Dentin bond strength evaluation between a conventional and universal adhesive using etch-and-rinse strategy

Aim: The aim of this study was to compare the microtensile bond strength (µTBS) and the characteristics of the adhesive interface of Scotchbond Universal - SU ­ etch-and-rise mode (3M ESPE) and Adper Scotchbond Multi-Purpose - MP (3M ESPE) to dentin over time. Methods: Class I cavity preparations were performed in 60 human molars that were randomly divided according to the dentin bonding system (DBS) used (n=30): (1) Acid conditioning + SU and (2) Acid conditioning + MP. For bonding strength (BS) analysis, 30 teeth (n = 15) were sectioned into sticks and submitted to the microtensile test in a universal testing machine after 24 hours and 12 months. The adhesive interface of the others 30 teeth was analyzed in a confocal microscope after 24 hours and 12 months. The data of µTBS were analyzed by two-way repeated measures ANOVA and Tukey's HSD (α = 0.05). Results: SU presented the lowest DBS compared to MP (p=0.000). Time did not influenced DBS for both adhesive systems (p=0.177). Confocal microscopy analysis showed no cracks between both adhesive systems tested. Conclusion: The results indicate that MP - µTBS showed a better performance compared to SU in total-etch mode

Biological properties of experimental methacrylate-based sealers containing calcium phosphates

Abstract This study aimed to evaluate, in vitro and in vivo, the biocompatibility of experimental methacrylate-based endodontic sealers containing α-tricalcium phosphate (α-TCP) or nanostructured hydroxyapatite (HAp). Experimental methacrylate-based dual-cure sealers with the addition of α-TCP or HAp, at 10%wt were formulated and compared to AH Plus (AHP). Cell viability was assessed by 3-(4,5-dimethyl-thiazoyl)-2,5-diphenyl-tetrazolium bromide (MTT), and sulforhodamine B (SRB). Sealers were implanted in rats' subcutaneous tissue and histologically evaluated. Bioactivity was assessed by alkaline phosphatase enzyme activity (ALP) and Alizarin Red (AR), using apical papillary cells (SCAPs), and by the bone deposition measured in surgical cavities on rats' femur filled with AH Plus or α-TCP. In both viability assays, HAp and AHP sealers were similar, and α-TCP presented lower viability compared to the others at MTT assay (p<0.05). A gradual decrease of the inflammatory response according to the periods was observed and AHP was the only that presented giant cells (7-day period). Collagen fibers condensation increased according to the periods, with no differences among sealers. There was an increase at ALP activity and mineralized nodules deposition according to periods. HAp and α-TCP presented higher values for ALP activity at 5 days and at 5, 10, and 15 days for AR and were different from AHP (p<0.05). α-TCP presented superior values at 10 and 15 days compared to HAp and AHP for AR (p<0.05). At 90 days, α-TCP and control (empty cavity) showed high bone deposition compared to AHP (p<0.05). α-TCP and HAp, in a methacrylate-based sealer, presented biocompatibility and bioactivity, with the potential to be used as endodontic sealers in clinical practice. Further investigations are required to gain information on the physicochemical properties of these sealers formulation before its clinical implementation.

Resumo O objetivo deste estudo foi avaliar a biocompatibilidade de cimentos endodônticos experimentais à base de metacrilato contendo fosfato α-tricálcico ou hidroxiapatita nanoestruturada in vitro e in vivo. Cimentos experimentais de cura dual à base de metacrilato com a adição de fosfato de α-tricálcico (α-TCP) ou hidroxiapatita (HAp), a 10% em peso, foram formulados e comparados com AH Plus (AHP). Viabilidade celular foi avaliada por brometo de 3- (4,5-dimetil-tiazoil) -2,5-difenil-tetrazólio (MTT) e sulforodamina B (SRB). Cimentos foram implantados no tecido subcutâneo dos ratos e avaliados histologicamente. Bioatividade foi avaliada pela atividade da enzima fosfatase alcalina (ALP) e Alizarin Red (AR) utilizando células da papila apical (SCAPs) e pela deposição óssea, medida em cavidades cirúrgicas no fêmur de ratos preenchidos com AH Plus e α-TCP. Nos dois ensaios de viabilidade, HAp e AHP não apresentaram diferenças estatísticas, α-TCP apresentou menores resultados de viabilidade para o ensaio MTT (p <0,05). Resultados histológicos mostraram que houve uma diminuição do conteúdo inflamatório de acordo com os períodos, e o AHP foi o único grupo que apresentou células gigantes (período de 7 dias). A condensação das fibras colágenas aumentou conforme os períodos, sem diferenças entre os grupos. Houve aumento da atividade da ALP e deposição de nódulos mineralizados de acordo com os períodos. HAp e α-TCP apresentaram maiores valores para a atividade de ALP em 5 dias e em 5, 10 e 15 dias para AR, com diferença para o AHP (p <0,05). O α-TCP apresentou valores superiores aos 10 e 15 dias quando comparado ao HAp e AHP para AR (p <0,05). Aos 90 dias, α-TCP e controle (cavidade vazia) apresentaram maior deposição de tecido ósseo quando comparado ao AHP (p <0,05). α-TCP e HAp, presentes nos cimentos à base de metacrilato, apresentaram biocompatibilidade e potencial para serem utilizados como seladores endodônticos na prática clínica. Investigações adicionais são necessárias para obter informações sobre as propriedades físico-químicas dessas formulações de cimentos antes de sua implementação clínica.

Can composition and preheating improve infiltrant characteristics and penetrability in demineralized enamel?

Abstract The composition of infiltrants can influence their physical properties, viscosity and depth of penetration (DP). Strategies are used to increase the DP, such as the addition of diluents or the use of heat. This study aimed to evaluate the effect of preheating and composition on physical properties and DP of infiltrants in demineralized enamel. The groups were assigned, and the following experimental formulations were made: 25%BisEMA +75%TEGDMA; 25%BisEMA +65%TEGDMA +10%ethanol; 25%BisEMA +65%TEGDMA +10%HEMA; 100%TEGDMA; 90%TEGDMA +10%ethanol; 90%TEGDMA +10%HEMA. The samples were photoactivated at two temperatures (25°C and 55°C). Degree of conversion (DC) was performed using an infrared spectrophotometer. Elastic modulus (E), flexural strength (FS) and contact angle (CA) tests were also performed. The DP of an infiltrant in demineralized enamel was determined by confocal laser scanning microscopy (CLSM) using an indirect labeling technique. The data were analyzed by two-way ANOVA and Tukey's test. DC increased after preheating in all the groups; however, 90%TEGDMA+10%ethanol showed the lowest DC for both temperatures, and the lowest E. Preheating did not influence E or FS. The CA increased at 55°C for most groups, but decreased for groups containing HEMA. Temperature did not seem to influence DP, and Icon showed the lowest DP values. The 100%TEGDMA composition showed more homogeneous penetration, whereas Icon showed heterogeneous and superficial penetration. The preheating technique does not improve all properties in all the material compositions. The composition of a material can influence and improve its properties.

Resin-dentin bond stability of etch-and-rinse adhesive systems with different concentrations of MMP inhibitor GM1489

Abstract Enzymatic degradation of the hybrid layer can be accelerated by the activation of dentin metalloproteinases (MMP) during the bonding procedure. MMP inhibitors may be used to contain this process. Objective To evaluate the degree of conversion (DC%), dentin bond strength (µTBS) (immediate and after 1 year of storage in water), and nanoleakage of an experimental (EXP) and a commercial (SB) adhesive system, containing different concentrations of the MMP inhibitor GM1489: 0, 1 µM, 5 µM and 10 µM. Methodology DC% was evaluated by FT-IR spectroscopy. Dentin bond strength was evaluated by µTBS test. Half of beams were submitted to the µTBS test after 24 h and the other half, after storage for 1 year. From each tooth and storage time, 2 beams were reserved for nanoleakage testing. Data were analyzed using ANOVA and Tukey's test to compare means (α=0.05). Results All adhesive systems maintained the µTBS after 1 year of storage. Groups with higher concentrations of inhibitor (5 µM and 10 µM) showed higher µTBS values than groups without inhibitor or with 1 µM. The nanoleakage values of all groups showed no increase after 1 year of storage and values were similar for SB and EXP groups, in both storage periods. The inhibitor did not affect the DC% of the EXP groups, but the SB5 and SB10 groups showed higher DC% values than those of SB0 and SB1. Conclusions The incorporation of GM1489 in the adhesive systems had no detrimental effect on DC%. The concentrations of 5 µM GM1489 for SB and 5 µM or 10 µM for EXP provided higher μTBS than groups without GM1489, in the evaluation after 1 year of storage; whereas the concentration of inhibitor did not affect adhesive systems nanoleakage.

Liberação de componentes orgânicos e resposta periodontal em relação a um sistema restaurador resinoso Bulk-fill: estudo in vitro / Liberação de componentes orgânicos e resposta inflamatória frente a um sistema restaurador resinoso bulk-fill: estudo in vivo / Release Of Organic Components and Inflammatory Response to a Bulk-Fill Resin Results System: In Vivo Study

A maioria das resinas compostas apresenta metacrilatos como principais monômeros em sua composição. A liberação de monômeros de metacrilato, associada aos produtos de polimerização, tem sido considerada como fonte de uma série de reações biológicas como toxicidade ou reações pulpares. Os objetivos deste estudo foram avaliar o desempenho clínico de restaurações em LCNC com resina composta considerando-se também a presença de citocinas IL-1ß e IL-6 no fluido crevicular gengival e a liberação de componentes resinosos para a saliva. Utilizou-se o sistema restaurador FL-Bond II, (sistema adesivo) / Beautifil Bulk (resina composta restauradora). Foi feito um estudo clínico longitudinal in vivo, no qual foram selecionados pacientes que apresentavam uma lesão cervical não cariosa com necessidade restauradora. Dentes anteriores e posteriores com LCNC e sensibilidade foram designados como grupo experimental e o dente correspondente como grupo controle. Previamente ao tratamento, houve avaliação periodontal, coleta de saliva e de fluido crevicular gengival (FCG). As restaurações foram confeccionadas e, após 10 minutos, 7 dias, 1 mês e 6 meses foi realizada avaliação clínica das mesmas de acordo com o critério Federal Dentist International (FDI) e da resposta periodontal. Adicionalmente, em todos estes períodos de avaliação houve coleta de saliva e de fluido crevicular. As amostras de saliva foram analisadas por LC-EM a fim de identificar eventual presença dos monômeros Bis-GMA e TEGDMA. As amostras de fluido crevicular foram analisadas utilizando-se método ELISA para identificação e quantificação de interleucinas. Para realizar as comparações inter e intragrupo dos parâmetros clínicos foi utilizado o teste de McNemar para as variáveis categóricas e o teste de Wilcoxon para as variáveis numéricas. Para comparar a classificação do critério FDI entre os tempos foi utilizado o teste de Stuart-Maxwell. Para a análise da saliva, os dados de quantidade de monômeros liberados ao longo do tempo foram submetidos ao teste t de Student e a relação com quantidade total liberada foram correlacionados com o número de restaurações e com o volume total coletado de cada restauração por meio da Correlação de Pearson. O desempenho clínico das restaurações de LCNCs de um sistema restaurador resinoso bulk- fill por meio dos critérios FDI foi considerado satisfatório ao longo de 6 meses. Os parâmetros clínicos periodontais Sangramento a Sondagem, Ìndice Gengival e Profundidade de Sondagem foram mais pronunciados em torno dos dentes restaurados. O material restaurador resinoso bulk-fill não causou alteração estatisticamente significante no volume de FCG e as citocinas ao redor de dentes restaurados na amostra avaliada. Não detectou-se Bis-GMA nas amostras de saliva coletadas antes, 01 e 06 meses após. A liberação de TEGDMA média antes da restauração foi estatisticamente menor do que após 10 minutos. Os resultados do presente estudo sugerem que a restauração do LCNC pode afetar os parâmetros clínicos periodontais, porém não foi capaz de afetar a liberação de citocinas e o volume de FCG. A liberação de Bis-GMA não foi considerada significante ao longo de 6 meses, entretanto a liberação de TEGDMA foi expressiva apenas 10 minutos após a execução da restauração.

Most composite resins present methacrylates as the main monomers of their composition. In composite resins, the release of methacrylate monomers, associated with the polymerization products, has been considered as the source of a series of biological reactions such as toxicity or pulp reactions. The objectives of this study were to evaluate the clinical performance of NCCL restorations with composite resin, to determine also the presence of IL-1ß and IL-6 cytokines in the gingival crevicular fluid (GCF) and the release of resinous components to saliva. The FL-Bond II restorative system (adhesive system) / Beautifil Bulk (restorative composite resin) was used. A longitudinal clinical study was performed in vivo, where patients with a non-carious cervical lesion with a restorative need were selected. Anterior and posterior teeth with NCCL and sensitivity were designated as experimental group and the corresponding tooth as control group. Prior to the treatment, were performed periodontal evaluation, collection of saliva and gingival crevicular fluid. The lesions were restored and, after 10 minutes, 7 days, 1 month and 6 months, there was a clinical evaluation of the restorations according to the FDI criteria and the periodontal response were made. Additionally, in all of these evaluation periods there was collection of saliva and crevicular fluid were colleted. Saliva samples were analyzed by LC-MS in order to identify the possible presence of monomers. Crevicular fluid samples were analyzed using the ELISA method for identification and quantification of interleukins. To perform intra- and inter group comparisons of clinical parameters, the McNemar test for categorical variables and the Wilcoxon test for numerical variables were used. To compare the classification of the FDI criterion between the times, the Stuart-Maxwell test was used. For the analysis of saliva, the data of quantity of monomers released over time were submitted to Student's t-test and the relation with total amount released were correlated with the number of restorations and with the total volume collected from each restoration by means of Pearson's Correlation. The clinical performance of NCCL restorations of a bulk-fill resin restorative system by FDI criteria was considered satisfactory over 6 months. Considering the periodontal response of the surrounding tissue to the NCCL restorations, it was observed that periodontal clinical parameters Bleeding on Probing, Gingival Index and Prohibing on Depth were more pronounced around the restored teeth. The bulk-fill resin restorative material did not cause statistically significant changes in the volume of GCF and in the IL-1ß and IL-6 cytokines around restored teeth in the evaluated sample. No Bis-GMA was detected in the saliva samples collected before, 01 and 06 months after. For the Bis-GMA, there was no statistical difference between the analyzed periods. The mean TEGDMA release before the restoration was statistically lower than after 10 minutes. The results of the present study suggest that NCCL restoration may affect periodontal clinical parameters, but it was not able to affect the release of cytokines and the volume of GCF. The release of Bis-GMA was not considered significant over 6 months. However, the release of TEGDMA was significant only 10 minutes after the restoration was performed.

Composite-derived monomers affect cell viability and cytokine expression in human leukocytes stimulated with Porphyromonas gingivalis

Abstract Objectives: Dental composites release unreacted resin monomers into the oral environment, even after polymerization. Periodontal cells are, therefore, exposed to substances that potentially elicit the immune inflammatory response. The underlying molecular mechanisms associated with the interaction between resin monomers and human immune cells found in the gingival crevicular fluid are not fully understood yet. This study investigated the ability of bisphenol A-glycidyl methacrylate (BISGMA), urethane dimethacrylate (UDMA) and triethylene glycol dimethacrylate (TEGDMA) to induce apoptosis and cytokine release by human leukocytes stimulated with a periodontal pathogen. Methodology: Peripheral blood mononuclear cells (PBMC) from 16 healthy individuals were included in this study. To determine the toxicity, the PBMC were incubated for 20 hours, with monomers, for the analysis of cell viability using MTT assay. To evaluate cell death in the populations of monocytes and lymphocytes, they were exposed to sub-lethal doses of each monomer and of heat-inactivated Porphyromonas gingivalis (P. gingivalis) for 5 hours. Secretions of IL-1β, IL-6, IL-10 and TNF-α were determined by ELISA after 20 hours. Results: UDMA and TEGDMA induced apoptosis after a short-time exposure. Bacterial challenge induced significant production of IL-1β and TNF-α (p<0.05). TEGDMA reduced the bacterial-induced release of IL-1β and TNF-α, whereas UDMA reduced IL-1β release (p<0.05). These monomers did not affect IL-10 and IL-6 secretion. BISGMA did not significantly interfere in cytokine release. Conclusions: These results show that resin monomers are toxic to PBMC in a dose-dependent manner, and may influence the local immune inflammatory response and tissue damage mechanisms via regulation of bacterial-induced IL-1β and TNF-α secretion by PBMC.

Twenty-four-month clinical performance of different universal adhesives in etch-and-rinse, selective etching and self-etch application modes in NCCL - a randomized controlled clinical trial

Abstract Objective The aim of this randomized, controlled, prospective clinical trial was to evaluate the performances of two different universal adhesives and one etch-rinse adhesive for restoration of non-carious cervical lesions (NCCLs). Material and Methods Twenty patients with at least seven NCCLs were enrolled. Lesions were divided into seven groups according to adhesive systems and application modes: GSE: GLUMA Universal-self-etch, GSL: GLUMA Universal-selective etching, GER: GLUMA Universal-etch-and-rinse, ASE: All-Bond Universal-self-etch, ASL: All-Bond Universal-selective etching, AER: All-Bond Universal-etch-and-rinse, SBE (Control): Single Bond2-etch-and-rinse. A total of 155 NCCLs were restored with a nano hybrid composite (Tetric N-Ceram). Restorations were scored with regard to retention, marginal discoloration, marginal adaptation, recurrent caries and post-operative sensitivity using modified United States Public Health Service (USPHS) criteria after one week, 6, 12 and 24 months. Statistical evaluations were performed using Chi-square tests (p=0.05). Results The recall rate was 81.9% after the 24-month follow-up. The cumulative retention rates for self-etch groups (GSE: 72.2%, ASE:75%) were significantly lower than other experimental groups (GSL: 93.7%, GER: 100%, ASL: 94.1%, AER: 100%, SBE: 100%) at the 24-month follow-up (p<0.05). Regarding marginal adaptation and marginal discoloration, GSE and ASE groups demonstrated more bravo scores after 6 and 12-month observations but differences were not significant (p>0.05). Only one restoration from ASL group demonstrated post-operative sensitivity at 6 and 12-month observations. No secondary caries was observed on the restorations at any recall. At the end of 24-month observations, no significant differences were detected among groups regarding any of the criteria assessed, except retention. Conclusion GLUMA Universal and All-Bond Universal showed better results in etch-and-rinse and selective etching mode compared to the self-etch mode regarding retention. Etch-and-rinse and selective etching application modes of the current universal adhesives tended to provide better clinical outcomes considering the criteria evaluated at the end of 24-month evaluation.

Influence of the incorporation of triclosan methacrylate on the physical properties and antibacterial activity of resin composite

Abstract The incorporation of antimicrobials in the composites as an attempt to reduce bacterial adhesion without jeopardizing mechanical properties is a challenge for Dentistry. Objective: To evaluate the bacterial adhesion and physical properties of a composite containing the methacrylate triclosan- derivative monomer (TM). Methodology: TM was synthesized and added to an experimental composite. Samples were divided into two groups: Control and TM (13.4 wt%). Antibacterial Activity: Three specimens of each material were prepared and placed on bacterial suspensions of Streptococcus mutans for 1, 5 and 10 days. After these periods the counting of the colonies (log10) was performed. Assays was performed in triplicate. Physical Properties: Three-body Abrasion (TBA): Ten specimens of each material were prepared and stored at 37°C/24 h. The surface roughness (Ra) and hardness (KHN) were analyzed. Next, the specimens were submitted to abrasive wear (30,000 cycles) and re-evaluated for Ra and KHN; Sorption/solubility (SS): cylindrical specimens (n=10) were prepared and weighted. The specimens were immersed in deionized water for 7 days at 37°C and then their weight was verified again. SS were calculated using accepted formulas; Diametral tensile strength (DTS): specimens (n=10) underwent test performed in an Instron universal testing machine at a crosshead speed of 1 mm/min. Data were submitted to appropriate statistical tests according to data distribution and assay (p<0.05). Results: Bacterial Adhesion: TM showed a significant reduction on biofilm accumulation in the evaluated periods: 1 day (1.537±0.146); 5 days (2.183±0.138) and 10 days (4.469±0.155) when compared with Control: 1 day (4.954±0.249); 5 days (5.498±0.257) and 10 days (6.306±0.287). Physical Properties: For TBA, SS and DTS no significant difference was found between groups Control and TM. The incorporation of methacrylate triclosan-based monomer in the experimental composite reduce bacterial adhesion of S. mutans and did not affect important polymer properties.

Shrinkage stress and elastic modulus assessment of bulk-fill composites

Abstract Bulk-fill composites were introduced in dentistry to accelerate clinical procedures while providing adequate outcomes. Concerns regarding the use of bigger composite increments rely on the polymerization shrinkage and shrinkage stress, which may generate gaps on the adhesive interface and result in a reduced success rate. Objective: To evaluate the polymerization shrinkage stress of different bulk-fill resin composites and their elastic modulus. Materials and Methods: Fourteen specimens were made for each of the nine different resin composites (seven with 12 mm3 and seven with 24 mm3): Surefill SDR flow (SDR), X-tra Base (XB), Filtek Bulk Fill Flowable (FBF), Filtek Z350XT Flow (Z3F); Tetric Evo Ceram Bulk Fill (TBF), X-tra Fil (XF), Filtek Bulk Fill (FBP), Admira Xtra Fusion (ADM) and Filtek Z350 XT (Z3XT). Linear shrinkage stress was evaluated for 300 s with the aid of a linear shrinkage device adapted to a Universal Testing Machine. For each composite group, seven additional specimens (2x2x25 mm) were made and Young's modulus was evaluated with a 3-point bending device adapted in a Universal Testing Machine with 0.5 mm/min crosshead speed and 50 KgF loading cell. Results: For 12 mm3 specimens, three-way ANOVA showed that only SDR and TBF generated lower stress after 20 s. Considering 300 s, TBF, SDR, and XF generated the lowest stress, followed by ADM, FBP, XB, and FBF, which were similar to Z3XT. Z3F generated the highest stress values for all time points. Considering 24 mm3 specimens after 20 s, all bulk fill composites generated lower stress than Z3XT, except XB. After 300 s, SDR, FBP, and ADM generated the lowest stress, followed by TBF and XF. For elastic modulus, one-way ANOVA showed that FBF, SDR, Z3F, and ADM presented the lowest values, followed by XB and TBF. FBP, Z3XT, and XF presented the highest elastic modulus among the evaluated composites. Conclusions: Bulk-fill resin composites presented equal to lower shrinkage stress generation when compared to conventional composites, especially when bigger increments were evaluated. Bulk-fill composites showed a wide range of elastic modulus values, but usually similar to "regular" composites.

Development and characterization of a novel bulk-fill elastomeric temporary restorative composite

Abstract Objectives: This study investigated the physical and mechanical properties, antibacterial effect and biocompatibility of novel elastomeric temporary resin-based filling materials (TFMs) containing zinc methacrylate (ZM). Material and Methods: Experimental TFMs were prepared by mixing the zinc methacrylate with monomer, co-monomer, photoinitiator and fillers. A ZM concentration of 0 (control), 0.5% (Z0.5); 1% (Z1), 2% (Z2), or 5% (ZM5) wt% was added to the TFMs. Fermit-N (F) was used for comparison with the experimental material. Microleakage, water sorption/solubility, degree of conversion, depth of cure, ultimate tensile strength, and hardness were determined and compared. A modified direct contact test (DCT) with Enterococcus faecalis and a Streptococcus mutans' biofilm accumulation assay was carried out to evaluate the antimicrobial effect and cytotoxicity of the assay. Statistical comparisons were performed (α=5%). Results: The results showed that the physical and mechanical properties of the experimental TFMs with ZM are comparable with the properties of the commercial reference and some properties were improved, such as lower microleakage and water sorption, and higher ultimate tensile strength values. TFMs with ZM killed E. faecalis only after 1 h. Biofilm development of S. mutans was not affected by the inclusion of ZM in the experimental TFMs. Conclusions: The present findings suggest that the physical, mechanical and biological properties of the experimental TFMs with ZM are comparable with the properties of the commercial reference. However, some properties were improved, such as lower microleakage and water sorption, and higher ultimate tensile strength values.

Mechanical-physicochemical properties and biocompatibility of catechin-incorporated adhesive resins

Abstract Several anti-proteolytic dentin therapies are being exhaustively studied in an attempt to reduce dentin bond degradation and improve clinical performance and longevity of adhesive restorations. Objectives This study assessed the effect of epigallocatechin-3-gallate (EGCG) on long-term bond strength when incorporated into adhesives. Material and Methods Adhesive systems were formulated with EGCG concentrations of 0 wt%: (no EGCG; control); 0.5 wt% EGCG; 1.0 wt% EGCG, and 1.5 wt% EGCG. Flexural strength (FS), modulus of elasticity (ME), modulus of resilience (MR), compressive strength (CS), degree of conversion (DC), polymerization shrinkage (PS), percentage of water sorption (%WS), percentage of water solubility (%WL) and cytotoxicity properties were tested. Dentin microtensile bond strength (µTBS) was evaluated after 24 h and again after 6 months of water storage. The adhesive interface was analyzed using scanning electron microscopy (SEM). Results No significant differences were found among the groups in terms of FS, ME, MR, CS and PS. EGCG-doped adhesives increased the DC relative to the control group. EGCG concentrations of 1.0 wt% and 0.5 wt% decreased the WS of adhesives. WL decreased in all cases in which EGCG was added to adhesives, regardless of the concentration. EGCG concentrations of 1.0 wt% and 0.5 wt% reduced cytotoxicity. EGCG concentrations of 1.0 wt% and 0.5 wt% preserved µTBS after 6 months of storage, while 1.5 wt% EGCG significantly decreased µTBS. SEM: the integrity of the hybrid layer was maintained in the 0.5 wt% and 1.0 wt% EGCG groups. Conclusion EGCG concentrations of 1.0 wt% and 0.5 wt% showed better biological and mechanical performance, preserved bond strength and adhesive interface, and reduced cytotoxicity.

Effect of filler size and filler loading on wear of experimental flowable resin composites

Abstract The relationship between wear resistance and filler size or filler loading was clarified for the universal resin composite; however, their relationship in flowable resin composites has not been clarified. Objectives: The purpose of this study was to investigate the effect of filler size and filler loading on wear of experimental flowable resin composites by using a cyclic loading device. Material and Methods: Nine experimental flowable resin composites consisting of three different sizes (70, 200 and 400 nm) and loading (50, 55 and 60 wt%) of filler were prepared. Bowl-shaped cavities were prepared on a flat surface of ceramic blocks using a No. 149 regular cut diamond point. The cavities were treated with a silane coupling agent and an all-in-one adhesive and then filled with each experimental flowable resin composite. The restored surfaces were finished and polished with a 1500-grit silicon carbide paper. The specimens were subjected to an in vitro two-body wear test using a cyclic loading device. The localized worn surfaces were evaluated at 10,000, 20,000, 30,000, and 40,000 cycles using a computer-controlled three-dimensional measuring microscope (n=5). The volumetric wear loss of the materials was calculated automatically by the equipment. Data were statistically analyzed with two-way ANOVA and post hoc Tukey test. Results: Two-way ANOVA showed that the filler size significantly influenced wear volume (p<0.003), but the filler loading did not have a significant effect (p>0.05). A post hoc Tukey test detected significant differences in filler size between 70 nm and 400 nm, and 200 nm and 400 nm (p<0.007). Conclusion: The experimental flowable resin composite containing a mean filler size of 400 nm exhibited significantly lower wear resistance in two-body wear compared with those containing mean filler sizes of 200 nm or 70 nm.

Effect of beverages on surface properties of resin-based sealants

Aim: The aim of this study was to determine degree of conversion of resin-based sealants and the effect of beverages on surface roughness and color change of materials. Methods: Two commercial resin-based sealants were evaluated (Defense Chroma® and BioSeal®). Degree of conversion (DC) was initially measured using Fourier-transformed infrared (FTIR). Specimens of each sealant were maintained in distilled water and immersed one hour daily in grape juice and cola drink for 30 days. One group was maintained only in distilled water, as a control. Surface roughness and color change were measured before immersion, after seven days of immersion and after 30 days of immersion. Results were analyzed using t-test, paired t-test, one-way repeated measures ANOVA, one-way ANOVA and post-hoc tests (0.05 level of significance). Results: There was no significant difference regarding degree of conversion and initial surface roughness comparing both commercial sealants. Surface roughness increased for BioSeal® immersed in cola drink for 30 days. After 30 days, all groups presented significant color change. Conclusions: The effect of beverages on color stability and surface roughness of resin-based sealants depended on exposure time and kind of beverage (AU)

Rubbing time and bonding performance of one-step adhesives to primary enamel and dentin

Abstract Objectives: This study investigated whether increasing the concentration of acidic monomers in one-step adhesives would allow reducing their application time without interfering with the bonding ability to primary enamel and dentin. Material and methods: Experimental one-step self-etch adhesives were formulated with 5 wt% (AD5), 20 wt% (AD20), or 35 wt% (AD35) acidic monomer. The adhesives were applied using rubbing motion for 5, 10, or 20 s. Bond strengths to primary enamel and dentin were tested under shear stress. A commercial etch-and-rinse adhesive (Single Bond 2; 3M ESPE) served as reference. Scanning electron microscopy was used to observe the morphology of bonded interfaces. Data were analysed at p<0.05. Results: In enamel, AD35 had higher bond strength when rubbed for at least 10 s, while application for 5 s generated lower bond strength. In dentin, increased acidic monomer improved bonding only for 20 s rubbing time. The etch-and-rinse adhesive yielded higher bond strength to enamel and similar bonding to dentin as compared with the self-etch adhesives. The adhesive layer was thicker and more irregular for the etch-and-rinse material, with no appreciable differences among the self-etch systems. Conclusion: Overall, increasing the acidic monomer concentration only led to an increase in bond strength to enamel when the rubbing time was at least 10 s. In dentin, despite the increase in bond strength with longer rubbing times, the results favoured the experimental adhesives compared to the conventional adhesive. Reduced rubbing time of self-etch adhesives should be avoided in the clinical setup.

Mechanical properties, water sorption characteristics, and compound release of grape seed extract-incorporated resins

Abstract Objective This study evaluated the effect of grape seed extract (GSE) incorporation on the mechanical properties, water sorption, solubility, and GSE release from the experimental adhesive resins. Material and Methods An experimental comonomer mixture, consisting of 40% Bis-GMA, 30% Bis MP, 28% HEMA, 0.26% camphorquinone and 1% EDMAB, was used to prepare four GSE-incorporated adhesive resins at concentrations of 0.5, 1, 1.5, and 2 wt%. The neat resin without GSE was used as the control. Six resin beams (25 mm x 2 mm x 2 mm) per group were prepared for flexural strength and modulus of elasticity evaluations using a universal testing machine at a crosshead speed of 1 mm/min. Five disks (6 mm in diameter and 2 mm in thickness) per group were used for microhardness measurements using a Leitz micro-hardness tester with Leica Qgo software. Five disks (7 mm in diameter and 2 mm in thickness) per group were prepared and stored in deionized water for 28 days. Water sorption, solubility, and GSE release in deionized water were calculated for each GSE-incorporated adhesive at the end of 28th day. Data was evaluated using one-way ANOVA and Tukey multiple comparisons. Results Flexural strength, modulus of elasticity and microhardness of GSE-incorporated adhesive decreased significantly with incorporation of 1.5% of GSE (p<0.05). Addition of GSE had no effect on the water sorption of the adhesive resins (p=0.33). The solubility of the resin also increased significantly with incorporation of 1.5% of GSE (p<0.05). Quantities of GSE release increased with increased concentration of GSE in the adhesive resin. Conclusion Up to 1% of GSE can be incorporated into a dental adhesive resin without interfering with the mechanical properties or solubility of the resins.

Effect of different composite core materials on fracture resistance of endodontically treated teeth restored with FRC posts

Abstract Objective This study evaluated the fracture resistance of endodontically treated teeth restored with fiber reinforced composite posts, using three resin composite core build-up materials, (Clearfil Photo Core (CPC), MultiCore Flow (MCF), and LuxaCore Z-Dual (LCZ)), and a nanohybrid composite, (Tetric N-Ceram (TNC)). Material and Methods Forty endodontically treated lower first premolars were restored with quartz fiber posts (D.T. Light-Post) cemented with resin cement (Panavia F2.0). Samples were randomly divided into four groups (n=10). Each group was built-up with one of the four core materials following its manufacturers’ instructions. The teeth were embedded in acrylic resin blocks. Nickel-Chromium crowns were fixed on the specimens with resin cement. The fracture resistance was determined using a universal testing machine with a crosshead speed of 1 mm/min at 1350 to the tooth axis until failure occurred. All core materials used in the study were subjected to test for the flexural modulus according to ISO 4049:2009. Results One-way ANOVA and Bonferroni multiple comparisons test indicated that the fracture resistance was higher in the groups with CPC and MCF, which presented no statistically significant difference (p>0.05), but was significantly higher than in those with LCZ and TNC (p<0.05). In terms of the flexural modulus, the ranking from the highest values of the materials was aligned with the same tendency of fracture loads. Conclusion Among the cores used in this study, the composite core with high filler content tended to enhance fracture thresholds of teeth restored with fiber posts more than others.

Effect of two desensitizing agents on dentin permeability in vitro

Abstract Objective The aim of this in vitro study was to investigate the effect of two desensitizing agents and water on hydraulic conductance in human dentin. Material and Methods GLUMA Desensitizer PowerGel (GLU) contains glutaraldehyde (GA) and 2-hydroxyethyl methacrylate (HEMA), and Teethmate Desensitizer (TD) is a powder comprising tetracalcium phosphate (TTCP) and dicalcium phosphate anhydrous (DCPA) that is mixed with water. Deionized water was used as a negative control (CTR). Thirty discs with a thickness of 1.2 mm were cut from the coronal dentin of the third molars and cleaned with 0.5 M EDTA (pH 7.4). After being mounted in a split-chamber device, the discs were pressurized with water at 1 kPa and 3 kPa in order to measure flow rates with a highly sensitive micro-flow sensor and to calculate hydraulic conductance as a baseline value (BL). Following the application of GLU, TD, and CTR (n=10), hydraulic conductance was remeasured with intermittent storage in water after 15 min, 1 d, 1 w, and 1 m. Reduction in permeability (PR%) was calculated from hydraulic conductance. Data were statistically analyzed using nonparametric methods (α<0.05). Representative discs were inspected by SEM. Results PR% for GLU and TD were 30-50% 15 min and 1 m after their application. Post hoc tests indicated that PR% of CTR was significantly greater than those of GLU and TD at all time points tested. The PR% of GLU and TD were not significantly different. SEM examinations showed noncollapsed collagen meshes at the tubular entrances after GLU, and crystalline precipitates occluding the tubular orifices after TD, whereas CTR specimens showed typical patterns of etched dentin. Conclusions The present study on hydraulic conductance in dentin discs treated with two chemically different desensitizing agents and water as a control demonstrated that both products may be characterized as effective.

Influência da técnica de polimento na rugosidade superficial e perfilometria de materiais à base de resina bisacrílica / Influence of the polishing technique on the roughness and profile of bis-acryl-based materials

Problematização. É de grande importância a escolha da técnica e do material a serem utilizados para a confecção das restaurações provisórias. O material deve apresentar espessura suficiente e resistência para suportar as cargas mastigatórias sem sofrer deformação ou fratura, bem como, sua superfície deve apresentar um bom acabamento e polimento, reduzindo assim o acúmulo de biofilme, facilitando a higienização pelo paciente. Objetivo. Investigar qual o melhor protocolo de polimento para as diferentes resinas bisacrílicas com a intenção de obter uma superfície lisa. Material e métodos. Um total de 104 amostras foram confeccionadas (15mm de comp. x 5mm de largura x 4mm de altura) e foram divididos em três fatores de estudo: material (Protemp 4, Structur 3, Dencor, Z350XT), polimento (discos Sof-Lex Pop On e Sof-Lex Spiral) e período (inicial, pós polimento, pós escovação). Foram confeccionadas 13 amostras por grupo de material, sendo que em cada etapa foi retirado uma amostra aleatoriamente com a finalidade de submeter à análise de microscopia eletrônica de varredura (MEV), totalizando 24 amostras para serem submetidas a este teste, e assim, resultando em 80 amostras para serem escovadas, e em 10 amostras por grupo para análise estatística (n=10). Em todas as amostras foram realizadas leituras (µm) da rugosidade de superfície (Ra) em todos os períodos, ou seja, logo após serem confeccionadas, após o polimento e após escovação, através do rugosímetro (Hommel tester). Ao final, as 80 amostras foram submetidas a leitura no perfilômetro, para análise do desgaste superficial. Os resultados para a rugosidade foram submetidos a ANOVA a três critérios seguido pelo teste de Tukey (α = 0,05). E para o desgaste superficial os resultados foram submetidos a ANOVA a dois critérios seguido pelo teste de Tukey (α = 0,05). Resultados. A resina bisacrílica Protemp 4 mostrou maiores valores de rugosidade superficial (Ra) quando polidos com os discos Sof-Lex Spiral (0,284 µm), quando comparado ao polimento com discos Sof-Lex Pop On (0,075 µm), após a escovação houve aumento da rugosidade superficial para ambos os tipos de polimentos, tanto os discos Sof-Lex Spiral (0,375 µm) quanto para o polimento com os discos Sof-Lex Pop On (0,359 µm), mas não houve diferença estatística significativa (p>0,05). Para os resultados de desgaste superficial, não houve diferença estatística entre os grupos: da resina bisacrílica Protemp 4 com polimento Sof-Lex Pop On (13,95 µm), e com o polimento com os discos Sof-Lex Spiral (14,91µm) e o grupo da resina composta Z350XT polidos com os dois sistemas de polimento ­ Sof-Lex Pop On e Sof- Lex Spiral (12,61µm, 12,70 µm respectivamente). A resina bisacrílica Structur 3 mostrou menores valores de rugosidade de superfície quando polidos com os discos Sof-Lex Pop On (0,113 µm) em comparação ao polimento com os discos Sof-Lex Spiral (0,223 µm). Para os resultados de desgaste superficial, não houve diferença entre os grupos da resina bisacrílica Structur 3, porem os valores tanto para o grupo polido com os discos Sof-Lex Pop On (15,77 µm) e o grupo polido com os discos Sof-Lex Spiral (15,40 µm) foram bem próximos aos valores do grupo da resina bisacrílica Protemp 4 e ao grupo da resina composta Z350XT, com diferença estatística. As duas resinas bisacrílicas testadas, a Protemp 4 e a Structur 3 nos dois sistemas de polimentos mostraram melhores valores de rugosidade superficial (Ra) e menores valores de desgaste superficial que a resina acrílica Dencor. Conclusão. Através do polimento é possível melhorar a rugosidade superficial dos materiais resinosos, entretanto, a técnica, o operador, os materiais a serem polidos e o sistema de acabamento e polimento estão diretamente correlacionados. Para este estudo, o sistema que obteve os melhores resultados foi o dos discos Sof-Lex Pop On, e a resina bisacrílica que apresentou o menor número de Ra foi a resina bisacrílica Structur 3. Para o desgaste superficial a resina bisacrílica Structur 3 mostrou valores maiores comparados aos resultados do grupo da resina bisacrílica Protemp 4, esta, por sua vez, mostrou valores de desgaste superficial próximos ao do grupo da resina composta Z350 XT.(AU)

Statement of the problem. The choice of technique and material for making provisional restorations is important. The material must have enough strength to withstand the masticatory loads without suffering deformation or fracture and its surface must have good finishing and polishing to reduce biofilm accumulation. Objective. The aim of this study was to investigate what is the best polishing protocol for different bis-acryl materials with the intention to obtain a smooth surface. Materials and methods. A total of 104 samples were made (15mm long x 5mm wide x 4mm high) and were divided into three study factors: material (Protemp 4, Structur 3, Dencor, Z350XT), polishing (Sof-Lex Pop On and Sof-Lex Spiral discs) and period (initial, postpolishing, post-brushing). Thirteen samples were made per material group, and at each step, a sample was randomly taken for the purpose of submitting to scanning electron microscopy (SEM) analysis, totaling 24 samples to be submitted to this test, and thus, resulting in 80 samples to be brushed, and 10 samples per group for statistical analysis (n = 10). In all samples, surface roughness readings (µm) were performed at all periods, that is, after they were made, after polishing and after brushing through the rugosimeter (Hommel tester). At the end, the 80 samples were read in a profilometer for analysis of surface wear. The results for the roughness were submitted to ANOVA for three criteria followed by the Tukey`s test (α = 0.05), and for the surface wear test, the results were submitted to ANOVA for two criteria followed by the Tukey`s test (α = 0.05). Results. Protemp 4 bis-acryl showed higher values of surface roughness when polished with Sof-Lex Spiral discs (0.284 µm) when compared to Sof-Lex Pop On discs polishing (0.075 µm). After brushing, there was an increase of surface roughness for both types of polishing. Sof-Lex Spiral discs (0.375 µm) and Sof-Lex Pop On discs (0.359 µm), but with no significant differences (p>0.05). For the surface wear results, there was no statistical difference between the groups: Protemp 4 bis-acryl resin with Sof-Lex Pop On polishing (13.95 µm) and polishing with the Sof-Lex Spiral discs (14.91 µm ) and the Z350XT composite resin group polished with the two polishing systems - Sof-Lex Pop On and Sof-Lex Spiral (12.61µm, 12.70µm, respectively). Structur 3 bis-acryl resin showed lower surface roughness results when polished with Sof-Lex Pop On discs (0.113 µm) compared to Sof-Lex Spiral discs (0.223 µm). For the surface wear results, there was no difference between the groups of the Structur 3 bis-acryl resin, but the values for both the polished group with Sof-Lex Pop On discs (15.77µm) and the group polished with the Sof-Lex discs Spiral (15.40 µm) were very close to the values of the group of the Protemp 4 bis-acryl resin and the Z350XT composite resin group, with statistical difference. The two tested bis-acryl resins, the Protemp 4 and Structur 3 in the two polishing systems, showed better surface roughness values (Ra) and lower surface wear values than the Dencor acrylic resin. Dencor acrylic resin group showed the highest values of surface roughness at all times. However, after polishing and brushing, the surface roughness presented lower values, when compared to Ra initial values, but this material showed the highest surface wear values (31.21 µm).The resin composite group Z350XT which polishing procedure was Sof-Lex Pop On discs showed lower values (0.039 µm). There were no statistically significant differences in surface roughness at all periods and the surface roughness increased after brushing, followed by lower values also for surface wear (12.61 µm). Conclusion. By polishing it is possible to improve the surface roughness of the resinous materials, however, the technique, the operator, the materials to be polished and the finishing and polishing system are directly correlated. For the present study, the system that obtained the best results was the Sof-Lex Pop On discs, and the bis-acryl resin that presented the lowest Ra number was the Structur 3 bis-acryl resin. For surface wear, the Structur 3 bis-acryl resin showed higher values compared to the results of the Protemp 4 bis-acryl resin group, which, in turn, showed surface wear values close to that of the Z350 XT composite resin group.(AU)

Cytotoxicity and cytokine expression induced by silorane and methacrylate-based composite resins

ABSTRACT The successful use of composite resins in Dentistry depends on physicochemical properties, but also on the biological compatibility of resins, because of the close association between pulp and dentin. Objective The aim of this study was to evaluate cytotoxicity and cytokine production induced by light-cured or non-light-cured methacrylate-based and silorane composite resins in RAW 264.7 macrophages. Material and Methods Cells were stimulated with the extracts from light-cured or non-light-cured composite resins. After incubation for 24 h, cytotoxicity was assessed with the lactate dehydrogenase (LDH) and methyl thiazolyl tetrazolium (MTT) assays, and total protein was quantified using the Lowry method. TNF-α detection was examined with an enzyme-linked immunosorbent assay (ELISA) conducted with cell supernatants after cell stimulation for 6, 12, and 24 h. Data were analyzed using one-way analysis of variance (ANOVA) and Tukey’s post hoc test (α=0.05). Results KaloreTM and FiltekTM Silorane were cytotoxic with or without light curing (p<0.05) after 24 h of incubation. KaloreTM stimulated the early production of TNF-α in comparison with control (p<0.05), whereas FiltekTM Silorane did not affect TNF-α levels after 6 and 12 h (p>0.05). However, after 24 h FiltekTM Silorane inhibited the production of TNF-α (p<0.05). Conclusions KaloreTM and FiltekTM Silorane were cytotoxic regardless of light curing. The extract obtained from KaloreTM after 15 days of incubation stimulated the production of TNF-α, unlike that obtained from FiltekTM Silorane.

Influence of the concentration of 10-metacryloxydecyl dihydrogen phosphate (10-MDP) on the degree of conversion of experimental adhesives applied with different manipulation protocols / Influência da concentração de 10-metacriloiloxidecil dihidrogeniofosfato (10-MDP) no grau de conversão de adesivos experimentais aplicados com diferentes protocolos de manipulação

Propósito: Avaliar a influência de diferentes concentrações do 10-MDP no grau de conversão (%GC) de adesivos experimentais (AE) em diferentes protocolos de manipulação (PM). Material e Métodos: Os AE contêm um sistema iniciador triplo (CQ/DABE/sal diodônio) e diferentes concentrações de 10-MDP A1 = 0%, A2 = 3%, A3 = 6%, A4 = 9%, A5 = 12% ou A6 = 15% em peso foram adicionadas. Um adesivo comercialmente disponível foi utilizado para comparação (Ambar, FGM). Os adesivos foram divididos em 4 PM: I) Controle (sem manipulação), II) 5 s de evaporação, III) 20 s de evaporação e IV) adição de água. O GC foi avliado com o FTIR-ATR. Os dados foram analisados com Anova a dois critérios e Tukey (α = 0,05). Resultados: Diferenças significativas foram encontradas entre os adesivos (p < 0.0001) e PM (p = 0.000001). Também foi encontrado um efeito de interação (p < 0.0001). Para os adesivos, foi observado que o A5 obteve o maior resultado (89.70% ± 4.21) e o com menor valor foi o AE sem MDP (76.35% ± 8.45). O Ambar obteve valores intermediários (83.68% ± 9.46). Para o PM, o maior valor foi para: Controle (88.50% ± 2.72) > 20-s-evaporação (85.13% ± 6.95) ≈ 5-s-evaporação (85.18% ± 6.08) ≈ adição de água (85.80% ± 10.33). Conclusão: Os resultados obtidos sugerem que o 10- MDP pode aumentar a %GC dos AE com o sistema iniciador triplo.(AU)

Purpose: To evaluate the influence of different concentrations of 10-MDP in degree of conversion (%DC) of experimental adhesives (EA) applied with different manipulation protocols (MP). Materials and Methods: EA containing a three-component-photoinitiator system (CQ/DABE/iodonium salt) were prepared and different concentrations of 10-MDP were added A1 = 0%, A2 = 3%, A3 = 6%, A4 = 9%, A5 = 12%, or A6 = 15% by weight. A commercially available adhesive was used as comparison (Ambar, FGM). The adhesives were divided into 4 MP: I) Control (without any manipulation), II) 5 s of evaporation, III) 20 s of evaporation and IV) addition of water to the adhesive. DC was evaluated by FTIR-ATR. The data were analyzed with two-way Anova and Tukey´s HSD (α = 0.05). Results: Significant differences were found between the adhesives (p < 0.0001) and MP (p = 0.000001). An interaction effect (p < 0.0001) was also observed. For adhesives, it was observed that the A5 showed the highest value (89.70% ± 4.21) and the lowest values to EA without MDP (76.35% ± 8.45). Ambar showed intermediate values (83.68% ± 9.46). For MP, the highest DC was observed to Control (88.50% ± 2.72) > 20-s-evaporation (85.13% ± 6.95) ≈ 5-s-evaporation (85.18% ± 6.08) ≈ addition of water (85.80% ± 10.33). Conclusion: The results suggest that 10- MDP can enhance the %DC of the threecomponent- photoinitiator system EAs evaluated.(AU)