Avaliação em MEV do padrão de condicionamento do esmalte dental promovido por monômeros ácidos e o ácido fosfórico

ABSTRACT OBJECTIVE: Although self-etching bonding systems (SES) are indicated to prepare dental enamel for bonding, concerns have been expressed regarding their effectiveness. The aim of this study was to analyze the etching pattern (EP) of nine SES in comparison with 35% and 34% phosphoric acid etchants (FA) on intact (IN) and ground (GR) enamel surface. MATERIALS AND METHODS: Twenty-two human third molars were sectioned in mesial-distal and buccal-lingual directions, and four dental fragments were obtained from each tooth. Half of the fragments were ground using 600-grit SiC paper and the other half remained intact. The fragments were randomly assigned into 22 groups, according to the texture of enamel surface (IN and GR) and the technique to etch the enamel (34% FA, 35% FA, AdheSE primer; Brush & Bond; Clearfil Protect Bond primer; iBond; One-up Bond F; OptiBond Solo Plus primer; Tyrian SPE primer; Unifil Bond primer and Xeno III). Conditioners were applied to IN and GR enamel surfaces, according to the manufacturer's instructions. Specimens etched with phosphoric acids were washed with water, while the surfaces treated with SES were submitted to alternate rinsing with alcohol and acetone. The specimens were dried, sputter-coated and examined under a scanning electron microscope. RESULTS: For both IN and GR enamel surfaces, the EP of 34 and 35% FA was deeper and more homogeneous in comparison to EP of SES, except for Tyrian SPE. The acidic monomer action of self-etching systems was more effective on GR enamel. CONCLUSION: Most of the SES are less aggressive than phosphoric acid etchants and their etching effects were reduced on intact enamel surfaces.OBJETIVO: Apesar dos sistemas adesivos autocondicionantes (SAA) serem indicados para aplicação no esmalte dental, preocupação tem sido relatada com relação a sua efetividade. O objetivo deste estudo foi avaliar o padrão de condicionamento ácido (PCA) promovido por nove SAA e comparar ao PCA produzido pelo ácido fosfórico (35% e 34% - AF) no esmalte intacto (EI) ou abrasionado (EA). MATERIAIS E MÉTODOS: Vinte e dois terceiros molares humanos foram seccionados nos sentidos mésio-distal e vestíbulo-lingual, e quatro fragmentos dentais foram obtidos a partir de cada dente. Metade dos fragmentos tiveram o esmalte abrasionado com lixas de SiC (600) e a outra metade permaneceu intacta. Os fragmentos foram divididos em 22 grupos, de acordo com a textura da superfície do esmalte (EI e EA) e a técnica de condicionar o esmalte (AF 34 %, AF 35%, AdheSE primer; Brush & Bond; Clearfil Protect Bond primer; iBond; One-up Bond F; OptiBond Solo Plus primer; Tyrian SPE primer; Unifil Bond primer e Xeno III). Os agentes condicionadores foram aplicados nos EI e EA, de acordo com as instruções dos fabricantes. Espécimes tratados com AF foram lavados com água, enquanto os dentes tratados com SAA foram tratados com banhos alternados de álcool e acetona. Os espécimes foram secos, metalizados e observados em microscopia eletrônica de varredura. RESULTADOS: Em ambas as superfícies (EI e EA), o PCA dos AF (34 e 35%) foi mais profundo e homogêneo, quando comparados ao PCA produzido pelos SAA, exceto para o adesivo Tyrian SPE. A ação dos monômeros ácidos dos SAA foi mais efetiva no EA. CONCLUSÃO: A maioria dos SAA é menos agressiva que o ácido fosfórico e seus efeitos condicionadores são reduzidos em superfícies de EI

Effectiveness of plant-derived proanthocyanidins on demineralization on enamel and dentin under artificial cariogenic challenge

Dental caries is considered a disease of high prevalence and a constant problem in public health. Proanthocyanidins (PAs) are substances that have been the target of recent studies aiming to control or treat caries. Objective The aim of this in vitro study was to evaluate the efficacy of a treatment with grape seed extract, under cariogenic challenge, to minimize or even prevent the onset of caries in the enamel and dentin. Material and Methods Blocks of enamel and dentin (6.0x6.0 mm) were obtained from bovine central incisors, polished, and selected by analysis of surface microhardness (SH). The blocks were randomly divided into 3 groups (n=15), according to the following treatments: GC (control), GSE (grape seed extract), GF (fluoride – 1,000 ppm). The blocks were subjected to 6 daily pH cycles for 8 days. Within the daily cycling, the specimens were stored in buffered solution. The blocks were then analyzed for perpendicular and surface hardness and polarized light microscopy. Results The means were subjected to statistical analysis using the ANOVA and Fisher's PLSD tests (

Effect of different conditions and modes of application on bond strength of adhesives to dentine

Objetivo: Evaluar la resistencia de la unión microtensil en diferentes condiciones de dentina (grabado-E, sin grabado-N, seco-D y húmedo-W) de un adhesivo multimodo (Scotchbond Universal-SU, 3M/ESPE) y un adhesivo de grabado total (Ambar-AB, FGM) utilizando un dispositivo sónico (Smart Sonic Device-SD, FGM). Material y Métodos: En este estudio in vitro, noventa y seis molares humanos extraídos sanos se dividieron en 12 grupos (n=8) de acuerdo con diferentes condiciones de dentina y sistemas adhesivos. Se eliminó el esmalte y se pulieron las superficies centrales de la dentina. Cada sistema adhesivo se aplicó de acuerdo con las diferentes condiciones de dentina, y los bloques de resina compuesta se acumularon de forma incremental y se almacenaron durante 24h. Las muestras se seccionaron en barras y los datos de resistencia de la unión se analizaron con la prueba de Kruskal-Wallis y la prueba de U de Mann-Whitney. Resultado: No se observaron efectos de la aplicación sónica. En general, AB mostró resultados más bajos en comparación con el SU. Las condiciones E y N no afectaron estadísticamente la fuerza de unión de los grupos SU. La dentina seca presentó valores de fuerza de adhesión estadísticamente superiores en comparación con la dentina húmeda para el grupo SU/E/SD. Conclusión: La adhesión de la dentina seca con un sistema adhesivo multimodo puede ser superior a la dentina húmeda con aplicación sónica. Los modos de aplicación no tuvieron influencia en la resistencia de la unión de los adhesivos estudiados

Avaliação in vitro da adesão de restaurações de resina composta em dentes submetidos ao clareamento dental interno

Orientador: Luiz Andre Freire PimentaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: O clareamento dental interno vem sendo empregado com sucesso no tratamento de dentes não vitais escurecidos. Após o tratamento clareador, muitas restaurações estéticas necessitam ser trocadas. Estudos têm revelado alterações na adesão da resina composta em dentes submetidos ao clareamento, mostrando a importância da avaliação interface dente-resina. Dessa forma, este estudo teve como objetivos: (1) discutir, por meio de uma revisão de literatura, a aplicação clínica do tratamento clareador interno; (2) analisar, através do grau de microinfiltração, a interface adesiva de restaurações classe V de resina composta em dentes submetidos ao clareamento interno; (3) avaliar a resistência de união de três sistemas adesivos em esmalte e dentina após o clareamento interno; (4) avaliar a resistência adesiva da resina composta aos dentes clareados, após diferentes tempos de espera pós clareamento (1, 7, 14 e 21 dias). Nos três estudos laboratoriais, os dentes bovinos foram submetidos ao clareamento interno, utilizando dois tipos de agentes clareadores: pasta de perborato de sódio mais água e peróxido de carbamida a 37% pela técnica walking bleach. Os resultados mostraram que o tratamento clareador interferiu na adesão da resina composta ao dente clareado, dependendo do substrato (esmalte ou dentina) e do teste aplicado (microinfiltração ou cisalhamento). O tipo de sistema adesivo utilizado não interferiu nos valores de adesão em dentes clareados. Após um determinado tempo de espera pós clareamento, a resistência de união é restabelecida. Um período de espera pós clareamento de 14 dias é satisfatório para se realizar os procedimentos restauradores tanto em esmalte quanto em dentinaAbstract: Nonvital bleaching has been successfully used to treat discolored nonvital teeth. After the bleaching treatment, many esthetic restorations need be replaced. Studies have shown alterations in bonding composite resin to teeth submitted to bleaching treatment, highlighting the importance to evaluate tooth-resin interface. Thus, the objectives in this study were: (1) to discuss, following the literature review, the clinical application of nonvital tooth bleaching; (2) to analyze, according to the degree of leakage, the adhesive interface of class V composite resin restorations to teeth submitted to nonvital bleaching; (3) to evaluate the shear bond strength of three adhesive systems on enamel and dentin after nonvital bleaching; (4) to evaluate the shear bond of composite resin to bleached teeth in different time delays after bleaching (1, 7, 14, and 21 days). For the three lab studies, the bovine teeth were submitted to nonvital bleaching, using two bleaching agents: paste of sodium perborate plus water and 37% carbamide peroxide using the 'walking bleach' technique. The results showed that the bleaching treatment interfered in adhesion of composite resin to bleached . teeth, depending on the substrate (enamel or dentin) and the test used (microleakage or shear bond strength). The type of adhesive system used did not interfere in shear bond strength values on bleached teeth. After a certain time delay post bleaching, shear bond is recovered. A 14 day period of time delay after bleaching is satisfactory to perform the restorative procedures for both enamel and dentinMestradoDentísticaMestre em Clínica Odontológic

Performance of a New One-step Multi-mode Adhesive on Etched vs Non-etched Enamel on Bond Strength and Interfacial Morphology

Purpose: To compare microtensile bond strength (mu TBS) and interfacial morphology of a new one-step multi-mode adhesive with a two-step self-etching adhesive and two etch-and-rinse adhesives systems on enamel.Materials and Methods: Thirty human third molars were sectioned to obtain two enamel fragments. For mu TBS, 48 enamel surfaces were ground using 600-grit SIC paper and randomly assigned into 6 groups (n = 8): non-etched Scotchbond Universal [SBU]; etched SBU [SBU-et]; non-etched Clearfil SE Bond [CSE]; etched CSE [CSE-et]; Scotchbond Multi-Purpose [SBMP]; Excite [EX]. The etched specimens were conditioned with 37% phosphoric acid for 30 s, each adhesive system was applied according to manufacturers' instructions, and composite resin blocks (Filtek Supreme Plus, 3M ESPE) were incrementally built up. Specimens were sectioned into beams with a cross-sectional area of 0.8-mm(2) and tested under tension (1 mm/min). The data were analyzed with one-way ANOVA and Fisher's PLSD (alpha = 0.05). For interface analysis, two samples from each group were embedded in epoxy resin, polished, and then observed using scanning electron microscopy (SEM).Results: The mu TBS values (in MPa) and the standard deviations were: SBU = 27.4 (8.5); SBU-et = 33.6 (9.3); CSE = 28.5 (8.3); CSE-et = 34.2 (9.0); SBMP = 30.4 (11.0); EX = 23.3 (8.2). CSE-et and SBU-et presented the highest bond strength values, followed by SBMP, CSE, and SBU which did not differ significantly from each other. EX showed the statistically significantly lowest bond strength values. SEM images of interfaces from etched samples showed long adhesive-resin tags penetrating into demineralized enamel.Conclusions: Preliminary etching of enamel significantly increased bond strength for the new one-step multi-mode adhesive SBU and two-step self-etching adhesive CSE.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Characterization of biomodified dentin matrices for potential preventive and reparative therapies

Biomodification of existing hard tissue structures, specifically tooth dentin, is an innovative approach proposed to improve the biomechanical and biochemical properties of tissue for potential preventive or reparative therapies. The objectives of the study were to systematically characterize dentin matrices biomodified by proanthocyanidin-rich grape seed extract (GSE) and glutaraldehyde (GD). Changes to the biochemistry and biomechanical properties were assessed by several assays to investigate the degree of interaction, biodegradation rates, proteoglycan interaction, and effect of collagen fibril orientation and environmental conditions on the tensile properties. The highest degree of agent–dentin interaction was observed with GSE, which exhibited the highest denaturation temperature, regardless of the agent concentration. Biodegradation rates decreased remarkably following biomodification of dentin matrices after 24 h collagenase digestion. A significant decrease in the proteoglycan content of GSE-treated samples was observed using a micro-assay for glycosaminoglycans and histological electron microscopy, while no changes were observed for GD and the control. The tensile strength properties of GD-biomodified dentin matrices were affected by dentin tubule orientation, most likely due to the orientation of the collagen fibrils. Higher and/or increased stability of the tensile properties of GD- and GSE-treated samples were observed following exposure to collagenase and 8 months water storage. Biomodification of dentin matrices using chemical agents not only affects the collagen biochemistry, but also involves interaction with proteoglycans. Tissue biomodifiers interact differently with dentin matrices and may provide the tissue with enhanced preventive and restorative/reparative abilities