Bleaching treatment influence on color stability of infiltrated enamel caries and on infiltrant degradation

Orientador: Regina Maria Puppin-RontaniTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: Os objetivos desta tese composta por dois capítulos foram: Capítulo 1- Avaliar a estabilidade de cor e efetividade de tratamentos clareadores em lesões iniciais em esmalte infiltradas com Icon®. Capítulo 2- Avaliar a efetividade do clareamento com um gel experimental contendo natrosol substituindo o carbopol e avaliar a degradação causada no infiltrante por estes géis. Capítulo 1: Foram confeccionados espécimes à partir de dentes bovinos (N=30, 5x5x3mm) e divididos em três grupos (n=10): controle, desmineralizado e infiltrado. Lesões subsuperficiais artificiais foram desenvolvidas utilizando solução para produção de cárie, exceto no grupo controle (esmalte hígido). Nos espécimes do grupo infiltrado, após o desenvolvimento das lesões foi aplicado Icon®(DMG, Hamburgo, Alemanha). Medidas iniciais de cor foram realizadas utilizando espectrofotômetro (CM-700d, Konica Minolta), utilizando o sistema CIE L*a*b*. Os espécimes foram imersos em café, três vezes ao dia, durante 15 minutos, por 14 dias e em seguida armazenados em saliva artificial. Após a pigmentação, medidas de cor foram realizadas novamente. Os espécimes foram submetidos ao clareamento com gel de peróxido de carbamida 16%, por 4h diárias durante 21 dias, e medidas finais de cor foram realizadas. Para comparar medidas iniciais e finais, foi aplicado o teste-t (?=0,05). A comparação entre os grupos foi realizada por ANOVA 1 fator e teste de Tukey (?=0,05). A pigmentação com café promoveu redução significativa nos valores de L* e aumento nos valores de a* e b* em todos os grupos (controle, clareado e infiltrado). O clareamento promoveu aumento nos valores de L* e redução nos valores de a* and b* em todos os grupos. Não houve diferença nos valores de ?E entre os grupos cariados e infiltrados antes do clareamento. Após o clareamento, o grupo infiltrado apresentou os menores valores de ?E, similares ao controle. Pode-se concluir que o esmalte infiltrado com Icon® apresentou alteração de cor após a pigmentação, similares ao esmalte cariado. Entretanto, se ocorrer pigmentação em dentes infiltrados, o tratamento com géis clareadores pode ser realizado com sucesso. Capítulo 2: Foram confeccionados 50 espécimes de infiltrante (Icon®, DMG, Hamburgo, Alemanha), divididos em 5 grupos (n=10), de acordo com o gel a ser exposto: controle (G1), peróxido de carbamida 16% com natrosol (G2), peróxido de carbamida 16% com carbopol(G3), natrosol(G4), carbopol(G5). Os tratamentos foram realizados durante 21 dias, 4 horas ao dia. Medidas de dureza Knoop (HMV-2, Shimadzu), rugosidade (Surfcorder SE1700, Kosaka), análise de cor utilizando espectrofotômetro (CM-700d, Konica Minolta) e imagens de microscopia por força atômica (EasyScan 2, Nanosurf) foram realizadas. Além disso, 50 blocos obtidos à partir de dentes bovinos foram submetidos à pigmentação com chá preto e clareamento utilizando os géis citados acima. Os resultados foram submetidos a ANOVA 1-fator para comparação entre os grupos e teste-t para comparação inicial e final de cada grupo (?=0,05). Pode ser observada redução de dureza nas amostras de Icon® após aplicação do peróxido de carbamida, independente do espessante (G2 inicial: 13,21/final:10,99 e G3 inicial:12,00/final:11,33). Comparando-se todos os grupos após o tratamento, o G4 apresentou maior valor de dureza (13,92), seguido pelo G1(12,77) e G5(12,27). Houve aumento de rugosidade após o tratamento em todos os grupos, porém não houve diferença estatística entre os grupos. Através das imagens de microscopia por força atômica pode-se observar maior irregularidades na superfície do G5. Em relação à efetividade do clareamento, os grupos G2 e G3 promoveram aumento nos valores de L* e maiores valores de ?E. Os grupos G4 e G5 apresentaram valores de L* semelhantes. Pode-se concluir que o peróxido de carbamida associado com natrosol ou carbopol é eficaz no clareamento de dentes infiltrados com Icon®, porém causam degradação superficial no infiltranteAbstract: The objectives of this thesis, accomplished on two chapters, were: Chapter 1- To evaluate color stability of white spot lesions with Icon® after staining and the bleaching effect in the infiltrated and stained surfaces. Chapter 2- to evaluate surface degradation of Icon® after application of bleaching gels containing natrosol as a thickener and their bleaching effectiveness. Chapter 1- Enamel-dentine specimens (N=30, 5x5x3mm, 1 mm enamel + 2 mm dentine thickness) were prepared from bovine incisors and randomly allocated into three groups (n=10): control, demineralized, infiltrated. Artificial enamel subsurface lesions were created using 50 mL of 0.05 M acetate buffer solution. Specimens were produced by the Icon®(DMG, Hamburgo, Alemanha) application in the enamel caries like-lesions. Baseline color reading were assessed using a spectrophotometer (CM-700d, Konica Minolta), and CIE L*a*b* measurements of each specimen were performed using a white background. In order to simulate extrinsic dietary staining, specimens were placed into 4 mL coffee infusion, three-times daily for 15 minutes, for 14 days. After the staining procedure, color measurements were performed again. Then, bleaching procedures were performed using 16% carbamide peroxide gel, for 4h daily, for 21 days and final measure assessment was performed. To compare baseline and final measurements, t-test was used (p<0.05). The statistical comparison between groups was performed using one-way ANOVA and Tukey tests (p<0.05). Coffee staining provided a significant reduction of L* values and increase of a* and b* in all groups (control, decayed and infiltrated). Bleaching procedure provided a significant increase on L* and decrease of a* and b* values in all groups. There was no significant difference on ?E values between decayed and Infiltrated groups before bleaching, and after bleaching, infiltrated group showed the lowest ?E values. It can be concluded that enamel infiltrated with Icon present significant color alteration after staining, when compared to sound enamel. However, if the infiltrant discoloration occurs, bleaching treatment can be used successfully. Chapter 2 - 50 specimens of infiltrant (Icon®, DMG, Hamburgo, Alemanha) were produced and allocated into 5 groups (n = 10) in accordance with the gel were made to be exposed: Control (G1), carbamide peroxide 16% with natrosol (G2), carbamide peroxide with carbopol (G3), natrosol (G4), carbopol (G5). Bleaching treatments were performed for 21 days, 4 hours per day. Hardness Knoop measurements (HMV-2, Shimadzu), roughness measurements (Surfcorder SE1700, Kosaka), and atomic force microscopy images (EasyScan 2, Nanosurf) were performed after bleaching treatments. In addition, the 50 blocks obtained from bovine teeth were submitted to bleaching treatment with gels mentioned above. The results were subjected to ANOVA one-way for comparison between groups and t-test for comparing initial and final of each group (?<0.05). Knoop Hardness decreased can be observed after application of carbamide peroxide, regardless of thickener (initial G2: 13.21 / final: 10.99 and G3 initial: 12.00 / final: 11,33). Comparing all groups after treatment, G4 showed higher hardness Knoop value (13.92), followed by G1 (12.77) and G5 (12.27). After bleaching, there was roughness increase for all groups, and there was no statistical difference between them. Atomic force microscopy images show higher surface irregularity in G5. Regarding bleaching effectiveness, G2 and G3 groups presented increase in L * values and highest ?E values. G4 and G5 groups showed statistically similar L* values. It can be concluded that carbamide peroxide with natrosol and carbamide peroxide with carbopol may cause surface degradation. Carbamide peroxide associated with natrosol or carbopol is effective in whitening teeth infiltrated with Icon®. Further studies should be performed to evaluate the leaching of components infiltrating subjected to degradation over timeDoutoradoMateriais DentariosDoutora em Materiais Dentário

Influence of chemical degradation and abrasion on surface properties of nanorestorative materials

Aim: The aim of this in vitro study was to investigate the synergistic effect of chemical degradation (erosion) and three-body abrasion (mechanical degradation) on the surface roughness (Ra) and hardness (KHN) of two nanorestorative materials and two conventional materials. Methods: Discshaped specimens (5 mm in diameter, 2 mm thick) of Filtek Z350™ and TPH Spectrum™ composites and Ketac Nano™ and Vitremer™ light-curing glass ionomer cements, nanomaterials and conventional materials were prepared according to the manufacturer's instructions. After 24 h, polishing procedures were performed and initial measurements of Ra and KHN were taken in all specimens. The specimens were divided into 12 groups (n = 10) according to material and storage media: artificial saliva, orange juice, and Coca-Cola®. After 30 days of storage, the specimens were submitted to mechanical degradation and re-evaluated for Ra and KHN. Data were tested for significant differences by repeated-measure three-way ANOVA and Tukey's tests (p<0.05). Results: Erosion and abrasion wear significantly decreased hardness of all materials. Only Filtek Z350 roughness, however, was not affected by erosion and abrasion. All materials showed a significant increase in surface roughness after erosion and abrasion, except for Filtek Z350. After chemical and mechanical degradation, the KHN of all samples had decreased significantly. After mechanical degradation, the acidic drinks (Coca-Cola® and orange juice) were more aggressive than artificial saliva to all materials. Conclusions: A synergistic effect was observed by the increase in roughness for all materials, except for Filtek Z350; hardness values decrease for all materials, regardless of whether they were nanofilled or not. The RMGICs were more susceptible to degradation than the composites, considering both hardness and roughness surface parameters142100105sem informaçã

Effect Of Photoinitiator Concentration On Marginal And Internal Adaptation Of Experimental Composite Blends Photocured By Modulated Methods.

The aim of this study was to evaluate the influence of photoinitiator concentration on marginal and internal adaptation of composites photocured by modulated methods. Composites based on BisGMA/triethylene glycol dimethacrylate and 65 wt% of filler were prepared with different concentrations of camphorquinone/amine (C1-0.5%, C2-1%, C3-1.5%). Cavities were prepared (3 mm × 3 mm × 2 mm) on the buccal surface of 120 bovine incisors and the adhesive system Adper Single Bond 2 was applied following manufactures instruction. Specimens were then distributed according to type of composite (C1, C2, C3) and photoactivation method (high-intensity - 750 mW/cm(2) for 40 s; low intensity - 150 mW/cm(2) for 200 s; soft-start - 150 mW/cm(2) for 10 s + 750 mW/cm(2) for 38 s; pulse-delay - 150 mW/cm(2) for 10 s + 3 min dark + 750 mW/cm(2) for 38 s). Superficial and internal margins were analyzed by scanning electron microscopy, using the epoxy replica technique. The length of gaps was expressed as a percentage of the total length of the margins. Data were submitted to two-way analysis of variance and Tukey's test (α =0.05). Modulated curing methods did not influence gap formation regarding both superficial and internal adaptation. The composite with the lower initiator concentration (C1) presented higher gap formation when compared with those with higher concentrations (C2 and C3). Modulated photoactivation methods did not reduce gap formation for the experimental composite restorations evaluated. However, higher photoinitiator concentrations promote better marginal seal.7S1-

Development of resin materials in incipient enamel caries infiltration : evaluation of the degree of conversion, cross-linking density and elastic modulus

Orientador: Regina Maria Puppin-RontaniDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: O objetivo neste trabalho foi avaliar o grau de conversão, densidade de ligações cruzadas e módulo de elasticidade de nove materiais resinosos experimentais contendo diferentes combinações de monômeros base e diluentes em comparação a um material comercialmente disponível,. Além disso, avaliar o módulo de elasticidade após aplicação em esmalte bovino cariado artificialmente. Foram preparados nove materiais resinosos experimentais contendo TEGDMA, BISEMA, HEMA, UDMA e etanol em diferentes proporções. O grau de conversão monomérico foi avaliado através da Espectroscopia Transformada por Infravermelho de Fourier (FTIR). A densidade de ligações cruzadas foi avaliada indiretamente através da taxa de redução de dureza após imersão em etanol. O módulo de elasticidade foi avaliado através do teste de flexão de três pontos para avaliação do módulo de elasticidade, utilizando máquina de ensaio universal (Instron). Adicionalmente, o módulo de elasticidade do esmalte bovino cariado e infiltrado com os materiais experimentais foi avaliado. Para tanto, blocos de esmalte bovino com 4mm x 2mm x 1mm foram preparados e submetidos ao desenvolvimento de cárie artificial. Os infiltrantes foram aplicados e o módulo de elasticidade foi determinado através do teste de flexão de três pontos em máquina de ensaio universal (Instron). Os resultados foram submetidos a dois tipos de análise, sendo a primeira ANOVA e teste de Tukey (5%), em que é feita a comparação entre os grupos experimentais. A segunda análise, os dados foram submetidos a ANOVA e teste de Dunnett (5%), em que é feita a comparação entre o grupo controle e os experimentais. Os materiais contendo etanol na composição apresentaram resultados inferiores em todos os testes, e os sem solvente na composição apresentaram os melhores resultados. A adição de UDMA não influenciou as propriedades testadas, porém o BisEMA influenciou de forma negativa.O material resinoso contendo TEGDMA e o comercial apresentaram os maiores valores de grau de conversão comparando-se aos demais grupos. Em relação à densidade de ligações cruzadas, houve maior redução de dureza do grupo contendo TEGDMA, UDMA e etanol em comparação com o grupo controle (comercial). Os grupos que continham etanol na composição apresentaram os menores valores de módulo de elasticidade, sendo diferentes do grupo controle. Em relação ao módulo de elasticidade das amostras cariadas e infiltradas não houve diferença significativa entre os grupos infiltrados e o grupo controle (cariados) e nem entre os grupos experimentais. A adição de etanol e HEMA influenciou de forma negativa todas as propriedades testadas O TEGDMA como monômero base, sem adição de solvente apresentou-se como o infiltrante com melhores propriedades em todos os testesAbstract: The aim of this study was to evaluate the degree of conversion, crosslink density and elastic modulus of nine experimental resin materials containing different combinations of base monomers and solvents on comparison to a material commercially available. Moreover, to evaluate the elastic modulus after application to artificially carious enamel. Were prepared nine experimental resin materials containing TEGDMA, BISEMA, HEMA, UDMA and ethanol in different proportions. The degree of conversion was measured by Fourier Transformed Infrared Spectroscopy (FTIR). The crosslink density was indirectly assessed by the rate of reduction of hardness after immersion in ethanol. The elastic modulus of was evaluated by three-point bending test to evaluate the elastic modulus, using a universal testing machine (Instron). Additionally, the elastic modulus of enamel caries and infiltrated with the experimental materials was evaluated. For that, bovine enamel blocks with 4mm x 2mm x 1mm were prepared and submitted to the development of caries. The experimental resin materials were applied and the elastic modulus was determined by three-point bending test in a universal testing machine (Instron). The results were subjected to two types of analysis, the first ANOVA and Tukey test (5%), in which a comparison is made between the experimental groups. The second analysis, data were analyzed by ANOVA and Dunnett's test (5%), in which a comparison is made between the control and experimental groups. The materials in the composition containing ethanol exhibited inferior in all tests, and the solvent-free composition showed the best results. The addition of UDMA not influence the properties tested, but the manner influenced BisEMA negativa.O resinous material containing commercial and TEGDMA showed the highest degree of conversion compared to the other groups. Regarding the crosslink density, a greater reduction of hardness of the group containing TEGDMA, UDMA and ethanol compared with the control group (commercial). The groups containing ethanol showed the lowest elastic modulus, being different from the control group. Regarding the elasticity of the samples infiltrated decayed and there was no significant difference between groups infiltrated and control group (decayed) or between experimental groups. The addition of ethanol, and HEMA influenced negatively all properties tested as the TEGDMA monomer base, without addition of solvent appeared as infiltrating the best properties in all testsMestradoMateriais DentariosMestre em Materiais Dentário

Biological and mechanical degradation affecting the surface properties of aesthetic restorative

evaluate the roughness (Ra), Knoop hardness (KHN) and change of color (&#8710;E) of esthetic restorative materials (Filtek Z350-composite nanoparticle; Empress Direct-composite nanohybrid and IPS e.Max-ceramic) subjected to contact with the Streptococcus mutans biofilm (biological degradation) associated with abrasion generated by tooth brushing (mechanical degradation). Methods: Ten specimens of each material were prepared, and the surface properties initial were evaluated. All specimens were exposed to Streptococcus mutans inoculum; after 7 days, surface properties were evaluated. The specimens were submitted to a 30,000 toothbrushing cycles, using a toothpaste slurry, then, surface properties were evaluated again. Data were analyzed by Proc-Mixed, One-way ANOVA, Tukey-Kramer and Tukeys tests (&#945; = 0.05). Results: At the baseline, ceramic showed the highest Ra and KHN values; after the biological degradation the composites showed increased Ra, but KHN did not change; after the mechanical degradation, Empress showed decreased Ra and Z350 showed similar Ra, the KHN increased to both composites, and all materials had increased lightness after the mechanical degradation. Conclusions: The results suggest that, when exposed to Streptococcus mutans biofilm and toothbrush abrasion, the ceramics undergoes minimal degradation and the composites exhibited variable degradation, depending on the composition of the material

Influence of chemical degradation and abrasion on surface properties of nanorestorative materials

e aim of this in vitro study was to investigate the synergistic effect of chemical degradation (erosion) and three-body abrasion (mechanical degradation) on the surface roughness (Ra) and hardness (KHN) of two nanorestorative materials and two conventional materials. Methods: Discshaped specimens (5 mm in diameter, 2 mm thick) of Filtek Z350TM and TPH SpectrumTM composites and Ketac NanoTM and VitremerTM light-curing glass ionomer cements, nanomaterials and conventional materials were prepared according to the manufacturers instructions. After 24 h, polishing procedures were performed and initial measurements of Ra and KHN were taken in all specimens. The specimens were divided into 12 groups (n = 10) according to material and storage media: artificial saliva, orange juice, and Coca-Cola®. After 30 days of storage, the specimens were submitted to mechanical degradation and re-evaluated for Ra and KHN. Data were tested for significant differences by repeated-measure three-way ANOVA and Tukeys tests (p<0.05). Results: Erosion and abrasion wear significantly decreased hardness of all materials. Only Filtek Z350 roughness, however, was not affected by erosion and abrasion. All materials showed a significant increase in surface roughness after erosion and abrasion, except for Filtek Z350. After chemical and mechanical degradation, the KHN of all samples had decreased significantly. After mechanical degradation, the acidic drinks (Coca-Cola® and orange juice) were more aggressive than artificial saliva to all materials. Conclusions: A synergistic effect was observed by the increase in roughness for all materials, except for Filtek Z350; hardness values decrease for all materials, regardless of whether they were nanofilled or not. The RMGICs were more susceptible to degradation than the composites, considering both hardness and roughness surface parameters