Rutin alleviates bisphenol A-glycidyl methacrylate-induced generation of proinflammatory mediators through the MAPK and NF-κB pathways in macrophages.

Bisphenol A-glycidyl methacrylate (BisGMA) is a methacrylate monomer that is mainly used in three-dimensional structures to reconstruct dental and bony defects. BisGMA has toxic and proinflammatory effects on macrophages. Rutin is a natural flavonol glycoside that is present in various plants and has useful biological effects, such as anti-inflammatory, anticancer, and antioxidative effects. The aim of this study was to investigate the anti-inflammation of rutin in macrophages after exposure to BisGMA. Pretreatment of the RAW264.7 macrophage with rutin at 0, 10, 30, and 100 µM for 30 min before being incubated with BisGMA at 0 or 3 µM. Proinflammatory cytokines and prostaglandin (PG) E2 were detected by enzyme-linked immunosorbent assay (ELISA). Nitric oxide (NO) was detected by the Griess assay. Expression and phosphorylation of proteins were measured by Western blot assay. Pretreatment with rutin inhibited the BisGMA-induced generation of proinflammatory cytokines, including tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, IL-6, and PGE2, in macrophages. Rutin also suppressed the BisGMA-induced secretion of NO and expression of inducible nitric oxide synthase (iNOS) in a concentration-dependent manner. Furthermore, rutin suppressed the mitogen-activated protein kinase (MAPK) phosphorylation in a concentration-dependent manner. Finally, rutin suppressed the BisGMA-induced phosphorylation of nuclear factor (NF)-κB p65 and degradation of inhibitor of κB (IκB). These results indicate that the concentration of rutin has an inhibitory effect on proinflammatory mediator generation, MAPK phosphorylation, NF-κB p65 phosphorylation, and IκB degradation. In conclusion, rutin is a potential anti-inflammatory agent for BisGMA-stimulated macrophages through NF-κB p65 phosphorylation and IκB degradation resulting from MAPK phosphorylation.

Toxicity of resin-matrix cements in contact with fibroblast or mesenchymal cells.

The main aim of this study was to perform an integrative review on the toxic effects of resin-matrix cements and their products in contact with fibroblasts or mesenchymal cells. A bibliographic search was performed on PubMed using the following search terms: "cytotoxicity" AND "fibroblast" OR "epithelial" OR "mesenchymal" AND "polymerization" OR "degree of conversion" OR "methacrylate" OR "monomer" AND "resin cement" OR "resin-based cement". The initial search in the available database yielded a total of 277 articles of which 21 articles were included in this review. A decrease in the viability of mouse fibroblasts ranged between 13 and 15% that was recorded for different resin-matrix cements after light curing exposure for 20 s. The viability of human fibroblasts was recorded at 83.11% after light curing for 20 s that increased up to 90.9% after light curing exposure for 40 s. Most of the studies linked the highest toxicity levels when the cells were in contact with Bis-GMA followed by UDMA, TEGDMA and HEMA. Resin-matrix cements cause a cytotoxic reaction when in contact with fibroblasts or mesenchymal cells due to the release of monomers from the polymeric matrix. The amount of monomers released from the resin matrix and their cytotoxicity depends on the polymerization parameters.

Effects of nanohybrid flowable resin-based composites on fibroblast viability using different light-curing units.

PURPOSE: To investigate the in vitro cytotoxic effects of Bis-GMA-containing and Bis-GMA-free flowable resin-based composites (RBCs) on primary human gingival fibroblast cells (hGFc) using direct and indirect curing methods and three different light-curing units (LCUs). MATERIALS AND METHODS: Cells were isolated and cultured in vitro in 24-well plates. The plates were divided into treatment (cells with RBC), control (cells only), and blank (media only) groups. In the treatment groups, two types of nanohybrid flowable RBCs were used: Bis-GMA-free and Bis-GMA groups. Each treatment group was subdivided according to the curing method, i.e., direct curing (RBC was injected into the wells and cured directly on the attached cells) and indirect curing (the samples were pre-cured outside of the well plate and then added to the well plate with cells). To vary the LCU, the subgroups were further divided into three groups: multiple-emission peak light-emitting diode, single-emission peak light-emitting diode, and quartz-tungsten-halogen units. Curing was conducted for 20 seconds. The hGFc cytotoxicity was evaluated via 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay after 24, 48, and 72 hours of culturing. RESULTS: The MTT assay results showed that both RBCs were significantly cytotoxic toward hGFc compared to the control group (p < 0.0001). The Bis-GMA group was significantly more cytotoxic to the cells compared to the Bis-GMA-free group. In addition, the curing method and time interval affected cell viability regardless of the LCU used. CONCLUSION: The Bis-GMA flowable RBC and direct curing method had the highest cytotoxic effects on hGFc regardless of the LCU used. Careful selection of flowable RBCs and proper curing techniques are required to decrease the cytotoxic effects on hGFc and improve the clinical handling of oral tissues.

Blood and fibroblast responses to thermoset BisGMA-TEGDMA/glass fiber-reinforced composite implants in vitro.

OBJECTIVES: This in vitro study was designed to evaluate both blood and human gingival fibroblast responses on fiber-reinforced composite (FRC) aimed to be used as oral implant abutment material. MATERIAL AND METHODS: Two different types of substrates were investigated: (a) Plain polymer (BisGMA 50%-TEGDMA 50%) and (b) FRC. The average surface roughness (Ra) was measured using spinning-disk confocal microscope. The phase composition was identified using X-ray diffraction analyzer. The degree of monomer conversion (DC%) was determined using FTIR spectrometry. The blood response, including the blood-clotting ability and platelet adhesion morphology, was evaluated. Fibroblast cell responses were studied in cell culture environment using routine test conditions. RESULTS: The Ra of the substrates investigated was less than 0.1 µm with no signs of surface crystallization. The DC% was 89.1 ± 0.5%. The FRC substrates had a shorter clotting time and higher platelets activation state than plain polymer substrates. The FRC substrates showed higher (P < 0.01-0.001) amount of adhered cells than plain polymer substrates at all time points investigated. The strength of attachment was evaluated using serial trypsinization, the number of cells detached from FRC substrates was 59 ± 5%, whereas those detached from the plane polymer substrates was 70 ± 5%, indicating a stronger (P < 0.01) cell attachment on the FRC surfaces. Fibroblasts grew more efficiently on FRC than on plain polymer substrates, showing significantly higher (P < 0.01) cell metabolic activities throughout the experiment. CONCLUSIONS: The presence of E-glass fibers enhances blood and fibroblast responses on composite surfaces in vitro.

In vitro blood and fibroblast responses to BisGMA-TEGDMA/bioactive glass composite implants.

This in vitro study was designed to evaluate both blood and human gingival fibroblast responses to bisphenol A-glycidyl methacrylate-triethyleneglycol dimethacrylate (BisGMA-TEGDMA)/bioactive glass (BAG) composite, aimed to be used as composite implant abutment surface modifier. Three different types of substrates were investigated: (a) plain polymer (BisGMA 50 wt%-TEGDMA 50 wt%), (b) BAG-composite (50 wt% polymer + 50 wt% fraction of BAG-particles, <50 µm), and (c) plain BAG plates (100 wt% BAG). The blood response, including the blood-clotting ability and platelet adhesion morphology were evaluated. Human gingival fibroblasts were plated and cultured on the experimental substrates for up to 10 days, then the cell proliferation rate was assessed using AlamarBlue assay™. The BAG-composite and plain BAG substrates had a shorter clotting time than plain polymer substrates. Platelet activation and aggregation were most extensive, qualitatively, on BAG-composite. Analysis of the normalized cell proliferation rate on the different surfaces showed some variations throughout the experiment, however, by day 10 the BAG-composite substrate showed the highest (P < 0.001) cell proliferation rate. In conclusion, the presence of exposed BAG-particles enhances fibroblast and blood responses on composite surfaces in vitro.

Carbon dioxide laser and bonding materials reduce enamel demineralization around orthodontic brackets.

Altering the structure of the enamel surface around the orthodontic bracket by reducing its content of carbonate and phosphate resulting from application of CO(2) laser may represent a more effective strategy in preventing caries in this region. This study aimed at determining whether irradiation with a CO(2) laser combined with fluoride-releasing bonding material could reduce enamel demineralization around orthodontic brackets subjected to cariogenic challenge. Ninety bovine enamel slabs were divided into five groups (n = 18): non-inoculated brain-heart infusion broth group, non-fluoride-releasing composite resin (NFRCR--control group), resin-modified glass ionomer cement (RMGIC), CO(2) laser + Transbond (L+NFRCR) and CO(2) laser + Fuji (L+RMGIC). Slabs were submitted to a 5-day microbiological caries model. The Streptococcus mutans biofilm formed on the slabs was biochemically and microbiologically analysed, and the enamel Knoop hardness number (KHN) around the brackets was determined. The data were analysed by ANOVA and Tukey tests (α = 0.05). Biochemical and microbiological analyses of the biofilm revealed no statistically significant differences among the groups. Lased groups presented the highest KHN means, which statistically differed from NFRCR; however, no difference was found between these lased groups. RMGIC did not differ from NFRCR which presented the lowest KHN mean. The CO(2) laser (λ = 10.6 µm; 10.0 J/cm(2) per pulse) use with or without F-bonding materials was effective in inhibiting demineralization around orthodontic brackets. However, no additional effect was found when the enamel was treated with the combination of CO(2) laser and an F-releasing material.

Novel mechanically strong and antibacterial dimethacrylate copolymers based on quaternary ammonium urethane-dimethacrylate analogues.

OBJECTIVES: This study assumed that the quaternary ammonium urethane-dimethacrylate derivative (QAUDMA-m, where m was 8, 10, 12, 14, 16, 18, and corresponded to the number of carbon atoms in the N-alkyl substituent) can be used to achieve copolymers with high mechanical performance and antibacterial activity. METHODS: Photocured copolymers of bisphenol A glycerolate dimethacrylate (Bis-GMA) 40 wt%, QAUDMA-m 40 wt%, and triethylene glycol dimethacrylate (TEGDMA) 20 wt% (BG:QAm:TEG) were characterized by the degree of conversion (DC), flexural strength (FS), flexural modulus (E), hardness (HB), and antibacterial properties (the number of bacteria colonies adhered to copolymer surfaces and inhibition zone diameter (IZD)) against Staphylococcus aureus and Escherichia coli. Reference copolymers of Bis-GMA, urethane-dimethacrylate monomer (UDMA), and TEGDMA (BG:TEG and BG:UD:TEG) were also characterized. RESULTS: The DC of BG:QAm:TEGs ranged from 0.59 to 0.68, HB from 83.84 to 153.91 MPa, FS from 50.81 to 74.47 MPa, and E from 1986.74 to 3716.68 MPa. The number of S. aureus and E. coli bacteria adhered to BG:QAm:TEG surfaces was from 0 (no bacteria observed) to 6.47 and 4.99 log(CFU/mL), respectively. IZD was from 10 and 5 mm (no inhibition zone) to 23 and 21 mm, respectively. Three copolymers: BG:QA8:TEG, BG:QA10:TEG, and BG:QA12:TEG had similar or better mechanical properties than the reference copolymers, but unlike them, they showed high antibacterial activity against both bacteria strains. SIGNIFICANCE: The obtained copolymers can offer a good, mechanically efficient, bioactive alternative to BG:TEG and BG:UD:TEG copolymers. The use of such materials can help to make progress in dental health care.

Terminal sterilization of BisGMA-TEGDMA thermoset materials and their bioactive surfaces by supercritical CO2.

The development of biomaterials endowed with bioactive features relies on a simultaneous insight into a proper terminal sterilization process. FDA recommendations on sterility of biomaterials are very strict: a sterility assurance level (SAL) of 10(-6) must be guaranteed for biomaterials to be used in human implants. In the present work, we have explored the potential of supercritical CO(2) (scCO(2)) in the presence of H(2)O(2) as a low-temperature sterilization process for thermoset materials and their bioactive surfaces. Different conditions allowing for terminal sterilization have been screened and a treatment time-amount of H(2)O(2) relationship proposed. The selected terminal sterilization conditions did not notably modify the mechanical properties of the thermoset nor of their fiber-reinforced composites. This was confirmed by µCT analyses performed prior to and after the treatment. On the contrary, terminal sterilization in the presence of H(2)O(2) induced a slight decrease in the surface hardness. The treatment of the thermoset material with scCO(2) led to a reduction in the residual unreacted monomers content, as determined by means of high performance liquid chromatography (HPLC) analyses. Finally, it was found that a thermoset coated with a polysaccharide layer containing silver nanoparticles maintained a very high antimicrobial efficacy even after the scCO(2)-based terminal sterilization.

Investigation of antimicrobial and mechanical effects of functional nanoparticles in novel dental resin composites.

OBJECTIVES: Imidazole and benzimidazole derivatives have recently attracted attention as remarkable materials due to their advantages in chemistry, pharmacology, and biomaterials. This article focuses on dental composites with azole functional groups incorporated to affect their physicochemical and mechanical properties and antibacterial activity. METHODS: Dental composites were fabricated by embedding the functionalized imidazole and benzimidazole nanoparticles into a Bis-GMA/TEGDMA matrix to form the imidazole and benzimidazole dental composites series (I and B). The material was produced through hand blending of the monomer (50:50, wt%), filler (0-30, wt%), and initiator combination (CQ/EDMAB:0.8:1.6, wt%), and LED light-curing unit for 60 s. RESULTS: Using various characterization techniques, I and B series were validated. The dental composites' approximate solubility and sorption significances were evaluated by conducting experiments on specific dental composite formulations. Fenton reaction test was performed to determine the chemical stability of the dental composites. The mechanical properties of the dental composites were investigated. Finally, by testing cell growth in the presence of composites, their antibacterial activities were determined. CONCLUSIONS: In this study, it was observed that the mechanical, physiochemical, and antibacterial properties of the functional azole-containing nanoparticles were positively improved by adding them to the structure of dental composites. These experimental results paved the way for the synthesized materials to be used in industrial applications. CLINICAL SIGNIFICANCE: Since the chemical, mechanical, and antimicrobial properties of dental composites containing 10% imidazole and benzimidazole functional nanoparticles are far superior, they constitute an excellent alternative for preventing dental caries and long-term use of dental composites.

Preparation of Bis-GMA free dental resin composites with anti-adhesion effect against Streptococcus mutans using synthesized fluorine-containing methacrylate (DFMA).

With purpose of preparing Bis-GMA free dental resin composites (DRCs) with anti-adhesion effect against Streptococcus mutans (S. mutans), a new fluorinated dimethacrylate (DFMA) was synthesized and used as base resin of DRCs. Two reactive diluents TEGDMA and SR833s were mixed with DFMA separately to prepare resin matrixes. After mixing with inorganic fillers, two DFMA based DRCs were obtained and named as DT (DFMA/TEGDMA) and DS (DFMA/SR833s) according to the resin matrix composition. Bis-GMA based DRC (BT) was used as control. The double bond conversion (DC), bacteria adhesion, mucin adsorption, contact angle, surface free energy, volumetric shrinkage (VS), shrinkage stress (SS), water sorption (WS) and solubility (SL), flexural strength (FS) and modulus (FM) before and after water immersion were investigated, and all the results were statistically analyzed with ANOVA analysis. The results showed that DT and DS had comparable (ρ > 0.05) surface free energy which was lower than that of BT (ρ < 0.05). Compared with BT, with the same surface roughness (ρ > 0.05), less amount of S. mutans was accumulated on the surface of DT and DS (ρ < 0.05). In all DRCs, the DS had the best resistance to mucin adsorption (ρ < 0.05) due to its high hydrophobicity. Compared with BT, both DFMA based DRCs had advantages such as lower VS and SS (ρ < 0.05), lower WS and SL (ρ < 0.05), and better water resistance. The DS, which had antibacterial adhesion effect, mucin adsorption resistance, lowest VS and SL (ρ < 0.05), and the highest FS and FM no matter before or after water immersion (ρ < 0.05) was considered to have the best comprehensive properties in all DRCs.

Bonding efficiency of contemporary adhesives to the dentinoenamel junction zone.

The aim of this study was to investigate the bonding of dental adhesives to the dentinoenamel junction (DEJ) zone. Bonding of four adhesives [two etch-and-rinse adhesives (ERAs) and two self-etching adhesives (SEAs)] to enamel, dentin, and the DEJ zone was evaluated using a micro-shear test. Based on the measured bond strengths of dentin/enamel and on the area percentages of dentin in the DEJ zone, predicted bond strengths for the DEJ zone were calculated and compared with those measured. The DEJ zone was analyzed, using scanning electron microscopy, after conditioning, resin infiltration, and debonding. Regardless of the adhesive, bond strengths were significantly influenced by substrates, exhibiting the following order of bond strength (strongest to weakest): dentin >DEJ zone > enamel. The predicted values of the DEJ zone for the ERA groups were significantly higher than the measured values. Analysis of the ERA specimens using scanning electron microscopy showed distinct etching textures of enamel and dentin, which outlined the DEJ and increased the adhesive thickness at the enamel side of the DEJ. Those characteristics could not be detected in the SEA groups. The DEJ zone displayed bond properties that were stronger than enamel but weaker than dentin and therefore may be considered as transitional bond properties. Enamel/dentin within the DEJ zone might bond more weakly to ERAs than its counterpart of the bulk tissue. The presence of the DEJ in the bond area might compromise the bonding efficiency of ERAs.

Protective effect of pit and fissure sealants on demineralization of adjacent enamel.

PURPOSE: This study's purpose was to evaluate the in vitro effect of sealants in protecting adjacent enamel from acid demineralization. METHODS: Occlusal fissures of extracted molars (N=10) were sealed with: conventional nonfluoride (DO; Delton Opaque) resin-based sealant (RBS); fluoride-containing RBS (US; UltraSeal XT plus, and CP; Clinpro); amorphous calcium phosphate-containing RBS (BW; Bosworth Aegis); or glass ionomer sealant (FT; Fuji Triage). The specimens were immersed in lactic acid gel for 20 days to create demineralized lesions on the occlusal enamel. Cross-sectional microhardness was measured at the lesion 0.5 mm from the sealant margin. Mineral loss (ΔZ, volume % mineral x µm) was calculated from the microhardness values and subjected to analysis of variance and student-Newman-Keuls tests. RESULTS: Mineral loss values (mean ±SD) were: 1,975 ± 806, 1,802 ± 512, 1,004 ± 421, 1,275 ± 375, and 88 ± 124 for DO, US, CP, BW, and FT, respectively; ΔZ for DO and US was significantly higher, and ΔZ for FT was significantly lower than that for CP and BW (P=.05). CONCLUSIONS: Resin-based sealants containing fluoride or amorphous calcium phosphate may provide some protective effect on demineralization of adjacent enamel vs conventional nonfluoride sealant. Glass ionomer sealant was the most effective in protecting adjacent enamel from acid demineralization.

Micro-shear bond strength of different adhesives to human dental enamel.

UNLABELLED: The aim of this study was to evaluate the micro-shear bond strength of 5 adhesive systems to enamel, one single-bottle acid-etch adhesive (O), two self-etching primers (P) and two all-in-one self-etching adhesives (S). METHOD: Sixty premolar enamel surfaces (buccal or lingual) were ground flat with 400- and 600-grit SiC papers and randomly divided into 5 groups (n = 12), according to the adhesive system: SB2--Single Bond 2 (O); CSE--Clearfil SE Bond (P); ADS--AdheSE (P); PLP--Adper Prompt L-Pop (S); XE3--Xeno III (S). Tygon tubing (inner diameter of 0.8 mm) restricted the bonding area to obtain the resin composite (Z250) cylinders. After storage in distilled water at 37 degrees C for 24h and thermocycling, micro-shear testing was performed (crosshead speed of 0.5 mm/min). Data were submitted to one-way ANOVA and Tukey test (a = 5%). Samples were also subjected to stereomicroscopic and SEM evaluations after micro-shear testing. Mean bond strength values (MPa +/- SD) and the results of Tukey test were: SB2: 36.36 (+/- 3.34)a; ADS: 33.03 (17.83)a; XE3: 32.76 (+/- 5.61)a; CSE: 30.61 (+/- 6.68)a; PLP: 22.17 (+/- 6.05)b. Groups with the same letter were not statistically different. It can be concluded that no significant difference was there between SB2, ADS, XE3 and CSE, in spite of different etching patterns of these adhesives. Only PLP presented statistically lower bond strengths compared with others.

Antibacterial activity of composite resin with glass-ionomer filler particles.

The purpose of this study was to examine the antibacterial activity of composite resin with glass-ionomer filler particles versus that of contemporary commercial composite resins. Three composite resins were used: Beautifil II (containing S-PRG filler), Clearfil AP-X, and Filtek Z250. Resin blocks were bonded to maxillary first molars, and plaque accumulation on the resin block surface was examined after 8 hours. For the antibacterial test, the number of Streptococcus mutans in contact with the composite resin blocks after incubation for 12 hours was determined, and adherence of radiolabeled bacteria was evaluated. Less dental plaque was formed on Beautifil II resin block as compared to the other two materials. Antibacterial test revealed that there were no significant differences in the number of Streptococcus mutans among the three composite resins. However, the adherence of radiolabeled bacteria to the saliva-treated resin surface was significantly (p<0.01) lower in Beautifil II than in the other two materials. These results suggested that Beautifil II could reduce dental plaque formation and bacterial adherence, leading to prevention of secondary caries.

Microbial contamination and inhibitory effect against Streptococcus mutans from fifth-generation bonding systems.

PURPOSE: The aim of this study was to evaluate microbial contamination and inhibitory effect against Streptococcus mutans (SM) of Prime & Bond (PB), Single Bond (SB) and Excite (EX) bonding systems before use, and after 10 and 20 applications. METHODS: The bonding material was collected by applying a drop of the material directly on broth brain-heart infusion. The samples were homogenized, diluted and seeded on blood agar plates. To evaluate the inhibitory effect on SM, a drop of each bonding material was dispensed on filter discs and placed on blood agar plates. The Cochran statistical analysis was used to evaluate the total amount of viable bacteria among the different bonding systems. Comparisons between the inhibitory effects on SM were made using the Kruskal-Wallis test. RESULTS: Adhesives SB and EX presented microbial contamination (p<0.05) and inhibitory effect (p<0.05) over SM strains with statistically significant differences concerning PB. SB and EX inhibitory capacity remained after 20 applications. CONCLUSIONS: The monomer's variation in chemical composition, solvent and application technique of the bonding systems had an influence on contamination by the total number of bacteria and on the inhibitory effect on SM.

The effects of the dental methacrylates TEGDMA, Bis-GMA, and UDMA on neutrophils in vitro.

OBJECTIVES: The prevalent usage of methacrylates in modern dentistry demands good knowledge of their biological impacts. While there have been several studies demonstrating the effects of different methacrylic monomers on mononuclear white blood cells, very little is known about the effects caused by these monomers on neutrophilic granulocytes. The objective of this study was to add novel knowledge about how neutrophils are affected by exposure to triethylene glycol dimethacrylate (TEGDMA), urethane dimethacrylate (UDMA), and bisphenol A glycol dimethacrylate (Bis-GMA) alone or in combinations. MATERIALS AND METHODS: Isolated neutrophils were cultured in the presence or absence of methacrylates. The IL-8 release was measured using a DuoSet ELISA development kit. Apoptosis and necrosis were analyzed using flow cytometry. The formation of neutrophil extracellular traps (NETs) was investigated using Sytox green DNA staining combined with microscopically examination of released DNA and myeloperoxidase (MPO). RESULTS: The release of IL-8 was significantly increased after exposure to TEGDMA, Bis-GMA, UDMA, or TEGDMA in combination with Bis-GMA or UDMA compared to the unstimulated controls. Exposure to TEGDMA, UDMA, and Bis-GMA for 24 hr separately or in combination did not affect apoptosis or necrosis of the exposed neutrophils. NET structures were formed by neutrophils after exposure to the different combinations of the methacrylates. CONCLUSION: The combination of TEGDMA and Bis-GMA had a synergistic proinflammatory effect on neutrophils by increasing the release of IL-8 and the formation of NET structures. The changes in the normal functions of neutrophils caused by methacrylate exposure may lead to altered inflammatory response and relate to previously reported adverse immune reactions caused by these substances.

Transdentinal diffusion and cytotoxicity of self-etching adhesive systems.

OBJECTIVE: To evaluated the transdentinal diffusion and subsequent cytotoxicity of self-etching adhesives on odontoblast-like cells. MATERIALS AND METHODS: Sixty dentin disks (0.4-mm thick) were produced from human molars and divided into six groups (n = 10). The dentin disks were placed in in vitro pulp chambers where MDPC-23 cells were planted on 0.28 cm(2) of exposed dentin on the pulpal side. The adhesives Clearfil SE Bond (CSE), Clearfil Protect Bond (CPB), Adper Prompt (PR), and Xeno III (XE) were applied on the occlusal side. Single Bond (SB) was used as positive and phosphate buffer solution (PBS) as negative control. The cytotoxicity was measured by MTT assay and cell characteristics were assessed by SEM. The transdentinal diffusion was qualified by GC/MS. RESULTS: Kruskal-Wallis and Mann-Whitney tests demonstrated a significant difference among the adhesives and PBS. Cellular viability reduction promoted by the self-etching systems was lower than that of SB (53.1%), except for CSE. Cell metabolism was reduced in 47.8%, 42.1%, 28.0%, and 46.5% for CSE, CPB, PR, and XE, respectively. HEMA was identified as the main diffused component. CONCLUSION: Components from all investigated self-etching adhesive systems were able to diffuse through the dentin resulting in significant reduction of the cellular metabolism.

In situ effects of restorative materials on dental biofilm and enamel demineralisation.

OBJECTIVES: Since secondary caries is one of the main reasons for replacing restorations, this study assessed the effects of different restorative materials on the microbiological composition of dental biofilm and on enamel demineralisation around the restoration. METHODS: A randomized, double-blind, split-mouth in situ design was conducted in one phase of 14 days, during which, 20 volunteers wore palatal devices containing five human dental enamel slabs. Each slab was randomly restored with one of the following materials: Filtek-Z-250/Single Bond, control group (composite resin), Permite (amalgam), Fuji II (encapsulated resin-modified glass ionomer), Vitremer (resin-modified glass ionomer) and Ketac Molar (conventional glass ionomer). The volunteers used fluoride dentifrice, 3x/day and a 20% sucrose solution was dripped onto the slabs 8x/day. The biofilm formed on the slabs was analyzed to determine the counts of total streptococci, mutans streptococci and lactobacilli. Enamel demineralisation was determined by cross-sectional microhardness (CSMH) at 20 and 70 microm from the margin of the restoration. Kruskal-Wallis and analysis of variance, followed by least mean squares (LMS) test, were used to evaluate microbiota and CSMH among the groups. The significance level used was 5%. RESULTS: No statistically significant differences were found in the cariogenic microbiota grown on the slabs. At a 20-mum distance, only Fuji II statistically differed from the other groups, showing the lowest demineralisation. At 70 microm, Fuji II significantly inhibited demineralisation when compared to Permite, Filtek-Z-250 and Ketac Molar. CONCLUSIONS: In the context of fluoride dentifrice and under the cariogenic exposure conditions of this study, only the encapsulated resin-modified glass ionomer material provided additional protection against secondary caries.

Effects of acidic primer/adhesives on primary and permanent dentin.

PURPOSE: To evaluate the quality of primary and permanent dentin by Fourier transformed Raman spectroscopy (FT-Raman), and scanning electron microscopy/energy-dispersive spectroscopy (SEM/EDS). METHODS: The middle dentin of crowns was reached by carbide bur abrading providing a uniform smear layer. Self-etching primers were applied in order to simulate the etching of self-etching adhesive systems. The groups were (n = 6): G1 (primary dentin smear layer); G2 (primary dentin etched by primer of Clearfil Protect Bond); G3 (primary dentin etched by Adper Prompt); G4 (permanent dentin smear layer); G5 (permanent dentin etched by primer of Clearfil Protect Bond); G6 (permanent dentin etched by Adper Prompt). SEM/EDS were made in order to obtain additional elemental data to complement FT-Raman. FT-Raman data were submitted to cluster analysis. RESULTS: Overall, FT-Raman showed differences between primary and permanent dentin concerning organic content, but not for inorganic content. FT-Raman showed differences in the organic content between primary and permanent dentin after self-etching primer use. HEMA usage caused molecular changes in the organic content, while phosphoric acidic ester caused molecular changes in the inorganic content of primary and permanent dentin. The SEM/EDS identified C, O, P, and Ca, which could not replace ions to change mineral molecular arrangement. Both organic and mineral content arrangements were similar after self-etching primers action. The organic content of dentin was modified by both Clearfil PB primer and Adper Prompt for primary dentin but only by Clearfil PB for permanent dentin. The inorganic content of primary middle dentin was similar to the inorganic content of permanent middle dentin, even when Adper Prompt is used.

Microleakage of ceramic inlays luted with different resin cements and dentin adhesives.

STATEMENT OF PROBLEM: Despite recent advances in adhesive dentistry, resin cement/dentin adhesive combinations are not able to prevent microleakage in ceramic inlays. Marginal quality of tooth-colored restorations in large Class II cavities is satisfactory in enamel margins, but microleakage in dentin margins remains a concern. PURPOSE: The purpose of this study was to evaluate the microleakage of all-ceramic inlays luted with 2 dual-polymerizing resin cements or 1 autopolymerizing resin cement in combination with different dentin adhesives. MATERIAL AND METHODS: One hundred and twenty extracted human mandibular third molars were used in this study. Teeth were prepared to receive Class II MOD inlays with enamel gingival margins on 1 proximal surface and dentin gingival margins on the other surface. One hundred and twenty prepared teeth were divided into 3 groups of 40; 1 group for each resin cement: RelyX ARC, Variolink II, or Panavia 21. Each of the 3 groups were further divided into 4 dentin adhesive groups; Single Bond, ExciTE DSC, ED Primer, or Admira Bond. Each of the resin cements were used in combination with the 4 dentin adhesives, and IPS Empress ceramic inlays were placed with 12 different cement/adhesive combinations. After 1000 thermal cycles in a 5 degrees -55 degrees C water bath with a dwell time of 30 seconds, all specimens were subjected to cyclic axial mechanical loading. Then the restored teeth were stored in 0.5% basic fuchsin solution for 24 hours. The extent of dye penetration along the margins was measured with a stereomicroscope at x40 magnification. The data were evaluated statistically using repeated-measures ANOVA and Duncan tests (alpha=.05). RESULTS: Microleakage at dentin margins was greater than that at enamel margins (P<.05) for all groups. Variolink II and RelyX ARC resin cements showed significantly lower microleakage results than Panavia 21 with all dentin adhesives in enamel margins. For dentin margins, Variolink II/Admira Bond combination showed the lowest microleakage value in dentin (P<.05). CONCLUSIONS: The overall microleakage at the enamel margins was significantly less than at the dentin margins (P<.05). Panavia 21 showed higher microleakage values than Variolink II and RelyX ARC in enamel margins.