Effect of bleaching on color change and surface topography of composite restorations

Effect of bleaching and repolishing on whiteness change and staining susceptibility of resin-based materials

BACKGROUND

The aim of this study was to investigate the effects of different types of bleaching methods and repolishing on the whiteness index and staining susceptibility of additive and subtractive production resin-based materials and direct composite resins.

METHODS

In this study, a total of 96 samples (8*8*2m) were prepared using a nanohybrid composite resin (Neo SpectraTM-ST (NS)), a subtractive-manufactured nanoceramic resin (CerasmartTM270 (CS)), and an additive-manufactured permanent resin (Saremco print Crowntec (CT)). The samples were randomly divided into four treatment groups: control (distilled water, 14 days), in-office bleaching (Opalescence Boost-40% HP, 3*20min), at-home bleaching (Opalescence PF-16% CP, 6 h, 14 days), and toothpaste group (Opalescence Whitening, 2*5min, 14 days) (n:8). After each the bleaching procedure was completed, the samples were kept in coffee solution for 7 days. Following, all samples were repolished. The color of the samples was measured with a spectrophotometer at baseline (T0), after bleaching (T1), after staining in coffee (T2) and after repolishing (T3). The whiteness index change (∆WID, T1-T0), staining susceptibility (∆E1, T2-T1) and color change after repolishing (∆E2, T3-T1) of the samples were calculated in the CIE (Commission International De I'Eclairage) system. The data were analyzed by SPSS software One-Way ANOVA, post-hoc Tukey, post-hoc Tamhane's-T2 and Paired-samples T test (α = 0.05).

RESULTS

The ∆WID of all tested materials was significantly different in the in-office bleaching group compared to the control group (p < 0.05). Among the bleaching groups, the highest ∆WID was obtained in-office bleaching group of CT (2.91 ± 4.12). Staining susceptibility after bleaching (∆E1) was higher in the in-office and at-home bleaching groups compared to the control group in all tested materials. However, the difference between the treatment groups was statistically significant in NS and CS (p < 0.05). The highest ∆E1 was obtained in the in-office group of CT (7.36 ± 4.82). Color changes after repolishing (∆E2) of the tested materials were less in all groups compared to ∆E1.

CONCLUSION

In-office and at-home bleaching can increase the whiteness index change and stain susceptibility of materials. Among the tested materials, the color stability of additive-manufactured CT was comparatively poorer. The repolishing was found to be beneficial in reducing staining.

In vitro study on the impact of various polishing systems and coffee staining on the color stability of bleach-shaded resin composite

OBJECTIVE

To evaluate the effects of different polishing techniques and coffee staining on the color stability of four commercially available bleach-shade composite resins, namely microhybrid, nanohybrid, nanofilled, and injectable nanohybrids.

MATERIAL AND METHODS

A total of 224 discs (8 mm diameter and 2 mm thickness) were fabricated from four different bleach-shade composite resins, namely microhybrid (Gradia Direct Anterior), nanohybrid (Palfique LX5), nanofilled (Filtek Universal), and injectable nanohybrid (flowable G-aenial universal injectable). The composite resin groups were polished via four techniques: no polishing, 4-step polishing using aluminum oxide discs, 3-step polishing using silicon rubber diamond discs, and one-step polishing. Half of each group was immersed in water, while the other half was immersed in coffee for 12 days (n = 7). Colors were measured using a clinical spectrophotometer, and color differences were calculated (ΔE). The results were analyzed statistically.

RESULTS

The alterations in color were significantly influenced by the techniques employed for finishing and polishing techniques, composite resin type, and degree of coffee staining. Regardless of the polishing technique and storage medium, different material types showed a significant color change (ΔE) at P < 0.001. Filtek exhibited the most significant color change, followed by Gradia and Palfique, with no significant differences between them. In addition, Different polishing techniques resulted in significant color changes (P < 0.001). The highest degree of color change was seen in the no-polishing group, followed by the 4-step and 1-step polishing groups, with negligible differences between each other. Also, Storage media had a significant effect on ΔE values.

CONCLUSION

Appropriate finishing and polishing procedures can improve the color stability of bleach-shaded composite resins. Coffee has a deleterious effect on color; however, injectable flowable nanohybrid composites are more resistant to staining.

Do Different Tooth Bleaching-Remineralizing Regimens Affect the Bleaching Effectiveness and Enamel Microhardness In Vitro?

Objective

Tooth bleaching may negatively affect the enamel surface properties, such as reduction in hardness values, and remineralizing agents can reverse these effects. This study evaluated the effect of remineralizing agents before, during, and after the bleaching process on enamel's whitening effectiveness and microhardness.

Methods and Materials

The initial color of 104 bovine incisors after immersion in tea solution was recorded, and then, the teeth were randomly divided into eight groups (n = 13). Group 1 (NC) was considered the control with no treatment, and Group 2 (B) was bleached with 40% hydrogen peroxide gel. The 3% fluorohydroxyapatite (FHA) and 2% sodium fluoride (NaF) were applied before (FHA/B, NaF/B), during (FHA + B, NaF + B) and after (B/FHA, B/NaF) the bleaching process in other groups. The final color and microhardness in three depths of 20-30, 50-60, and 100-120 µm were measured. Data were analyzed using Shapiro-Wilk, one-way ANOVA, Tukey, Games Howell, repeated measurement, and LSD tests.

Results

The FHA + B presented the lowest ΔE, significantly lower than other groups, except B/FHA. The ΔE in B/FHA was significantly lower than B/NaF. The bleaching significantly reduced the enamel hardness in three depths. The highest microhardness values were reported for B/NaF and NaF + B, which have no noticeable difference with NC, while FHA/B showed the lowest hardness in three depths, which was significantly lower than NC.

Conclusion

The application of NaF before, during, and after the bleaching improved the microhardness of bleached enamel as the unbleached one with no adverse effect on whitening effectiveness.

Susceptibility to discoloration of dental restorative materials containing dimethacrylate resin after bleaching

The aim of this study is to compare the susceptibility to discoloration of dental restorative materials containing dimethacrylate resin after bleaching. In this study, resin-modified glass ionomer, polyacid-modified composite resin, giomer, posterior composite resin, anterior composite resin, bulk fill composite resin, flowable bulk fill composite resin, ormocer, indirect composite resin and hybrid ceramics were used as restorative material containing dimethacrylate resin. 20 samples were prepared from each material in accordance with the manufacturer's instructions. After the baseline colors are measured, the samples were randomly divided into four subgroups as office bleaching, home bleaching and a separate control group for each type bleaching method. Then, the samples were bleached and colored. Color measurements of the samples were repeated after exposure to bleaching and coloring. Then, ΔE00 and whiteness index (WID) were calculated. Data were analyzed using Paired-Samples T Test, two-way ANOVA, Repeated Measures ANOVA and Tukey post-hoc tests. Statistical significance level was taken as p < 0.05. In terms of bleaching systems, Opalescence Boost was found to cause more whitening in materials but more discoloration (p < 0.05). In terms of materials, it was found that the most susceptible materials to coloration were Clearfil Majesty Posterior, Filtek Bulk Fill Posterior Restorative, Filtek Bulk Fill Flowable and Fuji II LC, while the least susceptible materials were CAD/CAM materials (p < 0.05). The bleaching process increases the susceptibility to coloration of materials containing dimethacrylate resin.

Evaluation of Smart Chromatic Technology for a Single-Shade Dental Polymer Resin: An In Vitro Study

The aim of the study was to assess the color matching ability and color stability of a single-shade resin-based composite (Omnichroma—OM) in comparison to a conventional dental composite. One hundred and sixty lower molar acrylic teeth in four different shades (B1, B2, A3, and C3) were prepared with class I cavities. Eighty teeth were divided into two groups based on the two resin composite materials (OM and Filtek Z-350 (FT)) for cavity restoration. Three groups were included in the color matching assessment, namely Gp 1-FT, Gp 2-OM-light cured (C), and Gp 3-OM-uncured (UC) groups. The color assessment was performed prior to cavity restoration and after cavity filling and before and after light curing to detect color matching. The 80 remaining teeth were restored with OM (n = 40) and FT (n = 40); half (n = 40) were submerged in coffee and the other half (n = 40) were submerged in cola for 2 weeks. The color stability was assessed by calculating material color (spectrophotometry) changes (∆E) before and after staining in immersion medium. The means and standard deviations of the ∆E values relating to color matching and color stability (stain resistance) among the study groups were analyzed using ANOVA and Tukey’s post hoc test. FT showed significantly better color matching (lower ΔE) in comparison to OM-UC specimens for shades B1, B2, and A3 (p < 0.01). Regarding the color stability in cola, the FT samples showed significantly lower ΔE values (indicating better color stability) compared to OM samples for all four shades (p < 0.01). The ΔE values of OM and FT samples in coffee were comparable (p > 0.01), showing comparable color stability. The color matching ability of the single-shade resin composite (OM) was influenced by the tooth color. The conventional resin composite showed better color matching than the single-shade composite (OM). The color stability of the single-shade resin composite (OM) was dependent on the staining medium. The OM composite showed more compromised color stability than the conventional resin composite in cola and comparable color stability to conventional resin composite in coffee.

Color Stability and Staining Susceptibility of Direct Resin-Based Composites after Light-Activated In-Office Bleaching

This study evaluated color stability and staining susceptibility of five direct resin-based composites (RBCs) subjected to light-activated in-office bleaching with 40% hydrogen peroxide (HP). The test materials included 5 RBCs, which consisted of one nano-filled, one sub-micron, one bulk-filled, and two nano-hybrid RBC types. Ten disc-shaped specimens of each RBC were fabricated and divided into bleaching (BLE) and non-bleaching (CON) groups (n = 5 for each group). Specimens were then immersed in red wine solution over 4 h. A spectrophotometer was used to obtain Commission Internationale de l'Eclairage (CIE) L*a*b* parameters for each of the following periods tested: before bleaching (T_BA), after bleaching (T_BL), and after staining (T_ST). Color stability and staining susceptibility were evaluated using two metrics, CIEDE2000 color differences (ΔE₀₀) and whiteness variations using the whiteness index (ΔWI_D). Data were analyzed using repeated measures two-way analysis of variance (ANOVA) (α = 0.05). Statistically significant and clinically unaccepted ΔE₀₀ and ΔWI_D were observed for all tested specimens between T_BA and T_BL. The nano-hybrid type RBCs showed the highest discoloration among materials after bleaching treatment. The BLE group exhibited significantly higher ΔE₀₀ and ΔWI_D than the CON group for all the tested RBCs between T_BA and T_ST. The sub-micron type RBC showed the highest discoloration among materials after immersion in the red wine. Conclusion. The light-activated in-office bleaching with 40% HP's influences on color and whiteness index were material-dependent. The use of bleaching treatment also increased the susceptibility to red wine for all RBCs.

Effect of different bleaching techniques on DNA damage biomarkers in serum, saliva, and GCF

Bleaching agents containing a high concentration of H₂O₂ in the dental market lead to formation of reactive oxygen species, which have genotoxic effects. However, ozone bleaching, one of the most effective oxidants known, stimulates blood circulation and immune response and thus it has strong antimicrobial activity against viruses, bacteria, fungi, and protozoa. For these reasons, one of our hypothesis was ozone bleaching would reduce local and systemic DNA damage in the body. Hence, we aimed to determine the oxidative DNA damage biomarker levels in serum, saliva, and gingival crevicular fluid (GCF) by measuring 8-hydroxy-2'-deoxyguanosine (8-OHdG) after different bleaching methods.Forty-eight volunteers who requested dental bleaching were divided into three treatment groups (n = 16). Group 1: ozone bleaching with the ozone-releasing machine; Group 2: chemical bleaching with 40% hydrogen peroxide (H₂O₂) gel; Group 3: 40% H₂O₂ gel activated with the diode laser. Initial and post-operative (immediately after bleaching and two weeks later) color measurements were performed with a spectrophotometer. The color changes were calculated with the CIEDE2000 (ΔE ₀₀) formula. 8-OHdG levels in serum, saliva, and GCF samples were determined with ELISA. All three treatments resulted in efficient and statistically similar bleaching. The 8-OHdG levels in the serum and saliva were not affected by all bleaching methods (p > 0.05), but a temporary increase was observed in the GCF for chemical and laser-assisted groups except the ozone group (p > 0.05). According to the findings, chemical and laser-assisted bleaching can affect DNA damage locally but not systemically. Bleaching with ozone may eliminate this local DNA damage.

Effects of Artificial Staining and Bleaching Protocols on the Surface Roughness, Color, and Whiteness Changes of an Aged Nanofilled Composite

This study evaluated the surface roughness and color alteration of an aged nanofilled composite exposed to different staining solutions and bleaching agents. Ninety nanofilled composite (Filtek Z350XT, 3M/Oral Care) specimens were submitted to 5,000 thermal cycles and immersed in (n = 30): red wine, coffee, and artificial saliva at 37°C for 48 h. Groups were subdivided according to the bleaching protocol (n = 10) with 20% carbamide peroxide, 38% hydrogen peroxide, or without bleaching - control. Mean surface roughness values (Ra - μm) and color parameters (L*, a*, b*) were measured at baseline (T0), after thermal cycling aging and staining (TS), and after bleaching (TB). Color (ΔE00) and whiteness index (ΔWID) changes were determined after aging and staining (Ts-T0) and after bleaching (TB-TS). The adopted perceptibility and acceptability thresholds of the nanofilled composite were 0.81 and 1.71 ΔE00 units and 0.61 and 2.90 ΔWID units, respectively. Ra was analyzed using mixed models for repeated measurements and L* by the Tukey-Kramer test. The a* and b* values were evaluated by generalized linear models for repeated measures. ΔE00 was tested using two-way ANOVA and Tukey tests, and ΔWID by Kruskal-Wallis and Dunn tests (α = 5%). Ra of all groups decreased after aging and staining (TS, p &lt; 0.05), but increased after bleaching only for groups stained with red wine (TB). Aging and staining decreased the luminosity of the composites, but L* increased after bleaching (p &lt; 0.05). Aging and staining increased a* and b* values, but after bleaching, b* values decreased (p &lt; 0.05). After bleaching, ΔE00 and ΔWID were greater in stained groups at both time intervals, regardless of the bleaching protocol. Stained resin composites exhibited perceptible but unacceptable color (ΔE00 &gt; 1.71) and whiteness (ΔWID &gt; 2.90) changes, regardless of the bleaching treatment performed. Therefore, red wine affected the surface roughness of the aged nanofilled resin submitted to bleaching. Bleaching was unable to reverse the color changes promoted by red wine and coffee on the aged nanofilled composite.

Surface Roughness of Different Composite Resins after Application of 15% Carbamide Peroxide and Brushing with Toothpaste: An In-Vitro Study

Objectives:

This study aimed to evaluate the effect of toothbrushing after application of 15% carbamide peroxide (CP) on the surface roughness of three types of composite resins.

Materials and Methods:

Twenty samples, measuring 4 mm in height and diameter, were fabricated of three composite resins namely microfilled (MF) Heliomolar HB, nanohybrid (NH) IPS Empress Direct and microhybrid (MH) Tetric Ceram HB. After polishing, the initial surface roughness was measured with a profilometer. The tray technique was used to apply 15% CP gel for 6 hours. Then, cleaning was carried out with an Oral-B electric toothbrush for 3 minutes in a tank containing a freshly mixed toothpaste. These procedures were repeated for 21 days. Then, the surface roughness was measured again and compared with the initial values. A mixed-design ANOVA model was used for the analysis of data (P<0.05).

Results:

The baseline roughness was significantly lower in MF compared to the NH and MH composites (P<0.001). Roughness increased in all study groups during the intervention period; however, this increase was not significant in the MH group (P=0.17). Furthermore, the increase in roughness in MF was smaller than that in NH (P<0.001) and MH (P=0.02) groups.

Conclusion:

The effect of intervention was more pronounced on NH and MH groups. Surface roughness changes were minor in MF composite resin.

O uso do gel de glicerina melhora a estabilidade de cor de resinas compostas?

Resumo Introdução A camada superficial de resina composta não polimerizada, em função da presença do oxigênio, ocasiona problemas clínicos, como alteração de cor por absorção de pigmentos. Objetivo Determinar o efeito de diferentes técnicas usadas no controle da formação da camada de dispersão sobre as propriedades ópticas de uma resina composta comercial. Material e método Espécimes foram produzidos com a resina composta Estelite Sigma. A fotoativação foi conduzida com uma fonte de luz LED Bluephase G2 (1.200 mW/cm2 por 40 s). Os grupos foram determinados em função de três técnicas distintas: 1) sem tratamento (controle); 2) fotoativação com gel de glicerina; 3) polimento com lixa abrasiva após a fotoativação. A estabilidade de cor (ΔE) e o parâmetro de translucidez foram determinados pelo método de espectroscopia de reflectância (Easyshade Compac, Vita) empregando o parâmetro CIELab. As análises foram realizadas imediatamente após a fotoativação e repetidas após 7 dias de armazenamento em água ou em café. Os resultados foram submetidos à análise de variância e ao teste de Tukey (α = 0,05). Resultado Não houve diferença para ΔE nos grupos envelhecidos em água. Quando armazenados em café, o grupo controle apresentou o maior valor de ΔE, enquanto o grupo polido gerou a menor alteração de cor. A aplicação do gel de glicerina produziu resultados intermediários. O parâmetro de translucidez não foi afetado pelos tratamentos testados. Conclusão O uso do gel de glicerina minimiza a alteração de cor nas regiões de difícil acesso aos instrumentos de acabamento e de polimento.

Color and translucency of finished and unfinished esthetic restorative materials after staining and bleaching

Purpose: To evaluate the effect of staining and bleaching on color and translucency of finished and unfinished nano-filled resin composite and giomer. Materials and methods: Twenty specimens (ten finished + ten unfinished) were fabricated from each material, then an initial color and translucency measurement was taken. Specimens were stained in coffee for 48 h at 37 °C, rinsed and dried. After which the second color and translucency measurement was taken. After in-office bleaching with 40% H₂O₂ Opalescence boost, a third color and translucency measurement was taken. CIE L^∗ a^∗ b^∗ system was used for measuring color change and translucency. Two-way ANOVA and paired t-test were used for statistical analysis at P ≤ 0.05. Results: After staining, all specimens showed clinically acceptable color change (ΔE ≤ 3.3) with no significant differences between groups. After bleaching, all specimens showed clinically unacceptable color change (ΔE > 3.3) and significant differences between finished & polished and unfinished groups (P = 0.024). Nano-composites recorded significantly higher translucency than giomer (P = 0.000) except after bleaching. In addition, the translucency of unfinished groups were significantly higher than finished & polished groups (P = 0.001). Conclusions: The tested materials responded similarly to staining and bleaching. High concentration bleaching increased color change and reduced translucency. Finishing & polishing restorative materials improves their resistance to color change after bleaching, but it adversely affects translucency.

Effect of preheat repetition on color stability of methacrylate- and silorane-based composite resins

Background. The aim of this study was to investigate the effect of preheating methacrylate- and silorane-based composite resins on their color stability up to 40 times at 55‒60°C.

Methods. Seventy-six methacrylate and silorane-based composite resin samples, with a diameter of 10 mm and a height of 2 mm, were divided into 4 groups (n=19). After the samples were prepared, their color parameters were determined using a reflective spectrophotometer. The composite resin samples were separately stored in a solution of tea for 40 consecutive days. Then the samples underwent a color determination procedure again using a spectrophotometer and color changes were recorded. Finally two-way ANOVA was used to study the effect of composite temperature on its staining (P<0.05). Independent-samples t-test was used to evaluate changes in conversion rates of preheated composite resin samples compared to non-heated samples at P=0.005 and P=0.029 for silorane-based and Z250 composite resin samples, respectively.

Results. Both composite resin type (P=0.014) and preheating (P<0.001) had significant effects on ΔE.

Conclusion. Repeated preheating of methacrylate- and silorane-based composite resin samples, up to 55‒60°C for 40 rounds, resulted in more color changes compared with unheated composite resin samples. After storage in a solution of tea the color change rate in the composite resin samples of silorane-based was higher than the Z250 composite resin samples.

Effect of two different tooth bleaching techniques on microhardness of giomer

BACKGROUND

Tooth bleaching is a safe and conservative treatment modality to improve the esthetic appearance of discolored teeth. One of the problems with the use of bleaching agents is their possible effect on surface microhardness of resin-based materials. The present study was carried out to evaluate the effect of in-office and at-home bleaching on surface microhardness of giomer.

MATERIAL AND METHODS

Seventy-five disk-shaped giomer samples (Beautifil II) were prepared and cured with a light-curing unit. The samples were randomly assigned to three groups (n=25). In group 1 (control), the samples were stored in distilled water for 14 days. The samples in groups 2 and 3 underwent a bleaching procedure with 15% carbamide peroxide (CP) (8 hours daily) and 45% CP (30 minutes daily), respectively, for 14 days. Finally, the microhardness of samples was measured with Vickers hardness tester using a 100-g force for 20 seconds. One-way ANOVA was used to compare the mean microhardness values among the study groups, followed by post hoc Tukey test for two-by-two comparison of the groups. Statistical significance was set at P<0.05.

RESULTS

One-way ANOVA showed significant differences in the mean microhardness values among the study groups (P<0.001). Based on the results of Tukey test, microhardness in the bleached groups was significantly less than that in the control group (P<0.0005). In addition, microhardness in the 45% CP group was significantly less than that in the 15% CP group (P<0.0005).

CONCLUSIONS

Use of both bleaching agents during in-office and at-home bleaching techniques resulted in a decrease in surface microhardness of giomer. The unfavorable effect of in-office bleaching (45% CP) was greater than that of at-home bleaching (15% CP). Key words:Dental restorations, hardness, tooth bleaching.

Análise da capacidade de remoção de pigmentos da resina composta pelo peróxido de hidrogênio 35%

Resumo Objetivo Avaliar in vitro a capacidade de remoção de pigmentos ocasionados em resina composta após aplicação de peróxido de hidrogênio 35%. Material e método Confeccionaram-se 20 amostras de resina composta Opallis (FGM), cor A1, em matriz metálica circular. As amostras foram divididas em quatro grupos (n=5) dos seguintes agentes corantes: água destilada (controle), café, vinho tinto e Coca-Cola®. No manchamento, as amostras ficaram imersas nas soluções durante 72 horas, com troca diária das bebidas. Procedeu-se à aplicação do gel de peróxido de hidrogênio 35% (Whiteness HP Blue Calcium, FGM) em três sessões, sendo uma aplicação do gel por sessão, o qual permaneceu nas amostras durante 40 minutos. Medidas de cor foram feitas inicialmente, após manchamento, após aplicação do peróxido e por mais 21 dias, usando espectrofotômetro Vita Easyshade. Os dados foram submetidos à análise de variância de dois fatores (tempo vs. corante) e ao teste de Tukey, para o contraste das médias (α=0,05). Resultado Apresentaram alteração de cor (ΔE - média/desvio padrão de L*) o café (15,7 ± 2,0) e o vinho (15,2 ± 4,6), quando comparados à Coca-Cola® (4,8 ± 1,9). O peróxido de hidrogênio removeu a pigmentação das amostras, porém, para nenhum dos corantes, houve retorno à coloração inicial, principalmente no grupo manchado por café (12,9 ± 1,5); este mostrou diferença significativa quando comparado ao controle (1,6 ± 0,6), diferentemente do vinho (3,3 ± 0,6) e da Coca-Cola® (2,1 ± 0,9), que se aproximaram do grupo controle. Conclusão As soluções corantes pigmentaram a resina composta, principalmente o café. A aplicação do peróxido de hidrogênio 35% foi eficaz na remoção de pigmentos das amostras, porém, em nenhum dos grupos, com diferentes corantes, houve retorno à coloração inicial (p>0,005).

Evaluation of the Surface Roughness and Microleakage of Dental Composites Exposed to Different Beverages

AIM

The purpose of this study was to determine the effect of different solutions cola soft drink (CSD) and coffee on roughness and microleakage of composite resin restorations.

MATERIALS AND METHODS

Sixty bovine incisors were prepared and restored using Filtek Z350 XT (3M/ESPE) nanoparticulate resin. The samples were divided into three groups (n = 20): A (control)-Immersion in artificial saliva (14 days); B: Immersion in coffee (14 days), for 15 minutes (3x/day) and C: Immersion in CSD for 14 days (3x/day). Then the samples were analyzed for microleakage (dye penetration) and surface roughness (atomic force microscope). The one-way analysis of variance (ANOVA) was applied to assess the surface roughness and microleakage. The Tukey's test was set at 0.05.

RESULTS

Group A (roughness-GAR) presented significantly the lowest average surface roughness. Group C (microleakage-GCM) showed significantly the highest average microleakage.

CONCLUSION

It was concluded that CSD and coffee change the surface roughness and increase the microleakage of restorations.

CLINICAL SIGNIFICANCE

Nowadays there is a high consumption of artificially sweetened soft drinks, sports drinks, high-energy beverages and coffee products by people that cause problems in composite resin restorations.

Comparative evaluation of effects of bleaching on color stability and marginal adaptation of discolored direct and indirect composite laminate veneers under in vivo conditions

Statement of Problem:

Change in color and loss of marginal adaptation of tooth colored restorative materials is not acceptable. Bleaching is commonly used for treating discolored teeth. However, the literature is scanty regarding its effect on color and marginal adaptation of direct and indirect composite laminate veneers (CLVs) under in vivo conditions.

Purpose:

Purpose of the study was to determine the effect of bleaching on color change and marginal adaptation of direct and indirect CLVs over a period of time when exposed to the oral environment.

Materials and Methods:

For this purpose, a total of 14 subjects irrespective of age and sex indicated for CLV restorations on maxillary anterior teeth were selected following the inclusion and exclusion criteria. For each subject, indirect CLVs were fabricated and looted in the first quadrant (Group 1) and direct CLV's (Group 2), were given in the second quadrant. Color change was assessed clinically using intra-oral digital spectrophotometer and marginal adaptation was assessed on epoxy resin replica of the tooth-restoration interface under scanning electron microscope. After 6 months, the subjects underwent a home bleaching regimen for 14 days using 10% carbamide peroxide. The assessment of color change and marginal adaptation was done at 6 months after veneering (0–180 days), immediately after the bleaching regimen (0–194 days) and 3 months after the bleaching regimen (0–284 days).

Results:

The difference in median color change (ΔE) between the groups was tested using Wilcoxon rank sum test while the median color change with time within the groups was tested using Wilcoxon signed rank test. The difference in the rates of marginal adaptation was tested between the groups using Chi-square/Fisher's exact test.

Bleaching led to statistically significant color change at cervical (CE), middle and incisal (IE) regions when direct and indirect composites were compared (P < 0.05). During intra-group comparison, direct CLV's showed significant color change at CE and IE regions when ΔE was compared at 180 days and 284 days (CE 10 vs. CE 30, P = 0.008, IE 10 vs. IE 30, P = 0.003). No significant differences were found when within group comparison was made for indirect laminates. Intergroup comparison between the groups showed significant difference in marginal adaptation at CE margin at all.time points (at baseline, P = 0.005; at 180 days, P = 0.007; 194 days, P = 0.025; at 284 days, P = 0.067).

Conclusion:

After bleaching, indirect CLVs performed better in terms of color stability whereas direct CLVs performed better in terms of marginal adaptation.

Clinical Significance:

Indirect composites should be preferred to direct composites as veneering materials as they have better color stability. Special attention should be given to their marginal adaptation especially in the CE region. Bleaching should be avoided in patients with composite restorations in the mouth.

The comparison of the effects of different whitening toothpastes on the micro hardness of a nano hybrid composite resin

Aim:

The aim of this study was to compare the micro hardness of a nanohybrid composite resin after brushing with two herbal and one non-herbal whitening toothpastes.

Materials and Methods:

We divided Eighty disk-shaped specimens of a nanohybrid composite (Tetric N Ceram, Ivoclar Vivadent, Asia) into 4 groups of 20 specimens each: Groups A, B, C, and D. Group A was control, Group B was brushed with Colgate total advanced whitening (Colgate-Palmolive (India) Limited), Group C with Salt and Lemon, Dabur (Dabur International Limited, Dubai, UAE), and Group D with HiOra Shine, Himalaya (The Himalaya Drug Company, India). The specimens were polished using medium, fine, and superfine discs (Sof-lex, 3M, ESPE, USA) and subsequently placed at 37°C in distilled water. They were brushed for 2 minutes twice daily with a soft motorized toothbrush (Colgate 360 sonic power battery-operated tooth brush, Colgate Palmolive, India) for 30 days. The samples were rinsed under running water to remove the toothpaste and stored in distilled water at 37°C until the readout was taken on the Vickers's hardness tester for microhardness.

Results:

The results revealed that the difference among the groups was statistically significant (P < 0.001). Tukey's test showed that reduction in microhardness for Group B was significantly higher than that for Group C and Group D (P < 0.001).

Conclusion:

Within the limitations of this study, non-herbal whitening toothpaste had a greater impact on the microhardness of nanohybrid resin composite than herbal whitening toothpastes.