Effects of different concentrations of sodium hypochlorite on dentine adhesion and the recovery application of sodium erythorbate / 中南大学学报(医学版)

OBJECTIVES@#Root canal therapy is the most effective and common method for pulpitis and periapical periodontitis. During the root canal preparation, chemical irrigation plays a key role. However, sodium hypochlorite (NaOCl), the widely used irrigation fluid, may impact the bonding strength between dentin and restorative material meanwhile sterilization and dissolving. Therefore, it's important to explore the influence of NaOCl on the adhesion between dentin and restoration materials to ensure clinical efficacy. This study aims to explore the effect of NaOCl on dentine adhesion and evaluate the effect of dentine adhesion induced by sodium erythorbate (ERY), and to provide clinical guidance on dentin bonding after root canal therapy.@*METHODS@#Seventy freshly complete extracted human third molars aged 18-33 years old, without caries and restorations were selected. A diamond saw was used under running water to achieve dentine fragments which were divided into 10 groups with 14 fragments in each group: 2 control [deionized water (DW)±10% ERY] and 8 experimental groups (0.5%, 1%, 2.5%, and 5.25% NaOCl±10% ERY). The dentine specimens in the control group (treated with DW) and the experimental groups (treated with 0.5% NaOCl, 1% NaOCl, 2.5% NaOCl, and 5.25% NaOCl) were immersed for 20 min using corresponding solutions which were renewed every 5 min. The other 5 groups were immersed in 10% ERY for 5 min after an initial washing with DW for 1 min. Then, we selected 4 dentine fragments from all 14 fragments in each group and the numbers and diameters of opening dentinal tubules were observed under scanning electron microscope (SEM). The other 10 dentine fragments from each group were used to make adhesive samples by using self-etch adhesive wand composite resin. All the above adhesive samples were sectioned perpendicular to the bonded interface into 20 slabs with a cross-sectional area of 1 mm×1 mm using a diamond saw under the cooling water, and then the morphology of 10 slabs in each group's bonding interface was observed from aspects of formation of resin tags, depth of tags in dentin, and formation of hybrid layer under SEM. The other 10 slabs of each group's microtensile bond strength and failure modes were also analyzed.@*RESULTS@#Among the 0.5% NaOCl, 1% NaOCl, 2.5% NaOCl, and 5.25% NaOCl groups, the number and diameter of patent dentinal tubules gradually increased with the rise of concentration of NaOCl solution (all P<0.05). Among the DW, 0.5% NaOCl, 1% NaOCl, 2.5% NaOCl, and 5.25% NaOCl groups, the number and diameter of patent dentinal tubules increased after using ERY, but without significant difference (all P>0.05). Among the DW, 0.5% NaOCl, 1% NaOCl, and 2.5% NaOCl groups, the scores of formation of resin tags under SEM gradually increased with the increase of concentration of NaOCl solution, while the score in the 5.25% NaOCl group decreased significantly compared with the score of the 2.5% NaOCl group (P<0.05). There was no significant difference between using 10% ERY groups and without using 10% ERY groups (all P>0.05). The scores of length of the tags under SEM in the 5.25% NaOCl group was significantly higher than the scores of DW, 0.5% NaOCl, and 1% NaOCl groups (all P<0.05), and it was also higher than the score of the 2.5% NaOCl group, but without significant difference (P>0.05). There was no significant difference between using 10% ERY groups and without using 10% ERY groups (P>0.05). The scores of formation of hybrid layer under SEM in the 2.5% NaOCl and 5.25% NaOCl groups significantly decreased compared with the score of the DW group (all P<0.05). There were significant differences between the 2.5% NaOCl±10% ERY groups and between the 5.25% NaOCl±10% ERY groups (all P<0.05). Microtensile bond strength was greater in the 0.5% NaOCl, 1% NaOCl, and 2.5% NaOCl groups, but lower in the 5.25% NaOCl group than that in the DW group (all P<0.05). There were significant differences between the 2.5% NaOCl±10% ERY groups and between the 5.25% NaOCl±10% ERY groups (all P<0.05). The incidence of type "Adhesive" of failure modes in the 5.25% NaOCl group was significantly higher than that in other groups (all P<0.05), while the incidence of type "Adhesive" in the 5.25% NaOCl+10% ERY group was lower than that in the 5.25% NaOCl group (P<0.05).@*CONCLUSIONS@#The bonding strength to dentine increases with the increase of NaOCl concentration when the concentration lower than 2.5%; whereas it is decreased at a higher concentration (such as 5.25%). 10% ERY has a definite recovery effect on attenuated bonding strength to 5.25% NaOCl-treated dentine.

Influence of resin-modified glass ionomer and topical fluoride on levels of Streptococcus mutans in saliva and biofilm adjacent to metallic brackets

Abstract Decalcification of enamel during fixed orthodontic appliance treatment remains a problem. White spot lesions are observed in nearly 50% of patients undergoing orthodontic treatment. The use of fluoride-containing orthodontic materials has shown inconclusive results on their ability to reduce decalcification. The aims of this investigation were to compare the levels of Streptococcus mutans (SM) in saliva and biofilm adjacent to orthodontic brackets retained with a resin-modified glass ionomer cement (RMGIC) (Fuji ORTHO LC) and a light cured composite resin (Transbond XT), and to analyze the influence of topical application of the 1.23% acidulated phosphate fluoride (APF) on SM counts. In a parallel study design, two groups (n=14/15) were used with random allocation and high salivary SM counts before treatment. Biofilm was collected from areas adjacent to the brackets on teeth 13, 22, 33, and 41. Both saliva and biofilm were collected on the 7th, 21st, 35th, and 49th days after appliance placement. Topical fluoride application was carried out on the 35th day. Bonding with RMGIC did not alter SM counts in saliva or biofilm adjacent to the brackets. On the other hand, the biofilm adjacent to brackets retained with composite resin showed a significant increase in SM counts along the trial period. Topical application of 1.23% APF did not reduce salivary or biofilm SM counts regardless of the bonding material. In conclusion, fluoride topical application did not show efficacy in reducing SM. The use of RMGIC as bonding materials allowed a better control of SM cfu counts in dental biofilm hindering the significant increase of these microorganisms along the trial period, which was observed in the biofilm adjacent to the composite material.

Caracterização físico-química, mecânica e biológica de cimento autoadesivo aditivado com nanotubos de dióxido de titânio / Physical-chemical, mechanical and biological characterization of reinforcement self-adhesive resin cement titanium dioxide nanotubes

O objetivo desse estudo foi realizar a caracterização do cimento resinoso autoadesivo RelyX U200 aditivado de nanotubos de dióxido de titânio (nt-TiO2) em diferentes concentrações (0,3, 0,6, e 0,9% em peso) quanto às suas propriedades físico-químicas, mecânicas e biológica. Duas condições de polimerização foram analisadas: autopolimerizável (grupos: AC, A03, A06 e A09) e dual (grupos: DC, D03, D06 e D09). Para análise do grau de conversão foi utilizada a espectroscopia de infravermelho com transformada de Fourier com registro do espectro nos tempos de 3, 6, 9, 12 e 15 minutos. Os picos das bandas de comprimento de onda de 1638 cm-1 e de 1608 cm-1 foram identificados para cálculo do grau de conversão. Os dados foram submetidos à ANOVA de medidas repetidas seguido de comparações múltiplas de Tukey (=0,05). A análise de sorção e solubilidade foi realizada por meio da confecção de discos de cimento resinoso (10 mm ø × 2 mm) (n=8) monitorados quanto à sua massa depois de ciclos de hidratação/desidratação. A resistência à flexão em 3 pontos e módulo de elasticidade foram mensurados por meio de barras (2 × 2 × 25 mm) de cimento resinoso (n=10) levadas à máquina universal de ensaios. Para análise de Dureza Knoop utilizou-se microdurômetro com carga de 50g /10 segundos. Nos discos de cimento resinoso de 10 mm ø × 2 mm foram realizadas 5 endentações equidistantes 0,5mm e medidas em aumento de 50×. Para resistência de união ao cisalhamento, sobre discos de zircônia sinterizados foi aplicado o cimento resinoso (n=10) nas dimensões de 3 mm ø × 2 mm. Por meio de dispositivo foram levados à máquina universal de ensaios. Os dados encontrados de sorção e solubilidade e de cada propriedade mecânica foram submetidos aos testes ANOVA a dois critérios e de comparações múltiplas de Tukey (=0,05). Exceto para resistência ao cisalhamento que se utilizou o teste de comparação de Fischer (=0,05). Para viabilidade celular (n=8) foi realizado teste de MTT apenas na condição dual. Os grupos estudados foram: DC, D03, D06, D09, CP (controle positivo), CN (controle negativo). Após 24, 48 e 72 horas os níveis de absorbâncias foram analisados por meio de espectrofotometria no leitor de ELISA. Os dados foram submetidos aos testes ANOVA a dois critérios e de comparações múltiplas de Tukey (=0,05). Os resultados mostraram que a adição de nt-TiO2, independente da concentração, aumentou os valores de grau de conversão do cimento resinoso para a condição autopolimerizável e dual em todos os tempos estudados. Já para sorção e solubilidade não houve influência nos resultados da concentração de nanotubos inseridos e da condição de polimerização. Para resistência flexural, a adição de nt-TiO2 nas concentrações de 0,3% (A03) e 0,9% (A09) resultou em dados similares ao controle na condição dual (DC). O valor médio de módulo de elasticidade aumentou com a adição de 0,9% (A09), similar a todos os grupos da condição dual, em que adição de nt-TiO2 não influenciou os resultados. A adição de 0,6% (A06 e D06) e 0,9% (A09 e D09) de nt-TiO2 ao cimento aumentou os valores de dureza quando comparado aos grupos controle (AC e DC). Para resistência de união ao cisalhamento, a concentração de 0,3% de nt-TiO2 (A03 e D03) aumentou os valores quando comparado aos grupos A06, D06, A09 e D09 porém sem diferença para os grupos controle (AC e DC). Para viabilidade celular no período de 24h, os grupos D03, D06 e D09 obtiveram resultado similar ao grupo CP, já o grupo DC apresentou valores de absorbância inferiores ao CP, usado como parâmetro de comparação. Em 48 e 72h, todos os grupos experimentais não demonstraram diferença significativa em comparação ao grupo CP. O grupo CN apresentou diferença para os demais em todos dos tempos estudados. A adição de nt-TiO2 ao cimento resinoso autoadesivo representa uma estratégia promissora para potencializar suas propriedades físico-químicas e mecânicas sem prejuízo das propriedades biológicas.(AU)

The aim of this study was to characterize the self-adhesive resin cement RelyX U200 additive, titanium dioxide nanotubes (nt-TiO2), at different concentrations (0.3%, 0.6%, and 0.9% by weight) and to determine their physicochemical, mechanical and biological properties. Two polymerization conditions were analyzed: self-curing (groups AC, A03, A06 and A09) and dual-curing (groups DC, D03, D06 and D09). To analyze the conversion degree, Fourier transform infrared spectroscopy was used, and the spectrum was recorded at 3, 6, 9, 12 and 15 minutes. The peaks of the wavelength bands, 1638 cm-1 and 1608 cm-1, were identified to calculate the degree of conversion. The data were subjected to a repeated-measures ANOVA followed by a Tukey multiple-comparison test (=0.05). The sorption and solubility analysis was performed by making resin-cement discs (10 mm ø × 2 mm) (n=8) and monitoring their masses after the hydration/dehydration cycles. The 3-point flexural strength and the modulus of elasticity of resin-cement bars (2 × 2 × 25 mm) (n=10) were measured using a universal testing machine. The Knoop microhardness was analyzed with a load of 50 g and a time of 10 seconds. On each resin cement disc, 5 equidistant indentations of 0.5 mm were made, and the measures were increased by 50×. To test bonding shear strength, resin cement was applied to sintered zirconia discs (3 mm ø × 2 mm) (n=10). The bonded discs were then taken to the universal testing machine. Their sorption, solubility and each mechanical property were submitted to a two-way ANOVA and a Tukey multiple-comparison test (=0.05). The shear strength was submitted to a Fischer comparison test (=0.05). To test cell viability (n=8), a MTT assay was performed using only the dual-curing condition. The studied groups were: DC, D03, D06, D09, CP (positive control) and CN (negative control). After 24, 48 and 72 hours, the absorbance levels were analyzed using an ELISA spectrophotometry reader. The data were submitted to a two-way ANOVA and a Tukey multiple-comparison test (=0.05). The results showed that the addition of nt-TiO2, regardless of concentration, increased the conversion degree values for the self-curing resin cement and for the dual-curing at all times studied. The sorption and solubility were not influenced by the concentration of the nanotubes or the polymerization condition. Regarding flexural strength, the addition of the nt-TiO2 in concentrations of either 0.3% (A03) or 0.9% (A09) resulted in data similar to those in the dual-curing control (DC) condition. The average modulus of elasticity increased with the addition of 0.9% nt-TiO2 (A09), and as with all the groups in the dual-curing condition, the addition of nt-TiO2 did not affect the results. The addition of either 0.6% (A06 and D06) or 0.9% (A09 and D09) of nt-TiO2 cement increased hardness values relative to the control groups (AC and DC). The group with a 0.3% concentration of nt-TiO2 (A03 and D03) showed higher bonding shear strength values than several of the groups with higher concentrations (A06, D06 and D09), but the A09 group had no difference relative to either control group (AC or DC). For cell viability in the 24-h period, the D03 D06 and D09 groups achieved a result similar to that of the CP group with significant difference to the DC group that had lower absorbance values. At the benchmarks of 48 and 72 h, and only the CN group showed a significant difference compared to others. The addition of nt-TiO2 is a promising strategy for improving the physical-chemical and mechanical properties without prejudice the biological properties.(AU)

Influência das unidades fotoativadoras e do material restaurador indireto sobre a dureza de um cimento resinoso dual auto-adesivo e um cimento resinoso dual convencional por meio de teste de nanoendentação / Influence of curing units and restorative indirect material on hardness of a dual cure self-adhesive resin cement and dual cure conventional resin cement through nanoindentadion test

O objetivo deste estudo foi avaliar a dureza de um cimento resinoso dual autoadesivo (RelyX U200) e um cimento resinoso dual convencional (RelyX ARC) fotoativados sob materiais restauradores indiretos, utilizando unidades fotoativadoras com diferentes comprimentos de ondas (LED Elipar Freelight 2, LED Bluephase, Laser AccuCure 3000TM), por meio de teste de nanoendentação. Para a obtenção dos espécimes foram utilizados incisivos bovinos que após profilaxia, foram submetidos a cortes no limite amelo-cementário para a separação da porção coronária. Após inclusão, os espécimes foram submetidos ao desgaste para exposição de dentina e padronização do substrato. Para simular clinicamente restaurações indiretas foram confeccionadas peças em cerâmica IPS e.max® Press (Ivoclar Vivadent) e em resina composta indireta SR Adoro (Ivoclar Vivadent) que foram cimentadas nas superfícies dentinárias. Os espécimes foram seccionados longitudinalmente em baixa velocidade e constante irrigação e polidos em politriz. Foi estabelecido um grupo controle positivo, no qual o cimento foi fotoativado sem a interposição de material restaurador indireto e um grupo controle negativo, no qual, após a cimentação do material restaurador indireto, a fotoativação foi suprimida, ocorrendo apenas a polimerização química do cimento. Todos os espécimes foram armazenados em água destilada a 37°C durante 7 dias e após esse período, foram submetidos ao teste de nanoendentação na linha de cimentação, com o auxílo do ultra-microdurômetro (Shimadzu Dynamic Ultra Micro Hardness Tester). O ciclo aplicado foi de 100mN. Foram realizadas cinco nanoendentações em cada espécime, cujas médias resultaram nos valores de cada superfície. Os resultados obtidos foram submetidos à Análise de Variância e Teste de Tukey (p<0,05). Pode se concluir que o cimento RelyX ARC apresentou maiores valores de dureza do que o RelyX U200 e este foi mais dependente da fotoativação para alcançar uma polimerização adequada. A dureza dos cimentos resinosos avaliados foi influenciada negativamente pela interposição do material restaurador indireto e apenas os LEDs foram capazes de manter o mesmo grau de polimerização dos cimentos quando interposto um material restaurador indireto.

This study aimed to evaluate the hardness of a dual cure self-adhesive resin cement (RelyX U200) and a dual cure conventional resin cement (RelyX ARC) light curing units with different wavelengths (Elipar Freelight 2 LED, Bluephase LED, AccuCure 3000TM Laser) through nanoindentadion test. To obtain the specimens bovine incisors were used after prophylaxis. The tooth were sectioned at the limit amelocement for the separation of the coronal portion. After inclusion, the dentin surface of the specimens were exposed to standardize the substrate. To clinically simulate indirect restorations ceramic pieces were made (IPS e.max® Press/Ivoclar Vivadent) and indirect composite resin (SR Adoro/Ivoclar Vivadent) were cemented on dentin surfaces. The specimens were sectioned longitudinally at low speed with constant irrigation and polished. A positive control group was stablished, in which the cement was light cured without the interposition of indirect restorative material, and a negative control group, in which, after cementation of the indirect restorative material, the light curing was removed, occurring only the chemical polymerization of the cement. All specimens were stored in distilled water at 37°C for 7 days. Nanoindentadion hardness of the cement layer was measured under 100mN load (Shimadzu Dynamic Ultra Micro Hardness Tester). Five nanoindentations in each specimen were obtained, which resulted in the average values of each surface. Data were statistically analyzed using ANOVA and Tukey test (p<0,05). RelyX ARC pesented higher values of hardness than RelyX U200 and this was more dependent on the polymerization. The hardness of the evaluated resin cements was negatively influenced by the interposition of an indirect restorative material and only the LEDs were able to maintain the same degree of polymerization of the cement when an indirect restorative material was used.

Clinical evaluation of postoperative sensitivity using self-etching adhesives containing glutaraldehyde

The present clinical study aimed to assess the postoperative sensitivity (POS) after 48 hours and seven days in occlusal restorations bonded with three different adhesive systems, two of them containing glutaraldehyde. The restorative procedures were performed using the three-step etch-and-rinse Adper SBMP-Plus adhesive (SBMP), the two-step etch-and-rinse Gluma Comfort One Bond + Desensitizer adhesive (GC+D) and the all-in-one self-etching/priming I Bond (IB) adhesive, which also has glutaraldehyde in its formula. All cavities were restored with Filtek Supreme nanoparticle composite resin. After 48 hours and seven days the patients were recalled and the postoperative sensitivity evaluated. The data analyzed by non-parametric Friedman test showed no significant differences in POS among the three tested groups after 48 hours and seven days.

Comparative scanning electron microscopic study of the effect of different dental conditioners on dentin micromorphology

This study evaluated comparatively by scanning electron microscopy (SEM) the effect of different dental conditioners on dentin micromorphology, when used according to the same protocol. Forty dentin sticks were obtained from 20 caries-free third human molars and were assigned to 4 groups corresponding to 3 conditioners (phosphoric acid 37 percent, Clearfil SE Bond and iBond) and an untreated control group. After application of the conditioners, the specimens were immersed in 50 percent ethanol solution during 10 s, chemically fixed and dehydrated to prepare them to SEM analysis. In the control group, dentin surface was completely covered by smear layer and all dentinal tubules were occluded. In the phosphoric acid-etched group, dentin surface was completely clean and presented exposed dentinal tubule openings; this was the only group in which the tubules exhibited the funnel-shaped aspect. In the groups conditioned with Clearfil SE Bond primer and iBond, which are less acidic than phosphoric acid, tubule openings were occluded or partially occluded, though smear layer removal was observed. SE Bond was more efficient in removing the smear layer than iBond. In the Clearfil SE Bond group, the cuff-like aspect of peritubular dentin was more evident. It may be concluded all tested conditioners were able to change dentin morphology. However, it cannot be stated that the agent aggressiveness was the only cause of the micromorphological alterations because a single morphological pattern was not established for each group, but rather an association of different aspects, according to the aggressiveness of the tested conditioner.

Effects of cleaning agents on bond strength to dentin

A limpeza das paredes cavitárias é um passo importante na clínica odontológica e visa otimizar os procedimentos adesivos e a longevidade das restauracões. O presente estudo comparou o efeito de três agentes de limpeza cavitária - jato abrasivo de bicarbonato de sódio/ar/água (Profi II, Dabi Atlante, São Paulo, Brasil); pasta de pedra-pomes e água, somada a um detergente biológico (Tergestesim, Probem, São Paulo, Brasil); e spray de ar/água - na resistência adesiva entre dentina e dois tipos de adesivos dentais: Clearfil SE Bond ("self-etching") (Kuraray, Kioto, Japão) e Scotchbond Multi-Purpose Plus ("all-etching") (3M-ESPE, São Paulo, Brasil). Seis grupos de espécimes (n = 10) obtidos a partir de elementos dentais humanos extraídos por indicacão foram preparados e cada um recebeu um dos tratamentos de superfície. Após aplicacão dos adesivos, uma porcão tronco-cônica de resina composta (AP-X, Kuraray, Kioto, Japão/Z-100; 3M-ESPE, São Paulo, Brasil) foi construída sobre os espécimes, com o auxílio de uma matriz bipartida de teflon e uma mesa metálica adaptadora para adaptacão na máquina de ensaio de tracão. Após armazenamento em água destilada a 37ºC por 7 dias, os mesmos foram submetidos às provas de tracão. Dois pares de cada grupo foram escolhidos aleatoriamente e processados para observacão ao microscópio eletrônico de varredura (MEV). A análise estatística dos valores obtidos demonstrou que não houve diferencas significantes entre as técnicas de limpeza empregadas e nem entre a interacão destas com os adesivos dentais, e as observacões ao MEV revelaram uma predominância de fraturas mistas ocorridas na interface dentina/resina. Baseados nas análises estatísticas e nas observacões ao MEV, concluiu-se que as técnicas de limpeza empregadas não interferem na resistência adesiva entre a dentina e os sistemas adesivos estudados, nas condicões experimentais adotadas.

Avaliaçäo do efeito de recimentaçöes sucessivas de coroas totais no desajuste marginal, retençäo friccional e retençäo final com três agentes cimentantes / Effect evaluation of consecutive recementations on marginal misfit, friccional retention and final retention of full crowns with three luting agents

Trinta dentes molares humanos recém-extraídos foram preparados para a confecçäo de infra-estruturas metalocerâmicas com o objetivo de avaliar o efeito de recimentaçöes sucessivas no desajuste marginal, retençäo friccional e retençäo final com três agentes cimentantes. Como parâmetro para as leituras de desajuste marginal, restauraçöes de amálgama de prata foram previamente realizadas nas raízes dos dentes em quatro pontos equidistantes nas faces vestibular, lingual, mesial e distal e posteriormente traçadas com uma lâmina de bisturi, duas linhas em cruz sobre as mesmas. Outras quatro cruzes foram demarcadas a ñ 1,5mm das margens das infra-estruturas. Após a confecçäo das peças fundidas, as amostras foram divididas em três grupos de dez, criando-se estes com médias equivalentes, tendo como base a retençäo friccional inicial. As amostras do Grupo 1 foram cimentadas com fosfato de zinco, as do Grupo 2 com ionômero de vidro modificado e as do Grupo 3 com resinoso. As medidas de desajustes das infra-estruturas foram realizadas com auxílio de microscópio óptico comparador e os valores médios foram: 177µm negativos para o Grupo 1, 100µm negativos para o Grupo 2 e 120µm para o Grupo 3. Estes valores de desajustes foram submetidos à análise de variância a dois critérios, demonstrando haver diferença significante entre os resultados. Baseado nisto, concluiu-se que houve melhor ajuste das infra-estruturas com as sucessivas recimentaçöes. Os testes de resistência à remoçäo por traçäo das infra-estruturas em relaçäo aos dentes preparados mostraram as seguintes variaçöes de valores de acordo com cada grupo de estudo: Grupo 1 de 774.0 a 137.6gf, Grupo 2: de 774.6 a 139.1gf e o Grupo 3: de 770.1 a 61.2gf. Os valores foram submetidos ao teste estatístico já citado e também houve uma diferença significante dos resultados...

Effect of 4-META adhesive on bond strength and marginal seal of amalgam restorations and repairs--an in vitro study.

Amalgam remains unchallenged as a posterior restorative material. But its inability to bond to the teeth leads to some amount of microleakage at the restoration-tooth interface with associated problems such as post operative sensitivity, pulpal complications etc. Also a broken amalgam restoration requires replacement which will further weaken the tooth structure. Recently, 4-META has been introduced which can graft amalgam and composite to enamel, dentin and old amalgam restorations. In this study, the bonding and marginal sealing abilities of 4-META was assessed both at the tooth-amalgam interface and old amalgam fresh amalgam interface.