Avaliação da resistencia da união composito/dentina ao cisalhamento em dentes deciduos submetidos ao tratamento com hipoclorito de sodio

Orientador: Regina Maria Puppin-RontaniDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: O objetivo deste estudo foi avaliar diferentes sistemas de união (Single Bond - SB, Prime & Bond 2.1 - PB e Clearfil SE Bond - CSEB), aplicados à dentina de dentes decíduos, submetida ou não ao tratamento prévio com hipoclorito de sódio (NaDCI), através da análise da resistência da união ao cisalhamento (RC) e do aspecto morfológico da união compósito/dentina. Foram selecionados 45 molares decíduos hígidos extraídos. As raízes dos dentes foram seccionadas na junção cemento-esmalte e as coroas ao meio, no sentido mésiodistal. As amostras foram então embutidas com resina de poliestireno em tubos de PV.C., com a superfície vestibular, lingual ou palatina externamente e lixadas até a obtenção de uma superfície plana em dentina (3 mm de diâmetro). A seguir, foram aleatoriamente distribuídas em 6 grupos (n=15), sendo: G1 - aplicação do sistema SB; G2 - condicionamento ácido (CA), aplicação de NaOCI seguida pelo sistema SB; G3 - aplicação do sistema PB; G4 - CA, aplicação do NaOCI seguida pelo sistema PB; G5 - aplicação do sistema CSEB e G6 - aplicação de NaOCI, seguida pelo CSEB. Todos os sistemas de união foram aplicados de acordo com as instruções dos fabricantes. O NaOCI a 10%foi aplicado nos grupos 2,4 (após o condicionamento ácido) e 6 (antes da aplicação do sistema de união) por 60s, e o dente foi lavado por 30s e seco com papel absorvente. Em seguida, o compósito Filtek Z-250 foi inserido em três incrementos (aproximadamente 2 mm), em uma matriz bipartida de silicone por adição adaptada a um posicionador metálico, e fotoativado por 20s cada incremento. As amostras foram armazenadas em água destilada a 37°C por 24h e então submetidas ao ensaio de cisalhamento em uma Máquina de Ensaio Universal (Instron - modelo 4411) à velocidade de 0,5mm/min. Os padrões de fratura foram observados em microscópio estereoscópico (aumento 25X), e os representativos de cada grupo foram observados em Microscopia Eletrônica de Varredura (MEV). Para a análise da união compósito/dentina foram utilizados três dentes para cada grupo e repetidos todos os procedimentos descritos anteriormente. Emseguida, foram seccionados no centro da restauração e preparados para observação em MEV. Os dados obtidos no ensaio de cisalhamento foram submetidos à análise de variância e teste de Tukey (p<0,05). Os valores obtidos em MPa foram: G1- 3,17 :t 1,97; G2 - 2,93 :t 1,36; G3 - 2,04 :t 0,27; G4 - 1,91 :t 0,74; G5 - 2,67 :t 1,22; G6 -2,14 :t 1,10. De acordo com os resultados, pôde-se observar que houve diferença estatística significativa (p<0,05) entre os materiais (SB-CSEB-PB). Não houve diferença estatística significativa entre os grupos com ou sem tratamento do substrato, independente do material utilizado (p>0,05). O tipo de falha freqüentemente observada em todos os grupos foi a falha mista (coesiva no compósito + adesiva). Com relação ao aspecto . morfológico da união, nas amostras sem tratamento do substrato foi observada a presença da camada híbrida e dos prolongamentos resinosos. Nas amostras com tratamento da superfície (com NaOCI) não foi observada a presença da camada híbrida, porém foram observados prolongamentos resinosos. Pôde-se concluir que o tratamento da superfície com hipoclorito de sódio não afetou a resistência da união compósito/dentina ao cisalhamento, porém, interferiu na formação da camada híbrida, em dentes decíduosAbstract: The aim of this study was to evaluate different bonding agents (Single Bond - SB, Prime & Bond 2.1 - PB e Clearfil SE Bond - CSEB), in primary teeth treated with sodium hypochlorite (NaOCI) on the shear bond strength (SBS) and micromorphology of the resin/dentin interface. Forty-five sound extracted primary molars were selected. The roots were sectioned in the enamel-cement junction and the crowns longitudinally, in the mesio-distal sense. The samples were embedded in polystyrene resin with the bucal, lingual or palatine surface externally and they were flattened until dentin surface was reached (3mm in diameter). Then, the samples were randomly assigned in 6 groups (n=15), and received the following treatments: G1 - SB; G2 - acid etching (AE), 10% NaOCI and the SB; G3 - PB; G4 - AE, 10% NaOCI and the PB; G5 - CSEB; G6 - 10% NaOCI followed by CSEB. Ali the adhesive systems were applied according to manufactures' instructions. The 10% NaOCI solution was applied for 60s in groups 2,4 (after acid etching), and 6 (before adhesive system), washed for 30s and dried with tissue paper. Next, the composite resin was inserted in increments (2mm) in a vinyl polysiloxane impression material matrix, adapted in a metallic holder, and light cured for 20s (each increment). The samples were stored in distilled water at 37°C for 24h and then, submitted to SBS test in a universal testing machine (Instron - model 4411) with a crosshead speed of 0.5mm/min. The failure sites were observed in stereoscope microscopy of 40X magnification, and the representative failures of each group were observed in Scanning Electron Microscopy (SEM). The results obtained were submitted to ANOVA and Tukey's tests (p<0.05). The values in MPa were: G1- 3.17 :t 1.97;G2 - 2.93:t 1.36;G3 - 2.04:t 0.27; G4- 1.91 :t 0.74; G5 - 2.67:t 1.2; G6 -2.4:t 1.0. According to the results, it could be noticed that there was a statistical significant difference (p0.05) among ali the groups with or without treatment of the substrate, independently of the material used. The mixed fail (cohesive in resin + adhesive) was the one most frequently observed in ali groups. Regarding the interface aspect in specimens without substrate treatment (NaDCI) it could be observed the presence of the hybrid layer and resin tags whereas treated specimens only resin tags could be observed. It could be concluded that the treatment of the dentin surface with sodium hypochlorite did not affect the resin/dentin bonding strength but interfered in the hybrid layer formation in primary teethMestradoMestre em Materiais Dentário

Efeito da contaminação salivar e do tempo de recondicionamento ácido na resistência da união ao cisalhamento de um selante de fóssulas e fissuras

O propósito deste estudo foi avaliar o efeito do tempo de contaminação salivar (TCS) e de recondicionamento ácido (TRA) na resistência da união ao cisalhamento (RC) do selante Fluroshield. Foram selecionados 45 terceiros molares. Os dentes foram seccionados no sentido mésio-distal e suas superfícies foram lixadas até a obtenção de uma área plana em esmalte. Em seguida, as amostras foram distribuídas aleatoriamente em 9 grupos (n=10), em função do TCS e TRA (segundos), respectivamente: G1 - controle; G2 - 30 e 0; G3 - 60 e 0; G4 - 30 e 2; G5 - 30 e 5; G6 - 30 e 15; G7 - 60 e 2; G8 - 60 e 5; G9 - 60 e 15. Em seguida, foi realizada a aplicação do selante de acordo com as instruções do fabricante. Os corpos-de-prova obtidos foram armazenados em água destilada a 37&ordm;C por 72 horas, e então submetidos ao ensaio de cisalhamento à velocidade de 0,5mm/min. Os resultados foram submetidos à análise de variância (ANOVA), e indicaram que não houve diferença estatística significativa (p>;0,05) entre todos os grupos. Observou-se que: 1 - quanto maior o TCS, menores os valores de RC (MPa); 2- quanto maior o TRA, maior o valor de RC (MPa). Pôde-se concluir que houve uma tendência para o menor TCS (30s) e os maiores TRA (5 e 15s) em retornar aos valores de RC do grupo controle.The aim of this study was to evaluate the effect of saliva contamination (SCT) and re-etching time (RET) on the shear bond strength (SBS) of the Fluroshield sealant. Forty-five extracted third molars were sectioned and flattened until reach an enamel surface area. Then, all samples were etched for 30 sec with 35% phosphoric acid and then they were distributed into 9 groups (n=10) according to SCT and RET (seconds), respectively: G1- control (no SCT and no RET); G2- 30s and 0s; G3- 60s and 0s; G4-30s and 2s; G5- 30s and 5s; G6- 30s and 15s; G7-60s and 2s; G8- 60s and 5s; G9- 60s and 15s. The sealant was applied according to the manufacturer's instructions. The samples were stored in distilled water at 37&ordm;C for 72h and subjected to the SBS test. The results indicated that there was no statistically significant difference between the groups (p>;0.05). However, it could be noticed that: 1- the longer the SCT, the lower the SBS values; 2 - the longer the RET, the higher the SBS values. It could be concluded that there was a tendency to the shortest SCT (30s) associated to the longest RET (5 and 15s) to reach similar SBS values for the control group

Effect of coffe and a cola-based soft drink on the color stability of bleached bovine incisors considering the time elapsed after bleaching

There is no consensus about the waiting time necessary for the patient to start consuming beverages containing colorants again after bleaching. Objective: To evaluate the influence of beverages with coloring agents on bleached bovine incisors considering the time elapsed after bleaching. Materials and methods: Sixty bovine incisors were bleached with 35% hydrogen peroxide for in-office use (Whiteness HP Max) and divided into 10 groups. The color was evaluated with a spectrophotometer (Spectro Shade MICRO) before and after bleaching, employing the CIE-Lab system. After bleaching, the teeth were exposed for 5 min to coffee or cola-based soft drink (CBSD) at different periods after bleaching: 10 min, 1 h, 24 h, 48 h, and 72 h. Color (∆E) and lightness (∆L) variations were obtained from the CIE-Lab coordinates. Data were subjected to two-way ANOVA and Tukey HSD tests (

Influence of post-fixation time on shear bond strength of brackets fixed with different bonding materials

Este estudo avaliou a resistência ao cisalhamento da união, nos tempos pós-fixação de 10 minutos e 24 horas, de quatro materiais para colagem de bráquetes e os tipos de falhas na fratura. Foram utilizados 64 pré-molares humanos recém-extraídos embutidos em resina. As faces vestibulares de 32 pré-molares foram condicionadas com ácido fosfórico a 35%, por 30 segundos e em 16 deles, os bráquetes foram colados com Concise Ortodôntico (3M) e nos demais com resina composta Z100 (3M). Em 32 dentes, os bráquetes foram colados sem condicionamento do esmalte, com ionômeros de vidro Fuji I (GC) e Fuji Ortho LC (GC). Após a fixação, 32 corpos-de-prova foram armazenados em água destilada a 37ºC, por 10 minutos e o restante por 24 horas e submetidos ao teste de cisalhamento numa máquina com velocidade de 0,5 mm/min. Os resultados submetidos à ANOVA e ao teste de Tukey (5%) mostraram que os maiores valores de resistência ao cisalhamento aos 10 minutos e 24 horas foram observados com o Concise Ortodôntico, com diferença estatística significativa em relação ao Fuji Ortho LC, Z100 e Fuji I. Nenhuma diferença estatística foi observada entre Fuji Ortho LC, Z100 e Fuji I. Os autores concluíram que o Concise Ortodôntico apresentou maiores valores de resistência ao cisalhamento em relação aos outros materiais, nos tempos de 10 minutos e 24 horas, os valores obtidos no período de 24 horas foram superiores em relação aos de 10 minutos, para todos materiais e um grande número de falhas adesivas foi observada para o Fuji I, Concise Ortodôntico e Z100.The purpose of this study was to evaluate the shear bond strength of four bonding materials for brackets, 10 minutes and 24 hours after their fixation, as well as the kinds of fracture observed. The buccal surfaces of 32 premolars were etched for 30 seconds with 35% phosphoric acid, and brackets were bonded using Orthodontic Concise (3M) and Z100 (3M). In other 32 premolars, brackets were bonded with Fuji I (GC) and Fuji Ortho LC (GC) on the buccal surfaces, without acid etching. After the bonding procedures, 32 samples were stored in distilled water at 37ºC for 10 minutes, and 32 samples were stored at the same temperature for 24 hours. The samples were then submitted to shear bond strength testing in an Instron testing machine, at a crosshead speed of 0.5 mm/min. The results were submitted to ANOVA and Tukeys test (p < 0.05). The results indicated that, for 10 minutes and 24 hours, Orthodontic Concise showed shear bond strength values (6.22 and 7.73 MPa, respectively) higher than Fuji Ortho LC (3.32 and 5.10 MPa), Z100 (2.72 and 4.51 MPa) and Fuji I (2.52 and 4.54 MPa). No statistical difference was verified between Fuji Ortho LC, Z100 and Fuji I (p < 0.05). In conclusion, Orthodontic Concise showed better shear bond strength values than the other three bonding materials, for both 10-minute and 24-hour storage periods; the shear bond strength averages were higher for the storage time of 24 hours, for all tested materials, and a great number of adhesive fractures were observed in the specimens which received Fuji I, Orthodontic Concise and Z100

Shear bond strength of brackets bonded with nanofilled flowable resins

Introduction and Objective: To evaluate the shear bond strength of brackets fixed with different materials (two light-cured nanofilled low-viscosity resins –Transbond Supreme LV and Flow Tain LV and two light-cured traditional resins – Transbond XT and Transbond Plus Color Change) after 10 min and 24 h, and to evaluate the type of failure. Material and methods: Eighty bovine incisors were selected and randomly divided into groups (n = 10) according to the material and fixation period. The brackets were bonded following the manufacturer's instructions and stored in deionized water at 37 oC for  10 min or 24 h. After, the specimens were submitted to shear bond strength test at 0.5 mm/min and evaluated for adhesive remnant index (ARI). The data were submitted to Kruskal Wallis and Wilcoxon tests (p Transbond Plus Color Change > Transbond  upreme LV = Flow Tain LV and after 24 h – Transbond XT > Transbond Plus Color Change = Transbond Supreme LV =  Flow Tain LV). There was osignificant difference in resistance values between 10 min and 24 h, except for Transbond Plus Color Change. Most groups showed adhesive remaining adhered to the enamel (scores 2 and 3) without statistical significant difference (p > 0.05). Conclusion: The light-cured traditional resins showed higher resistance than the nanofilled materials. The period of fixation had no influence on the resistance for different materials, except for Transbond Plus Color Change

Efeito da contaminação salivar e do tempo de recondicionamento ácido na resistência da união ao cisalhamento de um selante de fóssulas e fissuras

The aim of this study was to evaluate the effect of saliva contamination (SCT) and re-etching time (RET) on the shear bond strength (SBS) of the Fluroshield sealant. Forty-five extracted third molars were sectioned and flattened until reach an enamel surface area. Then, all samples were etched for 30 sec with 35% phosphoric acid and then they were distributed into 9 groups (n=10) according to SCT and RET (seconds), respectively: G1- control (no SCT and no RET); G2- 30s and 0s; G3- 60s and 0s; G4-30s and 2s; G5- 30s and 5s; G6- 30s and 15s; G7-60s and 2s; G8- 60s and 5s; G9- 60s and 15s. The sealant was applied according to the manufacturer's instructions. The samples were stored in distilled water at 37&ordm;C for 72h and subjected to the SBS test. The results indicated that there was no statistically significant difference between the groups (p>0.05). However, it could be noticed that: 1- the longer the SCT, the lower the SBS values; 2 - the longer the RET, the higher the SBS values. It could be concluded that there was a tendency to the shortest SCT (30s) associated to the longest RET (5 and 15s) to reach similar SBS values for the control group.O propósito deste estudo foi avaliar o efeito do tempo de contaminação salivar (TCS) e de recondicionamento ácido (TRA) na resistência da união ao cisalhamento (RC) do selante Fluroshield. Foram selecionados 45 terceiros molares. Os dentes foram seccionados no sentido mésio-distal e suas superfícies foram lixadas até a obtenção de uma área plana em esmalte. Em seguida, as amostras foram distribuídas aleatoriamente em 9 grupos (n=10), em função do TCS e TRA (segundos), respectivamente: G1 - controle; G2 - 30 e 0; G3 - 60 e 0; G4 - 30 e 2; G5 - 30 e 5; G6 - 30 e 15; G7 - 60 e 2; G8 - 60 e 5; G9 - 60 e 15. Em seguida, foi realizada a aplicação do selante de acordo com as instruções do fabricante. Os corpos-de-prova obtidos foram armazenados em água destilada a 37&ordm;C por 72 horas, e então submetidos ao ensaio de cisalhamento à velocidade de 0,5mm/min. Os resultados foram submetidos à análise de variância (ANOVA), e indicaram que não houve diferença estatística significativa (p>0,05) entre todos os grupos. Observou-se que: 1 - quanto maior o TCS, menores os valores de RC (MPa); 2- quanto maior o TRA, maior o valor de RC (MPa). Pôde-se concluir que houve uma tendência para o menor TCS (30s) e os maiores TRA (5 e 15s) em retornar aos valores de RC do grupo controle.20020

Effect of 2% chlorhexidine treated coronal dentin on bond strength of two self-adhesives cements

Despite advances in adhesive dentistry, lasting bonds between indirect restorations and dentin remain a challenge. Objective: Therefore, the aim of this study was to evaluate the effect of chlorhexidine on the bond strength of self-adhesive cements to dentin after storage for 24 h and 90 days. Material and methods: Forty-eight human third molars crowns were included in polyvinyl chloride matrices using acrylic resin and worn to expose a flat dentin area. The specimens were randomly distributed into 8 groups (n = 12) in accordance with the self-adhesive cement (Rely X U200 and Smart Cem 2), the dentin treatment (application or not of 2 % chlorhexidine digluconate solution for 1 min) and the storage period (24 h or 90 d). Two cylinders’ cements (1.4 x 1 mm) were constructed on the dentin surfaces of each sample, stored in distilled water for 24 h or 90 days and submitted to a micro-shear test. Subsequently, a failure analysis was performed to classify the failure into adhesive, cohesive, and mixed. Data were subjected to ANOVA and Tukey (0.05) tests. Results: There was a statistically significant difference between the materials (Rely X U200 > Smart Cem 2 – p < 0.05) regardless of the surface treatment and the storage period. Conclusion: The chlorhexidine application did not affect the immediate or delayed bond strength values, regardless of the self-adhesive cement

The bleaching efficacy of carbamide peroxide gels containing potassium nitrate desensitizer

To evaluate the bleaching efficacy of at-home carbamide peroxide (CP) gels in two concentrations, containing or not a desensitizing agent. Forty incisors were divided into four groups (n=10), according to gel concentrations (10% or 22%), and presence or not of 3% potassium nitrate in the gel. A thin layer of gel was applied to the buccal surface of each tooth for 2h/day for 4 weeks. Bleaching efficacy was measured using a spectrophotometer, and ?E*ab, ?E00 and ?WID were calculated. Measurements were performed at baseline, 7, 14, 21, 28, and 35 days following the first gel application. Data were analyzed by two-way RM-ANOVA and Tukey?s test (?=0.05). Regarding gel concentration or potassium nitrate inclusion, both gels resulted in color change above the perceptibility thresholds, which were similar between gels. Regarding time, significant differences were observed between color change values at 7 days and other time periods. ?WID ranged from 3.8 to 9.6. Significant moderate to strong positive correlation was observed among the parameters. Nor the CP concentration, neither the inclusion of potassium nitrate in the gel, had influence on bleaching efficacy. All gels were effective and showed good results from the first weeks? application

Influence of the conditioning technique of a lithium disilicate vitroceramic

Introduction: Lithium disilicate reinforced glass ceramics are materials that require good adhesion to ensure clinical success. Objective: To evaluate the bond strength of resin cements to lithium-disilicateenhanced vitroceramics using different cleaning techniques of recently conditioned ceramics. Material and methods: Twelve ceramic discs (IPS Empress II) were made and inserted into PVC pipes using acrylic resin. The ceramic surface was designed and submitted to a 10% hydrofluoric acid conditioning process for 20s. Then, the specimenswere divided into 3 groups (n = 16) according to the cleaning techniques of recently conditioned ceramics: 1) control - conventional technique (no cleaning after the conditioning process); 2) application of 37% phosphoric acid for 20s; 3) 90% ethyl alcohol bath in a ultrasound tub for 4 min. After cleaning, the silane agent was applied for 1 minute and silicon matrices (1 mm in diameter x 1 mm in height) were made for further application of the resin cement (Vitique, DMG), which was handled according to the manufacturer’s instructions. Four cylinders were prepared on each ceramic surface. The specimens were storedin distilled water for 48 hours and subjected to the micro-shear test in a universal testing machine. After the micro-shear test, a failure analysis of the specimens was performed. Data were submitted to ANOVA (analysis of variance for a criterion) with a significance level of 5%. Results: There was no significant difference between groups (p > 0.05). Conclusion: the cleaning technique of the recently conditioned ceramics does not interfere with the resin/cement bond strength valuesIntroduction: Lithium disilicate reinforced glass ceramics are materials that require good adhesion to ensure clinical success. Objective: To evaluate the bond strength of resin cements to lithium-disilicateenhanced vitroceramics using different cleaning techniques of recently conditioned ceramics. Material and methods: Twelve ceramic discs (IPS Empress II) were made and inserted into PVC pipes using acrylic resin. The ceramic surface was designed and submitted to a 10% hydrofluoric acid conditioning process for 20s. Then, the specimenswere divided into 3 groups (n = 16) according to the cleaning techniques of recently conditioned ceramics: 1) control - conventional technique (no cleaning after the conditioning process); 2) application of 37% phosphoric acid for 20s; 3) 90% ethyl alcohol bath in a ultrasound tub for 4 min. After cleaning, the silane agent was applied for 1 minute and silicon matrices (1 mm in diameter x 1 mm in height) were made for further application of the resin cement (Vitique, DMG), which was handled according to the manufacturer’s instructions. Four cylinders were prepared on each ceramic surface. The specimens were storedin distilled water for 48 hours and subjected to the micro-shear test in a universal testing machine. After the micro-shear test, a failure analysis of the specimens was performed. Data were submitted to ANOVA (analysis of variance for a criterion) with a significance level of 5%. Results: There was no significant difference between groups (p > 0.05). Conclusion: the cleaning technique of the recently conditioned ceramics does not interfere with the resin/cement bond strength value

Shear bond strength of nanofilled flowable resins used for indirect bracket bonding

AIM: To evaluate the bond strength of brackets fixed with different materials (two light-cured nanofilled resins - Transbond Supreme LV and Flow Tain LV, a light-cured resin - Transbond XT (control) and two chemically cured resins for indirect bonding - Sondhi Rapid- Set and Custom I.Q.) using the indirect bonding technique after 10 min and 24 h, and evaluate the type of failure. METHODS: One hundred premolars were selected and randomly divided into groups (n=10) according to the material and fixation period. The brackets were bonded through the indirect technique following the manufacturer's instructions and stored in deionized water at 37°C for 10 min or 24 h. After, the specimens were submitted to a shear bond strength (SBS) test (Instron) at 0.5 mm/min and evaluated for adhesive remnant index (ARI). The data were submitted to ANOVA and Tukey's test (p<0.05) and the ARI scores were submitted to the chi-square test. RESULTS: It could be observed a significant difference among the materials (Flow Tain LV = Transbond Supreme LV = Transbond XT&gt; Sondhi Rapid-Set &gt; Custom I.Q.). There was no significant difference in resistance values between 10 min and 24 h, regardless of the materials. Most groups showed adhesive remaining adhered to the enamel (scores 2 and 3) without statistically significant difference (p&gt;0.05). CONCLUSIONS: It was concluded that the light-cured nanofilled materials used in indirect bonding showed greater resistance than the chemically cured materials. The period of fixation had no influence on the resistance for different materials