- Email: [email protected]
bioactive phosphates based adhesives promote dentin collagen mineralization
d e n t a l m a t e r i a l s 3 2 S ( 2 0 1 6 ) e1–e103
Materials and methods: In this research, we fabricate the biocompatible calcium phosphate cement (CPC) scaffolds by 3D printing of a storable CPC paste based on water-immiscible carrier liquid with defined inner and outer morphology. We revealed the application of the 3D printing technique for the preparation of the CPC-based scaffolds. Printing and hardening of the CPCs were performed under mild and malleable conditions permitting the (precise and local) integration of biological elements. Results: The CPC pastes displayed an appropriate processability in the 3D printing technique and permitted the preparation of the stable 3D structures with sufficient compressive strength and young modulus. It was found that CPC pastes were stable and their setting reaction is initiated only after soaking in the water. Also, the Biocompatibility and bioactivity of the printed CPC-based scaffolds was ascertained in a cell culture experiment with osteoblast cells. Conclusions: The malleable and sterile conditions of the all experimental procedure during 3D make this technique highly attractive for production of customized scaffold with respect to patient-specific demands. http://dx.doi.org/10.1016/j.dental.2016.08.116 116 3D-printed -TCP/collagen scaffolds for bone tissue engineering F. Fahimipour 1,∗ , T.S. Jafarzadeh Kashi 2 , K. Khoshroo 1 , E. Dashtimoghadam 1 , M. Rasoulianborujeji 1 , L. Tayebi 1 1
Marquette University School of Dentistry, Milwaukee, USA 2 Dental Biomaterials Department, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran Purpose/Aim: Bone tissue engineering is sought to apply strategies for bone defects healing without limitations and short-comings of using either bone autografts or allografts and xenografts. The aim of this study was to fabricate and characterize the thin layer collagen- coated 3D printed betatricalcium phosphate (-TCP) scaffolds. Materials and methods: -TCP scaffolds were fabricated using 3D-printing technique. Scaffolds were prepared from 3D printed paste composed of -TCP, carboxymethyl cellulose (CMC) as binder and tripolyphosphate (TPP) as viscosity modifier. The printed scaffolds were then sintered at 1100 ◦ C, followed by coating with a thin layer collagen via dip coating. The prepared scaffolds were evaluated by scanning electron microscopy (SEM), X-ray diffraction (XRD) analyses. Also, the mechanical properties of theses printed scaffolds were determined. Finally, the in vitro biological characteristics of the scaffolds such as biocompatibility and bioactivity were assessed using human osteoblast cells (HOB). Results: The -TCP/collagen scaffolds were found to display compressive strength near cancellous bone. The mean porosity and pore size of the prepared printed scaffolds was about 87% and 500 micrometers, receptively. The obtained results from in vitro biological properties revealed that the
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rate of cell proliferation is significantly improved for collagencoated -TCP scaffolds than -TCP. Conclusions: In conclusion, this study ascertained that optimization of material parameters for 3D printed -calcium phosphate scaffolds and improvement of material characteristics by collagen incorporation via inkjet printing. http://dx.doi.org/10.1016/j.dental.2016.08.117 117 3-D printed PCL/halloysite scaffolds for craniomaxillofacial bone regeneration H.E. Jazayeri, E. Dashtimoghadam, M. Rasoulianbroujeni, M. Bures, L. Tayebi ∗ Marquette University School of Dentistry, Milwaukee, USA Purpose/Aim: The purpose of this experimental study is to assess the compressive durability of three-dimensionally printed PCL/Halloysite composite scaffolds in order to optimize their suitability for future clinical attempts at regenerating craniomaxillofacial bone. It is our hope that this study will affirm our hypothesis that the addition of Halloysite will improve the compression strength of PCL. Materials and methods: Following a solvent casting method to prepare the desired nanocomposite, the PCL/Halloysite was printed by hot extrusion with a commercial bioprinter at an optimal pressure and printing speed of 2.5 bar and 4 mm/s, respectively, to produce scaffolds of 3 wt% and cubic dimensions of 5 × 5 × 5 mm. Results: The samples exhibited proper bioactivity by being conducive to osteoblast growth and the addition of Halloysite improved, to a certain degree, the compression strength of the scaffolds. Additionally, SEM micrographs displayed excellent morphology. Conclusions: The experiment demonstrated that Halloysite concentrations can be manipulated to produce nanocomposite scaffolds with optimal mechanical characteristics, while still retaining its osteoconductivity, for craniomaxillofacial bone regeneration. With consistent durability shown in vitro, it is our hope to advance the scaffold’s capabilities to in vivo studies and clinical trials in the future. http://dx.doi.org/10.1016/j.dental.2016.08.118 118 Biomimetic analogs/bioactive phosphates based adhesives promote dentin collagen mineralization M.A.C. Sinhoreti 1 , E.F. Soares 1 , G.F. Abuna 1 , J.F. Roulet 2 , S. Geraldeli 2,∗ 1
State University of Campinas, Piracicaba Dental School, Piracicaba, Brazil 2 University of Florida, College of Dentistry, Gainesville, USA Purpose/Aim: The aim of this study was to use ultramorphology (TEM) to investigate the remineralization of
e58
d e n t a l m a t e r i a l s 3 2 S ( 2 0 1 6 ) e1–e103
resin–dentin interfaces (RDI) created with an experimental multi-mode adhesive system containing biomimetic analogs and bioactive phosphates. Materials and methods: The adhesive systems included: primer (15% GDMA-P; 10% HEMA, 10% TEG-DMA, 10% UDMA, and 40% ethanol); and adhesive resin (30% UDMA, 27% BisEMA, 10% TEGDMA, 10% GDMA-P and 3% photoinitiator system). The analogs (5% polyacrylic acid and 10% polyvinylphosphonic acid), and the bioactive phosphates (20%) were added to the primer and/or adhesive resin. The following groups were tested for ultra-morphology of the RDI (n = 24), according to either an etch-and-rinse (ER) or self-etching (SE) strategy: Control-E&R (n = 3)/SE (n = 3) (no analogs or bioactive phosphates); Exp-1 E&R (n = 3)/SE (n = 3) (no analogs but bioactive phosphates), Exp-2 ER (n = 3)/SE (n = 3) (analogs and no bioactive phosphates), Exp-3 ER (n = 3)/SE (n = 3) (analogs and bioactive phosphates). Flat sound mid dentin was revealed and a standard smear layer created. For E&R strategy, phosphoric acid was applied for 15 s, rinsed for 15 s and dried leaving dentin moist. A primer solution was applied for 20 s and dried for 15 s. For SE strategy, a primer solution was applied for 20 s, then dried for 10 s. Both strategies received a layer of adhesive and light cured for 20 s. A 0.5 mm layer of a microfilled resin-based composite was added/light cured 30 s. After 24 h and 4 M storage in simulated body fluid, beams of 0.3 × 0.3 × 4 mm were obtained from the resin–dentin interface (RDI) and processed following a conventional TEM protocol. Ultra-thin sections (90 nm) were obtained and the morphology evaluated (Hitachi, H-7600). Results: Ultra-thin sections demonstrated a wellestablished RDI for all groups. Phosphates conglomerates were observed in the adhesive layer only for groups containing the bioactive phosphate. In both strategies, only the experimental groups containing analogs showed a higher number of needle-like crystals at the bottom of the RDI. Conclusions: Incorporation of analogs, such as polyacrylic and polyvinylphosphonic acids, into etch-and-rinse and self-etching adhesive systems facilitates remineralization of depleted collagen present in the RDI. http://dx.doi.org/10.1016/j.dental.2016.08.119 119 Photo-fenton: An alternative for dental bleaching B.A. Lopes 1,∗ , P.E.C. Cardoso 1 , A.C.S.C. Teixeira 2 1
University of Sao Paulo, Brazil Polytechnic School of Engineering, University of São Paulo, Chemical Engineering Department, Brazil 2
Purpose/Aim: Consumption of colored drinks and food has been identified as one of the main causes for the staining of tooth structure. The oxidation of these pigments during dental bleaching treatment is achieved by the use of H2 O2 . Virtually unknown to the dental field are the advanced oxidation processes (AOPs), able to generate a large number of stronger oxidants, and which may be an alternative to conventional
Table 1 – Experimental design. Group
[%] Ferrous gluconate
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
0.0015 (−1) 0.0045 (+1) 0.0015 (−1) 0.0045 (+1) 0.0015 (−1) 0.0045 (+1) 0.0015 (−1) 0.0045 (+1) 0.0005 (−1.682) 0.0055 (+1.682) 0.0030 (0) 0.0030 (0) 0.0030 (0) 0.0030 (0) 0.0030 (0) 0.0030 (0)
[%] H2 O2
Irradiation time (min)
10 (−1) 10 (−1) 25 (+1) 25 (+1) 10 (−1) 10 (−1) 25 (+1) 25 (+1) 17.5 (0) 17.5 (0) 4.9 (−1.682) 30.1 (+1.682) 17.5 (0) 17.5 (0) 17.5 (0) 17.5 (0)
15 (−1) 15 (−1) 15 (−1) 15 (−1) 45 (+1) 45 (+1) 45 (+1) 45 (+1) 30 (0) 30 (0) 30 (0) 30 (0) 4.8 (−1.682) 55.2 (+1.682) 30 (0) 30 (0)
dental bleaching. This study evaluated, in vitro, the bleaching of a common food stain through the use of a well-known AOP called Photo-Fenton reaction. Materials and methods: Following the experimental planning (Table 1) 16 aqueous solutions containing cochineal carmine dye (0.17 g/L) (C) + hydrogen peroxide (5–30%) (P) + ferrous gluconate (0.0005–0.0055%) (G) were irradiated by the LED lamp Zoom! (Philips, ZOOM!) for a period of time between 5 and 55 min. With an absorption spectrophotometer UV–vis the remaining dye in the solutions was measured. For each solution three repetitions were carried out (n = 3). Results: The color removal values were analyzed based on a response surface obtained through the software Statigraphics 5.1, which indicated variations in the results dependent upon the experimental condition. The concentration of G and the irradiation time had a positive effect on dye removal, varying from 81% to 96%; nevertheless, the use of P alone showed no major effect on color removal, ranging from 5% to 14%. The hydrogen peroxide for the conditions evaluated did not have a significant improvement on the removal of the dye. Conclusions: The photo-Fenton reaction presented a high potential for dye removal for the conditions evaluated; the dye removal efficacy was dependent on the concentration of the ferrous gluconate and the irradiation time. Further evaluations should be made with different concentrations of P, G and irradiation time. http://dx.doi.org/10.1016/j.dental.2016.08.120 120 Resistance of resin-based materials against prolonged erosive and abrasive challenges D. Rios ∗ , G.C. De Oliveira, M.C. Jordão, M.A.G. Bassoto, E.J. Dionísio, L. Wang, H.M. Honório Bauru School of Dentistry, University of São Paulo, Bauru, Brazil Purpose/Aim: This in vitro study evaluated the effects of applying resin-based materials, including resin infiltration, on previously eroded enamel subjected to prolonged erosive and abrasive challenges (30 days).
Materials and methods: In this research, we fabricate the biocompatible calcium phosphate cement (CPC) scaffolds by 3D printing of a storable CPC paste based on water-immiscible carrier liquid with defined inner and outer morphology. We revealed the application of the 3D printing technique for the preparation of the CPC-based scaffolds. Printing and hardening of the CPCs were performed under mild and malleable conditions permitting the (precise and local) integration of biological elements. Results: The CPC pastes displayed an appropriate processability in the 3D printing technique and permitted the preparation of the stable 3D structures with sufficient compressive strength and young modulus. It was found that CPC pastes were stable and their setting reaction is initiated only after soaking in the water. Also, the Biocompatibility and bioactivity of the printed CPC-based scaffolds was ascertained in a cell culture experiment with osteoblast cells. Conclusions: The malleable and sterile conditions of the all experimental procedure during 3D make this technique highly attractive for production of customized scaffold with respect to patient-specific demands. http://dx.doi.org/10.1016/j.dental.2016.08.116 116 3D-printed -TCP/collagen scaffolds for bone tissue engineering F. Fahimipour 1,∗ , T.S. Jafarzadeh Kashi 2 , K. Khoshroo 1 , E. Dashtimoghadam 1 , M. Rasoulianborujeji 1 , L. Tayebi 1 1
Marquette University School of Dentistry, Milwaukee, USA 2 Dental Biomaterials Department, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran Purpose/Aim: Bone tissue engineering is sought to apply strategies for bone defects healing without limitations and short-comings of using either bone autografts or allografts and xenografts. The aim of this study was to fabricate and characterize the thin layer collagen- coated 3D printed betatricalcium phosphate (-TCP) scaffolds. Materials and methods: -TCP scaffolds were fabricated using 3D-printing technique. Scaffolds were prepared from 3D printed paste composed of -TCP, carboxymethyl cellulose (CMC) as binder and tripolyphosphate (TPP) as viscosity modifier. The printed scaffolds were then sintered at 1100 ◦ C, followed by coating with a thin layer collagen via dip coating. The prepared scaffolds were evaluated by scanning electron microscopy (SEM), X-ray diffraction (XRD) analyses. Also, the mechanical properties of theses printed scaffolds were determined. Finally, the in vitro biological characteristics of the scaffolds such as biocompatibility and bioactivity were assessed using human osteoblast cells (HOB). Results: The -TCP/collagen scaffolds were found to display compressive strength near cancellous bone. The mean porosity and pore size of the prepared printed scaffolds was about 87% and 500 micrometers, receptively. The obtained results from in vitro biological properties revealed that the
e57
rate of cell proliferation is significantly improved for collagencoated -TCP scaffolds than -TCP. Conclusions: In conclusion, this study ascertained that optimization of material parameters for 3D printed -calcium phosphate scaffolds and improvement of material characteristics by collagen incorporation via inkjet printing. http://dx.doi.org/10.1016/j.dental.2016.08.117 117 3-D printed PCL/halloysite scaffolds for craniomaxillofacial bone regeneration H.E. Jazayeri, E. Dashtimoghadam, M. Rasoulianbroujeni, M. Bures, L. Tayebi ∗ Marquette University School of Dentistry, Milwaukee, USA Purpose/Aim: The purpose of this experimental study is to assess the compressive durability of three-dimensionally printed PCL/Halloysite composite scaffolds in order to optimize their suitability for future clinical attempts at regenerating craniomaxillofacial bone. It is our hope that this study will affirm our hypothesis that the addition of Halloysite will improve the compression strength of PCL. Materials and methods: Following a solvent casting method to prepare the desired nanocomposite, the PCL/Halloysite was printed by hot extrusion with a commercial bioprinter at an optimal pressure and printing speed of 2.5 bar and 4 mm/s, respectively, to produce scaffolds of 3 wt% and cubic dimensions of 5 × 5 × 5 mm. Results: The samples exhibited proper bioactivity by being conducive to osteoblast growth and the addition of Halloysite improved, to a certain degree, the compression strength of the scaffolds. Additionally, SEM micrographs displayed excellent morphology. Conclusions: The experiment demonstrated that Halloysite concentrations can be manipulated to produce nanocomposite scaffolds with optimal mechanical characteristics, while still retaining its osteoconductivity, for craniomaxillofacial bone regeneration. With consistent durability shown in vitro, it is our hope to advance the scaffold’s capabilities to in vivo studies and clinical trials in the future. http://dx.doi.org/10.1016/j.dental.2016.08.118 118 Biomimetic analogs/bioactive phosphates based adhesives promote dentin collagen mineralization M.A.C. Sinhoreti 1 , E.F. Soares 1 , G.F. Abuna 1 , J.F. Roulet 2 , S. Geraldeli 2,∗ 1
State University of Campinas, Piracicaba Dental School, Piracicaba, Brazil 2 University of Florida, College of Dentistry, Gainesville, USA Purpose/Aim: The aim of this study was to use ultramorphology (TEM) to investigate the remineralization of
e58
d e n t a l m a t e r i a l s 3 2 S ( 2 0 1 6 ) e1–e103
resin–dentin interfaces (RDI) created with an experimental multi-mode adhesive system containing biomimetic analogs and bioactive phosphates. Materials and methods: The adhesive systems included: primer (15% GDMA-P; 10% HEMA, 10% TEG-DMA, 10% UDMA, and 40% ethanol); and adhesive resin (30% UDMA, 27% BisEMA, 10% TEGDMA, 10% GDMA-P and 3% photoinitiator system). The analogs (5% polyacrylic acid and 10% polyvinylphosphonic acid), and the bioactive phosphates (20%) were added to the primer and/or adhesive resin. The following groups were tested for ultra-morphology of the RDI (n = 24), according to either an etch-and-rinse (ER) or self-etching (SE) strategy: Control-E&R (n = 3)/SE (n = 3) (no analogs or bioactive phosphates); Exp-1 E&R (n = 3)/SE (n = 3) (no analogs but bioactive phosphates), Exp-2 ER (n = 3)/SE (n = 3) (analogs and no bioactive phosphates), Exp-3 ER (n = 3)/SE (n = 3) (analogs and bioactive phosphates). Flat sound mid dentin was revealed and a standard smear layer created. For E&R strategy, phosphoric acid was applied for 15 s, rinsed for 15 s and dried leaving dentin moist. A primer solution was applied for 20 s and dried for 15 s. For SE strategy, a primer solution was applied for 20 s, then dried for 10 s. Both strategies received a layer of adhesive and light cured for 20 s. A 0.5 mm layer of a microfilled resin-based composite was added/light cured 30 s. After 24 h and 4 M storage in simulated body fluid, beams of 0.3 × 0.3 × 4 mm were obtained from the resin–dentin interface (RDI) and processed following a conventional TEM protocol. Ultra-thin sections (90 nm) were obtained and the morphology evaluated (Hitachi, H-7600). Results: Ultra-thin sections demonstrated a wellestablished RDI for all groups. Phosphates conglomerates were observed in the adhesive layer only for groups containing the bioactive phosphate. In both strategies, only the experimental groups containing analogs showed a higher number of needle-like crystals at the bottom of the RDI. Conclusions: Incorporation of analogs, such as polyacrylic and polyvinylphosphonic acids, into etch-and-rinse and self-etching adhesive systems facilitates remineralization of depleted collagen present in the RDI. http://dx.doi.org/10.1016/j.dental.2016.08.119 119 Photo-fenton: An alternative for dental bleaching B.A. Lopes 1,∗ , P.E.C. Cardoso 1 , A.C.S.C. Teixeira 2 1
University of Sao Paulo, Brazil Polytechnic School of Engineering, University of São Paulo, Chemical Engineering Department, Brazil 2
Purpose/Aim: Consumption of colored drinks and food has been identified as one of the main causes for the staining of tooth structure. The oxidation of these pigments during dental bleaching treatment is achieved by the use of H2 O2 . Virtually unknown to the dental field are the advanced oxidation processes (AOPs), able to generate a large number of stronger oxidants, and which may be an alternative to conventional
Table 1 – Experimental design. Group
[%] Ferrous gluconate
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
0.0015 (−1) 0.0045 (+1) 0.0015 (−1) 0.0045 (+1) 0.0015 (−1) 0.0045 (+1) 0.0015 (−1) 0.0045 (+1) 0.0005 (−1.682) 0.0055 (+1.682) 0.0030 (0) 0.0030 (0) 0.0030 (0) 0.0030 (0) 0.0030 (0) 0.0030 (0)
[%] H2 O2
Irradiation time (min)
10 (−1) 10 (−1) 25 (+1) 25 (+1) 10 (−1) 10 (−1) 25 (+1) 25 (+1) 17.5 (0) 17.5 (0) 4.9 (−1.682) 30.1 (+1.682) 17.5 (0) 17.5 (0) 17.5 (0) 17.5 (0)
15 (−1) 15 (−1) 15 (−1) 15 (−1) 45 (+1) 45 (+1) 45 (+1) 45 (+1) 30 (0) 30 (0) 30 (0) 30 (0) 4.8 (−1.682) 55.2 (+1.682) 30 (0) 30 (0)
dental bleaching. This study evaluated, in vitro, the bleaching of a common food stain through the use of a well-known AOP called Photo-Fenton reaction. Materials and methods: Following the experimental planning (Table 1) 16 aqueous solutions containing cochineal carmine dye (0.17 g/L) (C) + hydrogen peroxide (5–30%) (P) + ferrous gluconate (0.0005–0.0055%) (G) were irradiated by the LED lamp Zoom! (Philips, ZOOM!) for a period of time between 5 and 55 min. With an absorption spectrophotometer UV–vis the remaining dye in the solutions was measured. For each solution three repetitions were carried out (n = 3). Results: The color removal values were analyzed based on a response surface obtained through the software Statigraphics 5.1, which indicated variations in the results dependent upon the experimental condition. The concentration of G and the irradiation time had a positive effect on dye removal, varying from 81% to 96%; nevertheless, the use of P alone showed no major effect on color removal, ranging from 5% to 14%. The hydrogen peroxide for the conditions evaluated did not have a significant improvement on the removal of the dye. Conclusions: The photo-Fenton reaction presented a high potential for dye removal for the conditions evaluated; the dye removal efficacy was dependent on the concentration of the ferrous gluconate and the irradiation time. Further evaluations should be made with different concentrations of P, G and irradiation time. http://dx.doi.org/10.1016/j.dental.2016.08.120 120 Resistance of resin-based materials against prolonged erosive and abrasive challenges D. Rios ∗ , G.C. De Oliveira, M.C. Jordão, M.A.G. Bassoto, E.J. Dionísio, L. Wang, H.M. Honório Bauru School of Dentistry, University of São Paulo, Bauru, Brazil Purpose/Aim: This in vitro study evaluated the effects of applying resin-based materials, including resin infiltration, on previously eroded enamel subjected to prolonged erosive and abrasive challenges (30 days).