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Experimental one-step, self-etch adhesives containing different contents of an acidic methacrylate monomer (GDMA-P) were formulated and their effectiveness in bonding to sound dentin (SoD) or caries-affected dentin (CAD) was investigated. The CAD was obtained using a microcosm biofilm model. HEMA-based adhesives were formulated with 5, 20, or 35 wt% of GDMA-P (AD5, AD20, AD35), with pH ranging between 1.05 ± 0.05 and 1.93 ± 0.15. Shear bond strength to dentin was assessed after storage for 24 h or 6 months. Morphology of the bonded interfaces was observed using SEM. The exposed collagen area at bonded interfaces was measured using a histological staining technique. Degree of C=C conversion within the hybrid layer, measured by micro-Raman spectroscopy, indicated that AD35 had lower in situ C=C conversion than the other adhesives. A more evident exposed collagen zone along the base of the hybrid layer was observed in CAD samples. The hybrid layer was generally thicker in CAD. AD20 had the highest in situ C=C conversion and yielded stable bond strengths that were generally independent of the dentin condition. Additionally, the bonding effectiveness was dependent on adhesive acidity, type of dentin bonding substrate, and water storage time.

This study examined the effects of two deproteinization protocols on dentin microtensile bond strength (µTBS), in situ degree of conversion (DC) and interfacial nanoleakage (NL) of two self-adhesive resin cements (SARCs) after 24 h or 200,000 load cycles. One hundred fourteen third molars were distributed into six groups according to the type of cement and the strategy of deproteinization. Resin cements used were RelyX U200 (RU) and Maxcem Elite (ME) following the manufacturer´s instructions and after deproteinization protocols (NaOCl for 2 min or acid etching before NaOCl for 2 min). The bonded specimens were randomly divided and submitted to microtensile test after 24 h or after 200,000 load cycles. Two slices from each subgroup were prepared for NL using ammoniacal silver nitrate solution, and analyzed through SEM. The in situ DC of three bonded-specimens from each group was measured through micro-Raman spectroscopy. Data was statistically analyzed by Two-way ANOVA and Tukey's test (p

Objectives The EDTMP (ethylenediamine-tetra-methylene phosphonate) is a molecule similar to EDTA (ethylenediamine-tetra-acetic acid), but with phosphonates, thereby presenting efficient chelating action and binding adequately to proteins, such as collagen. The objective of this study was to evaluate EDTMP as new etching solution to aid ion-releasing adhesive containing beta-tri-calcium phosphate (β-TCP) fillers used for intrarradicular dentin bonding. Materials and methods Thirty extracted single-rooted human teeth were prepared, and glass-fiber posts were adhesively luted with Scotchbond Multipurpose (SBMP, 3 M) adhesive after etching with 37% phosphoric acid for 15s, 15% EDTA or 15% EDTMP for 120s, and SBMP adhesive incorporated or not with β-TCP. RelyX ARC (3 M) was used as resin cement. The restored roots were cut horizontally in 1 mm-thick slabs and submitted to push-out bond strength test after 24h and 6 months of water storage. Interfacial silver nanoleakage was investigated in scanning electron microscopy. Micro-Raman spectroscopy was employed to track mineralization at the hybrid layer. Data were submitted to two-way ANOVA and Tukey’s test (p Results EDTMP without β-TCP achieved the overall highest bond strength in both storage times. The addition of β-TCP impaired the improvements of EDTMP. The presence of carbonated apatite (peak at 1090 cm-1) was found in EDTMP without β-TCP, thereby suggesting remineralization. Little silver impregnation was observed in general across groups. Conclusion: EDTMP could be an optimal alternative as root dentin etchant for luting glass-fiber posts with improvements in dentin bond stability.

Purpose To evaluate the effect of different pHs of 40% meta phosphoric acid (MPA) in comparison with a conventional 37% ortho-phosphoric acid under different application times in terms of resin-dentin bond strength (μTBS), nanoleakage (NL) and the dentin-etching pattern. Materials and methods Ninety-six molars were randomly assigned into 12 experimental conditions according to the combination of the independent variables: Acid [37% ortho-phosphoric acid (OPA), 40% meta-phosphoric acid (MPA) in the following pHs – 0.5, 1 and 2] and Application Time [7, 15 and 30 s]. After restorations, specimens were sectioned into resin–dentine beams (0.8 mm2) tested under tension (0.5 mm/min). Selected beams from each tooth were used for NL evaluation. The dentin-etching pattern of the OPA and MPA was examined under a scanning electron microscop. Acid vs application time data were subjected to two-way ANOVA and Tukey's test (α=0.05) Results MPA pH 0.5 showed μTBS means similar to OPA, independently the application time (p>0.05). A statistically higher NL was observed for OPA in comparison with MPA, regardless the application time (p Conclusion The use of 40% meta-phosphoric acid with pH 0.5 is an alternative acid-etching agent with similar immediate bond strength and lower nanoleakage than the traditional 37% ortho-phosphoric acid.

Objectives The aim of this study was to evaluate the effects of a hydrophobic layer of Bis-EMA 4 (B4, 4 ethoxilations), Bis-EMA 10 (B10, 10 ethoxilations) or Bis-EMA 30 (B30, 30 ethoxilations) on dentin adhesion and mechanical properties of a universal adhesive. Materials and methods Extracted human molars were cut and restored using self-etching mode of Ambar Universal (AU, FGM) adhesive and divided according to the hydrophobic layer employed (n = 8): only AU (Control), SBMP (Scotchbond Multi-Purpose adhesive, 3 M, Commercial Control), B4, B10 and B30. Microtensile bond strength (μTBS) and nanoleakage tests were performed after 24h and 6 months water storage. Interface micro-permeability was surveyed by confocal microscopy. Dynamic-mechanical analysis (DMA) of each adhesive combination (50 wt% Ambar + 50 wt% BisEMA or 100% Ambar) were assessed. The data were statistically analyzed using two-way ANOVA and Tukey's test (p Results SBMP achieved the highest μTBS, followed by B4, B10 and Control, whilst B30 presented significantly lowest μTBS when compared with further groups (p Conclusions Bis-EMA-4 might be a suitable monomer for a hydrophobic layer in adhesive strategy, reducing hydrolytic degradation and increasing the durability and mechanical properties of adhesive interfaces.

This study aimed at assessing the bonding performance after water storage (24 h/6-month) of a methacrylate-based cement applied onto Yttria-Tetragonal Zirconia Polycrystal(Y-TZP) pre-treated using an innovative in-situ silica nanoparticle deposition method and/or air-abrasion with Bioglass 45S5 (BAG) or aluminium oxide (AlO). Pre-sintered blocks of Y-TZP were coated with nano-silica using an experimental in-situ deposition method or used as received (control/silica-free). Air-abrasion was performed with AlO or BAG particles both on silica-coated and control Y-TZP specimens. All the specimens were then analysed using SEM– EDX. Further specimens were treated as described above, bonded using a dual-cure resin cement system and submitted to shear bond strength test after water storage (24 h and 6 months). Fracture analysis was subsequently performed using a stereo-microscope. Uniform nano-silica deposition was achieved in the Y-TZP specimens after in-situ silica deposition treatment. However, AlO air-abrasion removed the nano-silica and roughened the Y-TZP surfaces. Conversely, BAG air-abrasion caused partial removal of the nano-silica layer and created only little retention in the control/silica-free Y-TZP specimens. The highest bond strength both at 24 h and 6-month water storage was attained with the silica-coated specimens air-abraded with BAG and with those which received no air-abrasion. AlO air-abrasion increased the bond strength (24 h) in the Y-TZP specimens compared to the control/silica-free specimens which received no air-abrasion or BAG air-abrasion. The in-situ nano-silica coating method employed in this study may be a suitable, simplified and lowcost approach to provide reliable bond strength to Y-TZP ceramics. No air-abrasion is required after insitu nano-silica deposition. However, AlO air-abrasion can create micro-retentions on the surface of silica-free Y-TZP ceramics and increases the immediate bond strength of methacrylate-based resin cements.

This study aimed at comparing the microtensile bond strength (µTBS) of three simplified luting strategies after different aging processes. Sixty human molars were prepared to expose flat middle dentin surfaces which received the following luting procedures: (i) SB+ARC – two-step etch-and-rinse adhesive+conventional resin cement (Adper Singlebond 2+RelyX ARC, 3M-ESPE); (ii) S3+PAN – one-step self-etch adhesive+conventional resin cement (Clearfil S3+Panavia F2.0, Kuraray Medical); (iii) U200 – self-adhesive resin cement (RelyX U200,3M-ESPE). The specimens were finally restored by indirect resin composite procedures (Filtek Z100,3M-ESPE). The aging regimens were water storage at 37 °C for one week (control), one week of 20 cm H2O simulated pulpal pressure (SPP), 200,000 mechanical loading (ML) cycles, or 5000 thermal cycles (TC). The µTBS data was analyzed by two-way ANOVA and Tukey's test (α=0.05). SB+ARC showed significantly higher µTBS for control and all aging processes (p