Resistance to degradation biological, chemical and mechanical resin materials nanofillers

Orientador: Regina Maria Puppin-RontaniTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: O avanço da Odontologia Estética tem sido impulsionado pela introdução de novos materiais restauradores, tais como os nanoparticulados, os quais têm demonstrado bom desempenho mecânico e excelentes propriedades ópticas. Entretanto, deve-se considerar que os materiais restauradores estão constantemente sujeitos aos desafios térmicos, mecânicos e químicos na cavidade bucal que podem acarretar danos a estes materiais, num processo denominado degradação. Dessa forma, os objetivos nesta tese, composta por 2 capítulos, foram: (1) avaliar a morfologia e a rugosidade de superfície de materiais nanopartículados quando submetidos a biodegradação e abrasão por escovação e (2) avaliar os efeitos do armazenamento em diferentes soluções simuladoras da dieta ácida na rugosidade e dureza de superfície de materiais restauradores. No capítulo 1, vinte espécimes obtidos de cada material (Vitremer, Ketac N100, TPH Espectrum e Filtek Z350) foram divididos em dois grupos de armazenamento (n=10): umidade relativa e bioflime de S. mutans. Após sete dias, todos os espécimes foram lavados em ultrassom para a mensuração da rugosidade de superfície (Ra) e avaliação em microscopia eletrônica de varredura. Seguidamente, o teste de abrasão por escovação foi conduzido no grupo biodegradado e os espécimes reavaliados. Os dados foram submetidos aos testes ANOVA 3 fatores para medidas repetidas e Tukey (p<0.05). Após a biodegradação o ketac N100 apresentou os maiores valores de Ra. Quando as amostras biodegradadas foram submetidas à abrasão por escovação, o compósito Z350 apresentou os menores valores de Ra. No capítulo 2, foram confeccionados espécimes (5mm-diâmetro; 2mm-espessura), dos materiais utilizados no Capítulo 1, os quais foram divididos em 4 grupos (n=30). Após 24h, foram realizados os procedimentos de acabamento e polimento e os testes de dureza Knoop (KHN) e rugosidade de superfície. Seguidamente, cada grupo foi dividido em 3 subgrupos (n=10) de acordo com o meio de armazenagem: saliva artificial, suco de laranja e Coca-Cola®. A rugosidade de superfície e dureza Knoop dos espécimes foram reavaliadas após 30 dias de armazenamento e os dados submetidos aos testes ANOVA 3 fatores para medidas repetidas e Tukey (p<0,05). Os compósitos apresentaram menor Ra e maior KHN que os materiais ionoméricos em todas as situações estudadas. Após a degradação química, a diminuição significativa da KHN foi observada para todos os materiais, enquanto o aumento da Ra foi observado nos materiais ionoméricos armazenados em Coca-Cola® e suco de laranja. O compósito Z350 apresentou valores similares de KHN após a erosão qualquer que fosse a solução de armazenamento. Para os outros materiais, a Coca-cola e o suco de laranja provocaram maiores reduções nos valores de KHN. Com base nos resultados obtidos pode-se concluir que nanopartículas incorporadas aos materiais estudados exerceram influência significativa para a obtenção de maior resistência frente à degradação biomecânica. No entanto, a presença de nanopartículas não influenciou na resposta à erosão quanto à rugosidade e dureza KnoopAbstract: Esthetic Dentistry has increasingly advanced with the introduction of new restorative dental materials, such as nanofilled materials, which have demonstrated better mechanical behavior and excellent optical properties. However, restorative materials are constantly subjected to thermal, mechanical and chemical challenges in the oral cavity that leads to damage of these materials in a process called degradation. The objectives of this dissertation were to evaluate: (1) the morphology and surface roughness of nanofilled materials subjected to biodegradation and brushing and (2) the effects of storage in different acid diet simulating solutions on roughness and surface hardness of resin based restorative materials. In the study 1, twenty specimens obtained from each material (Vitremer, Ketac N100, TPH Espectrum e Filtek Z350) were divided into two storage groups (n=10): relative humidity (control) and Streptococcus mutans biofilm (biodegradation). After 7 days of storage, roughness values (Ra) and micrographs by Scanning Electron Microscopy (SEM) were obtained. In a second experimental phase, the specimens previously subjected to biodegradation were abraded via toothbrushes (mechanical degradation). Next, these specimens were washed, dried, and reassessed by roughness and SEM. The data were submitted to repeated measures three-way ANOVA and Tukey's tests (p<0.05). After biodegradation, Ketac N100 presented the highest Ra values. Concerning bio plus mechanical challenges the nano composite Filtek Z350 exhibited the best resistance to cumulative challenges proposed. In the study 2, disc-shaped specimens (5mm-diameter; 2mm-thick) of the same materials used on study 1 were obtained according to the manufacturers' instructions, thereby forming four groups (n=30). After 24h, polishing procedures were performed and initial hardness(KHN) and roughness(Ra) measurements were realized. Next, each group was divided into three subgroups (n=10) according to storage media: artificial saliva, orange juice and Coca-Cola®. After 30 days of storage, the specimens were reevaluated about Ra and KHN. Data were tested for significant differences by three-way ANOVA and Tukey (p<0.05). It was observed that composites presented lower roughness values and higher hardness values than ionomeric materials under all storage conditions. After erosion, KHN of all experimental samples dropped significantly, while only the Ra of ionomeric materials increased, depending on the media, with a markedly negative impact of Coca-Cola® and orange juice. There was not difference among storage media for Filtek Z350 regarding to KHN values. Based on the results it can be concluded that nanofillers incorporated into the studied materials was important to obtain greater resistance against biomechanics degradation. However, the presence of nanofillers did not influence the surface roughness and Knoop hardness when the tested materials underwent to erosionDoutoradoMateriais DentariosDoutor em Materiais Dentário

Doxycycline-containing glass ionomer cement for arresting residual caries: an in vitro study and a pilot trial

In a previous study, we demonstrated that the incorporation of doxycycline hyclate (DOX) into resin-modified glass ionomer cement (RMGIC) inhibited important cariogenic microorganisms, without modifying its biological and mechanical characteristics. In this study, we keep focused on the effect of that experimental material as a potential therapy for arresting residual caries by analyzing other in vitro properties and conducting a pilot clinical trial assessing the in vivo effect of DOX-containing RMGIC on residual mutans streptococci after partial carious removal in primary molars. Specimens of the groups RMGIC (control); RMGIC + 1.5% DOX; RMGIC + 3% DOX; and RMGIC + 4.5% DOX were made to evaluate the effect of DOX incorporation on surface microhardness and fluoride release of RMGIC and against biofilm of Streptococcus mutans. Clinical intervention consisted of partial caries removal comparing RMGIC and RMGIC + 4.5% DOX as lining materials. After 3 months, clinical and microbiologic evaluations were performed. Data were submitted to ANOVA/Tukey or Wilcoxon/Mann-Whitney set as α=0.05. Fluoride release and surface microhardness was not influenced by the incorporation of DOX (p&gt;0.05). There was a significant reduction of S. mutans biofilm over the material surface with the increase of DOX concentration. After clinical trial, the remaining dentin was hard and dry. Additionally, mutans streptococci were completely eliminated after 3 months of treatment with RMGIC + 4.5% DOX. The incorporation of DOX provided better antibiofilm effect, without jeopardizing fluoride release and surface microhardness of RMGIC. This combination also improved the in vivo shortterm microbiological effect of RMGIC after partial caries removal

Color stability and gloss of esthetic restorative materials after chemical challenges

This study evaluated gloss and color changes of esthetic restorative materials subjected to different acidic beverages. Specimens of resin composites (Z350XT (Z350), IPS Empress Direct (ED), Charisma Diamond (CD)) were prepared and the initial surface gloss and color (ΔE) were measured (n=10). Then, the specimens were immersed in 4 mL of each of the different beverages (cranberry juice; Coca-Cola; coffee or artificial saliva) during 15 min, 3x/day for 14 days and new gloss and color readings were obtained. Color change was evaluated with the ΔE formula and gloss change values were obtained by the formula: (final gloss - initial gloss). Data was submitted to two-way ANOVA followed by Tukey’s post hoc test (a=0.05). CD showed the lowest color change among resin composites. The highest ΔE values were obtained after immersion in coffee and cranberry juice. Coffee promoted the highest gloss change (worst gloss retention), followed by cranberry juice, Coca-cola and artificial saliva (p<0.05). The type of beverage significantly influenced the gloss of resin composites. Coca-cola reduced gloss of the three resin composites in a similar manner. Coffee affected the ED gloss more than that of Z350 and CD, while cranberry juice affected Z350 more than ED and CD. Saliva had a more pronounced effect on the gloss retention of CD than ED. The beverages used in this study influenced the optical surface properties of the composites studied301525

Influence of the incorporation of triclosan methacrylate on the physical properties and antibacterial activity of resin composite

The incorporation of antimicrobials in the composites as an attempt to reduce bacterial adhesion without jeopardizing mechanical properties is a challenge for Dentistry. Objective: To evaluate the bacterial adhesion and physical properties of a composite containing the methacrylate triclosan- derivative monomer (TM). Methodology: TM was synthesized and added to an experimental composite. Samples were divided into two groups: Control and TM (13.4 wt%). Antibacterial Activity: Three specimens of each material were prepared and placed on bacterial suspensions of Streptococcus mutans for 1, 5 and 10 days. After these periods the counting of the colonies (log10) was performed. Assays was performed in triplicate. Physical Properties: Three-body Abrasion (TBA): Ten specimens of each material were prepared and stored at 37°C/24 h. The surface roughness (Ra) and hardness (KHN) were analyzed. Next, the specimens were submitted to abrasive wear (30,000 cycles) and re-evaluated for Ra and KHN; Sorption/solubility (SS): cylindrical specimens (n=10) were prepared and weighted. The specimens were immersed in deionized water for 7 days at 37°C and then their weight was verified again. SS were calculated using accepted formulas; Diametral tensile strength (DTS): specimens (n=10) underwent test performed in an Instron universal testing machine at a crosshead speed of 1 mm/min. Data were submitted to appropriate statistical tests according to data distribution and assay (p&lt;0.05). Results: Bacterial Adhesion: TM showed a significant reduction on biofilm accumulation in the evaluated periods: 1 day (1.537±0.146); 5 days (2.183±0.138) and 10 days (4.469±0.155) when compared with Control: 1 day (4.954±0.249); 5 days (5.498±0.257) and 10 days (6.306±0.287). Physical Properties: For TBA, SS and DTS no significant difference was found between groups Control and TM. The incorporation of methacrylate triclosan-based monomer in the experimental composite reduce bacterial adhesion of S. mutans and did not affect important polymer properties.&nbsp

Evaluation of marginal fit and compression strenght of onlay esthetic restorations and Knoop hardness of a dual-cured resin cements

Orientador: Regina Maria Puppin-RontaniDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: O avanço da Odontologia Estética tem sido impulsionado pela introdução de novos compósitos resinosos e técnicas restauradoras. Para amenizar as falhas associadas à contração de polimerização, a técnica indireta tem se tornado uma alternativa na restauração de dentes com preparos extensos. Entretanto, a polimerização incompleta do agente cimentante pode ocasionar redução do desempenho físico e mecânico da restauração. Dessa forma, os objetivos desta dissertação foram: (1) avaliar o efeito da técnica restauradora e do tratamento termo/mecânico na adaptação marginal e resistência compressiva de restaurações estéticas tipo onlay fixadas com cimento resinoso e (2) a influência de diferentes espessuras de compósito resinoso e distâncias da ponta ativa do aparelho fotoativador na dureza Knoop do agente cimentante Rely-X ARC utilizado nas restaurações indiretas. No estudo 1, preparos tipo onlay foram realizados em 50 terceiros molares hígidos e restaurados com compósito resinoso Z-250. Os dentes foram separados em grupos de acordo com a técnica restauradora (direta/indireta) e a ciclagem termo/mecânica. Para a análise da adaptação marginal foi aplicada uma solução corante nas margens da restauração e as áreas coradas foram consideradas como presença de fendas marginais, as quais foram mensuradas através do software Image Tool 3.0. Todos os espécimes foram submetidos ao teste de resistência à compressão. No estudo 2 foi utilizado um incisivo bovino incluído em resina de poliestireno. A face vestibular foi planificada e sobre ela aplicada uma película de PVC e uma matriz de borracha, dentro da qual foi inserido o cimento resinoso Rely-X ARC e uma nova película de PVC. Discos de compósito resinoso, de espessuras diferentes, foram confeccionados e inseridos individualmente sobre este conjunto e fotoativados por 40 segundos, variando a distância da ponta ativa do fotoativador. Após armazenagem por 24h a 37oC, as amostras foram seccionadas longitudinalmente ao meio e polidas para mensuração da dureza Knoop em 3 profundidades do cimento. No estudo 1, não houve diferença estatisticamente significativa entre as técnicas restauradoras quanto à presença de fendas, entretanto, o tratamento termo/mecânico influenciou significativamente o aumento de fendas marginais. Na resistência à compressão não houve diferença estatística significativa entre as técnicas restauradoras empregadas e o tratamento termo/mecânico também não influenciou significativamente à resistência à compressão (RC). No estudo 2, a distância da ponta ativa do fotoativador assim como diferentes espessuras do disco de resina composta, resultou em valores de dureza Knoop estatisticamente distintos, nas profundidades. O aumento da espessura do disco de compósito resinoso ocasionou diminuição dos valores de dureza do cimento. Foi observado diminuição dos valores de dureza apenas quando foi utilizada a distância da ponta do fotoativador de 1mm. As regiões de base e centro apresentaram, respectivamente, os menores e maiores valores de dureza Knoop. Com base nos resultados obtidos pode-se concluir que as técnicas direta e indireta para restauração tipo onlay apresentaram similar resistência à fratura por compressão. A adaptação marginal foi influenciada pelo tratamento termo/mecânico; com o aumento da espessura do compósito restaurador e da distância do fotoativador, houve redução dos valores de dureza do cimento resinosoAbstract: Esthetic Dentistry has advanced increasingly with the introduction of new resin composites and restorative techniques. To reduce failures associated with polymerization contraction, indirect technique has become an alternative to restoration of teeth with extensive preparations. However, the incomplete polymerization of luting agent can cause a decrease in the physical/mechanical performance of restorations. The objectives of this dissertation were to evaluate: (1) the effect of restorative technique and thermo/mechanical cycling on themarginal adaptation and compressive strength of onlay esthetic restorations bonded with luting resin agent and (2) the influence of different thickness of resin composite discs and the distances of tip of curing unit on Knoop hardness of luting agent Rely-X ARC used in indirect restorations. In the study 1, onlay cavity preparations were performed in 50 sound third molars that were restored with resin composites Z-250. The teeth were divided in groups according to the restorative technique (direct/indirect) and the thermal/mechanical cycling. To analyze the marginal adaptation, a dye solution was applied on the restoration margins and the dyed areas were considered as marginal gaps and measured by means of Image Tool 3.0 software. All specimens were submitted to mechanical test of compressive strength. In the study 2, a bovine incisor was embedded in a polystyrene resin. The buccal surface was ground flatted and over it was applied a PVC pellicle and a rubber mold. The luting cement Rely-X ARC was inserted into the mold and a new PVC pellicle was applied. Resin composite discs, with different thickness, were performed and placed individually over this set (tooth/luting cement) and polymerized for 40 seconds, modifying the distance of tip of light curing. After storing at 37o C for 24 hours, specimens were longitudinally sectioned in two equal parts and polished to measure the Knoop hardness in three depth of cement. In the study 1, there was no statistically difference between the restorative techniques in relation to marginal gaps; however, thermal/mechanical cycling exerted significant influence on the increase of marginal gaps. About the compressive strength, any statistically difference was observed among the restorative techniques, independent of the thermal/mechanical cycling. In the study 2, the distance of tip of curing unit and distinct thickness of composite resin discs resulted in statistically different Knoop values when deepness was analyzed. The increase of resin disc thickness causes reduction on the hardness values of cement. Reductions on hardness values were observed only with 1mm tip curing unit distance. The base showed the lowest means while the center showed the highest. Based in the results obtained it could be concluded that direct and indirect techniques to onlay restoration had similar compressive strength. Marginal adaptation was influenced by thermal/mechanical cycling; increasing of resin composite thickness and distance of active tip of light curing unit, there was a reduction of hardness values of resin cementMestradoMestre em Materiais Dentário

Synthesis and application of triclosan methacrylate monomer in resin composites

Objectives To evaluate the antibacterial activity, bacterial viability, cytotoxicity, and mechanical/physical properties of a novel methacrylate triclosan-derivative monomer (TM) incorporated in dental resin composite.MethodsTM was synthesized by esterification and, after characterization by FT-IR, was added to an experimental composite. Samples were divided into two groups according to TM presence, i.e., C1 (control) and C2 (C1 + 14.4% TM). Microbiological properties: Specimens (C1 and C2) were prepared and placed on bacterial suspensions of Streptococcus mutans. Antibacterial activity, MTT, and live/dead bacterial viability were used to test the resin composites. All assays were performed in triplicates. Mechanical properties: Specimens underwent compression (CS) and flexural strength (FS) tests conducted in an Instron universal testing machine at a crosshead speed of 0.5mm/min. Physical properties: Specimens were assessed for Knoop hardness (KHN) and crosslink density (CD). Fourier transform infrared spectroscopy allowed the degree of conversion (DC) to be evaluated. Data were subjected to appropriate statistical tests according to data distribution and assay (p<0.05).ResultsMicrobiological properties: C2 showed the lowest biofilm accumulation and the highest membrane-compromised bacteria in the biofilm. Mechanical/physical properties: For CS, FS, KHN, and DC, there was no significant difference between groups C1 and C2; however, significant difference was observed for the CD assay.ConclusionsThe triclosan methacrylate reduces bacterial adhesion of S. mutans and decreased the formation of bacterial biofilm without affecting important polymer properties. The triclosan methacrylate incorporated in resin composite could greatly reduce the live bacterial adhesion of S. mutans and decrease the formation of bacterial biofilm without affecting important polymer properties.Clinical significanceThe resin composites containing triclosan methacrylate could greatly reduce the bacterial adhesion and biofilm formation. That might prevent the secondary caries round the margins of the restorations232965974FAPESP – Fundação de Amparo à Pesquisa Do Estado De São Paulo2011/14151-5; 2012/ 10750-

Doxycycline-containing glass ionomer cement for arresting residual caries: an in vitro study and a pilot trial

<div><p>Abstract In a previous study, we demonstrated that the incorporation of doxycycline hyclate (DOX) into resin-modified glass ionomer cement (RMGIC) inhibited important cariogenic microorganisms, without modifying its biological and mechanical characteristics. In this study, we keep focused on the effect of that experimental material as a potential therapy for arresting residual caries by analyzing other in vitro properties and conducting a pilot clinical trial assessing the in vivo effect of DOX-containing RMGIC on residual mutans streptococci after partial carious removal in primary molars. Specimens of the groups RMGIC (control); RMGIC + 1.5% DOX; RMGIC + 3% DOX; and RMGIC + 4.5% DOX were made to evaluate the effect of DOX incorporation on surface microhardness and fluoride release of RMGIC and against biofilm of Streptococcus mutans. Clinical intervention consisted of partial caries removal comparing RMGIC and RMGIC + 4.5% DOX as lining materials. After 3 months, clinical and microbiologic evaluations were performed. Data were submitted to ANOVA/Tukey or Wilcoxon/Mann-Whitney set as α=0.05. Fluoride release and surface microhardness was not influenced by the incorporation of DOX (p>0.05). There was a significant reduction of S. mutans biofilm over the material surface with the increase of DOX concentration. After clinical trial, the remaining dentin was hard and dry. Additionally, mutans streptococci were completely eliminated after 3 months of treatment with RMGIC + 4.5% DOX. The incorporation of DOX provided better antibiofilm effect, without jeopardizing fluoride release and surface microhardness of RMGIC. This combination also improved the in vivo shortterm microbiological effect of RMGIC after partial caries removal.</p></div

Influence of the incorporation of triclosan methacrylate on the physical properties and antibacterial activity of resin composite

The incorporation of antimicrobials in the composites as an attempt to reduce bacterial adhesion without jeopardizing mechanical properties is a challenge for Dentistry. Objective: To evaluate the bacterial adhesion and physical properties of a composite containing the methacrylate triclosan-derivative monomer (TM). Methodology: TM was synthesized and added to an experimental composite. Samples were divided into two groups: Control and TM (13.4 wt%). Antibacterial Activity: Three specimens of each material were prepared and placed on bacterial suspensions of Streptococcus mutans for 1, 5 and 10 days. After these periods the counting of the colonies (log10) was performed. Assays was performed in triplicate. Physical Properties: Three-body Abrasion (TBA): Ten specimens of each material were prepared and stored at 37°C/24 h. The surface roughness (Ra) and hardness (KHN) were analyzed. Next, the specimens were submitted to abrasive wear (30,000 cycles) and re-evaluated for Ra and KHN; Sorption/solubility (SS): cylindrical specimens (n=10) were prepared and weighted. The specimens were immersed in deionized water for 7 days at 37°C and then their weight was verified again. SS were calculated using accepted formulas; Diametral tensile strength (DTS): specimens (n=10) underwent test performed in an Instron universal testing machine at a crosshead speed of 1 mm/min. Data were submitted to appropriate statistical tests according to data distribution and assay (p<0.05). Results: Bacterial Adhesion: TM showed a significant reduction on biofilm accumulation in the evaluated periods: 1 day (1.537±0.146); 5 days (2.183±0.138) and 10 days (4.469±0.155) when compared with Control: 1 day (4.954±0.249); 5 days (5.498±0.257) and 10 days (6.306±0.287). Physical Properties: For TBA, SS and DTS no significant difference was found between groups Control and TM. The incorporation of methacrylate triclosan-based monomer in the experimental composite reduce bacterial adhesion of S. mutans and did not affect important polymer properties27COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPSem informação#2012/10750-