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Background: The study evaluated the influence of whitening dentifrice containing activated charcoal on microhardness (MH), surface roughness (Ra) and colorimetry of tooth enamel. Material and Methods: A total of 60 healthy bovine incisor teeth were used and divided into: G1 (regular non-whitening toothpaste), G2 (conventional whitening toothpaste), G3 (activated charcoal based whitening toothpaste) and G4 (10% carbamide peroxide gel - PC10). Groups G1, G2 and G3 underwent simulated toothbrushing for 14 days, while G4 received bleaching treatment for the same time. The readings of MH, Ra and colorimetry were performed before any intervention (T0 - baseline) and at the end of 14 days of the proposed treatments (T1). After confirming the normality of the data, the results of MH, Ra and colorimetry were subjected to 2-factor ANOVA for repeated measures (α = 5%). Results: For MH, there were no statistical differences in G1, G2 and G3, only in G4. Considering Ra, a significant increase was observed in G2 and G3, with no statistical differences found in the other groups. Regarding colorimetry, the average color difference (ΔE) was greater in the G4 group (11.30 ± 4.31), even compared to the groups submitted to the whitening dentifrices: G2 (5.13 ± 2.75) and G3 (5.86 ± 3.66). Conclusions: It was concluded that the use of a whitening toothpaste containing activated charcoal caused deleterious effects on the enamel Ra, but did not affect the microhardness of the substrate, besides promoting a color change inferior to the regular non-bleaching toothpaste or PC10 gel. Key words:Whitening dentifrice, charcoal, roughness, microhardness.
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The objective of this in vitro study was to assess the influence of prolonged bleaching pre- and postrestoration on the bond strength (microshear) to enamel using 4% hydrogen peroxide (PH4). In the postrestorative bleached specimens evaluation, the composite cylinders were assembled after bleaching, while in the prebleached specimens, the cylinders were assembled before. Therefore, in the postbleached specimens, 60 bovine teeth were randomly assigned as follows: G1: control; G2: 14 days bleaching before bond strength (BS) testing; G3: 21 days; and G4: 28 days. In prebleached specimens, 180 bovine teeth were randomly assigned as follows: G1: control; G5: 14 days bleaching, storage in artificial saliva (AS) for 24 h before BS testing; G6: 14 days beaching, AS storage for 7 days before BS testing; G7: 21 days bleaching, AS storage for 24 h before BS testing; G8: 21 days bleaching, AS storage for 7 days before BS testing; G9: 28 days bleaching, AS storage for 24 hours before BS testing; and G10 : 28 days bleaching, AS storage for 7 days before BS testing. The results were submitted to ANOVA one-way (postrestoration bleaching) and two-way (prerestoration bleaching) and Tukey's post hoc test (p ≤ 0.05). In the postrestoration bleaching, no statistical difference between times was found. However, when bleached groups were compared to the control (G1), an expressive difference was detected (p ≤ 0.0001). For prerestoration bleaching, all experimental groups were statistically different from G1 (p ≤ 0.05), except G6 (p ≥ 0.01), and for G5 and G6, statistical differences were found (p ≤ 0.01). There were no significant differences between G7 and G8 and between G9 and G10, regardless of the AS storage times (p ≥ 0.05). It was concluded that prolonged bleaching with PH4 decreased adhesion resistance regardless of the moment of the bleaching (post- and prerestoration bleaching).
RESUMO
AIMS: To assess the influence of different bleaching protocols on the bond strength to enamel. MATERIALS AND METHODS: In this laboratory experiment were used forty sound bovine incisors were divided into five groups. G1: No bleaching (control). G2: 14 days bleaching with 4% hydrogen peroxide containing calcium (4% HP+Ca2+) (2 hours/ day) and 24 hours of artificial saliva (AS) storage. G3: 14 days bleaching with 4% HP+Ca2+ (2 hours/day) and 7 days storage in AS. G4: 28 days bleaching with 4% HP+Ca2+(2 hours/day) and 24 hours storage in AS. G5: 28 days bleaching with 4% HP+Ca2+ (2 hours/day) and 7 days storage in AS. Following storage times, composite resin cylinders were built upon the enamel surfaces and tested for micros hearing. For statistical analysis, two-way ANOVA and Tukey's test was applied to the data (p≤0.05), for it was evaluated different times of bleaching and stored in artificial saliva. RESULTS: The highest mean was observed in G1 (14.61 MPa), and the lowest in G4 (9.22 MPa). Compared to the negative control (G1), no differences were found in 14 days bleaching and the same between G2 and G3 (p ≥0.01). However, in 28 days bleaching, the effects of the storage periods (24 hours and 7 days) were significantly different (p ≤0.05), besides G4 and G5 were statistically different from G1. CONCLUSIONS: Extended bleaching time (28 days) decreased the bond strength, independently of storage time in AS. CLINICAL SIGNIFICANCE: If adhesive procedures are required after extended at-home bleaching they may need to be delayed for at least for 7 days for the enamel adhesion ability to recover.
Assuntos
Colagem Dentária , Clareamento Dental , Animais , Cálcio , Bovinos , Esmalte Dentário , Peróxido de HidrogênioRESUMO
Objetivo: Avaliar a influência do clareamento dental com peróxido de hidrogênio a 35% (PH35), associado ao emprego de fonte luminosa de ativação, na resistência da união adesiva ao esmalte. Materiais e Métodos: Sessenta dentes bovinos incisivos hígidos foram divididos em seis grupos (n=10) de acordo com a realização do tratamento clareador, fotoativação do gel clareador, e tempo decorrido pós-clareamento para realização das uniões adesivas (24h ou 14d), sendo: G1 ? Sem clareamento (controle) / Sem fotoativação / 24h; G2 ? Sem clareamento (controle) / Sem fotoativação / 14d; G3 ? Clareamento / Sem fotoativação / 24h; G4 ? Clareamento / Sem fotoativação / 14d; G5 ? Clareamento / Fotoativação / 24h; G6 ? Clareamento / Fotoativação / 14d. Os dentes foram seccionados, suas coroas incluídas em matrizes PVC, e suas superfícies vestibulares planificadas. Os grupos controle foram armazenados em saliva artificial (37ºC) por um período de 24h ou 14d. Os grupos clareados foram expostos ao gel de PH35 (Whiteness HP Maxx - FGM) por um tempo total de 45 minutos (03 aplicações de 15 minutos cada). Quando fotoativado, o gel foi exposto ao aparelho fotopolimerizador de led (900 mW/cm2) (02 exposições de 20s cada). Em seguida, 24h ou 14d pós-clareamento, cilindros de resina composta foram confeccionados sobre as superfícies de esmalte. Os corpos-de-prova foram armazenados em água destilada (24h) (37ºC) até o ensaio de cisalhamento. Resultados: A maior média de resistência foi obtida para G3 (2,12 MPa), sendo a menor para G1 (1,29 MPa). A ANOVA 2-way (? ? 0,05) não demonstrou diferenças significativas para ambos os fatores considerados (clareamento e tempo de armazenamento), bem como para a interação entre estes. Conclusão: O clareamento com PH35, bem como o uso de fonte fotoativadora associado ao gel clareador, não interferiram na resistência da união adesiva ao esmalte, independente do tempo pós-clareamento adotado para realizar as uniões.
Objective: Evaluate the influence of dental bleaching with 35% hydrogen peroxide (35HP), associated to a photocuring source, on the enamel shear bond strength. Materials and method: Sixty sound incisive bovine teeth were randomly divided into six groups (n=10) according to bleaching treatment (not bleached, bleached, or photoactivated bleached) and storage time (24h or 14d), being: G1 ? Not bleached (control) / Not photoactivated / 24h; G2 ? Not bleached (control) / Not photoactivated / 14d; G3 ? Bleached / Not photoactivated / 24h; G4 ? Bleached / Not photoactivated / 14d; G5 ? Bleached / Photoactivated / 24h; G6 ? Bleached / Photoactivated / 14d. Teeth were sectioned, had crowns included in a PVC matrix, and the enamel surfaces gridded and polished with silicon carbide abrasive papers. Control groups were stored in artificial saliva (37ºC) for 24h or 14d. Bleached groups were exposed to 35HP gel (Whiteness HP Maxx ? FGM) for a period of 45 minutes (03 applications of 15 minutes each). Photoactivated groups had bleaching gel exposed to a led source (900 mW/cm2) twice for 20s each. 24h or 14d post-bleaching, composite resin cylinders were performed at enamel surfaces. After storage in distilled water (37ºC) (24h), samples were submitted to the shear bond test. Results: The higher mean value (2,12 MPa) was associated to G3, while the lower one (1,29 MPa) was associated to G1. ANOVA ? 2way (a £ 0,05) showed no significant differences for both factors (bleaching and storage time), so the interaction between these factors. Conclusion: Bleaching with 35HP, farther using a photocuring source to activate the gel, had no influence on the enamel shear bond strength, independently of post-bleaching time adopted to perform adhesive bonds.
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Este trabalho avaliou a influência da fonte de luz fotoativadorana fenda de contração de polimerização de três compósitosuniversais, Opallis (FGM), Filtek Z250 (3M Espe) e Filtek Z350(3M Espe). Foram confeccionadas quatro amostras para cadagrupo experimental, sendo: G1A ? Opallis + luz halógena; G1B? Opallis + Led; G1C - Opallis + arco de plasma; G2A ? FiltekZ250 + luz halógena; G2B ? Filtek Z250 + Led; G3B ? Filtek Z250+ arco de plasma; G3A ? Filtek Z350 + luz halógena; G3B ? FiltekZ350 + Led; G3C ? Filtek Z350 + arco de plasma. Cada compósitofoi inserido em uma matriz metálica circular e fotoativado pelotempo recomendado pelo respectivo fabricante. Logo após, oscorpos-de-prova foram lixados com lixas de granulação decrescente,sendo, após vinte e quatro horas, levados ao microscópioeletrônico de varredura para mensuração das fendas. As leiturasforam feitas em quatro pontos, correspondentes a três, seis,nove e doze horas da face de um relógio, perfazendo um total dedezesseis leituras para cada grupo. Os resultados foram submetidosà análise de variância e ao teste de Tukey (?=5%). A maiormédia foi obtida com o grupo G3A (26,07?m), sendo a menor nogrupo G1A (15,43?m). A comparação dos grupos foi significativapara ambos os fatores (resina composta / luz fotoativadora),bem como na interação entre estes. Concluiu-se que diferentescomposições de compósitos exibem distintos comportamentosde contração de polimerização quando fotoativadas por diferentesfontes luminosas.
The aim of this study was to investigate the influence ofphotoactivation light source on polymerization shrinkage gapformed by three different universal composite resins, Opallis(FGM), Filtek Z250 (3M Espe) and Filtek Z350 (3M Espe). So,four samples were achieved for each experimental group,being: G1A ? Opallis + halogen lamp; G1B ? Opallis + lightemitting diodes (Led); G1C ? Opallis + plasma arc; G2A - FiltekZ250 + halogen lamp; G2B - Filtek Z250 + Led; G2C - Filtek Z250+ plasma arc; G3A - Filtek Z350 + halogen lamp; G3B ? FiltekZ350 + Led; G3C - Filtek Z350 + plasma arc. Each composite wasplaced in a circular brass mold, and photocured according tomanufacturer?s instructions. An exception occurred with plasmaarc, when a three seconds photopolymerization time wasadopted. Thereupon, the specimens were polished and, aftertwenty four hours, the polymerization shrinkage gaps of thesesamples were measured by scanning electronic microscopy. Themeasurements were obtained in four points located in positionscorresponding to three, six, nine and twelve hours of a clockface. Results were submitted to analysis of variance and Tukey?stest with 5% confidence level. The highest mean of polymerizationshrinkage gap was related to G3A (26,07?m), while thelowest one was associated to G1A (15,43?m). Therefore, is possibleto conclude that different compositions of restorative resinsare particularly affected by different photoactivation lightsources in terms of polymerization shrinkage.