Effect of phytic acid on bond strength and interfacial integrity of universal adhesive to deep dentin

Abstract This study investigated the effect of phytic acid (IP6) in different concentrations and application times on microtensile bond strength (µTBS) and interfacial integrity of universal adhesive to deep dentin. Flat deep dentin surfaces of 48 human molars were either etched with 37% phosphoric acid (PA) for 15 sec (control); or received no acid treatment and universal adhesive was applied directly in a self-etch mode (SE); or divided according to IP6 concentration (C) into two main groups: C1, 0.5%, and C2, 1%. Specimens of IP6 groups were further subdivided into three subgroups according to application time of IP6 (T) where; T1, 15 sec; T2, 30 sec and T3, 60 sec. Single Bond Universal Adhesive was then applied and resin composite blocks were built-up. Forty Specimens were then sectioned to produce resin/dentin beams that were used for µTBS testing using a universal testing machine. The remaining eight specimens were sectioned into slabs that were immersed into ammonical silver nitrate solution and nanoleakage was observed using a field emission scanning electron microscope (FE-SEM). The results showed that the application of IP6 in 0.5% and 1% produced significantly higher µTBS and less nanoleakage compared to PA and SE groups. Also, the application of IP6 for 60 sec recorded the highest µTBS and the lowest nanoleakage followed by 30 sec, and 15 sec respectively. Therefore, conditioning of deep dentin with IP6 enhances µTBS and interfacial integrity of universal adhesive to deep dentin in comparison to PA etching or using the universal adhesive in SE mode.

Resumo Este estudo investigou o efeito do ácido fítico (IP6) em diferentes concentrações e tempos de aplicação na resistência da ligação microtensiva (µTBS) e na integridade interfacial do adesivo universal à dentina profunda. As superfícies planas de dentina profunda de 48 molares humanos foram preparadas com ácido fosfórico (PA) a 37% durante 15 seg. (controlo); ou não receberam tratamento ácido e o adesivo universal foi aplicado diretamente em modo de auto-adesivo (SE); ou dividido de acordo com a concentração de IP6 (C) em dois grupos principais: C1, 0,5%, e C2, 1%. Os espécimes dos grupos IP6 foram ainda subdivididos em três subgrupos de acordo com o tempo de aplicação do IP6 (T) em que; T1, 15 seg; T2, 30 seg e T3, 60 seg. Aplicou-se então Single Bond Universal Adhesive e construíram-se blocos compostos de resina. Quarenta espécimes foram então seccionados para produzir feixes de resina/dentina que foram usados para testes µTBS usando uma máquina de testes universal. Os restantes oito espécimes foram seccionados em placas que foram imersas em solução amoniacal de nitrato de prata e observou-se uma nano-infiltração utilizando um microscópio eletrônico de varrimento de emissões de campo (FE-SEM). Os resultados mostraram que a aplicação de IP6 em 0,5% e 1% produziu µTBS significativamente mais elevado e menos nano-infiltração em comparação com os grupos PA e SE. Além disso, a aplicação de IP6 durante 60 seg registou o µTBS mais alto e o mais baixo de nano-infiltração seguido de 30 seg, e 15 seg respectivamente. Portanto, o condicionamento da dentina profunda com IP6 melhora o µTBS e a integridade interfacial do adesivo universal à dentina profunda em comparação com a gravação de PA ou utilizando o adesivo universal no modo SE.

Phosphoric acid containing proanthocyanidin enhances bond stability of resin/dentin interface

Abstract Proanthocyanidin (PA) is a promising dentin biomodifier due to its ability to stabilize collagen fibrils against degradation by matrix metalloproteinases (MMPs); however, the most effective protocol to incorporate PA into bonding procedures is still unclear. This study evaluated the effect of dentin biomodification with a PA acid etchant on MMP activity, adhesive interface morphology and resin-dentin microtensile bond strength. Sound extracted human molars were flattened to expose dentin and acid-etched for 15 s according to the groups: EXP - experimental phosphoric acid; EXP+PA - experimental phosphoric acid 10% PA; TE - total-etching system; SE - self-etching system. Samples were restored with composite resin and stored in distilled water (37ºC). MMP activity and interface morphology were analyzed after 24 h by in situ zymography (n=6) and scanning electron microscopy (n=3), respectively. The resin-dentin microtensile bond strength (μTBS) was evaluated after 24 h and 6 months storage (n=6). Significantly higher MMP activity was detected in etched dentin compared with untreated dentin (p<0.05), but no difference among acid groups was found. Resin tags and microtags, indicative of proper adhesive system penetration in dentinal tubules and microtubules, were observed along the hybrid layer in all groups. There was no difference in μTBS between 24 h and 6 months for EXP+PA; moreover, it showed higher long-term μTBS compared with TE and EXP (p<0.05). The results suggest that 15 s of biomodification was not sufficient to significantly reduce MMP activity; nonetheless, EXP+PA was still able to improve resin-dentin bond stability compared with total- and self-etching commercial systems.

Resumo A proantocianidina (PA) é um biomodificador dentinário promissor devido a sua capacidade de estabilizar as fibrilas colágenas contra a degradação por metaloproteinases da matriz (MMPs); no entanto, o protocolo mais eficaz para a incorporação de PA em procedimentos adesivos ainda não está claro. Este estudo avaliou o efeito da biomodificação da dentina com um condicionador ácido contendo PA na atividade de MMPs, morfologia da interface adesiva e resistência à microtração resina-dentina. Molares humanos extraídos foram lixados para exposição da dentina e condicionados com ácido por 15 s de acordo com os grupos: EXP - ácido fosfórico experimental; EXP+PA - ácido fosfórico experimental com 10% PA; TE - sistema total-etch; SE - sistema self-etch. As amostras foram restauradas com resina composta e armazenadas em água destilada (37ºC). A atividade de MMP e morfologia da interface foram analisadas após 24 h por zimografia in situ (n=6) e microscopia eletrônica de varredura (n=3), respectivamente. A resistência à microtração resina-dentina (μTBS) foi avaliada após 24 horas e 6 meses de armazenamento (n=6). Atividade de MMP detectada na dentina condicionada foi significativamente maior em comparação com a dentina não tratada (p <0,05), mas não houve diferenças entre os diferentes ácidos. Tags e microtags de resina, indicativos de uma penetração adequada do sistema adesivo nos túbulos e microtúbulos dentinários, foram observadas ao longo da camada híbrida em todos os grupos. Não houve diferença entre os valores de μTBS de 24 h e 6 meses para EXP+PA; além disso, EXP+PA apresentou maiores valores de μTBS após 6 meses em comparação com TE e EXP (p <0,05). Os resultados sugerem que a biomodificação por 15 s não foi suficiente para reduzir significativamente a atividade de MMP; apesar disso, EXP + PA foi capaz de melhorar a estabilidade da interface resina-dentina em comparação com sistemas total- e self-etch comerciais.

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.

Collagen cross-linking agents + dimethyl sulfoxide improving the adhesive properties of erosive lesion dentin

Abstract To investigate the effect of the dimethyl sulfoxide combined with cross-linking agents on microtensile bond strength, silver nitrate penetration and in situ degree of conversion analysis of adhesives to the erosive dentin treatment with Cola-based soft drink. One hundred and sixty-six molars were assigned to 20 groups: (1) Treatment: Sound dentin; Erosive dentin; Erosive dentin treated with primer of dimethyl sulfoxide; Erosive dentin treated with DMSO primer containing proanthocyanidin and rivoflavin; (2) Adhesive systems: iBond Universal and Scotchbond Universal; and (3) adhesive strategy: etch-and-rinse or self-etch strategy. After restoration, specimens were sectioned into sticks to be tested. The data from microtensile bond strength (MPa), silver nitrate penetration (%) and in situ degree of conversion (%) were analyzed by (three- and two-factor ANOVA; Tukey's test α=5%). The application of dimethyl sulfoxide combined of not with cross-linkers improved all properties evaluated when compared to only erosive dentin treatment with Cola-based soft drink. However, only when dimethyl sulfoxide was combined to cross-linkers, the values of the microtensile bond strength, silver nitrate penetration and in situ degree of conversion in erosive dentin treatment with Cola-based soft drink was similar to sound dentin, for both adhesives and adhesive strategies. The application of dimethyl sulfoxide combined with the collagen cross-linking agent contributed to increasing the bond strength and degree of conversion in erosive lesion dentin, at the same time that significantly reduction of nanoleakage in this substrate.

Resumo Este estudo investigou o efeito do dimetil sulfóxido combinado a agentes de reticulação de colágeno na resistência de união à microtração, infiltração de nitrato de prata e análise do grau de conversão por Micro-Raman de sistemas adesivos universais para a dentina erosionada por refrigerante a base de Cola. Cento e sessenta molares foram divididos em 20 grupos: (1) Tratamento: Dentina sadia; Dentina erosionada; Dentina erosionada tratada com primer de dimetil sulfóxido; Dentina erosionada tratada com primer contendo 6,5% de proantocianidina e; Dentina erosionada tratada com primer contendo 0,1% de rivoflavina; (2) Sistemas adesivos: iBond Universal e Scotchbond Universal; e (3) estratégia adesiva: estratégia condicionamento e lavagem ou autocondicionate. Após a restauração, os espécimes foram seccionados em palitos e testados. Os dados dos três testes foram analisados estatisticamente (ANOVA de 2 e 3 fatores e teste de Tukey; α = 5%). A aplicação de dimetil sulfóxido combinado ou não agentes de reticulação de colágeno melhorou todas as propriedades avaliadas quando comparado a dentina erosionada. Entretanto, apenas quando o dimetil sulfóxido foi combinado com agentes de reticulação de colágeno, os valores de adesão a dentina, infiltração de nitrato de prata e grau de conversão em dentina erosionada foi semelhante a dentina sadia, para os dois adesivos e estratégias adesivas. A aplicação de dimetil sulfóxido combinado com agentes de reticulação de colágeno contribuiu para aumentar a resistência de união e o grau de conversão dentro da camada híbrida na dentina erodida, ao mesmo tempo que reduziu significativamente a nanoinfiltração neste substrato.

Effect of bioactive glass pretreatment on the durability of dentin bonding interface / 北京大学学报(医学版)

OBJECTIVE@#To study the effect of bioactive glass (BG) on the dentin bond strength and the microleakage of hybrid layer.@*METHODS@#In the study, 30 dentin planes were prepared from the third molars with no caries and equally assigned to the control group, BG group, and sodium trimetaphosphate (STMP)-polyacrylic acid (PAA)-BG group (S-P-BG group), randomly. After etched with 35% phosphoric acid, the dentin planes of BG group were pretreated with 0.5 g/L BG, and the dentin planes of S-P-BG group were pretreated with 5% STMP, 5% PAA and 0.5 g/L BG. No additional pretreatment was done to the dentin planes of control group. Then the dentin planes were bonded using 3M Single Bond 2 adhesive to 3M Z350XT composite resin, and cut into 0.9 mm×0.9 mm column samples, which were stored at 37 ℃ artificial saliva (AS). After 24 hours, 1 month, and 3 months, the microtensile bond strength test was performed. The data were analyzed using one-way ANOVA and LSD method. The morphology of the bond fracture interface was observed with scanning electron microscope. Other 27 teeth were collected and the enamel layer and roots cut off, with the pulp chamber exposed. 0.1% rhodamine B was added to the 3M Single Bond 2 adhesive, and then the adhesive was applied to complete the bonding procedures as above. The teeth were stored in 37 ℃ AS for 24 hours, 1 month, 3 months, and then 0.1% sodium fluorescein solution was placed in the chambers and stained for 1 hour. Confocal laser scanning microscopy was used to observe the interface morphology and microleakage of the hybrid layer.@*RESULTS@#At the end of 24 hours and 1 month, there was no significant difference in the microtensile bond strength among the three groups (P>0.05). After 3 months of soaking, the S-P-BG group [(36.91±7.07) MPa] had significantly higher microtensile bond strength than the control group [(32.73±8.06) MPa] (P=0.026); For the control group and the BG group, the microtensile bond strength significantly decreased at the end of 3 months compared with 24 hours (control group: P=0.017, BG group: P=0.01); The microtensile bond strength of S-P-BG group af the end of 3 months had no significant difference in compared with 24 hours [(37.99±7.98) MPa] (P>0.05). Observation of the fracture surface at the 24 hours showed no obvious mineralization in all the three groups. After 1 and 3 months, mineral formation was observed in BG group and S-P-BG group, and no obvious collagen exposure was observed in S-P-BG group. Confocal laser scanning microscopy revealed no obvious differences in the morphology and quantity of the resin tag in the control group, BG group and S-P-BG group. At the end of 24 hours, leakage was found in all the three groups. The microleakage of the control group increased at the end of 3 months, while the microleakage of the BG and S-P-BG groups decreased.@*CONCLUSION@#BG pretreatment of dentin bonding interface can induce mineralization at the bonding interface and reduce the microleakage of the hybrid layer; pretreating the dentin bonding interface with STMP, PAA and BG may enhance the maintaining of the dentin bonding durability.

Evaluation of microtensile bond strength between resin composite and glass ceramic / 北京大学学报(医学版)

OBJECTIVE@#To evaluate the microtensile bond strength of resin composite to glass ceramic, and the effect of surface treatment of resin composite and thermal cycling aging on the microtensile bond strength.@*METHODS@#Rectangular blocks were made with dentin of extracted molars, resin composite or feldspathic glass ceramic respectively. The bonding surfaces of these rectangular blocks were sanded by 600-grit silicon carbide paper before luting. A self-etching resin cement was used as luting agent. The specimens were divided into groups according to the types of substrates of adhesion (dentin/glass ceramic or resin composite/glass ceramic), the way of surface treatments and whether thermal cycling aging ocurred. The dentin blocks were adhered to ceramic blocks as controls (group A1 and A2). The resin composite blocks were adhered to the ceramic blocks as experiment groups. The resin composite surfaces were treated by different ways before luting: no extra surface treatment (group B1 and B2), treated by ethyl methacrylate solution (group C1 and C2) or silane coupling agent (group D1 and D2), coarsened by 360-grit silicon carbide paper (group E1 and E2) or polished by 1 200-grit silicon carbide paper (group F1 and F2). After luting, the microtensile bond strength of the specimens were tested before (group A1-F1) or after (group A2-F2) thermal cycling aging. After microtensile bond strength test, the fracture bonding surfaces of the specimens were observed by a scanning electron microscopy to determine the type of bonding failure. The data were statistically analyzed using one-way analysis of variance.@*RESULTS@#The microtensile bond strength of resin composite to glass ceramic with no extra treatment achieved high bond values before and after thermal cycling [B1 (30.02±3.85) MPa, B2 (26.83±3.14) MPa], which were statistically different from those of the control groups [A1 (20.55±4.51) MPa, A2 (12.94±0.69) MPa, P < 0.05]. The microtensile bond strength between the glass ceramic and resin composite did not increase after different surface treatments of resin composite.@*CONCLUSIONS@#The microtensile bond strength between resin composite and glass ceramic achieved as similar bond strength as that between dentin and glass ceramic and even better. Surface treatment of resin composite via methyl methacrylate solution, silane coupling agent, coarsening, or polishing did not increase the microtensile bond strength effectually.

Dental adhesive microtensile bond strength following a biofilm-based in vitro aging model

Abstract Laboratory tests are routinely used to test bonding properties of dental adhesives. Various aging methods that simulate the oral environment are used to complement these tests for assessment of adhesive bond durability. However, most of these methods challenge hydrolytic and mechanical stability of the adhesive- enamel/dentin interface, and not the biostability of dental adhesives. Objective To compare resin-dentin microtensile bond strength (μTBS) after a 15-day Streptococcus mutans (SM) or Streptococcus sobrinus (SS) bacterial exposure to the 6-month water storage (WS) ISO 11405 type 3 test. Methodology A total of 31 molars were flattened and their exposed dentin was restored with Optibond-FL adhesive system and Z-100 dental composite. Each restored molar was sectioned and trimmed into four dumbbell-shaped specimens, and randomly distributed based on the following aging conditions: A) 6 months of WS (n=31), B) 5.5 months of WS + 15 days of a SM-biofilm challenge (n=31), C) 15 days of a SM-biofilm challenge (n=31) and D) 15 days of a SS-biofilm challenge (n=31). μTBS were determined and the failure modes were classified using light microscopy. Results Statistical analyses showed that each type of aging condition affected μTBS (p<0.0001). For Group A (49.7±15.5MPa), the mean μTBS was significantly greater than in Groups B (19.3±6.3MPa), C (19.9±5.9MPa) and D (23.6±7.9MPa). For Group D, the mean μTBS was also significantly greater than for Groups B and C, but no difference was observed between Groups B and C. Conclusion A Streptococcus mutans- or Streptococcus sobrinus-based biofilm challenge for 15 days resulted in a significantly lower μTBS than did the ISO 11405 recommended 6 months of water storage. This type of biofilm-based aging model seems to be a practical method for testing biostability of resin-dentin bonding.

Microtensile Bond Strength and Failure Type Analysis of Self-Etch Adhesive Systems on Superficial and Deep Dentin After Long-term Water Storage / Análise de resistência de adesão à microtração e tipo de falha de sistemas adesivos autocondicionantes em dentina superficial e profunda após armazenamento longitudinal em água

Objective: The aim of this study was to evaluate and compare the microtensile bond strengths of four current adhesive materials that contain different monomers at deep and superficial dentin. Material and Methods: Forty non-carious human third molars (n=5) were used in the study. Specimens were divided into two main groups according to dentin thickness as superficial and deep dentin. Groups were further divided into four subgroups in terms of the adhesive systems used: Nova Compo B Plus (NCBP), Nova Compo B (NCB), Futurabond M (FB) and Clearfil S3 Bond Plus (CS3). All specimens were bonded to resin composite and stored in 37 °C water for 9-months. Teeth were sectioned into 3 x 3 mm thick beams. Microtensile bond strength test was carried out by using a universal testing device (1 mm/min). After fracture, failure types were observed using an optical microscope and the fractured dentin surfaces were observed by a scanning electron microscopy (SEM). One-way ANOVA and Tukey tests were used to compare the adhesive system in each dentin group. An unpaired T-test was used to compare the dentin thickness in each adhesive material. Results: As compared to deep dentin, superficial dentin showed higher µTBS values in groups NCBP, FB and CS, as opposed to group NCB. Only NCB revealed higher bond strength at deep dentin layers when compared to superficial dentin. In the superficial dentin group, NCBP showed the highest bond strength value while NCB showed the lowest bond strength. In the deep dentin group, while NCB showed the highest bond strength value, NCBP revealed the lowest bond strength value after 9-months storage. While 4-META and 10-MDP monomer combination (NCBP) resulted in the highest bond strength value among the adhesive systems in the superficial dentin group, the GPDMA and 4-META monomer combination (NCB) resulted in the highest bond strength in deep dentin group. Conclusions: Microtensile bond strength performance are affected by both the type of monomer in the adhesive combination and the depth of the dentin. (AU)

Objetivo: o objetivo deste estudo foi avaliar e comparar a resistência de união à microtração de quatro materiais adesivos atuais que contêm monômeros diferentes na dentina profunda e superficial. Material e Métodos: Quarenta terceiros molares humanos não cariados (n = 5) foram usados no estudo. Os espécimes foram divididos em dois grupos principais de acordo com a espessura da dentina em superficial e profunda. Os grupos foram subdivididos em quatro subgrupos quanto aos sistemas adesivos usados: Nova Compo B Plus (NCBP), Nova Compo B (NCB), Futurabond M (FB) e Clearfil S3 Bond Plus (CS3). Todos os espécimes foram aderidos à resina composta e armazenados em água a 37 ° C por 9 meses. Os dentes foram seccionados em palitos de 3 x 3 mm de espessura. O teste de microtração foi realizado com o uso de um dispositivo de teste universal (1 mm / min). Após a fratura, os tipos de falha foram observados em microscópio óptico e as superfícies de dentina fraturadas por microscopia eletrônica de varredura (MEV). Os testes ANOVA e Tukey um fator foram usados para comparar o sistema adesivo em cada grupo de dentina. Um teste T não pareado foi usado para comparar a espessura da dentina em cada material adesivo. Resultados: Em comparação com a dentina profunda, a dentina superficial apresentou maiores valores de µTBS nos grupos NCBP, FB e CS, ao contrário do grupo NCB. Apenas NCB revelou maior resistência de união na dentina profunda quando comparada à dentina superficial. No grupo de dentina superficial, NCBP apresentou o maior valor de resistência de união, enquanto NCB apresentou a menor resistência de união. No grupo de dentina profunda, enquanto NCB apresentou o valor de resistência de união mais alto, NCBP revelou o valor de resistência de união mais baixo após 9 meses de armazenamento. Enquanto a combinação de monômero 4-META e 10-MDP (NCBP) resultou no maior valor de resistência de união entre os sistemas adesivos no grupo de dentina superficial, a combinação de monômero (NCB) resultou na maior força de união no grupo de dentina profunda. Conclusões: O desempenho da resistência de união à microtração é afetado tanto pelo tipo de monômero na combinação adesiva quanto pela profundidade da dentina. (AU)

The influence of different surface treatment protocols and bonding agents on the repair microtensile bond strength of six-month' aged composite: An in vitro study / A influência de diferentes protocolos de tratamento de superfície e agentes de união na resistência de união à microtração de reparo de compósito envelhecido por seis meses: um estudo in vitro

Objective: To compare the effect of three surface treatment protocols and two intermediate agents on repairing aged composite, regarding microtensile bond strength (µTBS) and mode of fracture, at two time intervals. Material and methods: Six-monthaged microhybrid composite blocks, were randomly distributed into three groups, subjected to; Fine, Super Fine grit diamond burs or Erbium- Yag Laser surface treatment. Each block had both One Coat bond SL (Bond) and Brilliant Flow flowable composite (Flow) intermediate agents, alongside. Blocks were incrementally repaired using nanohybrid composite, cut into beams, then randomly subjected either immediately (IM) to µTBS test or after thermocycling (TC) for 5000 cycle. Mode of failure was determined using stereomicroscope. Data were analyzed through three-way ANOVA followed by pairwise comparison with Bonferroni correction. Kruskal Wallis test compared groups for failure mode analysis (α=0.05) Results: Super Fine grit showed the highest mean µTBScompared to control for both intermediate agents, IM and after TC at P<0.05. No difference between Fine grit and Laser application for all groups (P>0.05). IM, Bond showed the highest µTBS compared to TC, Flow for all tested groups. Beams roughened with Fine and Super Fine burs showed significantly lower adhesive failures than those roughened with Laser. Flow suffers significantly higher adhesive failure than those with Bond. For TC tested groups; beams with Super Fine bur and Bond showed significantly lower adhesive failure at P=0.029. Conclusion: Super Fine grit and Bond provide the highest µTBS and the least adhesive failure; moreover TC resulted in significant decrease in µTBS (AU)

Objetivo: Comparar o efeito de três protocolos de tratamento de superfície e dois agentes intermediários no reparo de compósito envelhecido, quanto à resistência à microtração (µTBS) e modo de fratura, em dois intervalos de tempo. Material e métodos: Blocos de compósito microhíbrido envelhecidos por seis meses, foram distribuídos aleatoriamente em três grupos, submetidos a; Pontas diamantadas de granulação Fina, Superfina ou tratamento de superfície com laser de Erbio-Yag. Cada bloco tinha ambos os agentes intermediários One Coat bond SL (Adesivo) ao lado de Brilliant Flow (Resina Fluida). Os blocos foram reparados de forma incremental usando compósito nanohíbrido, cortados em palitose, em seguida, submetidos aleatoriamente imediatamente (IM) ao teste de µTBS ou após termociclagem (TC) por 5000 ciclos. O modo de falha foi determinado usando estereomicroscópio. Os dados foram analisados por meio de ANOVA de três fatores, seguida de comparação pareada com correção de Bonferroni. O teste de Kruskal Wallis comparou os grupos para análise do modo de falha (α = 0,05). Resultados: a granulação Super fina apresentou a maior média de µTBS em comparação com o controle para ambos os agentes intermediários, IM e após TC (P <0,05). Não houve diferença entre granulação fina e aplicação de laser para todos os grupos (P> 0,05). IM, Adesivo apresentou a µTBS mais alta em comparação com TC, Resina Fluida para todos os grupos testados. Os palitos asperizados com pontas de granulações Fina e Superfina apresentaram falhas adesivas significativamente menores do que as asperizadas com Laser. Resina Fluida sofreu falhas adesivas significativamente maiores do que aquelas com Adesivo. Para grupos testados TC; palitos tratados com ponta Superfina e Adesivo apresentaram falha adesiva significativamente menor com P = 0,029. Conclusão: a granulação Superfina e o Adesivo fornecem a maior µTBS e o mínimo de falha adesiva; além disso, o TC resultou em uma diminuição significativa da µTBS. (AU)

Effect of chitosan nanoparticles on microtensile bond strength of resin composite to dentin: an in vitro study / Efeito de nanopartículas de quitosana na resistência a união por microtração da resina composta à dentina: um estudo in vitro

Objective: The purpose of this study was to evaluate the effect of chitosan nanoparticles on microtensile bond strength of resin composite to dentin using self etch adhesive after aging. Material and Methods: A total number of 90 freshly extracted, sound human molar teeth. Flat tooth surface was gained after cut of the occlusal surface. Three main groups according to pretreatment of dentin before adhesive application; 0.2 % chitosan, 2.5 % chitosan and no treatment control group. Universal self etch adhesive were applied according to manufacture instruction and 4 mm of Feltik Z250 xt composite. Storage of specimens for 1 day, 3 months and 6 months in 37O C distilled water. After that, the tooth was sectioned to beams of 1 mm x8 mm sticks for microtensile bond strength test using universal testing machine. Scanning electron microscope (SEM) was used to evalute the effect of chitosan nanoparticles on dentin and smear layer. Kruskal-Wallis test was used to compare between the three groups as well as the three aging periods. Dunn's test was used for pair-wise comparisons. The significance level was set at P ≤ 0.05. Results: chitosan 0.2% is statistically significant increase in bond strength than chitosan 2.5% and control in one day group. Three months chitosan 0.2 % groups have statistically significant increase in bond strength than chitosan 2.5%. It was found in 6 months that control and chitosan 0.2 % have statistically significant increase in bond strength than chitosan 2.5%. There was statistically significant difference found between the three studied groups regarding bond strength at different storage times . Conclusion: Microtensile bond strength was influenced by different chitosan concentration. Different aging periods had no effect on the microtensile bond strength without application of chitosan and with application of 2.5% chitosan concentration. (AU)

Introdução: O objetivo deste estudo foi avaliar o efeito das nanopartículas de quitosana na resistência da microtração de união do compósito de resina à dentina usando adesivo autocondicionante após o envelhecimento. Material e Métodos: Foram utilizados um total de 90 dentes molares humanos extraídos e sadios. A superfície plana do dente foi obtida após o corte da superfície oclusal. Os dentes foram divididos em três grupos principais de acordo com o pré-tratamento da dentina e antes da aplicação do adesivo: 0,2% de quitosana, 2,5% de quitosana e nenhum tratamento foi utilizado no grupo controle. O adesivo autocondicionante universal foi aplicado de acordo com as instruções do fabricante e 4 mm de composito Feltik Z250 xt foi inserido. O armazenamento de amostras foi realizado por 1 dia, 3 meses e 6 meses em água destilada a 37 °C. Depois disso, o dente foi seccionado em peças de 1 mm x 8 mm para teste de resistência de união por microtração, utilizando máquina de teste universal. Microscópio eletrônico de varredura (MEV) foi usado para avaliar o efeito das nanopartículas de quitosana na dentina e na camada de smear layer. O teste de Kruskal-Wallis foi utilizado para comparar os três grupos e os três períodos de envelhecimento. O teste de Dunn foi usado para comparação pareada dos grupos. O nível de significância foi estabelecido em P ≤ 0,05. (AU)

Different Concentrations of Ethanol as Dentin Pre-treatment to Bonding of an Etch-and-rinse Adhesive / Diferentes Concentrações de Etanol como Pré-Tratamento da Dentina na adesão de um Adesivo Convencional

Objective: to evaluate the bond strength (BS) to dentin pre-treated with ethanol in single application for 20 s after etching and before application of a two-step etch-and-rinse adhesive and to analyze the morphological features at the resin-dentin interface. Methods: twenty four third molars were collected and randomly assigned into four groups (n=5) according to the ethanol concentration: control (traditional water-wet technique), 50vol%, 70vol% and 100vol%. In experimental groups, ethanol was applied for 20 s and gently air-dried for 5 s. Bonding procedures were performed and resin composite was built up incrementally. Bonded teeth were sectioned into 0.8mm2 sticks on average. These specimens were submitted to microtensile bond strength test (µTBS). One-way ANOVA and post hoc Tukey's test were applied to analyze statistical data (α=0 05). Light microscopy (LM) assisted by Masson's trichrome staining was used to observe the features of resin/dentin interfaces. Results: control BS was not different from ethanol 50vol% (p>0.05). However, the pre-treatment using ethanol 70vol% and 100vol% showed increase on BS (p<0.001 and p=0.003 respectively) with no difference between these two groups. LM Showed a discrete decrease in denuded collagen fibrils to teeth treated with 70vol% and 100vol%. Conclusion: the pre-treatment of dentin using ethanol may increase the initial BS of resin/dentin interface when applied using 70vol% or 100vol% ethanol. Ethanol 70vol% is also able to decrease the thickness of the resin-sparse collagen fibrils.

Objetivo: avaliar a resistência de união (RU) à dentina pré-tratada com etanol em aplicação única por 20 s após condicionamento e antes da aplicação de um adesivo convencional de dois passos e analisar as características morfológicas na interface resina-dentina. Métodos: vinte e quatro terceiros molares foram coletados e distribuídos aleatoriamente em quatro grupos (n = 5) de acordo com a concentração de etanol: controle (técnica tradicional - úmida), 50%, 70% e 100%. Em grupos experimentais, o etanol foi aplicado por 20 s e gentilmente seco ao ar por 5 s. Procedimentos de colagem foram realizados e a restauração em resina composta foi construída de forma incremental. Os espécimes foram seccionados em palitos com média de 0,8 mm2 e submetidos ao teste de resistência à microtração (µTBS). One-way ANOVA e teste post hoc de Tukey foram aplicados para analisar os dados (α = 0,05). Microscopia ótica (MO) auxiliada pela coloração tricrômica de Masson foi usada para observar as características das interfaces resina-dentina. Resultados: a RU do controle não foi diferente do etanol a 50% (p > 0,05). No entanto, o pré-tratamento utilizando etanol a 70% e 100% apresentou aumento na RU (p < 0,001 e p = 0,003 respectivamente) sem diferença entre esses dois grupos. MO apresentou uma diminuição discreta nas fibrilas de colágeno desnudadas nos dentes tratados com 70% e 100%. Conclusão: o pré-tratamento da dentina usando etanol pode aumentar a RU inicial da interface resina-dentina quando aplicado nas concentrações de 70% ou 100%. O etanol a 70% também é capaz de diminuir a espessura das fibrilas de colágeno-resina esparsas.

Effect of Saliva Decontamination on Bond Strength of 1-step Self-etching Adhesives to Dentin of Primary Posterior Teeth / 대한소아치과학회지

The purpose of this study was to evaluate effect of saliva decontamination procedures on microtensile bond strength (MTBS) of 1-step self-etching adhesives to dentin of primary posterior teeth.63 sound primary-posterior teeth were randomly divided into 3 groups according to different kinds of 1-step self-etching adhesives: Scotchbond™ Universal Adhesive (SBU), All-Bond Universal® (ABU), and Tetric® N Bond Universal (TBU). Each group was randomly categorized into 7 subgroups: (I) application of adhesive without saliva contamination (control); (II – IV) contamination by saliva before photopolymerization; (V – VII) contamination by saliva after photopolymerization; (II, V) decontamination by drying; (III, VI) decontamination by washing and drying; (IV, VII) decontamination by washing, drying, and reapplication of adhesive. All samples were cut into the blocks. At least 15 blocks were tested for each subgroup.For SBU and ABU, the MTBS values of subgroups (I, IV, VII) were significantly higher than those of subgroups (II, III, V, VI). For TBU, the MTBS values of subgroups (I, IV) was significantly higher than those of subgroup (II, III, V, VI).The MTBS of 3 adhesives was reduced by saliva contamination. The adhesive strength on dentin of primary posterior teeth was restored by reapplication of the adhesives after washing and drying.

The effects of deproteinization and primer treatment on microtensile bond strength of self-adhesive resin cement to dentin / 대한치과재료학회지

The purpose of this study was to evaluate the effects of deproteinization and an additional primer treatment on the microtensile bond strength of a newly developed self-adhesive resin cement to dentin. The occlusal dentin of extracted human third molars was randomly divided into four groups according to the surface treatment: a control (CON) with no treatment; applying a deproteinizing agent (DPT) (5% sodium hypochlorite); using a primer (PRI) (G-CEM ONE Adhesive enhancing primer, GC); and applying a deproteinizing agent and a primer (DPT-PRI). Composite resin blocks with a disk shape (diameter, 10 mm; height, 4 mm) were bonded to the treated dentin using a self-adhesive resin cement (G-CEM ONE, GC). The specimens were sectioned into sticks with a cross-section of 1 mm² and tested to failure in tension mode at a crosshead speed of 1 mm/min. All groups showed a significantly higher microtensile bond strength compared to CON (p0.05). Within the limitations of this study, a deproteinizing agent or specific primer can enhance the microtensile bond strength of the self-adhesive resin cement to dentin. However, it is not recommended to use a primer in combination with the deproteinizing agents.

Effect of dentin preparation mode on the bond strength between human dentin and different resin cements

Abstract The aim was to evaluate the influence of different dentin preparation mode in the smear layer characteristics (SL), hybrid layer (HL), and microtensile bond strength (µTBS) to dentin with two resin cements. The occlusal dentin of 120 third molars was exposed. The teeth were divided into 4 groups (n=30) according to the dentin preparation mode: 1- fine grain diamond bur; 2- coarse grain diamond bur; 3- multi laminate carbide steel bur; and, 4- ultrasonic CV Dentus diamond bur. Each treated dentin group was divided into 2 sub-groups (n=15) according to the resin cement: (1) RelyX U200 and (2) RelyX ARC. Resin composite blocks were cemented on dentin. After storage at 37o C for 24 h, beams with a cross section area of 1.0 mm2 were obtained, and tested in a universal testing machine at a crosshead speed of 0.5 mm/min. Two additional teeth for each sub-group were prepared to analyze the SL and HL on a scanning electron microscopy. According to Kruskal-Wallis test and Dunn tests, there was no significant difference in µTBS among the rotary instruments within each resin cement group. RelyX ARC obtained higher µTBS values compared to RelyX U200 (p<0.05). RelyX ARC formed evident HL, which was not observed for RelyX U200. The dentin mode preparation did not influence the µTBS of the resin cements. The SL was different for all instruments. The cementing agent is more determinant in the hybrid layer formation and bond strength to dentin than the instruments applied on dentin.

Resumo O objetivo deste estudo foi avaliar a influência de diferentes modos de preparação da dentina nas características da smear layer (SL), da camada híbrida (CH) e na resistência de união à microtração (RUµT) à dentina com dois cimentos resinosos. A dentina oclusal de 120 terceiros molares humanos foi exposta. Os dentes foram divididos em 4 grupos (n=30) de acordo com o modo de preparação da dentina: 1 - ponta diamantada de granulação fina; 2 - ponta diamantada de granulação grossa; 3 - ponta de carboneto de aço multilaminada; 4 - ponta diamantada ultrassônica. Cada grupo foi subdividido em dois subgrupos (n=15) de acordo com o cimento resinoso: (1) RelyX U200 e (2) RelyX ARC. Blocos de resina composta foram cimentados na dentina. Após armazenamento a 37 °C por 24 h, as amostras foram cortadas para obter palitos com área de 1,0 mm2, os quais foram testados em máquina de ensaio universal com velocidade de 0,5 mm/min. Dois dentes adicionais por subgrupo foram preparados para analisar as características da SL e da CH em microscópio eletrônico de varredura. De acordo com o teste de Kruskal-Wallis e o teste de Dunn, não houve diferença significativa na RUµT entre os instrumentos rotatórios para cada cimento resinoso. RelyX ARC obteve maiores valores de RUµT em comparação ao RelyX U200 (p<0,05). RelyX ARC formou uma CH evidente, o que não foi observado para o RelyX U200. O modo de preparação da dentina não influenciou na RUµT dos cimentos resinosos. A SL foi diferente para todos os instrumentos. O agente de cimentação foi mais determinante na formação da camada híbrida e na resistência de união do que os instrumentos utilizados para preparar a dentina.

Evaluation of bioflavonoids on the immediate and delayed microtensile bond strength of self-etch and total-etch adhesive systems to sound dentin

Aim: This study aims to evaluate the effect of two bioflavonoids (epigallocatechin-3-gallate [EGCG] and catechin) and a protein inhibitor (chlorhexidine [CHX]) on the immediate and delayed microtensile bond strength of self-etch and total-etch adhesive systems to sound dentin. Materials and Methods: The occlusal surfaces of 96 mandibular human third molar teeth specimens were ground after removal of the excess tissues, to expose the middle dentin. The dentin specimens were randomly allocated into four groups, each consisting of 24 teeth (n = 24) according to the application of the enzyme inhibitor. The adhesive system used in this study was Adper easy bond, a self-etch adhesive system, and Adper Single Bond 2, a total-etch adhesive system. Microtensile bond strength testing was conducted using thermocycler 2000, Heto-Holten A/S. Results: All the three enzyme inhibitors increase the bond strength values of the resin–dentin interphase when used during dentin bonding. The EGCG enzyme inhibitor has shown the highest immediate bond strength to dentin when used with both the adhesive systems.

The effect of sandblasting duration on the bond durability of dual-cure adhesive cement to CAD/CAM resin restoratives

PURPOSE: To evaluate the effect of prolonged sandblasting on the bond durability of dual-cure adhesive resin cement to computer-aided design and computer-aided manufacturing (CAD/CAM) restoratives. MATERIALS AND METHODS: Nano-ceramic LAVA Ultimate and hybrid-ceramic VITA Enamic CAD/CAM blocks were used for this study. Each CAD/CAM block was sectioned into slabs of 4-mm thickness for the microtensile test (µTBS) test and 2-mm thickness for the surface roughness test. Three groups were created according to the sandblasting protocols; group 1: specimens were sandblasted for 15 seconds, group 2: specimens were sandblasted for 30 seconds, and group 3: specimens were sandblasted for 60 seconds. After sandblasting, all specimens were luted using RelyX Ultimate Clicker. Half the specimens were subjected to µTBS tests at 24 hours, and the other half were subjected to tests after 5000 thermocycles. Additionally, a total of 96 CAD/CAM block sections were prepared for surface roughness tests and scanning electron microscopy (SEM) evaluations. The Mann-Whitney U test, Kruskal-Wallis one-way analysis of variance, and Dunn's post hoc test were used to compare continuous variables among the groups. RESULTS: At baseline, group 1, group 2, and group 3 exhibited statistically similar µTBS results for LAVA. However, group 3 had significantly lower µTBS values than groups 1 and 2 for VITA. After 5000 thermocycles, µTBS values significantly decreased for each block (P < .05). CONCLUSION: It is important to perform controlled sandblasting because it may affect bond strength results. Sixty seconds of sandblasting disturbs the initial µTBS values and the stability of adhesion of CAD/CAM restoratives to dual-cure adhesive resin cement for VITA Enamic.

Evaluation of Microtensile Bond Strength of Sealant Depending on the Duration of Etching and the Use of Bonding Agent / 대한소아치과학회지

The aim of this study was to evaluate the effect of etching time and bonding agents on bond strength of sealant applied to the occlusal surface of primary molars.Forty non-carious exfoliated human primary molars were included in the study. The teeth were randomly divided into 4 groups for measurement. For group I, no acid etching treatment was used. For group II, III, and IV, acid etching gels were applied on the occlusal surface for 15, 30, and 60 seconds, respectively. Each group was divided into 2 subgroups; one group was treated with bonding agents on the enamel while the other was not. Microtensile bond strength was evaluated using a universal testing machine.There were no statistically significant differences in bond strength with varying duration of etching among groups. The results revealed that the use of bonding agents prior to application of fissure sealant increased the bond strength(p < 0.05).It could be concluded that etching time greater than 15 seconds does not significantly enhance the bond strength, but the use of bonding agents as an intermediate layer between the primary molar and fissure sealant would be beneficial in increasing the bond strength.

Microtensile bond strength of CAD/CAM-fabricated polymer-ceramics to different adhesive resin cements

OBJECTIVES: This study evaluated the microtensile bond strength (µTBS) of polymer-ceramic and indirect composite resin with 3 classes of resin cements. MATERIALS AND METHODS: Two computer-aided design/computer-aided manufacturing (CAD/CAM)-fabricated polymer-ceramics (Enamic [ENA; Vita] and Lava Ultimate [LAV; 3M ESPE]) and a laboratory indirect composite resin (Gradia [GRA; GC Corp.]) were equally divided into 6 groups (n = 18) with 3 classes of resin cements: Variolink N (VAR; Vivadent), RelyX U200 (RXU; 3M ESPE), and Panavia F2 (PAN; Kuraray). The μTBS values were compared between groups by 2-way analysis of variance and the post hoc Tamhane test (α = 0.05). RESULTS: Restorative materials and resin cements significantly influenced µTBS (p < 0.05). In the GRA group, the highest μTBS was found with RXU (27.40 ± 5.39 N) and the lowest with VAR (13.54 ± 6.04 N) (p < 0.05). Similar trends were observed in the ENA group. In the LAV group, the highest μTBS was observed with VAR (27.45 ± 5.84 N) and the lowest with PAN (10.67 ± 4.37 N) (p < 0.05). PAN had comparable results to those of ENA and GRA, whereas the μTBS values were significantly lower with LAV (p = 0.001). The highest bond strength of RXU was found with GRA (27.40 ± 5.39 N, p = 0.001). PAN showed the lowest µTBS with LAV (10.67 ± 4.37 N; p < 0.001). CONCLUSIONS: When applied according to the manufacturers' recommendations, the µTBS of polymer-ceramic CAD/CAM materials and indirect composites is influenced by the luting cements.

In-vitro comparative study of the use of 2 % chlorhexidine on microtensile bond strength of different dentin adhesives: a 6 months evaluation / Estudio comparativo in vitro del uso de clorhexidina al 2 % sobre la resistencia de unión microtensil de diferentes adhesivos dentinarios: una evaluación de 6 meses

The aim of this study was to evaluate the effect of chlorhexidine (CHX) dentin treatment on microtensile bond strength (µTBS) of adhesive systems in different storage times. Occlusal enamel was removed from ninety third-molars and flat surfaces of middle dentin were exposed. Teeth were randomly divided in 6 groups according to adhesive system (etch-and-rinse : Adper Scotchbond 1XT - ASB ; self-etch: Adper Prompt L-Pop ­ APP; and universal: Single Bond Universal - SBU) and chlorhexidine (CHX) dentin treatment (2 % CHX application for 20 s prior Primer). After resin composite build up, teeth were sectioned to obtain beam specimens and divided in 3 subgroups (n=5): 72h, 3 and 6 months storage times. After the storage times, teeth were tested in tension until failure (0.5 mm/min). SEM was performed to observe hybrid layer of adhesive systems. Data were analyzed using one-way ANOVA and Tukey tests. At 72 h, all equivalent groups (same adhesive system, different dentin treatments) maintained their µTBS when compared CHX-treatment. At 3 and 6 months, non-treated CHX groups showed less µTBS than CHX-treated ones. Six months storage time did not significantly decrease µTBS, except for G2-ASB. The effect of CHX on dentin µTBS depends on storage times and adhesive systems. While immediate µTBS was not affected by CHX treatment, CHX improved dentin µTBS after 3 and 6 months.

El objetivo de este estudio fue evaluar el efecto del tratamiento con clorhexidina (CHX) de la dentina sobre la resistencia de la unión microtensil (mTBS) de los sistemas adhesivos en diferentes tiempos de almacenamiento. Se retiró el esmalte oclusal de noventa terceros molares y se expusieron superficies planas de la dentina media. Los dientes se dividieron al azar en 6 grupos de acuerdo con el sistema adhesivo (con grabado ácido: Adper Scotchbond 1XT-ASB, auto-grabado: Adper Prompt L-Pop-APP y universal: Single Bond Universal- SBU) y el tratamiento de la dentina con clorhexidina (CHX) (aplicación de CHX al 2 % 20 s antes del Primer). Después de la aplicación de la resina compuesta, los dientes fueron seccionados para obtener muestras en forma de barras y divididos en 3 subgrupos (n = 5) con tiempos de almacenamiento de 72 h, 3 y 6 meses. Después de los tiempos de almacenamiento, los dientes se sometieron a tensión hasta la fractura (0,5 mm / min). SEM se realizó para observar la capa híbrida de sistemas adhesivos. Los datos se analizaron mediante ANOVA unidireccional y pruebas de Tukey. A las 72 h, todos los grupos equivalentes (el mismo sistema adhesivo, diferentes tratamientos de dentina) mantuvieron su mTBS cuando se comparó el tratamiento CHX. A los 3 y 6 meses, los grupos CHX no tratados mostraron menos mTBS que los tratados con CHX. Seis meses de tiempo de almacenamiento no disminuyó significativamente el mTBS, excepto para el G2-ASB. El efecto de CHX sobre la dentina mTBS depende del tiempo de almacenamiento y de los sistemas adhesivos. Mientras que el mTBS inmediato no se vio afectado por el tratamiento con CHX, CHX mejoró la mTBS a dentina después de 3 y 6 meses.

Influence of Different Dentin Substrate (Caries-Affected, Caries-Infected, Sound) on Long-Term muTBS

Abstract The aim of this study was to evaluate the μTBS in different dentin substrates and water-storage periods. Twenty-four dentin blocks obtained from sound third molars were randomly divided into 3 groups: Sound dentin (Sd), Caries-affected dentin (Ca) and Caries-infected dentin (Ci). Dentin blocks from Ca and Ci groups were subjected to artificial caries development (S. mutans biofilm). The softest carious tissue was removed using spherical drills under visual inspection with Caries Detector solution (Ca group). It was considered as Ci (softer and deeply red stained dentin) and Ca (harder and slightly red stained dentin). The Adper Single Bond 2 adhesive system was applied and Z350 composite blocks were built in all groups. Teeth were stored in deionized water for 24 h at 37 ºC and sectioned into beams (1.0 mm2 section area). The beams from each tooth were randomly divided into three storages periods: 24 h, 6 months or 1 year. Specimens were submitted to µTBS using EZ test machine at a crosshead speed of 1.0 mm/min. Failure mode was examined by SEM. Data from µTBS were submitted to split plot two-way ANOVA and Tukey’s HSD tests (a=0.05). The µTBS (MPa) of Sd (41.2) was significantly higher than Ca (32.4) and Ci (27.2), regardless of storage. Ca and Ci after 6 months and 1 year, presented similar µTBS. Mixed and adhesive failures predominated in all groups. The highest µTBS values (48.1±9.1) were found for Sd at 24 h storage. Storage of specimens decreased the µTBS values for all conditions.

Resumo O objetivo neste estudo foi avaliar a resistência de união à microtração (RUµT) de um sistema adesivo convencional (Adper Single Bond 2 - SB) em diferentes substratos dentinários e períodos de armazenagem. Vinte e quatro blocos de dentina foram obtidos de terceiros molares hígidos e separados aleatoriamente em 3 grupos (n=8): dentina sadia (Ds), dentina afetada (Da) e dentina infectada (Di). A Da e a Di foram submetidas ao desenvolvimento biológico artificial de cárie (S. mutans). O tecido cariado amolecido foi removido usando broca esférica sob inspeção visual com a solução Caries Detector (grupo Da). Considerou-se como Di a dentina amolecida e fortemente pigmentada de vermelho e como Da, a dentina hígida e levemente pigmentada de vermelho. O sistema adesivo SB foi aplicado de acordo com as recomendações do fabricante e blocos da resina composta Z350 foram construídos (6 mm de altura). O conjunto (dente/bloco de resina) foi armazenado em água deionizada por 24 horas a 37 °C. Estes foram seccionados em palitos (1,0 mm2 de área), que foram separados aleatoriamente em 3 períodos de armazenagem: 24 horas, 6 meses e 1 ano. Os palitos foram submetidos ao ensaio de resistência de união à microtração na máquina EZ teste a uma velocidade de 1,0 mm/min. Dados de RUµT foram submetidos à Análise de Variância 2 fatores em esquema de parcela subdividida e ao teste de Tukey (a=0,05). Os valores de resistência (MPa) da Ds (41,2) foram significativamente maiores do que os da Da (32,4) e Di (27,2), independente do tempo de armazenagem. Di e Da, 6 meses e 1ano, apresentaram valores similares de resistência de união. As falhas adesivas e mistas foram predominantes para todos os grupos. Em conclusão, os maiores valores de RUµT (48,1±9,1) foram verificados para a Ds e 24 h de armazenagem. A armazenagem diminuiu os valores de RUµT para todas as condições.