Composite resin reinforced with silk nanoparticles from Bombyx mori cocoon for dental applications

Abstract The objective of this work was to evaluate the mechanical performance of Z350 resin composite modified with Bombyx mori cocoons silk nanoparticles for dental applications. Four experimental groups were analyzed G0% = Filtek Z350 resin composite (control); G1% = Filtek Z350 with 1% of silk nanoparticles; G3% = Filtek Z350 with 3% of silk nanoparticles; G5% = Filtek Z350 with 5% of silk nanoparticles. It was employed scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, 3-point flexural strength test, Knoop hardness test, and surface roughness. From 3-point flexural strength tests the control group presented the best results G0% = 113.33 MPa (±23.73). The higher flexural modulus was shown by groups G3% = 29.150 GPa (±5.191) and G5% = 34.101 GPa (±7.940), which are statistically similar. The Knoop microhardness test has shown statistical difference only among the G3% group between the top 80.78 (± 3.00) and bottom 68.80 (±3.62) and no difference between the groups. The roughness test presented no statistical difference between the groups. The incorporation of silk nanoparticles reduced the flexural strength of Z350 resin composite. The surface roughness and microhardness tests showed no changes in any of the groups studied.

Resumo O objetivo deste trabalho foi avaliar o desempenho mecânico da resina composta Z350 modificada com nanopartículas de seda Bombyx mori cocoons para aplicações odontológicas. Quatro grupos experimentais foram analisados: G0%) Resina Z350 apenas (grupo controle); G1%) Reforço com 1% de nanopartículas de seda; G3%) Reforço com 3% de nanopartículas de seda; e G5%) Reforço com 5% de nanopartículas de seda. Foi empregado microscopia eletrônica de varredura, espectroscopia de energia dispersiva de raios X, difração de raios X, teste de resistência à flexão de 3 pontos, teste de dureza Knoop e rugosidade superficial. Nos testes de resistência à flexão de 3 pontos o grupo controle apresentou melhores resultados G0% = 0.113 GPa (±0.024). O maior módulo de flexão foi demonstrado pelos grupos G3% = 29.151GPa (±5.191) e G5% = 34.102 GPa (±7.94), que são estatisticamente semelhantes. O teste de microdureza Knoop mostrou diferença estatística apenas entre o grupo G3% entre os 80.78 superiores (± 3.00) e os 68.80 inferiores (±3.62). Não há diferença entre os grupos. O teste de rugosidade não apresentou diferença estatística entre os grupos. A incorporação de nanopartículas de seda reduziu a resistência à flexão da resina composta Z350. Os testes de rugosidade superficial e microdureza não apresentaram alterações em nenhum dos grupos estudados.

Enhancing glass ionomer cement features by using the calcium phosphate nanocomposite

Abstract This study showed the synthesis of Glass ionomer cements (GIC) modified with calcium phosphate nanoparticles (nCaP). The nCaP/GIC were submitted to mechanical compression and diametral tensile tests. The biocomposite were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). Cytotoxicity and cell viability tests were performed on the human bone marrow mesenchymal stem cells using a 3-(4,5-dimethylthiazol-2yl)2,5-diphenyl- tetrazolium-bromide assay and LIVE/DEAD assays. Statistically significant differences were observed for mechanical properties (Kruskal-Wallis, p<0.001), nCaP/GIC showed higher resistance to compression and diametral traction. The SEM analyses revealed a uniform distribution nCaP in the ionomer matrix. The EDX and XRD results indicated that hydroxyapatite and calcium β-triphosphate phases. The FTIR spectra revealed the asymmetric band of ν3PO43- between 1100-1030cm-1 and the vibration band associated with ν1PO43- in 963cm-1 associated with nCaP. The nCaP/GIC presented response to adequate cell viability and non-cytotoxic behavior. Therefore, the new nCaP/GIC composite showed great mechanical properties, non-cytotoxic behavior, and adequate response to cell viability with promising dental applications.

Resumo Este estudo apresenta a síntese de cimentos de ionômero de vidro (GIC) modificados com nanopartículas de fosfato de cálcio (nCaP). Os nCaP / GIC foram submetidos a ensaios mecânicos de compressão e tração diametral. Os biocompósitos foram caracterizados por microscopia eletrônica de varredura (MEV), espectroscopia de energia dispersiva de raios-X (EDX), difração de raios-X (XRD) e espectroscopia de infravermelho com transformada de Fourier (FTIR). Os testes de citotoxicidade e viabilidade celular foram realizados em células-tronco mesenquimais da medula óssea humana usando um ensaio de 3- (4,5-dimetiltiazol-2-il) 2,5-difeniltetrazólio-brometo e ensaios LIVE / DEAD. Diferenças estatisticamente significativas foram observadas para as propriedades mecânicas (Kruskal-Wallis, p <0,001), nCaP / GIC apresentou maior resistência à compressão e tração diametral. As análises de SEM revelaram uma distribuição uniforme de nCaP na matriz do ionômero. Os resultados de EDX e DRX indicaram fases de hidroxiapatita e β-trifosfato de cálcio. Os espectros de FTIR revelaram a banda assimétrica de ν3PO4 3- entre 1100-1030cm-1 e a banda de vibração associada a ν1PO4 3- em 963cm-1 associada a nCaP. O nCaP / GIC apresentou resposta adequada à viabilidade celular e comportamento não citotóxico. Portanto, o novo compósito nCaP / GIC apresentou ótimas propriedades mecânicas, comportamento não citotóxico e resposta adequada à viabilidade celular com promissoras aplicações odontológicas.

Ellagic acid on the quality of the adhesive interface of class I composite resin restorations after aging

To evaluate the effect of ellagic acid on the inhibition of matrix metalloproteinase by analyzing the quality of the adhesive interface with bond strength measures in periods of 24 hours and six months of storage. Method: 40 healthy human third molars were prepared with class I cavities (5x4x3mm). The teeth were divided into four experimental groups: Group 1- without application of ellagic acid and storage time of 24 hours; Group 2- with ellagic acid/24 hours; G3- without ellagic acid/six months; Group 4- with ellagic acid/six months. Then, the cavities were restored with Single Bond Universal adhesive and Z350 composite resin, with and without the previous application of ellagic acid. Subsequently, hourglass-shaped specimens were obtained and subjected to the bond strength (BS) test (n = 10) in a universal testing machine. The bond test was performed after 24 hours and six months of storage. For the standard evaluation (n = 3) the samples were infiltrated with silver nitrate and placed in a developing solution for analysis in a Scanning Electron Microscope (SEM). The data obtained were analyzed with the Kruskal-Wallis non-parametric test, showing a statistically significant difference. Results: The highest bond strength values were found for the 24-hour groups followed by the groups with six months of storage. For nano-infiltration, groups G1 and G2 showed lower infiltration than groups G3 and G4. Conclusion: The previous application of ellagic acid did not affect the BS of the adhesive interface of the adhesive system analyzed, regardless of storage time.

Comparative Analysis of Shear Bond Strength of Steel and Ceramic Orthodontic Brackets Bonded with Six Different Orthodontic Adhesives / Análisis Comparativo de la Resistencia al Corte de Brackets de Ortodoncia de Acero y Cerámica Unidos con Seis Adhesivos de Ortodoncia Diferentes

ABSTRACT: Orthodontic accessories bonding in tooth enamel has been a critical step since the introduction of direct bonding techniques due to the importance of bracket stability. The aim of this study was to evaluate adhesion strength of different adhesive systems used for bracket bonding on dental surface. The present in vitro study was made from the analysis of shear strength of steel and ceramic brackets bonding with six different types of orthodontic adhesives. The brackets were bonded to 120 human extracted first premolar teeth with Orthocem®, Orthocem® + Ambar Universal® primer, Orthobond Plus®, Biofix®, Transbond XT®, Ortholink VLC®. Shear strength tests were performed on a universal testing machine EZ-Test-Shimadzu® and the data were analyzed using ANOVA test with Post-Hoc Bonferroni and 95 % statistical significance (p <0.05). Transbond XT® and Ortholink VLC® resin values showed greater shear resistance for steel brackets bonding and Transbond XT® and Orthobond Plus® adhesives showed better adhesion results for ceramic brackets bonding.

RESUMEN: La unión de accesorios de ortodoncia en el esmalte dental ha sido un paso crítico desde la introducción de las técnicas de unión directa debido a la importancia de la estabilidad del soporte. El objetivo de este estudio fue evaluar la fuerza de adhesión de diferentes sistemas adhesivos utilizados para la unión de brackets en la superficie dental. El presente estudio in vitro se realizó a partir del análisis de la resistencia al corte de brackets de acero y de cerámica unidos con seis tipos diferentes de adhesivos de ortodoncia. Los brackets se unieron a 120 primeros premolares extraídos con los adhesivos Orthocem®, Orthocem® + Ambar Universal® primer, Orthobond Plus®, Biofix®, Transbond XT®, Ortholink VLC®. Las pruebas de resistencia al corte se realizaron en una máquina de prueba universal EZ-Test-Shimadzu® y los datos se analizaron usando la prueba ANOVA con Bonferroni Post-Hoc y 95 % de significación estadística (p <0,05). Los valores de resina Transbond XT® y Ortholink VLC® mostraron una mayor resistencia al corte para la unión de brackets de acero y los adhesivos Transbond XT® y Orthobond Plus® mostraron mejores resultados de adhesión para la unión de brackets cerámicos.

Evaluation of Finishing/Polishing Techniques on Low-Shrink Posterior Restorative After Mechanical Cycling / Avaliação de Técnicas de Acabamento/Polimento em Restaurações Posteriores de Baixa Contração Após Ciclagem Mecânica

The aim of this study was to evaluate the surface roughness of a silorane and methacrylate-based composite resins subjected to different finishing/polishing techniques. Twelve disk specimens were prepared from each composite resin: P90®, Z350® and Charisma, divided into 12 groups according to the finishing/polishing technique: no finishing/polishing (control); finishing with 1112 FF diamond burs; finishing with 1112 FF diamond burs associated to Enhance/Pogo; finishing with 1112 FF diamond burs associated to Enhance/Pogo/Polishing/Poli I and II pastes/Fotogloss. After initial readouts of surface roughness, the specimens were subjected to mechanical cycling (1.200.000 cycles) and immediately subjected to final roughness readouts. Surface roughness means was statistically analyzed by ANOVA and Tukey-Kramer test (α=0.05). SEM images were realized after finishing/polishing and after mechanical cycling. The P90 composite showed surface roughness values similar to other investigated composites. However, significant difference was observed in finishing/polishing techniques. The diamond burs group showed the highest surface roughness differing from the other composite resins (α < 0.05). Enance/Pogo showed the lowest results, which presented no difference compared to the polishing paste group (α > 0.05). The low-shrink posterior restorative showed similar surface roughness when compared to dimethacrylate composite resins and suitable to posterior restorations. (AU).

O objetivo deste estudo foi avaliar a rugosidade superficial de resinas compostas à base silorano e metacrilato submetidas a diferentes técnicas de acabamento/polimento. Foram preparadas 12 amostras de disco de cada resina composta: P90®, Z350® e Carisma, divididas em 12 grupos de acordo com a técnica de acabamento / polimento: sem acabamento / polimento (controle); acabamento com ponta diamantada 1112 FF; acabamento com ponta diamantada 1112 FF associada a Enhance / Pogo; acabamento com ponta diamantada 1112 FF associada a Enhance / Pogo / Polishing / Pastas Poli I e II / Fotogloss. Após as leituras iniciais da rugosidade da superfície, os espécimes foram submetidos a ciclos mecânicos (1.200.000 ciclos) e submetidos imediatamente a leituras de rugosidade final. As medias de rugosidade superfícial foram analisadas estatisticamente por ANOVA e teste de Tukey-Kramer (α = 0,05). As imagens de MEV foram realizadas após o acabamento / polimento e após a ciclagem mecânica. O compósito P90 mostrou valores de rugosidade superficial semelhantes a outros compósitos investigados. Tough, mostrou diferença significativa nas técnicas de acabamento / polimento. O grupo de pontas damantadas apresentou maior rugosidade superficial que diferiu das outras resinas compostas (α <0,05). Enance / Pogo mostrou os menores resultados, que não apresentaram diferença em relação ao grupo de pasta de polimento (α> 0,05). O material restaurador posterior de baixa contração apresentou rugosidade superficial semelhante quando comparado as resinas compostas de dimetacrilato e são restaurações adequadas para região posterior. (AU).

Influence of enamel acid-etching on mechanical properties and nanoleakage of resin composite after aging

The aim of this study was to evaluate how acid-etching of the cavosurface enamel in Class I resin composite restorations influences the bond strength to the pulpal wall and the restoration, Knoop microhardness and nanoleakage after thermomechanical aging. For this research 76 fresh human molars were selected and restored with Silorane or Clearfil SEBond/Z350XT composite divided in 4 groups (Silorane system restored with or without enamel cavosurface acid-etching and Clearfil SEBond/Z350XT with or without enamel cavosurface acid-etching). To induce artificial aging, samples were subjected to thermomechanical cycling through 200,000 and thermal cycling between 5 and 55 °C with 30 second filling and 15-second drainage steps. Microhardness and microtensile bond strength were evaluated in 32 teeth (n=8) each and nanoleakage evaluation was performed in 12 teeth (n=3). Samples restored by Clearfil SEBond/Z350 XT without cavosurface acid-etching showed significantly lower microtensile bond strength results. The resin composite Z350XT presented higher values of Knoop microhardness. It was observed little or no infiltration for Silorane groups and moderate infiltration for Clearfil SE Bond groups. Acid-etching of the cavosurface enamel during restoration procedure with Clearfil Se Bond resulted in a stronger bond after thermomechanical cycling. Silorane groups showed less infiltration than Clearfil SE Bond groups (AU)

Reconhecimento e avaliação da ansiedade em indivíduos com paralisia cerebral durante consultas odontológicas / Recognition and evaluation of anxiety in individuals with cerebral palsy during dental appointments

Objetivo: o objetivo deste estudo foi verificar a correlação entre a avaliação da ansiedade realizada por meio de medidas fisiológicas e pela observação do comportamento de pacientes com paralisia cerebral realizado pelo dentista durante a primeira consulta odontológica. Métodos: quarenta pacientes com idade variando de 7 a 26 anos, com paralisia cerebral foram submetidos a exames odontológicos. A pressão arterial e a frequência cardíaca foram aferidas no início e no final da primeira consulta odontológica. O dentista avaliou o comportamento antes e após o exame clínico dentário através da observação do comportamento do paciente (inquietação / agitação / tiques nervosos, palidez, transpiração excessiva, resistência e mudança aparente na frequência respiratória). Foi utilizado o teste de correlação de Spearman para determinar a correlação entre as medidas fisiológicas e a classificação comportamental da ansiedade feita pelo cirurgião dentista a um nível de significância de 95%. Resultados: os sinais comportamentais mais frequentes foram inquietação / agitação / tiques nervosos (50,0%) e resistência (27,5%). Foi encontrada uma correlação positiva significativa entre os dois métodos de avaliação de ansiedade utilizados (p <0,05). Os pacientes considerados ansiosos pelo dentista apresentaram medidas fisiológicas mais elevadas do que aqueles considerados calmos (p <0,05). Conclusão: a observação contínua do comportamento de pacientes com paralisia cerebral durante o exame odontológico é uma ferramenta valiosa para o reconhecimento e avaliação da ansiedade por parte da equipe odontológica. Estudos adicionais são necessários para validar um código de expressões faciais e corporais ou reações de ansiedade em pacientes com paralisia cerebral.(AU)

Aim: The present study aimed to verify the correlation between the evaluation of anxiety performed through physiological measures and the observation of the behavior of patients with cerebral palsy performed by the dentist during the first dental visit. Methods: Forty patients with cerebral palsy, varying from seven to 26 years of age, were submitted to dental examinations. The blood pressure and heart rate were measured at the beginning and end of the first dental appointment. The dentist evaluated the behavior before and after the dental exam by observing the patient's behavior (restlessness / agitation / nervous tics, pallor, excessive perspiration, resistance, and apparent change in breathing rate). The Spearman correlation test was used to determine the correlation between the physiological measures and the behavioral classification of anxiety made by the dentist at a significance level of 95%. Results: The most frequent behavioral signs were restlessness / agitation / nervous tics (50.0%), and resistance (27.5%). Through the Kruskal-Wallis test and Spearman's correlation, a significant positive correlation was found between the two anxiety assessment methods used in this study (p<0.05). The patients considered anxious by the dentist presented higher physiological measurements than did those considered calm (p<0.05). Conclusion: It can therefore be concluded that the continuous observation of the behavior of patients with cerebral palsy during the dental examination is a valuable tool for the recognition and evaluation of anxiety on the part of the dental team. Further studies are warranted to validate a code of facial and body expressions or anxiety reactions in patients with cerebral palsy.(AU)

Reforço intrarradicular de raízes debilitadas / Intra-root strengtening of weakened roots

A instrumentação dos canais radiculares através do uso de lima única em movimento recíproco vem se popularizando devido à redução do tempo de trabalho e menor tendência de fraturas dos instrumentos. Antes de escolher o sistema que vai utilizar, o cirurgião- -dentista deve conhecer as capacidades e limitações de cada sistema baseado em evidências científicas. Esse artigo realizou uma revisão de literatura sobre o movimento recíproco para instrumentação do sistema de canais radiculares apontando as vantagens e desvantagens da utilização dessa cinemática de instrumentação.

The canal’s instrumentation by using single file in reciprocation movement is gaining popularity due to the reduction of working time and less prone to fractures of the instruments. Before choosing which system will use, the dentist must know the capabilities and limitations of each system based on scientific evidence. This article reviews the literature on the reciprocation movement pointing out the advantages and disadvantages of this different kinematic instrumentation.

Influence of selective acid etching on microtensile bond strength of a self-adhesive resin cement to enamel and dentin

Aim: To evaluate the selective acid etching of enamel and dentin on microtensile bond strength (¦ÌTBS) of a self-adhesive resin cement. Methods: Forty-eight bovine teeth were selected and had the buccal surface ground to obtain a flat dentin (n=24) or enamel (n=24) surface. Z250 composite resin blocks (4 x 3 x 8 mm) were prepared for cementation at enamel and dentin. Each substrate received three experimental resin cementation strategies: 1) 37% phosphoric acid etching before the application of RelyX Unicem; 2) application of RelyX Unicem alone; 3) RelyX ARC as a control. Samples were light-cured using a halogen light (Optilux 501, 700mW/cm2), for 40 s. Hourglass-shaped specimens were obtained and submitted to a tensile strength at a crosshead speed of 0.5 mm/min in a universal testing machine. For statistical analysis, data were submitted to ANOVA and Tukey¡¯s test at a pre-set alpha (¨¢=0.05). Results: RelyX Unicem showed similar bond strength value (16.5 MPa) when compared to the pretreatment with acid etching (11.9 Mpa) and to the conventional resin cement (18.1 MPa) for enamel. All luting strategies presented similar dentin bond strength, but significantly lower than enamel bond strength. Conclusions: Acid etching prior to RelyX Unicem application did not improve microtensile bond strength for enamel and dentin.

Uso de princípios de ilusão óptica no contorno cosmético: previsibilidade e excelência estética / Using principles of optical illusion for cosmetic recontouring: predictability and esthetic excellence

O contorno cosmético é uma técnica operatória que requer do profissional amplo conhecimento de estética e reflexão da luz, pois implica desgaste irreversível da estrutura dental sadia. Este artigo relata um caso clínico de contorno cosmético que ilustra as possibilidades de remodelação estética do sorriso guiadas por princípios de ilusão de óptica, na qual foi possível, mediante a realização de desgastes em esmalte, obter resultados satisfatórios com previsibilidade.

Cosmetic recontouring is a technique that demands comprehensive skills and knowledge about esthetics light dynamics by the professional, since irreversible reduction of tooth sound structure is required. This paper is a case report of the cosmetic contouring showing the possibilities of esthetic recontouring of the smile following principles of optical illusion, from which it was possible through enamel reduction to achieve satisfactory, predictable results.