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

Abstract 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.

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.

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)

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.

Can whitening toothpastes maintain the optical stability of enamel over time?

Abstract Besides the effects on the health of individuals, cigarette smoking can also interfere with the appearance of their teeth. Objective: To evaluate the effect of cigarette smoking-toothbrushing-cycling (CSTC) with whitening toothpastes on the roughness and optical behavior of bovine enamel for eight weeks. Material and Methods: Thirty bovine dentin/enamel discs, 8.0 mm in diameter and 2.0 mm thick, were randomly divided into three groups according to the toothpastes: whitening (Colgate Luminous White - CW and Oral B 3D White - OW), and a non-whitening (Colgate - C). The roughness, color (CIE L*a*b* system), translucency and gloss were measured before and after the specimens were submitted to CSTC. The topography of the specimens was analyzed by scanning electron microscopy. During the first week, the specimens were daily subjected to the consumption of 20 cigarettes and brushed (40 strokes/100 g) with the toothpastes' slurries. Thereafter, the CSTC was weekly applied in an accumulated model (140 cigarettes/280 strokes) for seven weeks. The data were submitted to two-way ANOVA, Tukey's HSD test, and paired-t test (α=0.05). Results: The three toothpastes produced significant changes in roughness, color, translucency and gloss (p<0.05). After eight weeks, the roughness and the gloss produced by the three toothpastes were similar (p>0.05), while OW produced the lowest color change and the translucency of C was lower than that of CW (p<0.05). The three toothpastes produced a significant decrease in L* values and a significant increase in a* values after eight weeks (p<0.05). No significant difference in the b* coordinate was found for OW (p=0.13) There were topographic changes in the enamel surfaces. Conclusions: The whitening toothpastes increased the roughness, changed the topography and were not able to maintain the optical stability of enamel exposed over eight weeks.

Model resin composites incorporating ZnO-NP: activity against S. mutans and physicochemical properties characterization

Abstract Although resin composites are widely used in the clinical practice, the development of recurrent caries at composite-tooth interface still remains as one of the principal shortcomings to be overcome in this field. Objectives To evaluate the activity against S. mutans biofilm of model resin composites incorporating different concentrations of ZnO-nanoparticles (ZnO-NP) and characterize their physicochemical properties. Materials and Methods Different concentrations of ZnO-NP (wt.%): E1=0, E2=0.5, E3=1, E4=2, E5=5 and E6=10 were incorporated into a model resin composite consisting of Bis-GMA-TEGDMA and barium borosilicate particles. The activity against S. mutans biofilm was evaluated by metabolic activity and lactic acid production. The following physicochemical properties were characterized: degree of conversion (DC%), flexural strength (FS), elastic modulus (EM), hardness (KHN), water sorption (Wsp), water solubility (Wsl) and translucency (TP). Results E3, E4, E5 and E6 decreased the biofilm metabolic activity and E5 and E6 decreased the lactic acid production (p<0.05). E6 presented the lowest DC% (p<0.05). No significant difference in FS and EM was found for all resin composites (p>0.05). E5 and E6 presented the lowest values of KHN (p<0.05). E6 presented a higher Wsp than E1 (p<0.05) and the highest Wsl (p<0.05). The translucency significantly decreased as the ZnO- NP concentration increased (p<0.05). Conclusions The incorporation of 2 - 5 wt.% of ZnO-NP could endow antibacterial activity to resin composites, without jeopardizing their physicochemical properties.

Characterization of Conventional and High-Translucency Y-TZP Dental Ceramics Submitted to Air Abrasion

Abstract This study evaluated the effect of air-abrasion on t®m phase transformation, roughness, topography and the elemental composition of three Y-TZP (Yttria-stabilized tetragonal zirconia polycrystal) dental ceramics: two conventional (Lava Frame and IPS ZirCad) and one with high-translucency (Lava Plus). Plates obtained from sintered blocks of each ceramic were divided into four groups: AS (as-sintered); 30 (air-abrasion with 30 mm Si-coated Al2O3 particles); 50 (air-abrasion with 50 mm Al2O3 particles) and 150 (air-abrasion with 150 mm Al2O3 particles). After the treatments, the plates were submitted to X-ray diffractometry; 3-D profilometry and SEM/EDS. The AS surfaces were composed of Zr and t phases. All treatments produced t®m phase transformation in the ceramics. The diameter of air-abrasion particles influenced the roughness (150>50>30>AS) and the topography. SEM analysis showed that the three treatments produced groove-shaped microretentions on the ceramic surfaces, which increased with the diameter of air-abrasion particles. EDS showed a decrease in Zr content along with the emergence of O and Al elements after air-abrasion. Presence of Si was also detected on the plates air-abraded with 30 mm Si-coated Al2O3 particles. It was concluded that irrespective of the type and diameter of the particles, air-abrasion produced t®m phase transformation, increased the roughness and changed the elemental composition of the three Y-TZP dental ceramics. Lava Plus also behaved similarly to the conventional Y-TZP ceramics, indicating that this high translucency ceramic could be more suitable to build monolithic ceramic restorations in the aesthetic restorative dentistry field.

Resumo Este estudo avaliou o efeito da abrasão a ar na transformação de fase t®m, na rugosidade, topografia e composição elementar de três cerâmicas Y-TZP (Zircônia tetragonal policristalina estabilizada por ítrio): duas convencionais (Lava Frame e ZirCad) e uma de alta translucidez (Lava Plus). Placas obtidas de blocos sinterizados de cada cerâmica foram divididos em quatro grupos: AS (pré-sinterizado); 30 (jateamento com partículas de Al2O3 de 30 mm cobertas com Si); 50 (jateamento com partículas de Al2O3 de 50 mm) e 150 (jateamento com partículas de Al2O3 de 150 mm). Após os tratamentos, as placas foram submetidas à difratometria de Rx, perfilometria 3-D e microscopia eletrônica de varredura com espectroscopia de energia dispersiva de Rx (SEM/EDS). As superfícies pré-sinterizadas apresentaram predominantemente Zr e fase tetragonal. Todos os tratamentos superficiais produziram transformação t®m nas cerâmicas avaliadas. A topografia e a rugosidade foram influenciadas pelo diâmetro das partículas abrasivas (150>50>30>AS). A análise através de SEM mostrou que os três tratamentos produziram fendas retentivas nas superfícies das cerâmicas, por influência do tamanho das partículas. A análise através de EDS mostrou uma diminuição da concentração de Zr, paralela ao surgimento de O e Al, após o jateamento. No grupo tratado com partículas de Al2O3 de 30 mm cobertas com Si foi também observado um aumento de Si após o jateamento. Concluiu-se que, independente do tipo e do diâmetro das partículas, o jateamento produziu transformação t®m, aumentou a rugosidade e alterou a composição elementar das cerâmicas avaliadas. A Lava Plus apresentou comportamento semelhante às cerâmicas convencionais, indicando que esta cerâmica de alta translucidez pode ser mais adequada à confecção de restaurações monolíticas no campo da odontologia estética restauradora.

Characterization and coating stability evaluation of nickel-titanium orthodontic esthetic wires: an in vivo study

Abstract The objective of this study was to compare coating dimensions and surface characteristics of two different esthetic covered nickel-titanium orthodontic rectangular archwires, as-received from the manufacturer and after oral exposure. The study was designed for comparative purposes. Both archwires, as-received from the manufacturer, were observed using a stereomicroscope to measure coating thickness and inner metallic dimensions. The wires were also exposed to oral environment in 11 orthodontic active patients for 21 days. After removing the samples, stereomicroscopy images were captured, coating loss was measured and its percentage was calculated. Three segments of each wire (one as-received and two after oral exposure) were observed using scanning electron microscopy for a qualitative analysis of the labial surface of the wires. The Lilliefors test and independent t-test were applied to verify normality of data and statistical differences between wires, respectively. The significance level adopted was 0.05. The results showed that the differences between the wires while comparing inner height and thickness were statistically significant (p < 0.0001). In average, the most recently launched wire presented a coating thickness twice that of the control wire, which was also a statistically significant difference. The coating loss percentage was also statistically different (p = 0.0346) when the latest launched wire (13.27%) was compared to the control (29.63%). In conclusion, the coating of the most recent wire was thicker and more uniform, whereas the control had a thinner coating on the edges. After oral exposure, both tested wires presented coating loss, but the most recently launched wire exhibited better results.

Effect of Non-Thermal Argon Plasma on Bond Strength of a Self-Etch Adhesive System to NaOCl-Treated Dentin

Abstract Studies have been showing a decrease of bond strength in dentin treated with sodium hypochlorite (NaOCl). The aim of this study was to evaluate the effect of non-thermal argon plasma on the bond strength of a self-etch adhesive system to dentin exposed to NaOCl. Thirty-two flat dentin surfaces of bovine incisors were immersed in 2.5% NaOCl for 30 min to simulate the irrigation step during endodontic treatment. The specimens were divided into four groups (n=8), according to the surface treatment: Control (without plasma treatment), AR15 (argon plasma for 15 s), AR30 (argon plasma for 30 s) and AR45 (argon plasma for 45 s). For microtensile bond strength test, 5 specimens were used per group. In each group, the specimens were hybridized with a self-etch adhesive system (Clearfil SE Bond) and resin composite buildups were constructed. After 48 h of water storage, specimens were sectioned into sticks (5 per tooth, 25 per group) and subjected to microtensile bond strength test (μTBS) until failure, evaluating failure mode. Three specimens per group were analyzed under FTIR spectroscopy to verify the chemical modifications produced in dentin. μTBS data were analyzed using ANOVA and Tamhane tests (p<0.05). AR30 showed the highest μTBS (20.86±9.0). AR15 (13.81±6.4) and AR45 (11.51±6.8) were statistically similar to control (13.67±8.1). FTIR spectroscopy showed that argon plasma treatment produced chemical modifications in dentin. In conclusion, non-thermal argon plasma treatment for 30 s produced chemical changes in dentin and improved the μTBs of Clearfil SE Bond to NaOCl-treated dentin.

Resumo Estudos vêm demonstrando uma diminuição na resistência adesiva em dentina tratada com hipoclorito de sódio (NaOCl). O objetivo desse estudo foi avaliar o efeito do plasma de argônio não-térmico na resistência de união de um sistema adesivo autocondicionante à dentina exposta ao NaOCl. Trinta e duas superfícies dentinárias lisas de incisivos bovinos foram imersas em NaOCl a 2,5% por 30 min para simular o passo de irrigação durante o tratamento endodôntico. Os espécimes foram divididos em 4 grupos (n=8), de acordo com o tratamento de superfície: Controle (sem tratamento de plasma), AR15 (plasma de argônio por 15 s), AR30 (plasma de argônio por 30 s) e AR45 (plasma de argônio por 45 s). Para teste de resistência de união por microtração, cinco espécimes foram utilizadas por grupo. Em cada grupo, os espécimes foram hibridizados com um sistema adesivo autocondicionante (Clearfil SE Bond, Kuraray) e blocos de resina composta foram construídos. Após 48 h de armazenamento em água, os espécimes foram seccionados em palitos (5 por dente - 25 por grupo) e submetidos ao teste de resistência de união por microtração (μTBS) até a fratura, avaliando o padrão de fratura. Três amostras por grupo foram analisadas sob espectroscopia por FTIR para verificar as modificações químicas produzidas pelos tratamentos na dentina. Os dados de microtração foram avaliados estatisticamente utilizando os testes de ANOVA e Tamhane (p<0,05). AR30 apresentou o maior μTBS (20,86±9,0). AR15 (13,81±6,4) e AR45 (11,51±6,8) foram estatisticamente semelhantes ao controle (13,67±8,1). A espectroscopia por FTIR mostrou que o tratamento de plasma produziu modificações químicas na dentina. Como conclusão, o tratamento de plasma de argônio não-térmico por 30 s produziu alterações químicas na dentina e melhorou o μTBS do Clearfil SE Bond à dentina tratada com NaOCl.

Análise comparativa da resistência de união de um cimento convencional e um cimento autoadesivo após diferentes tratamentos na superfície de pinos de fibra de vidro / Bond strength comparative analysis of a conventional cement with a self-adhesive cement after different treatments on the fiberglass post surface

Introdução: Os pinos de fibra de vidro são uma alternativa aos núcleos metálicos e apresentam vantagens, tais como: estética, módulo de elasticidade semelhante à dentina e cimentação imediata após o término do tratamento endodôntico. Ainda, apresentam a capacidade de aderir ao cimento resinoso e este, à dentina, por meio de técnicas adesivas. Objetivo: Comparar a adesão de um cimento resinoso convencional e um autoadesivo a pinos de fibra de vidro, e os efeitos de diferentes tratamentos de superfície na resistência adesiva dos pinos. Material e método: Trinta pinos foram divididos em três grupos: Controle: sem tratamento na superfície; Jateamento: jateamento com óxido de alumínio por 30 segundos, e Peróxido: imersão em peróxido de hidrogênio 24% por um minuto. Em seguida, corpos de prova foram obtidos a partir de cilindros de cimento resinoso contendo o pino de fibra posicionado no centro de seu longo eixo. Em cada grupo, cinco pinos foram associados ao adesivo Âmbar + cimento convencional AllCem Core e os outros cinco pinos, ao cimento autoadesivo RelyX U200. O conjunto pino/cimento foi segmentado e avaliado em relação à resistência de união (RU) por push-out. Os dados foram analisados estatisticamente pelos testes de ANOVA e Tukey (p< 0,05). Resultado: Os cimentos avaliados exibiram valores de RU semelhantes. Em relação aos tratamentos de superfície, os maiores valores de RU foram encontrados no grupo Jateamento. Conclusão: O cimento convencional, AllCem Core, e o cimento autoadesivo, RelyX U200, mostraram valores de resistência de união semelhantes. Ainda, o jateamento com óxido de alumínio favoreceu a adesão dos pinos aos cimentos.

Introduction: The fiberglass posts are an alternative to the metal cast, presenting some advantages, such as aesthetics, tensile modulus similar to dentin and can be placed in a single session, immediately after the endodontic treatment. It also has the ability to adhere to the resin cement and the last to dentin by means of bonding techniques. Objective: To compare the adhesion of a conventional resin cement with a self-adhesive to fiberglass posts, and the effects of different surface treatments on adhesion of posts. Material and method: Thirty fiber posts were divided into 3 groups: control: untreated surface; Blasting: blasting with aluminum oxide for 30 seconds and peroxide: immersion in 24% hydrogen peroxide for 1 minute. Then, the samples were obtained from resin cement cylinders containing the fiber post positioned in the center of its long axis. In each group 5 posts were associated with the adhesive Ambar+conventional cement Allcem Core and the other 5 posts with the self-adhesive cement RelyX U200. The post/cement sample was segment in discs and evaluated for bond strength (BS) by push-out test. Data were analyzed statistically by ANOVA and Tukey tests (p< 0.05). Result: The cements evaluated exhibited similar BS values. Regarding surface treatments, the highest BS values were found in blasting group. Conclusion: Conventional cement, Allcem Core, and self-adhesive, RelyX U200, showed similar bond strength values. Also, blasting with aluminum oxide favored the adhesion of posts to cements.

Influence of Organic Acids from the Oral Biofilm on the Bond Strength of Self-Etch Adhesives to Dentin

Abstract: The aim of this study was to evaluate the microtensile bond strength of self-etch adhesive systems to dentin after storage in acids from oral biofilm. Three adhesive systems were used in the study: a two-step self-etch adhesive for use with a silorane-based resin composite (Filtek P90 adhesive system - P90), a two-step self-etch adhesive (Clearfil SE Bond - CSE) and a one-step self-etch adhesive (Adper Easy One - AEO). The bond strength of these products was evaluated by bonding resin composite (Filtek Z350 for CSE and AEO; and Filtek P90 for P90) to 90 bovine dentin tooth fragments, according to the manufacturer's instructions. After 24 h of water storage at 37 °C, the specimens were sectioned into beams (1 mm2) divided and stored in distilled water, lactic acid and propionic acid, for 7 and 30 days. After storage, the specimens were tested for microtensile bond strength. Data were analyzed by three-way ANOVA and Tukey´s test (α=0.05). CSE presented the highest microtensile bond strength after storage in distilled water for 7 and 30 days. The microtensile bond strength of all adhesive systems was lower after storage in lactic acid and propionic acid than after water storage. Significant difference was not found between storage times.

Resumo: O objetivo deste trabalho foi avaliar a resistência de união de sistemas adesivos autocondicionantes após estocagem em ácidos presentes no biofilme oral. Foram utilizados três sistemas adesivos: um autocondicionante de dois frascos indicado para uso com a resina composta à base de silorano (P90 System Adhesive- P90), um autocondicionante de dois frascos (Clearfil SE Bond - CSE) e um autocondicionante de frasco único (AdperEasyOne - AEO). Para avaliação da resistência de união à dentina, 90 fragmentos de dentes bovinos foram restaurados de acordo com as recomendações dos fabricantes. Após a confecção de blocos de resina composta (Filtek Z350 para os sistemas adesivos AEO e CSE; Filtek P90 para o sistema adesivo P90) e estocagem em água destilada por 24 h a 37 °C, os fragmentos foram seccionados para a obtenção de palitos (1 mm2) que foram divididos e estocados nos três diferentes meios de imersão (água destilada, ácido lático e ácido propiônico) por períodos de 7 dias e 30 dias (n=5). Em seguida, foi realizado o ensaio de resistência à microtração. Os dados foram submetidos à Análise de Variância (3 fatores) e ao Teste de Tukey (α=0,05). O sistema adesivo CSE apresentou maior resistência de união após imersão em água por 7 ou 30 dias. A resistência de união de todos os sistemas adesivos foi menor após imersão em ácido lático e propiônico do que após imersão em água. Não foi observada diferença significativa entre os tempos de imersão.

Marginal integrity of restorations produced with a model composite based on polyhedral oligomeric silsesquioxane (POSS)

Marginal integrity is one of the most crucial aspects involved in the clinical longevity of resin composite restorations.Objective To analyze the marginal integrity of restorations produced with a model composite based on polyhedral oligomeric silsesquioxane (POSS).Material and Methods A base composite (B) was produced with an organic matrix with UDMA/TEGDMA and 70 wt.% of barium borosilicate glass particles. To produce the model composite, 25 wt.% of UDMA were replaced by POSS (P25). The composites P90 and TPH3 (TP3) were used as positive and negative controls, respectively. Marginal integrity (%MI) was analyzed in bonded class I cavities. The volumetric polymerization shrinkage (%VS) and the polymerization shrinkage stress (Pss - MPa) were also evaluated.Results The values for %MI were as follows: P90 (100%) = TP3 (98.3%) = B (96.9%) > P25 (93.2%), (p<0.05). The %VS ranged from 1.4% (P90) to 4.9% (P25), while Pss ranged from 2.3 MPa (P90) to 3.9 MPa (B). For both properties, the composite P25 presented the worst results (4.9% and 3.6 MPa). Linear regression analysis showed a strong positive correlation between %VS and Pss (r=0.97), whereas the correlation between Pss and %MI was found to be moderate (r=0.76).Conclusions The addition of 25 wt.% of POSS in methacrylate organic matrix did not improve the marginal integrity of class I restorations. Filtek P90 showed lower polymerization shrinkage and shrinkage stress when compared to the experimental and commercial methacrylate composite.

Scanning electron microscopy analysis of microstructure of the adhesive interface between resin and dentin treated with papain gel.

Aim: The aim of this in vitro study was to observe and compare the microstructure of the adhesive interface between resin and dentin treated with Papacarie® using scanning electron microscopy (SEM). Materials and Methods: Totally, 10 human dentin slabs were randomly distributed into two groups. The control group (n = 5) was subjected to etching with 37% phosphoric acid for 20 s and washed for 30 s, dried with absorbent paper, and the bonding agent was applied along with low viscosity resin. In turn, the experimental group (n = 5) was subjected to the same procedure, but Papacarie® (Fórmula and Ação, São Paulo, Brazil) was added for 30 s prior to etching. Adper™ Single Bond 2 (3M ESPE, São Paulo, Brazil) adhesive was applied to both groups following manufacturer instructions. The specimens were prepared for observation under SEM with ×1.000, ×2.000, ×2.200 and ×5.000 magnification. The micrographs were evaluated with respect to the formation of the hybrid layer, thickness, shape and length of the tags and microtags. Results: In the experimental group there was the formation of more fine hybrid layer and tags with average of similar length to the control group; microtags in less number and without formation of lateral branches. The resin tags presented conical, smooth and uniform characteristics. Conclusions: When Papacarie® was used prior to the application of a bonding agent it could interfere with the formation of the hybrid layer without changing the length of the tag. Moreover, the morphology in the experimental group was found to be more uniform and regular.

Degradation of Resin Composites in a Simulated Deep Cavity

The aim of this study was to analyze the sorption and solubility of a nanofilled (Filtek Z350) and a midifilled (Filtek P60) resin composite in oral environment-like substances, in a simulated deep cavity. A cylindrical cavity prepared in a bovine incisor root was incrementally filled with resin composites. The obtained resin composite cylinders were cut perpendicularly to the axis to obtain 1-mm-thick discs that were divided into fifteen groups (n=5) according to depth (1, 2, 3, 4 and 5 mm) and immersion media (distilled water - DW, artificial saliva - AS and lactic acid - LA). The sorption and solubility were calculated based on ISO 4049:2000. Additionally, the degree of conversion (DC%) was calculated by FT-IR spectroscopy. Data were analyzed using multifactor analysis of variance (MANOVA) followed by Tukey's HSD post-hoc test and linear regression analysis (a=0.05). The DC% was higher for the midifilled resin composite and was negatively influenced by cavity depth (p<0.05). The nanofilled resin composite presented higher sorption and solubility than did the midifilled (p<0.05). The immersion media influenced the sorption and the solubility as follows: LA>AS>DW, (p<0.05). Both phenomena were influenced by cavity depth, with the sorption and solubility increasing from 1 to 5 mm (p<0.05). The degradation of resin composite restorations may be greater in the deepest regions of class II restorations when the composite is exposed to organic acids present in the oral biofilm (lactic acid).

O objetivo deste estudo foi analisar a absorção e a solubilidade de uma resina composta nanopartículada (Filtek Z350) e de uma híbrida (Filtek P60) em substâncias simuladoras do ambiente oral em um modelo de cavidade profunda. Uma cavidade cilíndrica, construída em uma raiz de um incisivo bovino, foi preenchida incrementalmente com as resinas compostas. Os cilindros obtidos foram seccionados perpendicularmente ao eixo para obtenção de discos com 1 mm de espessura, que foram divididos em 15 grupos (n=5) de acordo com a profundidade (1, 2, 3, 4 e 5 mm) e o meio de imersão (água destilada - AD, saliva artificial - SA e ácido lático - AL). A absorção e a solubilidade foram calculadas com base na norma ISO 4049:2000(E). Adicionalmente, o grau de conversão (GC%) foi calculado através de espectroscopia FT-IR. Os dados obtidos foram analisados usando análise de variância multifatorial, teste de Tukey HSD e análise de regressão linear (a=0,05). A resina composta híbrida apresentou o maior grau de conversão, sendo este influenciado pela profundidade da cavidade (p<0,05). A resina composta nanopartículada apresentou maiores valores de absorção e solubilidade (p<0,05). O meio de imersão influenciou a absorção e a solubilidade: AL>SA>AD (p<0,05). Ambos os fenômenos foram influenciados pela profundidade da cavidade, com os valores aumentando de 1 para 5 mm (p<0,05). A degradação de restaurações de resinas compostas pode ser maior em regiões profundas de restaurações classe II e quando o material é exposto à ácidos orgânicos produzidos pelo biofilme oral (ácido lático).

Long-term degradation of resin-based cements in substances present in the oral environment: influence of activation mode

Indirect restorations in contact with free gingival margins or principally within the gingival sulcus, where the presence of organic acids produced by oral biofilm is higher, may present faster degradation of the resin-based cement pellicle. Objectives To investigate the degradation of four resin-based cements: Rely X ARC (R), Variolink II (V), Enforce (E) and All Cem (A), after immersion in distilled water (DW), lactic acid (LA) and artificial saliva (AS) and to analyze the influence of the activation mode on this response. Material and Methods Two activation modes were evaluated: chemical (Ch) and dual (D). In the dual activation, a two-millimeter thick ceramic disk (IPS Empress System) was interposed between the specimen and light-curing unit tip. Specimens were desiccated, immersed in distilled water, artificial saliva and lactic acid 0.1 M at 37°C for 180 days, weighed daily for the first 7 days, and after 14, 21, 28, 90 and 180 days and were desiccated again. Sorption and solubility (µg/mm 3 ) were calculated based on ISO 4049. The data were submitted to multifactor analysis of variance (MANOVA) and Tukey's HSD test for media comparisons (α=0.05). Results Sorption was higher after immersion in LA (p<0.05) and increased significantly with time (p<0.05). Sorption was influenced by the activation mode: Ch>D (p<0.05). The lowest solubility was presented by R (p<0.05). Conclusions Lactic acid increased the degradation of resin-based cements. Moreover, the physical component of activation, i.e., light-activation, contributed to a low degradation of resin-based cements. .

A critical analysis of the degree of conversion of resin-based luting cements

OBJECTIVE: This study analyzed the degree of conversion (DC percent) of four resin-based cements (All Ceram, Enforce, Rely X ARC and Variolink II) activated by two modes (chemical and dual), and evaluated the decrease of DC percent in the dual mode promoted by the interposition of a 2.0-mm-thick IPS Empress 2 disc. MATERIAL AND METHODS: In the chemical activation, the resin-based cements were prepared by mixing equal amounts of base and catalyst pastes. In the dual activation, after mixing, the cements were light-activated at 650 mW/cm² for 40 s. In a third group, the cements were light-activated through a 2.0-mm-thick IPS Empress 2 disc. The DC percent was evaluated in a FT-IR spectrometer equipped with an attenuated total reflectance crystal (ATR). The data were analyzed by two-way ANOVA and Tukey's HSD test. RESULTS: For all resin-based cements, the DC percent was significantly higher with dual activation, followed by dual activation through IPS Empress 2, and chemical activation (p<0.05). Irrespective of the activation mode, Rely X presented the highest DC percent (p<0.05). Chemically activated Variolink and All Ceram showed the worst results (p<0.05). The DC percent decreased significantly when activation was performed through a 2.0-mm-thick IPS Empress 2 disc (p<0.05). CONCLUSION: The results of the present study suggest that resin-based cements could present low DC percent when the materials are dually activated through 2.0 mm of reinforced ceramic materials with translucency equal to or less than that of IPS-Empress 2.

Influence of post-cure treatments on hardness and marginal adaptation of composite resin inlay restorations: an in vitro study

OBJECTIVES: The purpose of this study was to evaluate the Vickers hardness number (VHN) and the in vitro marginal adaptation of inlay restorations of three hybrid composite resins (Filtek Z250, Opallis and Esthet-X) subjected to two post-cure treatments. MATERIAL AND METHODS: For the microhardness test, three different groups were prepared in accordance with the post-cure treatments: control group (only light cure for 40 s), autoclave group (light cure for 40 s + autoclave for 15 min at 130ºC); and microwave group (light cure for 40 s + microwave for 3 min at 450 W). To assess the marginal adaptation, the composite resin was inserted incrementally into a mesial-occlusal-distal cavity brass mold and each increment light-cured for 40 s. A previous reading in micrometers was taken at the cervical wall, using a stereomicroscope magnifying glass equipped with a digital video camera and image-analysis software. Subsequently, the specimens were subjected to the post-cure treatments (autoclave and microwave) and a reading was taken again at the cervical wall. Data were compared using ANOVA for the hardness test, split-plot ANOVA for the adaptation assessment and Tukey's test for multiple comparisons. A significance level of 5 percent was adopted for all analyses. RESULTS: The post-cure treatments increased the hardness of conventional composites (p<0.001) and the gap values of inlay restorations (p<0.01). Filtek Z250 showed higher hardness (p<0.001) and lower gap values than Opallis and Esthet-X (p<0.05). Gap values did not exceed 90 µm for any of the experimental conditions. CONCLUSION: The post-cure treatments increased the VHN and the gap values on the cervical floor of composite resin inlays. Moreover, Filtek Z250 showed the best results, with higher hardness and lower gap values.

Cytotoxicity of current adhesive systems: in vitro testing on cell culture of L929 and balb/c 3T3 fibroblasts / Citotoxicidade de sistemas adesivos atuais: teste in vitro em cultura de células fibroblásticas L929 e balb/c 3T3

Purpose: The aim of this study was to evaluate the cytotoxicity of three current adhesives: Prime&Bond NT (PBNT), Single Bond (SB) and XENO III (XENO). Methods: After embedding and curing circles of filter paper with the tested adhesives, the filters were placed in contact with the solidified agar surface over L929 monolayer cells plated in 6-well cell culture plate and incubated for 24 h. The inhibition zone around the filter papers was measured in mm. MTT assay was performed using fibroblasts Balb/c 3T3 cell lines in multiwell culture plates. All assays were done in triplicate. Results: All materials were cytotoxic (Kruskal-Wallis, P<0.05) in a similar level to latex (P>0.05). For intra-groups analysis, SB presented the lowest cytotoxicity (P<0.01), while there was no statistical difference between PBNT and XENO (P>0.05). MTT assay confirmed the cytotoxicity of the tested adhesives. Conclusion: Considering the limits of this work, all adhesives tested were as cytotoxic as latex.

Objetivo: O objetivo deste estudo foi avaliar a citotoxicidade de três adesivos: Prime & Bond NT (PBNT), Single Bond (SB) e XENO III (XENO). Metodologia: Após embebição e polimerização de filtros de papel com os referidos adesivos, estes foram colocados em contato com a superfície de agar solidificada sobre a monocamada de células L929 plaqueadas em cultura celular de 6-poços e incubadas por 24 h. A zona de inibição formada ao redor dos filtros de papel foi medida em milímetros. Outro teste realizado foi o do MTT, utilizando fibroblastos Balb / c 3T3 em placas de multi-poços, sendo os ensaios realizados em triplicatas. Resultados: Todos os materiais testados foram citotóxicos (Kruskal-Wallis, P < 0,05) e semelhantes ao látex (P > 0,05). Para a análise intra-grupos, o SB apresentou a mais baixa citotoxicidade (P < 0,01), enquanto não houve diferença estatística entre PBNT e XENO (P > 0,05). O ensaio de MTT confirmou a citotoxicidade dos adesivos. Conclusão: Considerando as limitações deste trabalho, todos os adesivos testados foram tão citotóxicos quanto o látex.