Performance of MDP-based system in eroded and carious dentin associated with proteolytic inhibitors: 18-Month exploratory study.

The aim of this study was to explore the impact of the interaction between an MDP-based universal adhesive system in etch-and-rinse mode and two proteolytic inhibitors on the longevity of restorations bonded to artificially-affected-dentin substrates. 90 sound human third molars were randomly distributed into three groups according to the substrate: N-no challenges-control (stored in artificial saliva), ACD-artificial caries dentin (6 h DE + 18 h-RE/5 days + 48 h RE) and ERO-artificial erosion dentin (3 × 5 min/5 days with orange juice). They were further redistributed according to dentin pretreatment: W- water (control), CHX-2% digluconate chlorhexidine and E64- 5 µM E64-Trans-Epoxysuccinyl-L-Leucylamido-(4-guanidino) butane, which resulted in the following 9 groups (n = 10): N-W, N-CHX, N-E64, ACD-W, ACD-CHX, ACD-E64, ERO-W, ERO-CHX and ERO-E64. All specimens were restored with Adper Single Bond Universal (Etch-and-rinse mode)/Filtek Z250. Sticks (0.64 mm2) were obtained and subjected to microtensile test (µTBS) in a universal testing machine at 0.5 mm/min for 7-days, 6 and 18-month analyses. Failure modes were classified using optical microscopy (40X). Data were statistically analyzed by three-way ANOVA and Tukey tests (p < 0.05). All individual factors (p < 0.0001) and interaction between factors were statistically significant (substrate X pretreatment (p = 0.00093); substrate X time (p = 0.01035) and pretreatment X time (p = 0.0035). Caries-affected substrate was the most compromised one, disregarding the pretreatment. CHX was mostly affected compared with E64 up to 18 months, possibly due to its calcium-dependent mechanism.

Profile of a 10-MDP-based universal adhesive system associated with chlorhexidine: Dentin bond strength and in situ zymography performance.

The incorporation of functional monomers and proteolytic inhibitors into adhesive systems have shown to be promising strategies to improve the longevity of adhesive restorations. The aim of this study was to evaluate the long-term bonding performance and anti-gelatinolytic effect of a 10-MDP-based universal adhesive system applied in combination with 2% chlorhexidine digluconate (CHX). For that, this study assessed the resin-dentin bond strength and the in situ gelatinolytic activity profile at the adhesive interface at initial and after 6 month of storage. One hundred and two sound human third molars were prepared and randomly divided into 3 groups according to the adhesive strategy: SB (two-step etch-and-rinse adhesive, Adper Single Bond 2, 10-MDP-free control group); SU-ER (Adper Single Bond Universal, 10-MDP containing universal adhesive applied on etch-and-rinse mode); and SU-SE (SU applied on self-etching mode). The groups were subdivided into two according to the dentin pretreatment: W - water or CHX- 2% chlorhexidine digluconate aqueous solution (SB-W; SB-CHX; SU-ER-W; SU-ER-CHX; SU-SE-W; SU-SE-CHX) and subsequently restored according to the manufacturer's instructions. Bond strength (n = 12) was assessed by a microtensile test (µTBS) (500N/0.5 mm/min) after 24h or after 6 months of storage. In situ zymography was performed to evaluate anti-gelatinolytic activity (n = 5). Resin-dentin samples were incubated with fluorescein-conjugated gelatin for 24 h at 37 °C and analyzed by confocal laser scanning microscopy. Fluorescence indicating gelatinolytic activity at hybrid layer zone and adjacencies was quantified using Image J. Data was analyzed by three-way ANOVA and Tukey post-hoc tests (p < 0.05). Results: SU-SE showed the highest bond strength values, while similar results were observed for SU-ER and SB. No statistical significant differences were observed between pretreatment (CHX vs. W) or storage time (initial vs. 6 months of aging). For in situ zymography, fluorescence was detected in all groups and CHX pre-treatment was able to inhibit the gelatinolytic activity in all conditions. The 10-MDP-based universal adhesive system in self-etching mode was the strategy that showed the best bonding performance irrespective of its combination with chlorhexidine. Pre-treatment with CHX did not impair the bond strength when used in combination with 10-MDP and it may promote collagen stability overtime.

Effect of sealing infected dentin with glass ionomer cement on the abundance and localization of MMP-2, MMP-8, and MMP-9 in young permanent molars in vivo.

BACKGROUND: The study of MMPs' behavior in carious lesions contributes to the understanding of the mechanisms involved in dentin reorganization after restoration. AIM: To compare the abundance and localization of MMPs 2, 8, and 9 in infected dentin before and after restoration. DESIGN: The sample consisted of 23 young permanent molars with active deep carious lesions. Infected carious dentin samples were collected from the same tooth at baseline and 60 days after cavity lining with GIC and composite resin restoration and processed for immunohistochemistry assays. After digital images were obtained, two calibrated operators analyzed the samples according to the immunostaining intensity and the MMPs' localization. Chi-square test was used for statistical analysis. RESULTS: The intensity of immunostaining for MMP-8 was reduced after 60 days (P = 0.02), and no difference was observed for MMP-2 (P = 0.32) and MMP-9 (P = 0.14). The MMPs' distribution was generalized in the intertubular dentin and absent or located in the intratubular dentin, regardless of the period. CONCLUSION: The sealing of infected carious dentin in young permanent molars reduced the expression of MMP-8, which is consistent with the initial remodeling process of the dentin matrix.

Chlorhexidine does not improve but preserves bond strength to eroded dentin.

PURPOSE: To evaluate the effect of aqueous solutions of chlorhexidine digluconate (CHX) in different concentrations on bond strength to eroded dentin up to 6 months, using normal dentin as a control. METHODS: Exposed flat dentin of extracted third molars was only ground with 600-grit SiC paper/1 minute (normal dentin - N), or subsequently eroded by a regular-cola soft-drink (eroded dentin - E). N and E were acid-etched, washed, dried and rehydrated with 1.5 µL, respectively, of distillated water (control - NC / EC); of 0.004% CHX (N0.004% / E0.004%); or of 2% CHX (N2% / E2%). Adper Single Bond 2 was applied in all specimens and resin composite buildups were constructed with Filtek Z350. Specimens were sectioned in beams, which were tested (µTBS) immediately or after 6 months of aging. RESULTS: Microtensile bond strength to eroded dentin was always significantly lower than that to normal dentin. Application of tested CHX solutions did not exert a significant effect immediately; however, after aging, the 2% CHX prevented abrupt bond strength loss both to eroded and normal dentin.

Cytotoxicity of adhesive systems of different hydrophilicities on cultured odontoblast-like cells.

This study evaluated the cytotoxicity of experimental adhesive systems (EASs) on odontoblast-like cells. Paper discs (n = 132) were impregnated with 10 µL of each EAS-R1, R2, R3, R4, and R5 (in an ascending order of hydrophilicity), followed by photoactivation. R1 and R2 are nonsolvated hydrophobic blends, R3 represents a simplified etch-and-rinse adhesive system, and R4 and R5 represent simplified self-etch adhesive systems. Discs were immersed in Dulbecco's modified Eagle's medium for 24 h to obtain eluates applied on MDPC-23 cell cultures. No material was applied on discs used as control (R0). Cell viability [3-(4,5-dimethythiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay], total protein (TP) production, alkaline phosphatase (ALP) activity, type of cell death, and degree of monomer conversion Fourier transform infrared (%DC-FTIR) were evaluated. Data were analyzed by Kruskal-Wallis and Mann-Whitney tests (α = 0.05). Considering R0 (control) as having 100% of cell viability, R1, R2, R3, R4, and R5 reduced the metabolic activity of cells by 36.4, 3.1, 0.2, 21.5, and 65.7%, respectively, but only R1 and R5 differed from R0. Comparing with R0, lower TP production was observed for R1, R4, and R5, while ALP activity decreased for R1 and R5. Necrotic cell death was predominant for all EASs, but only R1, R4, and R5 differed from R0. Only R5 presented a different apoptotic cell death ratio from R0. R1 presented the lowest %DC (ca. 37%), whereas R4 and R5 presented the highest (ca. 56%). In conclusion, R2 and R3 were not toxic to the MDPC-23 cells, suggesting that the degree of hydrophilicity or %DC of the EASs alone were not responsible for their cytopathic effects.

Microtensile bond strength test and failure analysis to assess bonding characteristics of different adhesion approaches to ground versus unground enamel.

This study evaluated the bonding characteristics to ground and unground enamel obtained with different strategies. For this purpose, 24 sound third-molars were bisected mesiodistally to obtain tooth halves. A flat enamel area was delimited in the tooth sections, which were randomly distributed into 8 groups (n=6), according to the enamel condition (ground and unground) and adhesive system (Adper Single Bond 2 - SB2; Adper Prompt L-Pop - PLP; Adper Prompt - AD; Clearfil SE Bond - SE). Each system was applied according manufacturers' instructions and a 6-mm-high resin composite "crown" was incrementally built up on bonded surfaces. Hourglass-shaped specimens with 0.8 mm(2) cross-section were produced. Microtensile bond strength (µTBS) was recorded and the failure patterns were classified. Results were analyzed by two-way ANOVA and Tukey's test (α=0.05). There were no statistically significant differences among the µTBS values of SB2, PLP and AD (p>0.05). SE values were significantly lower (p0.05). There was prevalence of cohesive failure within enamel, adhesive system and resin composite for SB2. The self-etch systems produced higher incidence of cohesive failures in the adhesive system. Enamel condition did not determine significant differences on bonding characteristics for the same bonding system. In conclusion, the bonding systems evaluated in this study resulted in specific µTBS and failure patterns due to the particular interaction with enamel.

Microtensile bond strength test and failure analysis to assess bonding characteristics of different adhesion approaches to ground versus unground enamel

This study evaluated the bonding characteristics to ground and unground enamel obtained with different strategies. For this purpose, 24 sound third-molars were bisected mesiodistally to obtain tooth halves. A flat enamel area was delimited in the tooth sections, which were randomly distributed into 8 groups (n=6), according to the enamel condition (ground and unground) and adhesive system (Adper Single Bond 2 - SB2; Adper Prompt L-Pop - PLP; Adper Prompt - AD; Clearfil SE Bond - SE). Each system was applied according manufacturers' instructions and a 6-mm-high resin composite "crown" was incrementally built up on bonded surfaces. Hourglass-shaped specimens with 0.8 mm² cross-section were produced. Microtensile bond strength (μTBS) was recorded and the failure patterns were classified. Results were analyzed by two-way ANOVA and Tukey's test (α=0.05). There were no statistically significant differences among the μTBS values of SB2, PLP and AD (p>0.05). SE values were significantly lower (p0.05). There was prevalence of cohesive failure within enamel, adhesive system and resin composite for SB2. The self-etch systems produced higher incidence of cohesive failures in the adhesive system. Enamel condition did not determine significant differences on bonding characteristics for the same bonding system. In conclusion, the bonding systems evaluated in this study resulted in specific μTBS and failure patterns due to the particular interaction with enamel.

Este estudo avaliou a união ao esmalte íntegro e desgastado obtida com diferentes estratégias. Para tanto, 24 terceiros molares hígidos foram seccionados ao meio. Um plano de esmalte foi delimitado nos fragmentos de dente, aleatoriamente distribuídos em 8 grupos (n=6) conforme a condição do esmalte (íntegro ou desgastado) e o adesivo (Adper Single Bond 2: SB2; Adper Prompt L-Pop: PLP; Adper Prompt: AD; Clearfil SE Bond: SE). Estes foram aplicados seguindo recomendações dos fabricantes e uma "coroa" de compósito (altura - 6 mm) incrementalmente construída. Espécimes (ampulheta/secção transversal - 0,8 mm²) foram confeccionados. O ensaio de resistência da união à micro-tração (RUµT) foi realizado e os padrões de fratura classificadas. Os resultados analisados pela ANOVA (dois fatores) e teste de Tukey (α=0,05). Os valores de RUµT do SB2, PLP e AD não foram significativamente diferentes entre si (p>0,05); SE foi inferior (p0,05). Houve prevalência de fratura no esmalte, adesivo e compósito no SB2. Nos adesivos autocondicionantes, predominou a fratura no adesivo. A condição do esmalte não influenciou significativamente as características da união, considerando o mesmo adesivo. Em conclusão, os adesivos apresentaram RUµT e padrões de fratura específicos, devido a forma de interação com o esmalte.

Influences of surface and solvent on retention of HEMA/mixture components after evaporation.

OBJECTIVES: This study examined the retention of solvents within experimental HEMA/solvent primers after two conditions for solvent evaporation: from a free surface or from dentine surface. METHODS: Experimental primers were prepared by mixing 35% HEMA with 65% water, methanol, ethanol or acetone (v/v). Aliquots of each primer (50 microl) were placed on glass wells or they were applied to the surface of acid-etched dentine cubes (2mm x 2mm x 2mm) (n=5). For both conditions (i.e. from free surface or dentine cubes), change in primers mass due to solvent evaporation was gravimetrically measured for 10min at 51% RH and 21 degrees C. The rate of solvent evaporation was calculated as a function of loss of primers mass (%) over time. Data were analysed by two-way ANOVA and Student-Newman-Keuls (p<0.05). RESULTS: There were significant differences between solvent retention (%) and evaporation rate (%/min) depending on the solvent present in the primer and the condition for evaporation (from free surface or dentine cubes) (p<0.05). For both conditions, the greatest amount of retained solvent was observed for HEMA/water primer. The rate of solvent evaporation for HEMA/acetone primer was almost 2- to 10-times higher than for HEMA/water primer depending whether evaporation occurred, respectively, from a free surface or dentine cubes. The rate of solvent evaporation varied with time, being in general highest at the earliest periods. CONCLUSIONS: The rate of solvent evaporation and its retention into HEMA/solvent primers was influenced by the type of the solvent and condition allowed for their evaporation.

Effect of an additional hydrophilic versus hydrophobic coat on the quality of dentinal sealing provided by two-step etchand-rinse adhesives

OBJECTIVE: To test the hypothesis that the quality of the dentinal sealing provided by two-step etch-and-rinse adhesives cannot be altered by the addition of an extra layer of the respective adhesive or the application of a more hydrophobic, non-solvated resin. MATERIAL AND METHODS: full-crown preparations were acid-etched with phosphoric acid for 15 s and bonded with Adper Single Bond (3M ESPE), Excite DSC (Ivoclar/Vivadent) or Prime & Bond NT (Dentsply). The adhesives were used according to the manufacturers' instructions (control groups) or after application to dentin they were a) covered with an extra coat of each respective system or b) coated with a non-solvated bonding agent (Adper Scotchbond Multi-Purpose Adhesive, 3M ESPE). Fluid flow rate was measured before and after dentin surfaces were acid-etched and bonded with adhesives. RESULTS: None of the adhesives or experimental treatments was capable to block completely the fluid transudation across the treated dentin. Application of an extra coat of the adhesive did not reduce the fluid flow rate of adhesive-bonded dentin (p>0.05). Conversely, the application of a more hydrophobic non-solvated resin resulted in significant reductions in the fluid flow rate (p<0.05) for all tested adhesives. CONCLUSIONS: The quality of the dentinal sealing provided by etch-and-rinse adhesives can be significantly improved by the application of a more hydrophobic, non-solvated bonding agent.

Effect of an additional hydrophilic versus hydrophobic coat on the quality of dentinal sealing provided by two-step etch-and-rinse adhesives.

OBJECTIVE: To test the hypothesis that the quality of the dentinal sealing provided by two-step etch-and-rinse adhesives cannot be altered by the addition of an extra layer of the respective adhesive or the application of a more hydrophobic, non-solvated resin. MATERIAL AND METHODS: full-crown preparations were acid-etched with phosphoric acid for 15 s and bonded with Adper Single Bond (3M ESPE), Excite DSC (Ivoclar/Vivadent) or Prime & Bond NT (Dentsply). The adhesives were used according to the manufacturers' instructions (control groups) or after application to dentin they were a) covered with an extra coat of each respective system or b) coated with a non-solvated bonding agent (Adper Scotchbond Multi-Purpose Adhesive, 3M ESPE). Fluid flow rate was measured before and after dentin surfaces were acid-etched and bonded with adhesives. RESULTS: None of the adhesives or experimental treatments was capable to block completely the fluid transudation across the treated dentin. Application of an extra coat of the adhesive did not reduce the fluid flow rate of adhesive-bonded dentin (p>0.05). Conversely, the application of a more hydrophobic non-solvated resin resulted in significant reductions in the fluid flow rate (p<0.05) for all tested adhesives. CONCLUSIONS: The quality of the dentinal sealing provided by etch-and-rinse adhesives can be significantly improved by the application of a more hydrophobic, non-solvated bonding agent.

Microtensile bond strength of adhesive systems to dentin with or without application of an intermediate flowable resin layer.

This study evaluated the effect of flowable composite resin application on the microtensile bond strength (microTBS) of adhesive systems to dentin. Occlusal surfaces of human third molars were ground to obtain flat dentin surfaces. The crown of each tooth was sectioned occluso-gingivally into four quarters with a water-cooled diamond saw. One of the following adhesive systems was applied to dentin surface in each quarter of the same tooth, following manufacturers' instructions: Scotchbond Multipurpose, Single Bond Adper Prompt and Clearfil SE Bond. Experimental and control groups received the same treatment, except for the fact that a layer of flowable composite (Filtek Flow) was placed and light-cured on top of the adhesive layer in the specimens of the experimental groups. Resin composite (Filtek Z250) crown buildups were then made on the bonded surfaces and incrementally light-cured for 20 s. The restored teeth were stored in water at 37 degrees C for 24 h. Each tooth quarter was serially cut in a longitudinal direction in order to obtain several bonded sticks (0.9-mm(2) in cross-section). Maximal microtensile stress (in MPa) at failure was recorded using a universal testing machine. Data were analyzed by two-way ANOVA and Tukey's test at 5% significance level. Placement of a low-viscosity resin to the hybridized dentin increased the microTBS for all tested adhesive systems. However, such increase was significant only for Clearfil SE Bond (p<0.05). When the restorations were placed without low-viscosity resin, Clearfil SE Bond presented higher microTBS than Adper Prompt (p<0.05). For the groups treated with flowable composite, Clearfil SE Bond produced the highest microTBS means to dentin. In conclusion, the effect of the addition of an intermediate flowable composite layer on microTBS to dentin was material-dependent and resulted in an increased adhesion for all tested materials, though with significance only for Clearfil SE Bond.

Microtensile bond strength of adhesive systems to dentin with or without application of an intermediate flowable resin layer

This study evaluated the effect of flowable composite resin application on the microtensile bond strength (muTBS) of adhesive systems to dentin. Occlusal surfaces of human third molars were ground to obtain flat dentin surfaces. The crown of each tooth was sectioned occluso-gingivally into four quarters with a water-cooled diamond saw. One of the following adhesive systems was applied to dentin surface in each quarter of the same tooth, following manufacturers' instructions: Scotchbond Multipurpose, Single Bond Adper Prompt and Clearfil SE Bond. Experimental and control groups received the same treatment, except for the fact that a layer of flowable composite (Filtek Flow) was placed and light-cured on top of the adhesive layer in the specimens of the experimental groups. Resin composite (Filtek Z250) crown buildups were then made on the bonded surfaces and incrementally light-cured for 20 s. The restored teeth were stored in water at 37ºC for 24 h. Each tooth quarter was serially cut in a longitudinal direction in order to obtain several bonded sticks (0.9-mm² in cross-section). Maximal microtensile stress (in MPa) at failure was recorded using a universal testing machine. Data were analyzed by two-way ANOVA and Tukey's test at 5 percent significance level. Placement of a low-viscosity resin to the hybridized dentin increased the muTBS for all tested adhesive systems. However, such increase was significant only for Clearfil SE Bond (p<0.05). When the restorations were placed without low-viscosity resin, Clearfil SE Bond presented higher muTBS than Adper Prompt (p<0.05). For the groups treated with flowable composite, Clearfil SE Bond produced the highest muTBS means to dentin. In conclusion, the effect of the addition of an intermediate flowable composite layer on muTBS to dentin was material-dependent and resulted in an increased adhesion for all tested materials, though with significance only for Clearfil SE Bond.

Este estudo avaliou o efeito da aplicação de uma resina flow na resistência de união (RU) (microtração) de sistemas adesivos à dentina. Superfícies oclusais de terceiros molares humanos foram abrasionadas para formar superfícies dentinárias planificadas. As coroas foram seccionadas no sentido ocluso-gengival em quatro partes de tamanhos similares com disco diamantado sob refrigeração. Os sistemas adesivos (Scotchbond Multipurpose; Single Bond; Adper Prompt e Clearfil SE Bond) foram aplicados nas superfícies dentinárias, de acordo com as instruções dos fabricantes, sendo cada um deles em uma das quatro partes de um mesmo dente. Os grupos experimentais e controle receberam o mesmo tratamento, porém a resina flow (Filtek Flow) foi aplicada e fotoativada sobre os sistemas adesivos nos espécimes dos grupos experimentais. Um bloco de compósito (Filtek Z250) foi confeccionado em incrementos sobre as superfícies tratadas com o sistema adesivo e fotoativado por 20 s. Os dentes restaurados foram armazenados em água a 37ºC por 24 h e seccionados longitudinalmente para obtenção de espécimes com formato de paralelepípedo, com 0,9 mm² na área de união. O ensaio de tração foi realizado em máquina universal de ensaios e os valores de RU foram expressos em MPa. Os dados foram analisados pela ANOVA (dois fatores) e teste de Tukey (5 por cento). A aplicação da resina flow na dentina previamente hibridizada aumentou a RU para todos os sistemas adesivos, entretanto, foi estatisticamente significativa somente para o adesivo Clearfil SE Bond (p<0,05). Quando as restaurações foram confeccionadas sem a resina de baixa viscosidade, o Clearfil SE Bond obteve maior valor de RU que o adesivo Adper Prompt (p<0,05). Para os grupos com a resina flow, o Clearfil SE Bond resultou no maior valor médio de RU à dentina. Conclui-se que o efeito da aplicação da resina flow foi depende do sistema adesivo utilizado e indicou um aumento na RU para todos os sistemas adesivos...

Effects of a combined application of potassium oxalate gel/adhesive agent on dentin permeability in vitro.

PURPOSE: To test the effects of sequential application of potassium oxalate gel/adhesive agent on in vitro dentin permeability. MATERIALS AND METHODS: Full crown preparations were made in extracted human molars to expose deep coronal dentin. The roots and pulp were removed and the resulting crown segments were connected to a special device (Flodec) to permit the measurement of the permeability of the specimens before and after treatments. Minimum and maximum permeability were recorded after smear layer and phosphoric acid treatment. A new smear layer was created and the permeability measured after the crowns were bonded with Single Bond (3M ESPE), One-Up Bond F (Tokuyama), and AdheSE (Ivoclar Vivadent), either according to manufacturer's instructions or after treating the acid-etched dentin with a 3 wt% potassium oxalate gel. The results were expressed as a percentage of maximum permeability values. Impressions and epoxy resin replicas from the crown segments were produced for SEM examination. RESULTS: None of the adhesives were able to eliminate the fluid flow through dentin. Two-way ANOVA revealed that the application of potassium oxalate prior to the bonding procedures was the most effective technique in reducingthe dentin permeability (p < 0.05), regardless of the adhesive used. SEM micrographs showed that transudation of dentinal fluid could be identified on the surfaces of all replicas. CONCLUSION: The use of potassium oxalate gel was effective in reducing the permeability of bonded dentin.

Effect of 2 percent iodine disinfecting solution on bond strength to dentin

INTRODUCTION: Disinfection of dentin surfaces is desirable so long as it does not interfere with subsequent bonding of adhesive resins. OBJECTIVE: To test the null hypothesis that bond strengths to dentin are not affected by previous application of an iodine disinfecting solution. MATERIALS AND METHODS: Twenty-four extracted non-carious molars were selected. Occlusal enamel was removed producing a flat dentin substrate. Test teeth were all treated with 2 percent Iodine disclosing/disinfecting solution (I2DDS) for 20 sec and rinsed for 20 sec followed by the application of self- or total- etching bonding systems, generating five adhesive groups (n=3): Single Bond; ; Prime & Bond NT; Clearfil SE Bond; Opti-Bond Plus. The control groups (n=3 per adhesive) had no disclosing/disinfectant application prior to adhesive application. A 4-mm thick resin restoration was built up on each tooth for microtensile testing. Statistical analyses between experimental and control groups were performed by student's t-test (alpha= 0.05). RESULTS: In general, experimental groups (previously treated with I2DDS) showed significantly lower bond strength values when compared with their respective controls (p<0.05), except for group Prime &Bond I2 that did not significantly differ from its control (p>0.05). CONCLUSION: Acetone-base adhesive systems seem not to be affected by the application of I2DDS prior to etching and bonding procedures.

INTRODUÇÃO: A desinfecção das superfícies de dentina é desejada desde que não haja interferência na adesão dos agentes adesivos. OBJETIVO: Testar a hipótese nula de que a resistência adesiva não é afetada pela aplicação prévia de uma solução desinfetante de iodo. MATERIAL AND MÉTODO: Vinte e quatro molares hígidos foram selecionados. O esmalte oclusal destes dentes foi removido, e sobre as superfícies planas de dentina expostas foi aplicada da solução desinfetante de Iodo a 2 por cento (I2DDS), que permaneceu sobre a superfície por 20 s e foi lavada por 20 s com água deionizada. Sobre as superfícies desinfetadas foram aplicados um dos seguintes sistemas adesivos (n=3): Single Bond; Prime & Bond NT; Clearfil SE Bond; Opti-Bond Plus. Os grupos controle (n=3) não tiveram a supeficie de dentina tratada com I2DDS antes dos precedimentos adesivos. Em todos os grupos, após hibridização da dentina, foi construída uma "restauração" de resina composta com cerca de 4 mm de espessura. Após 7 dias de armazenagem em água destilada, os dentes foram secionados de modo a originarem espécimes a serem submetidos ao teste de microtração (palitos). Análise estatística para comparação dos dados foi realizada pelo teste t de student (alfa=0,05). RESULTADOS: De forma geral, os grupos experimentais (tratados com I2DDS) apresentraram resistência adesiva significativamente menor do que os respectivos grupos controle (p<0.05), exceção se fez apenas para o grupo P&BI2, que não diferiu significativamente de seu grupo controle P&BC (p>0.05). Assim, a hipótese nula deve ser rejeitada para os adesivos a base de etanol e/ou a base de água, mas aceita para o adesivo a base de acetona. CONCLUSÃO: O uso da solução experimental de iodo previamente à realização dos procedimentos adesivos afetou a efetividade da união à dentina apenas quando do emprego de sistemas adesivos a base de etanol e/ou água.

Effect of chemical irrigants on the bond strength of a self-etching adhesive to pulp chamber dentin.

The aim of this study was to evaluate the influence of endodontic irrigants on adhesion to pulp chamber dentin. Seventy crowns of bovine incisors were cut to expose the pulp chamber. Specimens were divided into seven groups, according to the irrigant solution used: G1, 0.9% sodium chlorite (control); G2, 5.25% NaOCl; G3, 5.25% NaOCl + 17% EDTA; G4, 2% chlorhexidine solution; G5, 2% CHX solution + 17% EDTA; G6, 2% chlorhexidine in a gel base; and G7, 2% CHX gel + 17% EDTA. After irrigation, Clearfil SE Bond was applied to pulp chamber dentin, followed by Filtek Z250 composite. Six rectangular sticks were obtained from each specimen and dentin/resin interface was tested in tension. Bond strength means were analyzed by ANOVA and Tukey test. There was a significant decrease in bond strength associated to NaOCl, whereas chlorhexidine irrigation showed no effects on adhesion. It was concluded that endodontic irrigants affected differently bond strength to pulp chamber dentin.

Water sorption/solubility of dental adhesive resins.

OBJECTIVES: This study evaluated the water sorption, solubility and kinetics of water diffusion in commercial and experimental resins that are formulated to be used as dentin and enamel bonding agents. METHODS: Four commercial adhesives were selected along with their solvent-monomer combination: the bonding resins were of Adper Scotchbond Multi-Purpose (MP) and Clearfil SE Bond (SE) systems, and the "one-bottle" systems, Adper Single Bond (SB) and Excite (EX). Five experimental methacrylate-based resins of known hydrophilicities (R1, R2, R3, R4 and R5) were used as reference materials. Specimen disks were prepared by dispensing the uncured resin into a mould (5.8mm x 0.8mm). After desiccation, the cured specimens were weighed and then stored in distilled water for evaluation of the water diffusion kinetics over a 28-day period. RESULTS: Resin composition and hydrophilicity (ranked by their Hoy's solubility parameters) influenced water sorption, solubility and water diffusion in both commercial and experimental dental resins. The most hydrophilic experimental resin, R5, showed the highest water sorption, solubility and water diffusion coefficient. Among the commercial adhesives, the solvated systems, SB and EX, showed water sorption, solubility and water diffusion coefficients significantly greater than those observed for the non-solvated systems, MP and SE (p<0.05). In general, the extent and rate of water sorption increased with the hydrophilicity of the resin blends. SIGNIFICANCE: The extensive amount of water sorption in the current hydrophilic dental resins is a cause of concern. This may affect the mechanical stability of these resins and favor the rapid and catastrophic degradation of resin-dentin bonds.

Effect of 2% iodine disinfecting solution on bond strength to dentin.

INTRODUCTION: Disinfection of dentin surfaces is desirable so long as it does not interfere with subsequent bonding of adhesive resins. OBJECTIVE: To test the null hypothesis that bond strengths to dentin are not affected by previous application of an iodine disinfecting solution. MATERIALS AND METHODS: Twenty-four extracted non-carious molars were selected. Occlusal enamel was removed producing a flat dentin substrate. Test teeth were all treated with 2% Iodine disclosing/disinfecting solution (I(2)DDS) for 20 sec and rinsed for 20 sec followed by the application of self- or total- etching bonding systems, generating five adhesive groups (n=3): Single Bond; Prime & Bond NT; Clearfil SE Bond; Opti-Bond Plus. The control groups (n=3 per adhesive) had no disclosing/disinfectant application prior to adhesive application. A 4-mm thick resin restoration was built up on each tooth for microtensile testing. Statistical analyses between experimental and control groups were performed by student's t-test (alpha= 0.05). RESULTS: In general, experimental groups (previously treated with I(2)DDS) showed significantly lower bond strength values when compared with their respective controls (p<0.05), except for group Prime & Bond I(2) that did not significantly differ from its control (p>0.05). CONCLUSION: Acetone-base adhesive systems seem not to be affected by the application of I(2)DDS prior to etching and bonding procedures.

SEM evaluation of contemporary self-etching primers applied to ground and unground enamel.

PURPOSE: This study evaluated the etching effect of self-etching priming agents applied to intact and ground enamel. MATERIALS AND METHODS: Thirty-two human molars were used. Each tooth was divided into two halves. The buccal or lingual mid-coronal surface of 32 half-teeth was ground with 600-grit silicon carbide paper. The other half-teeth were left intact (control). Teeth were treated with Clearfil SE Bond (SE), Prompt L-Pop (PLP) or Adper (AD). Those in the control group were etched with 35% phosphoric acid. The etching effect of such systems on enamel surfaces was assessed by three different approaches using scanning electron microscopy: 1) in situ or direct morphological examination of the etched enamel; 2) indirect morphological examination, that is, evaluation of the etching pattern left on resin reproductions; 3) adhesive interface examination. RESULTS: SE exhibited the least aggressive dissolution of the intact and ground enamel, with many sites of the intact enamel remaining completely unetched. SE monomer infiltration into etched enamel was restricted to the superficial layer. PLP and AD produced equivalent etching patterns on intact and ground enamel, which resemble that produced by the phosphoric acid control group. PLP and AD monomer penetration extended along the porous subsurface enamel layer. CONCLUSION: SE produced mild morphological changes on intact and ground enamel surface, resulting in a very superficial resin infiltration particularly into intact enamel. No differences were evident among the etching and resin infiltration pattern produced by both all-in-one self-etching adhesives, PLP and AD, and the phosphoric acid system.

Influence of specimen size and regional variation on long-term resin-dentin bond strength.

OBJECTIVES: Verify whether the dimension of a bonded specimen stored prior microtensile testing and its regional variation may affect the resin-dentin bond strength (BS) over time. METHODS: Thirty human third molars had a flat dentin surface exposed and all peripheral enamel removed. Two adhesive systems (Single-Bond and One-Step) were applied and composite resin crowns (Z250) were constructed. Teeth were divided into three groups (n = 5). Group A specimens were sectioned to obtain sticks to be tested in tension (0.5 mm/min) immediately. Group B specimens were stored in water for 6 months, before sectioning and testing. Group C specimens were sectioned; the sticks were stored for 6 months and tested. In groups A and B, the origin of the sticks, periphery and inner regions was controlled. Bond strength (BS) was expressed as an index that considers cohesive failures and estimated values of premature debonded specimens. One-way ANOVA and Tukey's test (alpha = 0.05) were used to compare groups A, B and C, and a second analytical approach (A and B) employed a two-way ANOVA (time versus regional differences) for each adhesive system. RESULTS: For Single-Bond (SB), the BS for specimens in group A was higher than for groups B and C. For One-Step (OS), the BS in group A was higher than for B, which was in turn higher than for C. In the second group approach, no difference was found when the test was performed immediately; however, after 6 months, the inner sticks from group B showed significantly higher BS. SIGNIFICANCE: (1) The amount of decrease in BS is dependent on the specimen size; (2) the decrease in BS was greater for peripheral specimens than more centrally located specimens.

Mechanical stability of resin-dentin bond components.

OBJECTIVES: To evaluate the effects of long-term storage on the mechanical properties of the components of resin-dentin bonds, that is, resin composite, adhesive system, demineralized and mineralized dentin. METHODS: Specimens of resin composite (Z250) and adhesive systems (Single Bond-SB; One-Step-OS and Clearfil Liner Bond 2V-CL) were cast in molds. Dentin specimens were prepared from dentin discs obtained from the crowns of extracted human molars. Specimens of demineralized dentin were obtained by immersion of dentin discs for 6 days in 0.5 mol/l EDTA (pH 7.0). Both dentin and resin-based substrates were shaped to hourglass or I-beam specimens that were used to determine the true stress (TS) or apparent modulus of elasticity (E), respectively. Control specimens were subjected to tensile testing at 0.6 mm/min after 24 h of immersion in distilled water. Experimental specimens were stored at 37 degrees C in either distilled water or mineral oil and tested after 12 months. The data of each group were individually analyzed by ANOVA and Tukey's test. RESULTS: Both TS and E of the resin-based materials decreased significantly after 12 months of storage in water (p < 0.05) except the TS of SB (p > 0.05). No changes were observed for specimens of mineralized dentin, regardless of storage condition (p > 0.05). Storage of demineralized dentin in water did not cause any significant effect in either TS or E (p > 0.05), however, significant reductions of TS and E of demineralized dentin occurred after storage in oil for 1 year (p < 0.05). SIGNIFICANCE: Storage time and medium may be deleterious to the mechanical properties of the resin-dentin bond components, which ultimately could compromise the durability of resin-dentin bonds.