Efeito das dimensões do espécime na resistência à flexão de uma resina composta

PUORPOSE: The aim of this study was to evaluate the effect of specimen dimensions on the flexural strength of a composite resin (Heliomolar RO). METHODS: The different dimensions tested - length x width x height (mm) were: 25x2x4; 25x2x2 (ISO 4049); 15x2x2; 10x2x2 and 10x2x1. Light-curing was performed at 600 mW/cm² for 40s, three times along the 25mm specimens, twice along 15mm specimen and once for the 10mm specimens. Specimens of all dimensions were light-cured on both surfaces, or only on one side. In the latter, the load was applied on the irradiated side or on the opposite one. RESULTS: It was shown that the flexural strength was not affected by specimen length. When light-curing was performed on both surfaces, similar flexural strength values were obtained for any dimension. Despite the number of irradiated surfaces, specimens with a height of 1mm also obtained similar values. On the contrary, specimens with a height of 4mm, exposed only on one surface, reached the lowest strength. CONCLUSION: The use of specimens with lower dimensions can lead to flexural strength values similar to the ones obtained with standardized specimen (ISO 4049), with the advantage of demanding less amount of material and being less time consuming.OBJETIVO: A finalidade da presente investigação foi avaliar a influência das dimensões dos corpos-de-prova (cp) e da superfície de irradiação na resistência à flexão de uma resina composta (Heliomolar RO). MÉTODOS: As diversas dimensões adotadas - comprimento x largura x altura (mm) foram: 25x2x4; 25x2x2 (ISO 4049); 15x2x2; 10x2x2; 10x2x1. A fotoativação foi realizada por 40 segundos a 600mW/cm²; três vezes ao longo dos cp de 25mm, duas vezes ao longo dos cp de 15mm e uma vez nos cp de 10mm de comprimento. Os corpos-de-prova de todas as dimensões foram ativados em ambas as superfícies, ou apenas em uma; neste caso a carga de ruptura era aplicada na face de irradiação ou na oposta. RESULTADOS: Foi mostrado que a resistência à flexão não foi afetada pelo comprimento dos cp. Com a fotoativação em ambas as superfícies, as resistências obtidas eram semelhantes nos diversos comprimentos. Independentemente do número de faces irradiadas, os cp com 1mm de altura apresentaram resistências semelhantes. Contudo, cp com 4mm de altura e irradiados apenas por um lado, alcançaram os menores valores. CONCLUSÃO: Com o emprego de cp com dimensões menores são alcançados valores de resistência à flexão semelhante aos obtidos com cp padronizados (ISO 4049), com a vantagem de menor demanda de material e menor consumo de tempo (o menor comprimento dos cp requer apenas uma ativação por lado)

Effectiveness of sealing active proximal caries lesions with an adhesive system: 1-year clinical evaluation

The objective of this study was to evaluate the effectiveness of a therapeutic sealant to arrest non-cavitated proximal carious lesion progression. The study population comprised 44 adolescents who had bitewing radiographs taken for caries diagnosis. Non-cavitated lesions extending up to half of dentin thickness were included in the sample. In the experimental group (n = 33), the proximal caries-lesion surfaces were sealed with an adhesive (OptiBond Solo, Kerr) after tooth separation. The control group (n = 11) received no treatment, except for oral hygiene instructions including use of dental floss. Follow-up radiographs were taken after one year and were analyzed in comparison with baseline radiographs. In a blind study setting, visual readings were performed by two examiners, blinded to whether the examined radiograph was baseline or follow-up, and whether it concerned a test or control lesion. The efficacy of sealing treatment was evaluated by the McNemar test (0.05). About 22% of the sealed lesions showed reduction, 61% showed no change and 16% showed progression. For the control lesions, the corresponding values were 27%, 36% and 36% respectively. The number of lesions that showed reduction and no changes were merged and therefore 83.3% of the sealed lesions and 63.6% of the control lesions were considered clinically successful. No statistical significance was detected (p > 0.05). In the course of 1 year, sealing proximal caries lesions was not shown to be superior to lesion monitoring.Dr. Priscila Bresciani, Dr. Bernardo Hahn and Dr. Franciele Loeblein for the help provided in the clinical part of this stud

Efeito da termociclagem e da técnica de inserção na infiltração de restaurações em resina composta

The objective of this study was to evaluate in vitro the effect on leakage of two incremental filling techniques and two composite resins with different elastic modulus and similar polymerization shrinkage. Eighty Class V cavities (4x4x2mm) were prepared in bovine incisors and were randomly restored with Z-250 (Z) or Durafill VS (D) + Single Bond in axial (a) or oblique (o) increments. The restorations were divided into two groups: Not Aged - N (4-hour-storage in water at 37ºC) and Aged - A (1-week storage in water at 37ºC + 1000 x - 5º-55ºC / 1-min dwell time). The specimens were covered with 2 coats of nail varnish so that only the restoration margins were exposed to silver nitrate 50% (2h) and developed under fluorescent light (8h). After they were sectioned twice in buccal-lingual direction, the four exposed surfaces were digitized (Vidcap) and the silver nitrate penetration was measured (ImageLab) at the incisal and gingival walls. Data were analyzed by a 3-way ANOVA (Resin, Filling Technique and Aging) separately for incisal and gingival walls (alpha=0.05). Resin and Aging were statistically significant either for the incisal and the gingival walls. The microfill composite resin infiltrated more than the hybrid composite. The thermal cycling caused an overall increase in silver nitrate penetration. The filling technique affected leakage depending on the composite resin and aging regimen.O objetivo deste estudo foi avaliar o efeito de duas técnicas incrementais de inserção na infiltração de restaurações de resinas compostas com módulos de elasticidade distintos e contração de polimerização semelhante. Para isto, foram preparadas 80 cavidades Classe V (4x4x2 mm) em incisivos bovinos que foram restauradas de modo aleatório com Z-250 (Z) ou Durafill VS (D) + Single Bond em incrementos axiais (a) ou oblíquos (o). As restaurações foram divididas em dois grupos: Não Envelhecidas - N (4 h em água destilada a 37º C) e Envelhecidas - E (1 semana de armazenagem em água a 37º C + 1000 x - 5º-55ºC / 1 min de imersão). Os espécimes foram recobertos com duas camadas de esmalte cosmético de modo que apenas as margens das restaurações ficassem expostas ao nitrato de prata (2h) seguido de imersão em revelador (8h) sob luz fluorescente. Posteriormente, eles foram secionados duas vezes no sentido vestíbulo-lingual, as superfïcies expostas (4) foram digitalizadas (Vidcap) e a penetração do nitrato de prata medido (ImageLab) nas paredes incisal e gengival. Os dados foram analisados por análise de variância de três fatores (Resina, Técnica de Inserção e Envelhecimento) separadamente para as paredes incisal e gengival. Resina e Envelhecimento foram significativos. A resina composta de micropartículas mostrou maior infiltração que a híbrida. A técnica de inserção influenciou a infiltração marginal dependendo da resina e do emprego ou não de ciclos térmicos

Efeitos de métodos para envelhecimento na microinfiltração de um sistema adesivo usado como selante em superfícies contaminadas

This study evaluated the effects of aging methods on the microleakage of an adhesive system used for sealing pit and fissure surfaces. After acid etching, the occlusal surfaces of 60 permanent teeth were contaminated with 1mL of human plasma and then sealed with OptiBond dual cure, activated in the ramp mode (Optilux 501). The sample was then divided into eight experimental and a control groups. Aging was performed for 20 days in 5, 37, 55 and 5-55ºC (200 cycles/day) under water contact or not. After subjecting the specimens to the AgNO3 technique, they were sectioned twice. Dye penetration was measured and the mean values were subjected to ANOVA. No group provided hermetic seal against dye penetration, even the control group (without treatment). Significant aging x water interaction effect (p=0.033) was observed. The group without water contact at 5ºC (p=0.015) showed the least dye penetration value. The results led to the main conclusions: 1) all groups showed dye penetration, even the control group; 2) storage teeth at 5ºC on dry condition provided the lowest degree of dye penetration; 3) in the presence of water, the temperature variations seem not to affect the microleakage values.Este estudo avaliou os efeitos de métodos para envelhecimento na microinfiltração de um sistema adesivo usado para selar superfícies oclusais. Após o condicionamento com ácido, as superfícies de 60 dentes permanentes foram contaminadas com 1 mL de plasma e seladas com OptiBond dual cure, ativado pelo Optilux 501, no modo rampa. A amostra foi dividida em oito grupos experimentais e um grupo controle ou imediato O envelhecimento dos espécimes foi realizado por 20 dias a 5, 37, 55 e 5-55°C (200 ciclos/dia) em contato com a água ou não. Após submeter os espécimes à técnica de infiltração com AgNO3, eles foram secionados duas vezes e os valores médios da penetração do corante foram tratados por análise de variância. Nenhum grupo apresentou vedamento hermético na interface, nem mesmo o grupo sem envelhecimento (imediato ou controle). O grupo que permaneceu a 5°C sem contato com a água mostrou o menor grau de penetração (p=0,015) e a interação envelhecimento x água foi significante (p=0,033). Os resultados levam às seguintes conclusões: 1) todos os grupos mostram microinfiltração, inclusive o controle; 2) o grupo mantido a 5ºC sem contato com a água mostrou os menores valores de microinfiltração; 3) em contato com a água, as variações térmicas parecem não afetar o grau de penetração do corante

Evaluating resin-enamel bonds by microshear and microtensile bond strength tests: effects of composite resin

OBJECTIVES: The aims of this study were to evaluate the effect of resin composite (Filtek Z250 and Filtek Flow Z350) and adhesive system [(Solobond Plus, Futurabond NR (VOCO) and Adper Single Bond (3M ESPE)] on the microtensile (&#956;TBS) and microshear bond strength (&#956;SBS) tests on enamel, and to correlate the bond strength means between them. MATERIAL AND METHODS: Thirty-six extracted human molars were sectioned to obtain two tooth halves: one for &#956;TBS and the other one for &#956;SBS. Adhesive systems and resin composites were applied to the enamel ground surfaces and light-cured. After storage (37(0)C/24 h) specimens were stressed (0.5 mm/min). Fracture modes were analyzed under scanning electron microscopy. The data were analyzed using two-way ANOVA and Tukey's test (&#945;=0.05). RESULTS: The correlation between tests was estimated with Pearson's product-moment correlation statistics (&#945; =0.05). For both tests only the main factor resin composite was statistically significant (p<0.05). The correlation test detected a positive (r=0.91) and significant (p=0.01) correlation between the tests. CONCLUSIONS: The results were more influenced by the resin type than by the adhesives. Both microbond tests seem to be positive and linearly correlated and can therefore lead to similar conclusions.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Bond strength and morphology of enamel using self-etching adhesive systems with different acidities

OBJECTIVES: To assess the bond strength and the morphology of enamel after application of self-etching adhesive systems with different acidities. The tested hypothesis was that the performance of the self-etching adhesive systems does not vary for the studied parameters. MATERIAL AND METHODS: Composite resin (Filtek Z250) buildups were bonded to untreated (prophylaxis) and treated (bur-cut or SiC-paper) enamel surfaces of third molars after application of four self-etching and two etch-and-rinse adhesive systems (n=6/condition): Clearfil SE Bond (CSE); OptiBond Solo Plus Self-Etch (OP); AdheSe (AD); Tyrian Self Priming Etching (TY), Adper Scotchbond Multi-Purpose Plus (SBMP) and Adper Single Bond (SB). After storage in water (24 h/37°C), the bonded specimens were sectioned into sticks with 0.8 mm² cross-sectional area and the microtensile bond strength was tested at a crosshead speed of 0.5 mm/min. The mean bond strength values (MPa) were subjected to two-way ANOVA and Tukey's test (&#945;=0.05). The etching patterns of the adhesive systems were also observed with a scanning electron microscope. RESULTS: The main factor adhesive system was statistically significant (

Effect of the application time of phosphoric acid and self-etch adhesive systems to sclerotic dentin

Objective: To evaluate the effect of application time on the resin-dentin bond strength (µTBS) and etching pattern of adhesive systems applied on sclerotic dentine. Material and Methods: A total of forty-two bovine incisors had their roots removed. The 1-step self-etch GO (SDI), the 2-step self-etch Adper SE Bond (3MESPE) and the 35% phosphoric acid (3MESPE) from the 2-step etch-and-rinse Adper Single Bond 2 (3MESPE) were applied on the bovine incisal surfaces according to the manufacturer's instructions or duplicating the recommended conditioning time. After adhesive application, thirty teeth were restored with composite resin, stored for 24 h in distilled water at 37°C, and sectioned into resin-dentin bonded sticks (0.8 mm 2 ) and tested according to the µTBS at 0.5 mm/min. The etching pattern of the remaining twelve teeth (n=4 for each material) was examined under scanning electron microscopy. Each tooth was divided into a buccal-to-lingual direction into three thirds, and each third randomly assigned to the groups: control (no treatment), according to the manufacturers' instructions and duplicating the recommended application time. The µTBS and the relative percentage of the tubule area opening were evaluated by two-way repeated measures ANOVA and Tukey's tests (α=0.05). Results: The duplication of the conditioning time favored only the GO adhesive (

Tensile bond strength of adhesive systems: effects of primer and thermocycling

O objetivo desta pesquisa foi o de verificar o efeito do "primer" e dos ciclos térmicos na resistência da união entre adesivos multiuso e esmalte dental, sob ensaios de tração. Os seguintes sistemas adesivos foram aplicados, de acordo com as instruções dos fabricantes, na superfície vestibular (sem desgaste) de 96 pré-molares com ou sem a aplicação prévia do "primer": Scotchbond MP, OptiBond FL, Amalgambond Plus e OptiBond - "dual cure". Após a aplicação do sistema adesivo, foi confeccionado um cone de resina composta (Z100, 3M), e fotoativado dentro de um molde metálico. Metade do total de espécimes foi submetida a 3.000 ciclos térmicos (5-37ºC; 37-55ºC, 60 s de imersão); a outra metade permaneceu imersa em água a 37ºC pelo mesmo tempo dispensado no procedimento anterior. Os dados foram submetidos a uma análise de variância (p = 0,05) e nenhum efeito significante foi detectado, indicando que a resistência de união não foi afetada pelo sistema adesivo, pela aplicação do "primer" ou pelos ciclos térmicos.The objective of this study was to evaluate the effects of primer and thermocycling on the bond strength of multi-purpose adhesive systems applied to enamel, under tensile stress. The following bonding systems were applied, according to the manufacturers' instructions, on unground enamel buccal surfaces of 96 premolars, with or without the application of primer: Scotchbond MP, OptiBond FL, Amalgambond Plus and OptiBond (dual-cure). A composite resin (Z100, 3M) was applied and light-cured in a cast metal hollow cone, which was previously fixed to the enamel surfaces. Half of the sample was subjected to 3,000 thermocycles (5-37ºC; 37-55ºC, dwell time of 60 s), and the other half was stored in water at 37ºC for the same period. The data were treated by means of ANOVA and no significant effects were detected, which indicates that tensile bond strength was not affected by the adhesive systems, application of primer or thermocycling

Characterization of aqueous silver nitrate solutions for leakage tests

OBJECTIVE: To determine the pH over a period of 168 h and the ionic silver content in various concentrations and post-preparation times of aqueous silver nitrate solutions. Also, the possible effects of these factors on microleakage test in adhesive/resin restorations in primary and permanent teeth were evaluated. MATERIAL AND METHODS: A digital pHmeter was used for measuring the pH of the solutions prepared with three types of water (purified, deionized or distilled) and three brands of silver nitrate salt (Merck, Synth or Cennabras) at 0, 1, 2, 24, 48, 72, 96 and 168 h after preparation, and storage in transparent or dark bottles. Ionic silver was assayed according to the post-preparation times (2, 24, 48, 72, 96, 168 h) and concentrations (1, 5, 25, 50%) of solutions by atomic emission spectrometry. For each sample of each condition, three readings were obtained for calculating the mean value. Class V cavities were prepared with enamel margins on primary and permanent teeth and restored with the adhesive systems OptiBond FL or OptiBond SOLO Plus SE and the composite resin Filtek Z-250. After nail polish coverage, the permanent teeth were immersed in 25% or 50% AgNO3 solution and the primary teeth in 5% or 50% AgNO3 solutions for microleakage evaluation. ANOVA and the Tukey's test were used for data analyses (&#945;=5%). RESULTS: The mean pH of the solutions ranged from neutral to alkaline (7.9±2.2 to 11.8±0.9). Mean ionic silver content differed depending on the concentration of the solution (4.75±0.5 to 293±15.3 ppm). In the microleakage test, significant difference was only observed for the adhesive system factor (p=0.000). CONCLUSIONS: Under the tested experimental conditions and based on the obtained results, it may be concluded that the aqueous AgNO3 solutions: have neutral/alkaline pH and service life of up to 168 h; the level of ionic silver is proportional to the concentration of the solution; even at 5% concentration, the solutions were capable of indicating loss of marginal seal in the composite restorations; the 3-step conventional adhesive system had better performance regarding microleakage in enamel on primary and permanent teeth.FAPESPCNPqCAPES - PQ

Antioxidant activity by DPPH assay of potential solutions to be applied on bleached teeth

The aim of this study was to assess, using the DPPH assay, the antioxidant activity of several substances that could be proposed to immediately revert the problems caused by bleaching procedures. The percentage of antioxidant activity (AA%) of 10% ascorbic acid solution (AAcidS), 10% ascorbic acid gel (AAcidG), 10% sodium ascorbate solution (SodAsS), 10% sodium ascorbate gel (SodAsG), 10% sodium bicarbonate (Bicarb), Neutralize® (NE), Desensibilize® (DES), catalase C-40 at 10 mg/mL (CAT), 10% alcohol solution of alpha-tocopherol (VitE), Listerine® (LIS), 0.12% chlorhexidine (CHX), Croton Lechleri (CL), 10 % aqueous solution of Uncaria Tomentosa (UT), artificial saliva (ArtS) and 0.05% sodium fluoride (NaF) was assessed in triplicate by 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) free radical assay. All substances exhibited antioxidant activity, except for CL. AAcidS, AAcidG and VitE exhibited the highest AA% (p<0.05). On the contrary, CHX, NE, LIS and NaF showed the lowest AA% (p<0.05). In conclusion, AAcidS, AAcidG, SodAsS, SodAsG and VitE presented the highest antioxidant activity among substances tested in this study. The DPPH assay provides an easy and rapid way to evaluate potential antioxidants