevidade, do ponto de vista funcional, incluindo ausência de infiltrações, e sua função estética, por meio da manutenção de coloração e lisura superficial adequada. Objetivo O presente trabalho busca analisar a alteração de cor de duas marcas de compósitos odontológicos nanoparticulados ‒ Z350 e Bulk Fill (3M ESPE) ‒ e dois sistemas de polimento ‒ Disco SofLex e Disco SofLex espiral emborrachado (3M ESPE) ‒, com as subdivisões em grupos controle (água destilada) e experimental (café), em um período de 21 dias. Material e método Os espécimes foram confeccionados de modo padronizado e armazenados por sete dias em água deionizada a 37 °C, em estufa para análise da cor inicial, seguido do armazenamento nas respectivas soluções para a análise cromática, ao final do período de estudo, sendo ambas as análises realizadas através de espectrofotômetro (CM-700d, Konica Minolta, Osaka, Japão) e escala ΔE CIELAB. Resultado Observou-se que ambas as resinas tiveram sua coloração alterada na presença do café, entretanto a resina Z350 apresentou maiores variações em comparação à Bulk Fill. Conclusão Apesar de a solução corante café ser capaz de promover mudança de cor nas resinas estudadas, os sistemas de polimento, isoladamente, não apresentam efeito final sobre a alteração cromática desses materiais restauradores.

Spectrophotometric Evaluation of Colour Stability of Nano Hybrid Composite Resin in Commonly Used Food Colourants in Asian Countries

INTRODUCTION

There is growing interest in colour stability of aesthetic restorations. So far few studies have been reported.

AIM

This study was designed to investigate the effects of different common food colourants i.e., Turmeric and Carmoisine (orange red dye) consumed by patients in Asian countries on a recent nano hybrid composite resin.

MATERIALS AND METHODS

A total of sixty disk shaped specimens measuring 10 mm in diameter and 2 mm in thickness were prepared. The samples were divided into two groups {Z 100 (Dental restorative composite) Filtek Z 250 XT (Nano hybrid universal restorative)}. Baseline colour measurement of all specimens were made using reflectance spectrophotometer with CIE L*a*b* system. Specimens were immersed in artificial saliva and different experimental solutions containing food colourants (carmoisine solution and turmeric solution) for three hours per day at 37°C. Colour measurements were made after 15 days. Colour difference (ΔE*) was calculated. Mean values were compared by one-way analysis of variance (ANOVA). Multiple range test by Tukey Post-hoc test procedure was employed to identify the significant groups at 5% level.

RESULTS

Z 100 showed minimum staining capacity when compared to Z 250 XT in both the colourant solutions.

CONCLUSION

The nanohybrid composite resin containing TEGDMA showed significant colour change when compared to that of microhybrid composite resin as a result of staining in turmeric and carmoisine solution.

Colour Stability of Various Types of Acrylic Teeth Exposed to Coffee, Tea and Cola

STATEMENT OF PROBLEM

Acrylic teeth of dentures are prone to discoloration due to frequent exposure to different colouring solutions in the oral environment. Thus, in order to maintain their aesthetic appearance, they must possess high colour stability while exposed to colorant solutions.

OBJECTIVES

To compare the colour stability of three different brands of acrylic teeth following immersion in coffee, tea and cola.

MATERIALS AND METHODS

This in vitro experimental study was conducted on 90 acrylic teeth in three groups (n = 30) of Ivoclar (Italy), PolyDent (Slovenia) and Apple (Iran). The teeth were immersed in coffee, cola and tea for one, three and six weeks (the teeth were not in contact with each other). Colour parameters were assessed before and after immersion using a spectrophotometer, and overall change in colour parameters was calculated. The overall colour change (ΔE) of the three groups at different time points was analyzed using one-way ANOVA. Pairwise comparisons were performed using Tukey's test.

RESULTS

Coffee caused the greatest colour change in Apple acrylic teeth after six weeks (mean ΔE of 4.6 for coffee and 3.4 for tea and cola). Tea caused an almost equal colour change in the three groups. The greatest colour change in the Ivoclar teeth occurred in cola after six weeks (mean ΔE of 3.3, 3.4 and 2.8 for cola, tea and coffee, respectively). The greatest ΔE occurred at six weeks and was the highest in Apple, followed by PolyDent and then Ivoclar teeth in coffee (mean ΔE of 4.6, 3.4 and 3.3, respectively p < 0.001).

CONCLUSIONS

Despite the significant colour change in the three groups, ΔE in Ivoclar group was within the clinically acceptable range of ≤ 3.3. A slight colour change was expected regarding the Apple and PolyDent acrylic teeth clinically.

Effect of surface sealing on stain resistance of a nano-hybrid resin composite

Purpose:

This study investigated the influence of sealant application on stain resistance of a nanohybrid resin composite compared to the efficacy of a bonding agent used as a surface sealant on prolonging color stability of the resin composite.

Materials and Methods:

28 disc-shaped materials were prepared from a nano-hybrid resin composite Filtek Z550 and assigned to four groups: G1K: nonsealed; G2:Adper Single Bond; G3: Fortify ; G4: Biscover LV. After 24 h storage in distilled water at 37˚C, all specimens were subjected to thermocycling and immersed into coffee solution. Color measurements were performed using spectrophotometer (VITA Easyshade; Vident) according to CIEL*a*b* system.

Results:

Color change values were significantly different among the groups in each evaluation period except for after thermocycling (p<0.05). For 7 days evaluation period, the difference between G3 and G4 group was statistically significant while G4 exhibited statistically significant differences (p<0.05 and p<0.0001 respectively) compared to control (G1) in 14 day whereas no significant difference was found between GI and GII in 28-day evaluation period. However, ΔE values of sealed specimens (GIII, GIV) differed significantly from non-sealed (GI) specimens after 28 days of immersion in coffee solution (p<0.05 and p<0.0001 respectively).

Conclusion:

It may be concluded that using a bonding agent as a surface sealant does not increase stain resistance of resin composites of the sealants evaluated. Biscover LV showed the highest efficacy to prolong color stability of the resin composite.

Color stability and surface roughness of polished anterior restorative materials

The purpose of this study was to investigate the effects of different finishing-polishing techniques on the color stability and surface roughness of various anterior restorative materials after staining. A composite, a compomer, and a resin-modified glass ionomer were used to prepare 120 specimens. Specimens were divided into subgroups: polishing discs, liquid polishing material, aluminium oxidebonded discs, and control. The specimens were stained in a coffee solution. Color parameters (L*a*b*) and surface roughness before and after staining were measured. The color was affected by the material type (p<0.05) and finishing-polishing systems (p<0.05). The composite showed the highest color stability; however, the color differences of all groups were visible even to the nonskilled operator. The Ra values did not significantly change after staining for any of the restorative groups (p>0.05). The finishing-polishing systems had an effect on color after storing in staining solution.

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

Objective

To evaluate the hardness (KHN), color stability (DE), and superficial micromorphology of two categories of composites after immersion in either distilled water or grape juice for up to 45 days.

Material and Methods

Cylindrical specimens (6 mm diameter x 2 mm thick) were obtained according to the factors: composite [Opallis (FGM) and Filtek Z350XT (3M ESPE)]; immersion solution (distilled water and grape juice); and evaluation time: 24 h and 7, 14, 21, 28, and 45 days. After photoactivation, the specimens were stored at 37ºC for 24 h. KHN (50 g/15 s) and ΔE were then repeatedly assessed according to the immersion solutions. Data were analyzed (three-way ANOVA/Tukey's test). Scanning electron microscopy (SEM) topographic analysis was also performed.

Results

In general, KHN of both composites reduced after 24 h, irrespective of the immersion solution and time. A significantly lower KHN was noted for Opallis compared with Filtek Z350XT in all parameters. An increase in ΔE over time was noted for both composites, irrespective of the immersion solution. Significantly higher ΔE was noted for Filtek Z350XT immersed in grape juice compared with Opallis, regardless of the evaluation time. The grape juice caused significantly higher DE compared with water in all periods. SEM analysis showed eroded areas for Filtek Z350XT but not for Opallis.

Conclusions

The compositions and immersion solutions influence the composite hardness and the color stability. In spite of the higher hardness, the nanofilled composite is more susceptible to color change than the microhybrid when immersed in an acidic dyed solution.

Anterior composite restorations in clinical practice: findings from a survey with general dental practitioners

Objectives

The aim of this study was to assess technical preferences of general dental practitioners when restoring anterior composite restorations. How the level of clinical experience or post-graduate training infuenced their options was also tested.

Material and Methods

A cross-sectional study was performed using a questionnaire with general dental practitioners (GDPs) (n=276) in Southern Brazil. Information regarding post graduation training (specialization, master's or PhD degree) and linical experience (years since completing graduation) were gathered. The options regarding anterior composite restorations (type of composite, adhesive system, light curing unit, polishing procedures and rubber dam use) were collected. Data were submitted to descriptive analysis and associations were tested.

Results

Response rate was 68% (187). GDPs selected microhybrid composite (52%) and 2-step total etch adhesive system (77%). LED was the preferred method of activation for 72.8%. Immediate polishing was preferred by 75%, using a combination of techniques. Most of the respondents (74.3%) did not use rubber dam. More experienced clinicians used more halogen lights (p<0.022), performed more light monitoring (p<0.001) and were resistant to use rubber dam (p<0.012). Dentists with post-graduation training used 3-etch-and-rinse system more frequently (p<0.04), usually monitored light intensity (p<0.014) and placed rubber dam more frequently (p<0.044).

Conclusions

Hybrid composite, simplifed adhesives, LED units and immediate polishing were preferred by Southern Brazilian dentists for anterior composite restorations. Few dentists used rubber dam to perform composite restorations in anterior teeth. Clinical experience and post-graduation training infuenced the dentists' choices.

Finishing and polishing procedures of composite restorations by Saudi dentists: a cross-sectional study

AIM

The purpose of this study was to assess the knowledge and practices of Saudi dentists in finishing and polishing composite restorations.

MATERIALS AND METHODS

A cross-sectional questionnaire-based study was conducted among 306 Saudi dentists from March to April 2012. The collected data were analyzed using Microsoft Excel 2010 program and descriptive statistics were obtained.

RESULTS

Completed questionnaires were returned by 191 participants, giving a response rate of 62.4%. 115 (65.7%) respondents are using fine diamond finishing burs for finishing occlusal surfaces, 82 (48%) used fine aluminum oxide finishing discs for finishing facial surfaces, 130 (76%) used diamond finishing strips for finishing interproximal surfaces.121 (63.4%) respondents were of the view that the type of filler content has a major influence in providing color stability to the composite restoration and 137 (72.1%) believed nano-composites provided enhanced color stability.

CONCLUSION

Dentists in Saudi Arabia are aware of the benefits of proper finishing and polishing of composite restorations. They however need to use finishing and polishing burs, disks, strips and pastes in a sequential series. Usage of composite polishing pastes and composite surface sealants should be emphasized in undergraduate curriculum.

The effectiveness of four methods for stain removal from direct resin-based composite restorative materials

BACKGROUND/PURPOSE

Few studies investigated the best method for removing stains from different types of resin-based composite restorations and compared them to the more recently introduced nanocomposites. This study compared the effect of four methods for stain removal from composite resins; finishing with Sof-lex disks, using pumice and brush, bleaching with 10% carbamide peroxide and 38% hydrogen peroxide.

MATERIALS AND METHODS

Twenty disk specimens were prepared. Specimens were immersed in a staining solution for 3 weeks. The stained surfaces of five specimens from each RBC material were treated with one of the treatment procedures. Colorimetric measurements were taken using spectrophotometer prior to and after staining, and then repeated after surface treatments. Color difference values were calculated.

RESULTS

One-way ANOVA indicated significant differences in color change of the three composite resin materials following staining. Filtek Z250 showed the least susceptibility to discoloration followed by Renamel, Filtek Supreme was the material most prone to discoloration. Two-way ANOVA and Tukey's Post Hoc showed that all stain removing procedures except polishing with pumice, were able to return Filtek Z250 to clinically acceptable color difference. While bleaching with 38% carbamide peroxide was not effective with Renamel. Only pumice and 10% carbamide peroxide were able to return Renamel to clinically acceptable color difference.

CONCLUSION

Compositions of resin-based composite resins play an important role in their susceptibility to stain and their amenability to stain removal procedures. Home bleaching showed good results for the three materials, while office bleach was the least effective.

Interaction between staining and degradation of a composite resin in contact with colored foods

Composite resins might be susceptible to degradation and staining when in contact with some foods and drinks. This study evaluated color alteration and changes in microhardness of a microhybrid composite after immersion in different colored foods and determined whether there was a correlation between these two variables. Eighty composite disks were randomly divided into 8 experimental groups (n = 10): kept dry; deionized water; orange juice; passion fruit juice; grape juice; ketchup; mustard and soy sauce. The disks were individually immersed in their respective test substance at 37 ºC, for a period of 28 days. Superficial analysis of the disk specimens was performed by taking microhardness measurements (Vickers, 50 g load for 45 seconds) and color alterations were determined with a spectrophotometer (CINTRA 10- using a CIEL*a*b* system, 400-700 nm wavelength, illuminant d65 and standard observer of 2º) at the following times: baseline (before immersion), 1, 7, 14, 21 and 28 days. Results were analyzed by ANOVA and Tukey's test (p < 0.05). Both variables were also submitted to Pearson's correlation test (p < 0.05). The passion fruit group underwent the greatest microhardness change, while the mustard group suffered the greatest color alteration. Significant positive correlation was found between the two variables for the groups deionized water, grape juice, soy sauce and ketchup. Not all color alteration could be associated with surface degradation.

Effect of the polishing procedures on color stability and surface roughness of composite resins

Objectives. To evaluate the polishing procedures effect on color stability and surface roughness of composite resins. Methods. Specimens were distributed into 6 groups: G1: Filtek Supreme XT + PoGo; G2: Filtek Supreme XT + Sof-Lex; G3: Filtek Supreme XT + no polishing; G4: Amelogen + PoGo; G5: Amelogen + Sof-Lex.; G6: Amelogen + no polishing. Initial color values were evaluated using the CIELab scale. After polishing, surface roughness was evaluated and the specimens were stored in coffee solution at 37°C for 7 days. The final color measurement and roughness were determined. Results. Sof-Lex resulted in lower staining. Amelogen showed the highest roughness values than Filtek Supreme on baseline and final evaluations regardless of the polishing technique. Filtek Supreme polished with PoGo showed the lowest roughness values. All groups presented discoloration after storage in coffee solution, regardless of the polishing technique. Conclusion. Multiple-step polishing technique provided lower degree of discoloration for both composite resins. The final surface texture is material and technique dependent.

Difference in the color stability of direct and indirect resin composites

Indirect resin composites are generally regarded to have better color stability than direct resin composites since they possess higher conversion degree

The Efficiency of a New Polishing Material: Nanotechnology Liquid Polish

It is well known that the esthetic properties and clinical stability of resin composites are increased by finishing and polishing procedures. However, there is still a question of which techniques or materials should be preferred. The use of nanotechnology may be the best way of creating more esthetic composite restorations.

Review: Resin Composite Filling

The leading cause of oral pain and tooth loss is from caries and their treatment include restoration using amalgam, resin, porcelain and gold, endodontic therapy and extraction. Resin composite restorations have grown popular over the last half a century because it can take shades more similar to enamel. Here, we discuss the history and use of resin, comparison between amalgam and resin, clinical procedures involved and finishing and polishing techniques for resin restoration. Although resin composite has aesthetic advantages over amalgam, one of the major disadvantage include polymerization shrinkage and future research is needed on reaction kinetics and viscoelastic behaviour to minimize shrinkage stress.