Short curing time bulk fill composite systems: volumetric shrinkage, degree of conversion and Vickers hardness.

This study aimed to evaluate volumetric polymerization shrinkage, degree of conversion and Vickers hardness of four bulk-fill resin composites light-activated with their dedicated light curing units (LCUs). Four groups were evaluated, according to the type of composite and curing mode: Tetric EvoCeram Bulk-fill (TEBO) and Tetric EvoFlow Bulk-fill (TEBF) were light-activated with Bluephase Style 20i (20s, in high-mode), while Tetric Powerfill (TEPO) and Tetric Powerflow (TEPF) were light-activated with Bluephase PowerCure (3s). Volumetric polymerization shrinkage test (n = 6) was performed in standardized box-shaped class-I cavities of extracted third molars (4 x 4 x 4 mm). Teeth were scanned before and after resin composite application by micro-computed tomography, and acquired data were evaluated with Amira software. Degree of conversion (n = 5) was evaluated at the top and bottom surfaces of composite cylindric samples (4 mm diameter, 4 mm thickness) using an FT-IR spectrometer (spectra between 1,500 and 1,800 cm-1, 40 scans at a resolution of 4 cm-1). Three Vickers indentations (50 g / 15 s), spaced 500 µm apart, were performed on the top and bottom composite surfaces and averaged. One-way ANOVA was used for data evaluation. TEPF showed the lowest volumetric polymerization shrinkage (p < 0.05), while the other composites were not significantly different within each other (p > 0.05). All materials presented a significant decrease in degree of conversion and Vickers hardness when compared top to bottom surfaces (p < 0.05). Bottom to top surface ratios for degree of conversion ranged from 0.8 (TEBO and TEPO) to 0.9 (TEBF and TEPF), and from 0.4 (TEPO) to 0.7 (TEBF and TEPF) for hardness. In conclusion, resinous materials present a decrease in hardness and degree of conversion from top to bottom even when a higher power is used, while the flowable material TEPF showed the lowest volumetric shrinkage values compared to the other materials.

Influence of Specimen Dimension, Water Immersion Protocol, and Surface Roughness on Water Sorption and Solubility of Resin-Based Restorative Materials.

The evaluation of water sorption and solubility is pivotal for the development of new resin-based restorative materials with the potential for clinical application. The purpose of the present study was to evaluate the influence of the specimen dimension, water immersion protocol, and surface roughness on the water sorption and solubility of three resin-based restorative materials. Disk-shaped specimens of 15 mm × 1 mm, 10 mm × 1 mm, and 6 mm × 1 mm were produced with a composite resin (Z100), a resin cement (RelyX ARC), and an adhesive system (Single Bond 2-SB2). The specimens were immersed in distilled water according to four protocols: ISO (all the specimens for each group were vertically immersed in 50 mL); IV-10 (the specimens were individually and vertically immersed in 10 mL); IH-10 (the specimens were individually and horizontally immersed in 10 mL); and IH-2 (the specimens were individually and horizontally immersed in 2 mL). The surface roughness (Sa and Sp) was evaluated using an atomic force microscope, and the degree of conversion was determined using FT-IR spectrometry. The specimen dimension and water immersion protocol had no effect on water sorption and solubility. For the three resin-based restorative materials, Sp was higher than Sa. The degree of conversion was not influenced by the specimen dimension. The variations in the specimen dimension and water immersion protocol compared to those determined by ISO 4049 did not prevent the comparison between the values of water sorption and solubility obtained for a given resin-based restorative material.

The Influence of Adhesive Strategy, Type of Dental Composite, and Polishing Time on Marginal Gap Formation in Class I-like Cavities.

Even after more than six decades of dental composite invention (1962), there is still controversial information about the time in which composite restorations should be polished in order to avoid marginal gap formation at the tooth-composite interface. The aim of the present study was to analyze the influence of adhesive strategy, the type of dental composite, and polishing time on marginal gap formation (%MG) at the tooth-composite interface. Class I-like cavities were hybridized with a universal adhesive system (Single Bond Universal) through two strategies: selective enamel etching (SEE) or self-etching mode (SEM). Cavities were filled with two types of dental composites: nanofilled (Z350) or bulk fill (Filtek One Bulk Fill-ONE), and polishing was performed immediately or delayed for 7 days (n = 5). %MG was evaluated by using a 3D laser confocal microscope. As flexural modulus (FM) and degree of conversion (DC%) are determinants of marginal integrity in dental composite restorations, these properties were evaluated for both composites. Data were analyzed by ANOVA and Tukey's HSD test (α = 0.05). Cavities hybridized following the SEE strategy presented lower %MG (p < 0.05). Z350 showed higher %MG than ONE (p < 0.05). There was no difference in %MG between the polishing times when the SEE strategy was used (p > 0.05). Z350 presented higher FM than ONE (p < 0.05). DC% was found to be not significant (p > 0.05). The results suggest that selective enamel etching (SEE) is a better strategy for producing less %MG in composite restorations with enamel margins irrespective of the time in which the restoration is polished.

Effect of oral exposure on chemical, physical, mechanical, and morphologic properties of clear orthodontic aligners

The dental industry is heavily committed to developing more esthetic solutions for orthodontic treatments. Invisalign is a system of transparent orthodontic aligners introduced as an alternative to conventional orthodontic fittings with brackets and metal wires. This study aimed to assess the chemical, physical, mechanical and morphologic changes in these polymeric aligners after exposure to the oral environment. Twenty-four Invisalign orthodontic aligners were equally divided into 2 groups: an in vivo aged group in which patients used aligners for 14 days and the reference group, unexposed to the oral environment. Different experimental techniques were used to study the chemical structure, the color changes and translucency, the density and subsequent volume of the aligners, mechanical properties, surface roughness, morphology and elemental composition. The data were subjected to several statistical analyses. Clear orthodontic aligners exhibit chemical stability but undergo a statistically significant optical change in color and translucency. There was a gradual increase in the water absorption rate and the dimensional variation of the polymer, indicating a strong correlation among these factors. The mechanical properties of the polymer showed a statistically significant decrease in its elastic modulus and hardness. There was a slight tendency toward increased surface roughness of the material, but no statistical differences were found between reference and aged groups. The surface morphology of the used aligners demonstrates microcracks, distortions and biofilm formation. Intraoral aging adversely affected the physical, mechanical, and morphologic properties of the Invisalign appliance.

Manufacturing and characterization of a 3D printed lithium disilicate ceramic via robocasting: A pilot study.

OBJECTIVE: The objective of this study was to manufacture and to evaluate the physico-mechanical properties of the Lithium disilicate (Li2O5Si2) ceramic structures fabricated using additive manufacturing (3D printing). METHODS: Li2O5Si2 samples were divided into (n = 30/group): SM (subtractively manufactured) and AR (additive/robocasting). For the AR group, Li2O5Si2 powder was combined with ammonium polyacrylate, hydroxypropyl methylcellulose, and polyelectrolyte to create a colloidal gel, which was then used for printing. A digital CAD model of a disc was designed, and the G-code transferred to a custom built DIW 3D printer. The control group samples were prepared using pre-crystallized ceramic blocks, which were cut to obtain discs with same dimensions as the AR group. Disc-shaped specimens from both groups were crystallized at 840 °C. Mechanical properties were evaluated using biaxial flexural strength test (BFS) and Vickers hardness test. Representative fractographic images of the specimens were acquired using scanning electron microscopy (SEM) to analyze the fracture origin and crack propagation. Energy-dispersive X-ray spectroscopy (EDS) and attenuated total reflection Fourier transform infrared spectroscopy (FTIR-ATR) were used for chemical analysis, and X-ray diffractometry (XRD) was performed to analyze the crystalline phases. RESULTS: AR group yielded lower values of BFS (120.02 MPa ±33.91) and hardness (4.07 GPa ±0.30), relative to the SM group, (325.09 MPa ±63.98) and (5.63 GPa ±0.14), respectively. For EDS analysis, AR and SM groups showed similar elemental composition. In FTIR-ATR analysis, higher peaks referring to the crystalline structure were found for SM group. XRD analysis indicated a decreased formation of Li2O5Si2 from Lithium metasilicate (Li2O-SiO2) in the AM group. SEM micrographs showed a more porous microstructure associated with the 3D printed samples. SIGNIFICANCE: The viability of fabricating Li2O5Si2 ceramic constructs using the Robocasting technique was successful. However, the samples prepared using subtractive manufacturing presented higher mechanical properties compared to the 3D printed constructs. The difference in properties between the manufacturing may be correlated to the decreased formation of Li2O5Si2 crystals and higher degrees of porosity.

Evolution of roughness and optical properties of resin composites submitted to whitening toothpastes-cigarette smoking cycling.

PURPOSE: To evaluate the effect of cycling whitening toothpaste with cigarette smoking (WTCS) on the evolution of roughness, color, translucency, and gloss of microfilled, microhybrid, and nanofilled resin composites. METHODS: 15 specimens of Durafill - DVS, Empress Direct - ED, and Z350 - FZ were divided into three groups according to the toothpastes:: conventional, control group, (Colgate - C) and Whitening (Colgate Luminous White - CW and Oral B 3D White - OW) and roughness, color, translucency, and gloss were evaluated before and after the specimens were submitted to WTCS for 8 weeks. Data were analyzed by two-way ANOVA, 3-way repeated measures ANOVA, and Tukey HSD post hoc test (α= 0.05). RESULTS: Only ED and FZ brushed with CW and FZ brushed with C presented an increase in roughness after WTCS. The three composites suffered a significant color alteration after WTCS. Excepting DVS brushed with CW, all the other groups presented a significant reduction in translucency after WTCS. DVS was the only resin composite that maintained its gloss stability after WTCS. Whitening toothpastes behaved similarly to conventional (control) toothpaste regarding the evolution of roughness and optical stability of the three resin composites. CLINICAL SIGNIFICANCE: Whitening toothpastes were not capable of maintaining the color stability of the three resin composites after 8 weeks of toothpastes-cigarette smoking cycling.

Dentine biomodification by sulphonamides pre-treatment: bond strength, proteolytic inhibition, and antimicrobial activity.

We evaluated the effects of dentine biomodification after pre-treatment with two sulphonamide carbonic anhydrase inhibitors (CAIs) of the N-[4-sulphamoylphenethylcarbamoyl]benzenesulphonamide type, investigating matrix metalloproteases activity, resin-dentine micro tensile bond strength, dentine surface wettability, and antimicrobial activities. Ninety-five sound-extracted human molars were selected for the study. Inhibitory effects were evaluated by gelatinase and collagenase activity tests and collagen degradation FT-IR spectroscopic analysis. Pre-treatment with the two CAIs kept the micro tensile values after 12 months of storage (32.23 ± 5.95) and cariogenic challenge (34.13 ± 2.71) similar to the initial, pre-treatment values (33.56 ± 4.34). A decreased Streptococcus mutans biofilm formation on dentine surfaces and antibacterial activity against planktonic bacteria were observed after CAI treatment. Dentine pre-treatment with sulphonamide CAIs maintained adhesion strength stability, allowed better dentine wettability, maintained matrix collagen, and showed anti-S. mutans activity.

The influence of methodology on the comparison of cytotoxicity of total-etch and self-etch adhesive systems.

OBJECTIVES: The present study aimed to compare the in vitro cytocompatibility of two etch-and-rinse (Adper Scothbond, Optibond) and two self-etch (Clearfill SE Bond and Single Bond Universal) dental adhesives through a dentin-barrier model with human pulp fibroblasts. METHODS: Human fibroblasts were placed on a plastic device containing 500µm human dentin discs treated with each adhesive or without treatment (control). Other groups were directly exposed to media conditioned with adhesive samples according to ISO 10993-5:2009. After 24h exposure, cell viability was assessed by XTT, and released inflammatory mediators were detected with a multiparametric immunoassay. RESULTS: The standardized test without barrier indicated both etch-and-rinse adhesives and self-etch as cytotoxic, promoting viabilities under 70% of the control group (p<0.05). The dentin-barrier model identified increased cell viability for self-etch adhesives, with Clearfill SE Bond identified as non-cytotoxic. The immunoassay evidenced high rates of cytokines by cells exposed to the conditioned media of Adper Scotchbond, Optibond S, and Single Bond Universal. CONCLUSIONS: The use of a dentin-barrier in vitro model detected a better biocompatibility for self-etching adhesives and, in the case of Clearfill SE Bond, with a reversion from cytotoxic to biocompatible when compared to the indirect standardized test. CLINICAL SIGNIFICANCE: The use of a dentin-barrier in vitro model was able to detect a better biocompatibility for self-etching adhesives when compared to the indirect standardized test and presents itself as a predictive in vitro method for assessing the cytotoxicity of dental restorative materials that may simulate the clinical condition more accurately.

Glass fiber posts relining: can composite opacity influence retention to root canal dentin?

This study aimed at evaluating the influence of glass-fiber post (GFP) relining with composites of different opacities on resin cement layer thickness (CLT), bond strength (BS) to root dentin, and resin cement degree of conversion (DC%). Standardized roots of 52 bovine incisors had their canals prepared and were distributed into 4 groups (n = 10 for CLT and BS; n = 3 for DC%) according to the post used: WP3 (Control)-Whitepost DC3; groups DE, EN and TR-Whitepost DC0.5 relined, respectively, with dentin, enamel, and translucent shade composites. After cementation, specimens were sectioned into six 1.0 mm-thick discs that were submitted to push-out BS test. CLT and failure pattern were evaluated using a stereomicroscope and DC% by micro-Raman spectroscopy. Data were analyzed by two-way ANOVA and Tukey test (α = 0.05). The control group showed greater CLT than all relined groups (p < 0.05), which did not differ from each other (p > 0.05). Groups relined with low opacity composites (TR; EN) showed the highest BS and DC% means (p < 0.05). BS was not different among root thirds (p > 0.05), while DC% decreased from cervical to apical third (p < 0.05). Adhesive failures between cement and dentin were predominant, except for group DE with frequent mixed failures. It could be concluded that composite opacity did not influence CLT, which was thinner when GFP were relined and that relining GFP with lower opacity composites led to higher BS and DC%.

Doenças peri-implantares e fatores de risco associados ao paciente, que levam a perda do implante - uma revisão / Peri-implant diseases and risk fatores associated with the patient, leading to loss of the implant - a review

Os tecidos moles periodontais e peri- implantares possuem muitas características em comum, tanto clínicas como histológicas. Para controle e manutenção adequados destes tecidos, é necessário melhor entendimento das diferenças e similaridades que existem entre eles. Os biofilmes se formam em todas as superfícies aderentes em sistemas fluidos, tanto em dentes como em implantes orais. Como um resultado da presença bacteriana, o hospedeiro responde desenvolvendo um mec anismo de defesa que levará à inflamaç ão dos tecidos moles. Na unidade dentogengival, os resultados são as lesões de gengivite. Na unidade implantar, essa inflamaç ão é denominada de muc osite. Se for permitido o acúmulo de placa por períodos prolongados de tempo, pesquisas experimentais demonstraram que a muc osite pode evoluir para peri-implantite, isto na dependência dos fatores e indicadores de risc o, afetando o osso peri- implantar de suporte circunferencialmente. Embora o osso de suporte seja perdido coronalmente, o implante ainda permanec erá ósseo integrado e, portanto, clinicamente estável. Essa é a razão pela qual a mobilidade representa uma característica de diagnóstico de peri-implantite pouco sensível, mas específica. Parâmetros mais sensíveis e confiáveis do desenvolvimento e da presença de infecções peri- implantares são o sangramento a sondagem, profundidade de sondagem e a interpretações radiográficas , visam detectar o mais cedo possível as lesões peri-implantares, possibilitando assim que o tratamento, que nessa revisão é descrito como sendo cumulativo, começ ando por procedimentos mais simples até os mais avançados, tendo em vista, paralisar e evitar a progressão dessas lesões, o que fatalmente resultaria no fracasso do implante.

Implantes imediatos, e seus defeitos peri-implantares (GAP) preenchidos com o uso de biomateriais sintéticos / Implants, and their peri-implant defects (GAP) filled with the use of synthetic biomaterials

A colocação de implantes osseointegráveis requer volume ósseo adequado, porém, a extração de dentes leva a diferentes padrões de remodelaç ão e reabsorção óssea. A reabsorção do rebordo alveolar tem sido considerada uma consequência inevitável da extração dentária e pode ser um problema significativo em Implantodontia. Após a extração dentária, mesmo com a instalação de implantes imediatos, o sítio desdentado do processo alveolar sofre substancial modelagem óssea, com a diminuiç ão das dimensões da crista alveolar. Após a inserção de um implante em um local de extração fresco, um defeito marginal (GAP) ocorre, frequentemente, entre o rebordo e a superfície do implante, A fim de superar esse problema e para facilitar a formaç ão de osso no defeito marginal, vários processos de enxerto têm sido utilizados, associados ou não ao uso de membranas de barreira, bem como diversos tipos de substitutos ósseos que podem ser utilizados para tal procedimento. Esse trabalho tem por objetivo revisar e discutir a literatura relacionada ao uso de biomateriais sintéticos para preenchimento desses defeitos que se formam ao redor de implantes instalados em alvéolos frescos. No entanto, ainda não existe um biomaterial ideal que possua todas as pro- priedades desejáveis. Além disso, o volume de osso residual deve ser avaliado antes da extração de dentes, de modo que os cirurgiões possam utilizar técnicas diferentes para preservar o osso alveolar.

Dietary Intake of Flaxseed Oil since Early Stages of Life Promotes Femur Quality in Male Rats.

BACKGROUND: Flaxseed oil (FO) is an alpha linolenic acid source important for growth and body development. However, there is little literature on the role of FO in critical stages of bone development and formation. OBJECTIVE: This study evaluated the influence of a diet containing FO on rat femurs. METHODS: After birth, mothers and pups were divided into control and flaxseed groups (n = 6 pups each) fed diets containing 7% soybean oil (C) or 7% FO. At 21 days, pups were weaned and separated from the mothers, and control or experimental diets were continued. At 67 days, the following were analyzed: osteocalcin and osteoprotegerin (OPG) levels, bone mineral density (BMD) and content, and bone area; the dimension, BMD, head radiodensity, and biomechanical proprieties of the right femur; and histomorphometric parameters of the left femur. RESULTS: Compared to the C group, the FO group presented (p < 0.05) a lower body mass (-3.7%) and medullary area (-10.1%) and higher osteocalcin (+36.7%), OPG (+52.5%), femur width (+3.8%), absolute mass (+2.3%), femur BMD (+3.6%), head radiodensity (+6.1%), maximum force (+7.4%), breaking strength (+17.3), and cortical thickness (+7.0). CONCLUSION: The FO diet contributed to femur quality in healthy male Wistar rats.

Fabrication and characterization of low-shrinkage dental composites containing montmorillonite nanoclay.

Dental composites are aesthetic materials widely used in Dentistry for replacing hard dental tissues lost due to caries or traumas. The aim of this study was to fabricate low-shrinkage dental composite charged with nanoclay fillers (montmorillonite Cloisite®-MMT) and evaluate their cytotoxicity and physicomechanical properties. Four dental composites were produced from the same organic matrix: Bis-GMA/TEGDMA (30 wt.%). The filler system was constituted of BaSi, SiO2, and MMT in the following concentrations (wt.%): 93.8/6.2/0, 89.1/5.9/5, 86.7/5.8/7.5, and 84.4/5.6/10 (E0: 0; E5: 5%; E7.5: 7.5%; E10: 10% of MMT nanoclays). The following properties were tested: in vitro cytotoxicity, flexural strength, elastic modulus, volumetric shrinkage, water sorption, water solubility, and hygroscopic expansion. Scanning electron microscopy was used to characterize composites' topography. Data were analyzed by one-way ANOVA and Tukey's HSD post hoc test (p < 0.05). MMT nanoclays did not affect the cytotoxicity. E5 and E7.5 groups showed a significant decrease in polymerization shrinkage while maintained the overall physicomechanical properties. The inclusion of 5 and 7.5 wt.% of MMT nanoclays allowed the fabrication of dental composites with low cytotoxicity and low polymerization shrinkage, without jeopardizing the overall behaviour of their physicomechanical properties (flexural strength, elastic modulus, water sorption, water solubility, and hygroscopic expansion). These aspects suggest that the usage of MMT nanoclays could be an effective strategy to formulate new dental composites with clinical applicability.

Characterization and Anti-Caries Effect of an Experimental Adhesive Containing Natural Antimicrobial Agents.

PURPOSE: To characterize experimental adhesives containing natural antimicrobial agents (proanthocyanidins, apigenin, tt-farnesol) in the primer and to evaluate their anti-caries effect. MATERIALS AND METHODS: Natural agents were incorporated in the primer of an experimental adhesive: 4.5% proanthocyanidins (PA), 1 mM apigenin (API), 1 mM apigenin + 5 mM tt-farnesol (API + FAR), and primer without antimicrobial agent (control). Microtensile bond strength (µTBS) to dentin and nanoleakage were measured immediately (n = 7) and after 1 year of storage (n = 7). Water sorption (WS), solubility (SO), and degree of conversion (DC%) of the adhesives were measured. The hardness loss of enamel (n = 6) and dentin (n = 6) at the restorative margin was evaluated after biofilm formation. RESULTS: DC%, nanoleakage, and immediate µTBS were similar for all groups. After 1 year, API + FAR showed higher nanoleakage and lower µTBS than the other groups, which were similar. WS and SO of API + FAR were lower than in the other groups. PA, API, and API + FAR presented less hardness loss than did the control group. At enamel, PA and API presented less hardness loss than the control and API + FAR groups at distances 50 µm and 100 µm; the hardness loss of enamel was similar for all groups 150 µm from the margin. CONCLUSION: The addition of proanthocyanidins and apigenin to the adhesives decreased the hardness loss of dentin and enamel submitted to biofilm formation, without jeopardizing the physical properties of the adhesives. The combination of apigenin + tt-farnesol decreased the hardness loss of dentin but not of enamel, and decreased the µTBS after 1 year of storage.

O consumo de farinha de taro (Colocasia esculenta) favorece a integridade óssea em ratos machos / Taro (Colocasia esculenta) flour intake enable bone integrity in male rats

Objetivo: A proposta deste estudo foi investigar a composição óssea em ratos tratados com dieta suplementada com farinha de taro (Colocasia esculenta) até eles completarem 90 dias de idade. Métodos: No momento do desmame, os ratos foram divididos em grupo controle (C, n = 11) e experimental (T, n = 12) ­ composto por animais tratados com farinha de taro até os 90 dias de idade. Ingestão alimentar, massa e comprimento corporal foram avaliados semanalmente ao longo de todo o período experimental. Dimensões ósseas, bem como a densidade mineral óssea (DMO), conteúdo mineral ósseo (CMO), área óssea total e propriedades biomecânicas foram determinadas no final de 90 dias. Resultados: Grupo T apresentou elevados valores (P<0.05) para massa e comprimento corporal; DMO, CMO e área óssea da coluna vertebral; DMO na quarta vértebra lombar; massa femoral, distância entre as epífises, largura do ponto médio da diáfise, DMO, força máxima e concentrações séricas de osteocalcina, quando comparado ao grupo controle. Conclusões: A ingestão da farinha de taro apresentou efeito positivo na saúde óssea. (AU)

Objective: This study aimed to investigate bone composition in male rats treated with diet supplemented with taro (Colocasia esculenta) flour until their 90 days. Methods: Weanling male rats were divided into control (C, n=11) and experimental group (T, n=12); the latter comprised animals treated with taro flour until their 90 days. Food intake, body mass and length were evaluated on a weekly basis throughout the experimental period. Spine bone dimension, as well as bone mineral density (BMD), mineral content (BMC), total area and biomechanical properties were determined after 90 days. Results: T group recorded higher values for (P<0.05) body mass and length; BMD, BMC and total spinal area; BMD of the fourth lumbar vertebra; femoral mass, distance between epiphysis, medial point of diaphysis width, BMD, maximum strength and osteocalcin concentrations than the control. Conclusion: Taro flour intake had positive effect on bone health. (AU)

Effects of a biomimetic analog-based experimental bonding system on caries-affected and sound dentin.

This study compared the ultrastructure, chemical composition, and proteases activity (PA) of sound (SD) and caries-affected dentin (CAD) in the dentin hybrid layer after using an experimental bonding system containing pyromellitic dianhydride glycerol methacrylate and biomimetic analogs. The bonding system used a three step and a total-etch procedure. Polyacrylic acid (5%) and sodium trimetaphosphate (5%) were added to the primer and monocalcium phosphate monohydrate (9%), beta-tricalcium phosphate (10.5%), and calcium hydroxide (0.5%) were added to the adhesive. Transmission electron microscopy (TEM) was used to evaluate the resultant structure, particularly the adhesive-dentin and the demineralized-SD interfaces. The chemical composition was evaluated through energy-dispersive X-ray spectroscopy (EDS) and selected area electron diffraction (SAED). The PA was measured with the Coomassie Blue-G250 coloring test, and the PA data were analyzed by ANOVA. EDS identified the presence of isolated calcium phosphate nanoparticles in the demineralized region; however, the SAED analysis did not show any evidences of hydroxyapatite (HA) neoformation in SD and CAD. The biomimetic analog-based adhesive system inhibited the activities of dentin proteases immediately after treatment. Additionally, the proteolytic activity on the affected dentin resembled that of the SD. In conclusion, no HA formed in the demineralized SD and CAD although there were calcium and phosphate deposits. The experimental adhesive system inhibited dentin proteases. The present study uses a new approach to investigate the hybrid layer behavior in dentin. The experimental adhesive system was synthesized and used on sound and affected-caries dentin as the substrate to reproduce real clinical conditions.

Characterization and Antibacterial Effect of an Experimental Adhesive Containing Different Concentrations of Proanthocyanidin.

PURPOSE: To evaluate the degree of conversion (DC%), water sorption (Sp), solubility (Sl), dentin bond strength (µTBS) (immediate and after 12 months of storage), and the antibacterial effect of an experimental adhesive containing different concentrations (%) of proanthocyanidin (PA): 0, 1%, 2%, 4.5%, and 6% (PA0, PA1%, PA2%, PA4.5% and PA6%, respectively). MATERIALS AND METHODS: DC% was measured by FT-IR and the Sp and Sl were determined based on the ISO 4049 specification. For µTBS, resin composite buildups were constructed incrementally and specimens (n = 8) were sectioned to obtain sticks (1 mm2). The µTBS was evaluated after 24 h and 12 months of water storage at 37°C. The failure mode was analyzed. The antibacterial effects were evaluated by analyzing the bacterial growth (S. mutans) (n = 5) and antibiofilm activity (n = 5) of the adhesives by spectrophotometry. RESULTS: The incorporation of PA did not affect the Sp, Sl, or DC%. Immediate µTBS was similar for all groups. After 12 months, PA4.5% presented significantly higher µTBS than PA0, while the other groups did not differ from PA0 and PA4.5%. Groups PA0 and PA1% underwent significant reduction in µTBS. In the experimental groups PA2%, PA4.5% and PA6%, µTBS was maintained after storage. All groups showed antibacterial activity. CONCLUSION: Incorporation of 2%, 4.5%, and 6% PA maintained the dentin µTBS after 12-month storage, without affecting the Sp, Sl, or DC% of experimental adhesives. PA4.5% presented higher µTBS values than PA0 after 12 months. The adhesive presented antibacterial effect irrespective of PA concentration.

Resin-dentin bond stability of etch-and-rinse adhesive systems with different concentrations of MMP inhibitor GM1489.

Enzymatic degradation of the hybrid layer can be accelerated by the activation of dentin metalloproteinases (MMP) during the bonding procedure. MMP inhibitors may be used to contain this process. Objective To evaluate the degree of conversion (DC%), dentin bond strength (µTBS) (immediate and after 1 year of storage in water), and nanoleakage of an experimental (EXP) and a commercial (SB) adhesive system, containing different concentrations of the MMP inhibitor GM1489: 0, 1 µM, 5 µM and 10 µM. Methodology DC% was evaluated by FT-IR spectroscopy. Dentin bond strength was evaluated by µTBS test. Half of beams were submitted to the µTBS test after 24 h and the other half, after storage for 1 year. From each tooth and storage time, 2 beams were reserved for nanoleakage testing. Data were analyzed using ANOVA and Tukey's test to compare means (α=0.05). Results All adhesive systems maintained the µTBS after 1 year of storage. Groups with higher concentrations of inhibitor (5 µM and 10 µM) showed higher µTBS values than groups without inhibitor or with 1 µM. The nanoleakage values of all groups showed no increase after 1 year of storage and values were similar for SB and EXP groups, in both storage periods. The inhibitor did not affect the DC% of the EXP groups, but the SB5 and SB10 groups showed higher DC% values than those of SB0 and SB1. Conclusions The incorporation of GM1489 in the adhesive systems had no detrimental effect on DC%. The concentrations of 5 µM GM1489 for SB and 5 µM or 10 µM for EXP provided higher µTBS than groups without GM1489, in the evaluation after 1 year of storage; whereas the concentration of inhibitor did not affect adhesive systems nanoleakage.

Topography and Microhardness Changes of Nanofilled Resin Composite Restorations Submitted to Different Finishing and Polishing Systems and Erosive Challenge

Abstract Objective: To evaluate the topography and microhardness of composite resin restorations submitted to different finishing and polishing systems before and after erosive challenge. Material and Methods: Thirty standardized cavities prepared in enamel-dentin blocks of bovine incisors were restored with Z350 composite resin, and randomly distributed into three groups (n=10) according to the finishing and polishing systems: G1 = Soflex 4 steps, G2 = Soflex Spiral 2 steps and G3 = PoGo (single step). The specimens were half protected with nail varnish and submitted to five immersions in Pepsi Twist®, for 10 minutes each, five times/day during six consecutive days. The initial and final challenge surface microhardness (SMHinitial and SMHfinal) of the composite resin was evaluated and the percentage of SMH loss (%SMHL) was calculated. After protection removal, the topographic change linear (Ra) and volumetric (Sa) roughness was evaluated in initial and final areas by using 3D non-contact optical profilometry and scanning electron microscopy (SEM). Data were analyzed by paired Student's t-test, Kruskal-Wallis test, and by ANOVA and Tukey's test. Results: There was significant intra-group %SMHL in composite resin (p<0.05). Differences among groups in %SMHL, Ra/Sa in resin composite were not observed (p>0.05). SEM images revealed structural changes between the initial and final surfaces for all groups. Conclusion: The three types of finishing and polishing systems had a similar influence on %SMHL, Ra and Sa in the nanofilled composite resin.

Resin-dentin bond stability of etch-and-rinse adhesive systems with different concentrations of MMP inhibitor GM1489

Abstract Enzymatic degradation of the hybrid layer can be accelerated by the activation of dentin metalloproteinases (MMP) during the bonding procedure. MMP inhibitors may be used to contain this process. Objective To evaluate the degree of conversion (DC%), dentin bond strength (µTBS) (immediate and after 1 year of storage in water), and nanoleakage of an experimental (EXP) and a commercial (SB) adhesive system, containing different concentrations of the MMP inhibitor GM1489: 0, 1 µM, 5 µM and 10 µM. Methodology DC% was evaluated by FT-IR spectroscopy. Dentin bond strength was evaluated by µTBS test. Half of beams were submitted to the µTBS test after 24 h and the other half, after storage for 1 year. From each tooth and storage time, 2 beams were reserved for nanoleakage testing. Data were analyzed using ANOVA and Tukey's test to compare means (α=0.05). Results All adhesive systems maintained the µTBS after 1 year of storage. Groups with higher concentrations of inhibitor (5 µM and 10 µM) showed higher µTBS values than groups without inhibitor or with 1 µM. The nanoleakage values of all groups showed no increase after 1 year of storage and values were similar for SB and EXP groups, in both storage periods. The inhibitor did not affect the DC% of the EXP groups, but the SB5 and SB10 groups showed higher DC% values than those of SB0 and SB1. Conclusions The incorporation of GM1489 in the adhesive systems had no detrimental effect on DC%. The concentrations of 5 µM GM1489 for SB and 5 µM or 10 µM for EXP provided higher μTBS than groups without GM1489, in the evaluation after 1 year of storage; whereas the concentration of inhibitor did not affect adhesive systems nanoleakage.