Publications by authors named "Eliseu A Münchow"

23 Publications

  • Page 1 of 1

Effects of alternatively used thermal treatments on the mechanical and fracture behavior of dental resin composites with varying filler content.

J Mech Behav Biomed Mater 2021 05 25;117:104424. Epub 2021 Feb 25.

Department of Conservative Dentistry, School of Dentistry, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil; Graduate Program in Dentistry, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil. Electronic address:

The purpose of this study was two-fold: (i) to investigate whether the thermal treatment of direct dental resin composites (RCs) using microwave or autoclave heating cycles would modify the materials' strength as compared to the protocol without heating (control); and (ii) to compare the mechanical performance of direct and indirect RCs. Three RCs (from 3M ESPE) were tested: one indirect (Sinfony); and two direct materials (microhybrid - Filtek Z250; and nanofilled - Filtek Z350). Specimens from the direct RCs were prepared and randomly allocated into three groups according to the thermal treatment (n = 10): Control - no thermal treatment was performed; Microwave - the wet heating was performed using a microwave oven; and Autoclave - the wet heating was performed in an autoclave oven. The indirect RC was prepared following the instructions of the manufacturer. All materials were tested using flexural strength, elastic modulus, work of fracture (W), microhardness, and scanning electron microscopy (SEM) analyses. Data were analyzed with ANOVA and Tukey as well as Weibull analysis (α = 0.05). The thermal treatments tended to produce slight changes in the topography of direct RCs, especially by the autoclave' wet heating. Overall, the physico-mechanical properties changed after thermal treatment, although this effect was dependent on the type of RC and on the heating protocol. Sinfony showed the lowest modulus and hardness of the study, although it was the most compliant system (higher work of fracture). The load-deflection ability was also greater for the indirect RC. Reliability of the tested materials was similar among each other (p > 0.05). In conclusion, the alternative thermal treatments suggested here may significantly influence some aspects of the mechanical behavior of dental resin composites, with negative effects relying on both the chemical composition of the restorative material as well as on the wet heating protocol used. Clinicians should be aware of the possible effects that additional wet heating of direct resin composites using microwave or autoclave thermal protocols as performed here could have on the overall fracture and mechanical responses during loading circumstances.
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http://dx.doi.org/10.1016/j.jmbbm.2021.104424DOI Listing
May 2021

Development of an antibacterial and anti-metalloproteinase dental adhesive for long-lasting resin composite restorations.

J Mater Chem B 2020 12 10;8(47):10797-10811. Epub 2020 Nov 10.

Department of Conservative Dentistry, School of Dentistry, Federal University of Rio Grande do Sul, Porto Alegre, RS 90035-003, Brazil.

Despite all the advances in adhesive dentistry, dental bonds are still fragile due to degradation events that start during application of adhesive agents and the inherent hydrolysis of resin-dentin bonds. Here, we combined two outstanding processing methods (electrospinning and cryomilling) to obtain bioactive (antimicrobial and anti-metalloproteinase) fiber-based fillers containing a potent matrix metalloproteinase (MMP) inhibitor (doxycycline, DOX). Poly(ε)caprolactone solutions containing different DOX amounts (0, 5, 25, and 50 wt%) were processed via electrospinning, resulting in non-toxic submicron fibers with antimicrobial activity against Streptococcus mutans and Lactobacillus. The fibers were embedded in a resin blend, light-cured, and cryomilled for the preparation of fiber-containing fillers, which were investigated with antibacterial and in situ gelatin zymography analyzes. The fillers containing 0, 25, and 50 wt% DOX-releasing fibers were added to aliquots of a two-step, etch-and-rinse dental adhesive system. Mechanical strength, hardness, degree of conversion (DC), water sorption and solubility, bond strength to dentin, and nanoleakage analyses were performed to characterize the physico-mechanical, biological, and bonding properties of the modified adhesives. Statistical analyses (ANOVA; Kruskal-Wallis) were used when appropriate to analyze the data (α = 0.05). DOX-releasing fibers were successfully obtained, showing proper morphological architecture, cytocompatibility, drug release ability, slow degradation profile, and antibacterial activity. Reduced metalloproteinases (MMP-2 and MMP-9) activity was observed only for the DOX-containing fillers, which have also demonstrated antibacterial properties against tested bacteria. Adhesive resins modified with DOX-containing fillers demonstrated greater DC and similar mechanical properties as compared to the fiber-free adhesive (unfilled control). Concerning bonding performance to dentin, the experimental adhesives showed similar immediate bond strengths to the control. After 12 months of water storage, the fiber-modified adhesives (except the group consisting of 50 wt% DOX-loaded fillers) demonstrated stable bonds to dentin. Nanoleakage was similar among all groups investigated. DOX-releasing fibers showed promising application in developing novel dentin adhesives with potential therapeutic properties and MMP inhibition ability; antibacterial activity against relevant oral pathogens, without jeopardizing the physico-mechanical characteristics; and bonding performance of the adhesive.
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http://dx.doi.org/10.1039/d0tb02058cDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7744429PMC
December 2020

The role of nanohydroxyapatite on the morphological, physical, and biological properties of chitosan nanofibers.

Clin Oral Investig 2020 Oct 13. Epub 2020 Oct 13.

Department of Dental Materials and Prosthodontics, Institute of Science and Technology (IST), São Paulo State University (UNESP), Av Engenheiro Francisco José Longo, 777, Jardim São Dimas, São José dos Campos, SP, 12245-200, Brazil.

Objectives: This study aimed to evaluate the effects of nanohydroxyapatite (nHAp) particles on the morphological, chemical, physical, and biological properties of chitosan electrospun nanofibers.

Materials And Methods: nHAp particles with a 1.67 Ca/P ratio were synthesized via the aqueous precipitation method, incorporated into chitosan polymer solution (0.5 wt%), and electrospun into nHAp-loaded fibers (ChHa fibers). Neat chitosan fibers (nHAp-free, Ch fibers) were used as the control. The electrospun fiber mats were characterized using morphological, topographical, chemical, thermal, and a range of biological (antibacterial, antibiofilm, cell viability, and alkaline phosphatase [ALP] activity) analyses. Data were analyzed using ANOVA and Tukey's test (α = 0.05).

Results: ChHa fibers demonstrated a bead-like morphology, with thinner (331 ± 110 nm) and smoother (Ra = 2.9 ± 0.3 μm) distribution as compared to the control fibers. Despite showing similar cell viability and ALP activity to Ch fibers, the ChHa fibers demonstrated greater antibacterial potential against most tested bacteria (except for P. intermedia), and higher antibiofilm activity against P. gingivalis biofilm.

Conclusions: The incorporation of nHAp particles did not jeopardize the overall morphology, topography, physical, and biological characteristics of the chitosan nanofibers.

Clinical Relevance: The combination of nHAp particles with chitosan can be used to engineer bioactive, electrospun composite nanofibers with potential applications in regenerative dentistry.
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http://dx.doi.org/10.1007/s00784-020-03633-6DOI Listing
October 2020

Single-session Endodontic Treatment is a Reality in Low-income Areas in Brazil?

J Contemp Dent Pract 2020 Jun 1;21(6):657-665. Epub 2020 Jun 1.

Department of Clinical Dentistry, Endodontics, Federal University of Bahia, Salvador, Bahia, Brazil.

Aim: The present study aimed to investigate the total number of visits required to conclude root canal treatments (RCTs) as well as the motivations associated to the choice of dentists practicing in low-income areas of Brazil.

Materials And Methods: A total of 3,103 questionnaires were electronically and individually delivered to professionals of Salvador, Sergipe, and Alagoas (Brazil). The questionnaire encompassed sociodemographic data and questions regarding the number of sessions required to conclude RCT. Also, postoperative pain, professional qualification, the use of technological resources, and time for one-visit treatment were evaluated. Data were analyzed using Chi-square and Poisson regression analyses ( < 0.05).

Results: A total of 326 responses were obtained with higher prevalence of specialists in the field of endodontics (36.8%). Dentists reported greater preference for rotary instrumentation (Alagoas 54.6%, Aracaju 62.1%, and Salvador 83.5%), and most of the participants reported multiple visits to treat root canals with the necrotic pulp tissue associated or not to periapical radiolucency, excluding Salvador (53.8%). Dentists who graduated in public dental schools were less likely to perform RCT of necrotic teeth with periapical lesion in one clinical appointment ( = 0.034). The single-session therapy was positively associated to continuing education attendance ( = 0.004) and to the occurrence of clinical complications ( < 0.001). Dentists who graduated in programs were more likely to conclude RCT in less than 60 minutes ( < 0.001), although the occurrence of postoperative pain was more likely observed upon this scenario ( < 0.001).

Conclusion: Despite the social inequalities in the analyzed area, professionals have been seeking for knowledge by means of continuing education programs and the implementation of technological resources in their clinical routine, although this fact has poorly influenced the acceleration of RCT. Clinical significances: The total number of visits to conclude endodontic treatment may be influenced by both professional and biological parameters such as the attendance to postgraduation programs and the use of technology as well as to the biological condition of the pulp and the occurrence of postoperative complications.
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June 2020

Antimicrobial Therapeutics in Regenerative Endodontics: A Scoping Review.

J Endod 2020 Sep;46(9S):S115-S127

Department of Cariology, Restorative Sciences, and Endodontics, University of Michigan School of Dentistry, Ann Arbor, Michigan. Electronic address:

Introduction: This review aimed to provide a critical appraisal of alternative antimicrobial strategies in lieu of traditional triple antibiotic paste (TAP).

Methods: This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. The literature search was performed in 8 databases (PubMed/Medline, Embase, LILACS, Web of Science, Scopus, BVS, SciELO, and the Cochrane Library), selecting clinical, in vitro, in vivo, and in situ studies that evaluated antimicrobial alternatives to TAP in regenerative endodontics. Studies lacking an experimental TAP group were excluded.

Results: A total of 1705 potentially relevant records were initially identified. From the 38 studies retrieved for full-text reading, 16 fulfilled all selection criteria and were included in the qualitative analysis. According to the study design, 11 studies were solely in vitro, 1 study was both in vitro and in vivo (animal model), 2 studies were solely animal experiments, and 2 studies were clinical trials. The alternative antimicrobial agents to TAP consisted of modified TAP formulations (eg, a combination of TAP with chitosan); TAP-eluting nanofibers; propolis; chlorhexidine (CHX) gels/solutions; double antibiotic pastes composed of distinct combinations of antibiotics; Ca(OH)-based formulations; and sodium hypochlorite. Overall, most of the alternative agents performed similarly to TAP, although some strategies (eg, Ca(OH)- and CHX-based formulations) seemed to present dubious importance in the control of infection.

Conclusions: TAP still remains an excellent option in terms of the complete elimination of microorganisms. This review points to the use of electrospun fibers as a drug delivery system to offer a controlled release of the antimicrobial agent, as well as the use of natural compounds, deserving future investigation.
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http://dx.doi.org/10.1016/j.joen.2020.06.032DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7508353PMC
September 2020

The role of polymeric nanofibers on the mechanical behavior of polymethyl methacrylate resin.

J Mech Behav Biomed Mater 2020 12 27;112:104072. Epub 2020 Aug 27.

Department of Dental Materials and Prosthodontics, Institute of Science and Technology, UNESP, São José dos Campos, SP, Brazil. Electronic address:

This study aimed to synthesize and characterize non-woven acrylonitrile butadiene styrene (ABS), polyamide-6 (P6), and polystyrene (PS) nanofibers, and evaluate their effects on the flexural strength and fracture resistance of fiber-modified polymethyl methacrylate (PMMA) resin. ABS, P6, and PS polymer solutions were prepared and electrospun into fiber mats, which were characterized by means of morphological, chemical, physical, and mechanical analyses. The fiber mats were then used to modify a thermally-activated PMMA resin, resulting in four testing groups: one unmodified group (control) and three fiber-modified groups incorporated with ABS, P6, or PS fiber mats. Flexural strength, work of fracture, and fractographic analysis were performed for all groups. Data were analyzed using Kruskal-Wallis or ANOVA tests (α = 0.05). The fiber diameter decreased, respectively, as follows: ABS > P6 > PS. Only the P6 fiber mats demonstrated a crystalline structure. Wettability was similar among the distinct fiber mats, although tensile strength was significantly greater for P6, followed by ABS, and then PS mats. Flexural strength of the fiber-modified PMMA resins was similar to the control, except for the weaker P6-based material. The work of fracture seemed to be greater and lower when the P6 and PS fibers were used, respectively. The fiber-modified groups exhibited a rougher pattern in the fractured surfaces when compared to the control, which may suggest that the presence of fibers deviates the direction of crack propagation, making the fracture mechanism of the PMMA resin more dynamic. While the neat PMMA showed a typical brittle response, the fiber-modified PMMA resins demonstrated a ductile response, combined with voids, suggesting large shear deformation during fracture. Altogether, despite the lack of direct reinforcement in the mechanical strength of the PMMA resin, the use of electrospun fibers showed promising application for the improvement of fracture behavior of PMMA resins, turning them into more compliant materials, although this effect may depend on the fiber composition.
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http://dx.doi.org/10.1016/j.jmbbm.2020.104072DOI Listing
December 2020

Harnessing biomolecules for bioinspired dental biomaterials.

J Mater Chem B 2020 10 4;8(38):8713-8747. Epub 2020 Aug 4.

Minnesota Dental Research Center for Biomaterials and Biomechanics, University of Minnesota, 16-250A Moos Tower, 515 Delaware St. SE, Minneapolis, Minnesota 55455, USA.

Dental clinicians have relied for centuries on traditional dental materials (polymers, ceramics, metals, and composites) to restore oral health and function to patients. Clinical outcomes for many crucial dental therapies remain poor despite many decades of intense research on these materials. Recent attention has been paid to biomolecules as a chassis for engineered preventive, restorative, and regenerative approaches in dentistry. Indeed, biomolecules represent a uniquely versatile and precise tool to enable the design and development of bioinspired multifunctional dental materials to spur advancements in dentistry. In this review, we survey the range of biomolecules that have been used across dental biomaterials. Our particular focus is on the key biological activity imparted by each biomolecule toward prevention of dental and oral diseases as well as restoration of oral health. Additional emphasis is placed on the structure-function relationships between biomolecules and their biological activity, the unique challenges of each clinical condition, limitations of conventional therapies, and the advantages of each class of biomolecule for said challenge. Biomaterials for bone regeneration are not reviewed as numerous existing reviews on the topic have been recently published. We conclude our narrative review with an outlook on the future of biomolecules in dental biomaterials and potential avenues of innovation for biomaterial-based patient oral care.
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http://dx.doi.org/10.1039/d0tb01456gDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7544669PMC
October 2020

Chlorhexidine-modified nanotubes and their effects on the polymerization and bonding performance of a dental adhesive.

Dent Mater 2020 05 30;36(5):687-697. Epub 2020 Mar 30.

Department of Cariology, Restorative Sciences and Endodontics, University of Michigan School of Dentistry, Ann Arbor, MI, USA. Electronic address:

Objectives: The purpose of this study was to synthesize chlorhexidine (CHX)-encapsulated aluminosilicate clay nanotubes (Halloysite®, HNTs) and to incorporate them into the primer/adhesive components of an etch-and-rinse adhesive system (SBMP; Scotchbond Multipurpose, 3M ESPE) and to test their effects on degree of conversion, viscosity, immediate and long-term bonding to dentin.

Methods: CHX-modified HNTs were synthesized using 10% or 20% CHX solutions. The primer and the adhesive components of SBMP were incorporated with 15wt.% of the CHX-encapsulated HNTs. Degree of conversion (DC) and viscosity analyses were performed to characterize the modified primers/adhesives. For bond strength testing, acid-etched dentin was treated with one of the following: SBMP (control); 0.2%CHX solution before SBMP; CHX-modified primers+SBMP adhesive; SBMP primer+CHX-modified adhesives; and SBMP primer+CHX-free HNT-modified adhesive. The microtensile bond strength test was performed after immediate (24h) and long-term (6 months) of water storage. Data were analyzed using ANOVA and Tukey (α=5%) and the Weibull analysis.

Results: DC was greater for the CHX-free HNT-modified adhesive, whereas the other experimental adhesives showed similar DC as compared with the control. Primers were less viscous than the adhesives, without significant differences within the respective materials. At 24h, all groups showed similar bonding performance and structural reliability; whereas at the 6-month period, groups treated with the 0.2%CHX solution prior bonding or with the CHX-modified primers resulted in greater bond strength than the control and superior reliability.

Significance: The modification of a primer or adhesive with CHX-encapsulated HNTs was an advantageous approach that did not impair the polymerization, viscosity and bonding performance of the materials, showing a promising long-term effect on resin-dentin bonds.
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http://dx.doi.org/10.1016/j.dental.2020.03.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7224330PMC
May 2020

Curcumin-A Natural Medicament for Root Canal Disinfection: Effects of Irrigation, Drug Release, and Photoactivation.

J Endod 2019 Nov 18;45(11):1371-1377. Epub 2019 Sep 18.

Department of Cariology, Restorative Sciences, and Endodontics, University of Michigan School of Dentistry, Ann Arbor, Michigan. Electronic address:

Introduction: Curcumin incorporation into polymeric fibers was tested for its antimicrobial properties and potential use in root canal disinfection.

Methods: Curcumin-modified fibers were processed via electrospinning and tested against a 7-day old established Actinomyces naeslundii biofilm. The medicaments tested were as follows: curcumin-modified fibers at 2.5 and 5.0 mg/mL, curcumin-based irrigant at 2.5 and 5.0 mg/mL, saline solution (negative control), and the following positive controls: 2% chlorhexidine, 1% sodium hypochlorite, and triple antibiotic paste (TAP, 1 mg/mL). All medicaments, except for the positive controls, were allocated according to the light exposure protocol (ie, photoactivation with a light-emitting diode every 30 seconds for 4 minutes or without photoactivation). After treatment, the medicaments were removed, and 1 mL saline solution was added; the biofilm was scraped from the well and used to prepare a 1:2000 dilution. Spiral plating was performed using anaerobic blood agar plates. After 24 hours, colony-forming units (colony-forming units/mL, n = 11/group) were counted to determine the antimicrobial effects.

Results: Data exhibited significant antimicrobial effects on the positive control groups followed by the curcumin irrigants and, lastly, the photoactivated curcumin-modified fibers. There was a significant reduction of viable bacteria in curcumin-based irrigants, which was greater than the TAP-treated group. Curcumin-free fibers, saline, and the nonphotoactivated curcumin-modified fibers did not display antimicrobial activity.

Conclusions: Curcumin seems to be a potential alternative to TAP when controlling infection, but it requires a minimal concentration (2.5 mg/mL) to be effective. Photoactivation of curcumin-based medicaments seems to be essential to obtain greater antibiofilm activity.
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http://dx.doi.org/10.1016/j.joen.2019.08.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6823155PMC
November 2019

A novel patient-specific three-dimensional drug delivery construct for regenerative endodontics.

J Biomed Mater Res B Appl Biomater 2019 07 3;107(5):1576-1586. Epub 2018 Oct 3.

Department of Oral Pathology, Medicine, and Radiology, IUSD, Indianapolis, Indiana, 46202.

Evoked bleeding (EB) clinical procedure, comprising a disinfection step followed by periapical tissue laceration to induce the ingrowth of undifferentiated stem cells from the periodontal ligament and alveolar bone, is currently the only regenerative-based therapeutic approach to treating pulp tissue necrosis in undeveloped (immature) permanent teeth approved in the United States. Yet, the disinfection step using antibiotic-based pastes leads to cytotoxic, warranting a biocompatible strategy to promote root canal disinfection with no or minimal side-effects to maximize the regenerative outcomes. The purpose of this investigation was to develop a tubular three-dimensional (3D) triple antibiotic-eluting construct for intracanal drug delivery. Morphological (scanning electron microscopy), chemical (Fourier transform infrared spectroscopy), and mechanical (tensile testing) characteristics of the polydioxanone-based triple antibiotic-eluting fibers were assessed. The antimicrobial properties of the tubular 3D constructs were determined in vitro and in vivo using an infected (Actinomyces naeslundii) dentin tooth slice model and a canine method of periapical disease, respectively. The in vitro data indicated significant antimicrobial activity and the ability to eliminate bacterial biofilm inside dentinal tubules. In vivo histological findings demonstrated that, using the EB procedure, the tubular 3D triple antibiotic-eluting construct allowed the formation of an appropriate environment that led to apex closure and the ingrowth of a thin layer of osteodentin-like tissue into the root canal. Taken together, these findings indicate that our novel drug delivery construct is a promising biocompatible disinfection strategy for immature permanent teeth with necrotic pulps. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1576-1586, 2019.
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http://dx.doi.org/10.1002/jbm.b.34250DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6447484PMC
July 2019

Recent Advances in Adhesive Bonding - The Role of Biomolecules, Nanocompounds, and Bonding Strategies in Enhancing Resin Bonding to Dental Substrates.

Curr Oral Health Rep 2017 Sep 10;4(3):215-227. Epub 2017 Jul 10.

Department of Biomedical and Applied Sciences, Division of Dental Biomaterials, Indiana University School of Dentistry, Indianapolis, IN 46202, USA.

Purpose Of Review: To present an overview on the main agents (i.e., biomolecules and nanocompounds) and/or strategies currently available to amplify or stabilize resin-dentin bonding.

Recent Findings: According to studies retrieved for full text reading (2014-2017), there are currently six major strategies available to overcome resin-dentin bond degradation: (i) use of collagen crosslinking agents, which may form stable covalent bonds with collagen fibrils, thus strengthening the hybrid layer; (ii) use of antioxidants, which may allow further polymerization reactions over time; (iii) use of protease inhibitors, which may inhibit or inactivate metalloproteinases; (iv) modification of the bonding procedure, which may be performed by using the ethanol wet-bonding technique or by applying an additional adhesive (hydrophobic) coating, thereby strengthening the hybrid layer; (v) laser treatment of the substrate prior to bonding, which may cause specific topographic changes in the surface of dental substrates, increasing bonding efficacy; and (vi) reinforcement of the resin matrix with inorganic fillers and/or remineralizing agents, which may positively enhance physico-mechanical properties of the hybrid layer.

Summary: With the present review, we contributed to the better understanding of adhesion concepts and mechanisms of resin-dentin bond degradation, showing the current prospects available to solve that problematic. Also, adhesively-bonded restorations may be benefited by the use of some biomolecules, nanocompounds or alternative bonding strategies in order to minimize bond strength degradation.
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http://dx.doi.org/10.1007/s40496-017-0146-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5697773PMC
September 2017

Stain removal effect of novel papain- and bromelain-containing gels applied to enamel.

Clin Oral Investig 2016 Nov 12;20(8):2315-2320. Epub 2016 May 12.

Department of Biomedical and Applied Sciences, Division of Dental Biomaterials, Indiana University School of Dentistry (IUSD), Indianapolis, IN, 46202, USA.

Objectives: The aims of the study are to prepare novel stain removal gel-based formulations containing papain or bromelain and to investigate their stain removal effect when applied to enamel.

Materials And Methods: Experimental bromelain- and papain-based stain removal gels were prepared. Next, enamel/dentin tooth samples (6 × 6 mm, 4 mm in thickness) were obtained from bovine teeth, stained in coffee solution for 1 week, and measured with a digital spectrophotometer (Easyshade, Vita Zahnfabrik) for color assessment (baseline). The samples were then randomly allocated into four groups (n = 7), according to the stain removal agent applied: ContrastPM+ (Discus Dental, LLC), which is based on 20 wt.% carbamide peroxide (positive control); bromelain-based; papain-based; and no agent (negative control). The materials were applied once a week, three times per day, during 4 weeks, and following the directions of use from positive control. The samples were measured again with the Easyshade and using the CIEL a b color system. The color change (ΔE ) results were obtained by subtracting the baseline values from the final color values obtained at each time point. The data were statistically analyzed using two-way repeated-measures analysis of variance and Student Newman Keuls's test as a post hoc test (α = 5 %).

Results: All stain removal agents produced greater color change than the negative control (p < .001), with the positive control demonstrating greater ΔE values when compared to the experimental gels (p ≤ .004). The second application of all gels resulted in greater ΔE values compared to the first application (p ≤ .025), although no color change was observed after the third application (p ≥ .051), regardless of the material evaluated.

Clinical Significance: The proposed gels containing proteolytic enzymes (bromelain or papain) of vegetal origin may hold significant clinical potential as active agents for the preparation of stain removal agents free of hydrogen/carbamide peroxide.
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http://dx.doi.org/10.1007/s00784-016-1840-1DOI Listing
November 2016

Synthesis and characterization of CaO-loaded electrospun matrices for bone tissue engineering.

Clin Oral Investig 2016 Nov 27;20(8):1921-1933. Epub 2015 Nov 27.

Division of Dental Biomaterials, Department of Biomedical and Applied Sciences, Indiana University School of Dentistry , 1121 W. Michigan Street, Indianapolis, IN, 46202, USA.

Objectives: This study aims to synthesize and characterize biodegradable polymer-based matrices loaded with CaO nanoparticles for osteomyelitis treatment and bone tissue engineering.

Materials And Methods: Poly(ε-caprolactone) (PCL) and PCL/gelatin (1:1, w/w) solutions containing CaO nanoparticles were electrospun into fibrous matrices. Scanning (SEM) and transmission (TEM) electron microscopy, Fourier transformed infrared (FTIR), energy dispersive X-ray spectroscopy (EDS), contact angle (CA), tensile testing, and antibacterial activity (agar diffusion assay) against Staphylococcus aureus were performed. Osteoprecursor cell (MC3T3-E1) response (i.e., viability and alkaline phosphatase expression/ALP) and infiltration into the matrices were evaluated.

Results: CaO nanoparticles were successfully incorporated into the fibers, with the median fiber diameter decreasing after CaO incorporation. The CA decreased with the addition of CaO, and the presence of gelatin made the matrix very hydrophilic (CA = 0°). Increasing CaO concentrations progressively reduced the mechanical properties (p ≤ 0.030). CaO-loaded matrices did not display consistent antibacterial activity. MC3T3-E1 cell viability demonstrated the highest levels for CaO-loaded matrices containing gelatin after 7 days in culture. An increased ALP expression was consistently seen for PCL/CaO matrices when compared to PCL and gelatin-containing counterparts.

Conclusions: Despite inconsistent antibacterial activity, CaO nanoparticles can be effectively loaded into PCL or PCL/gelatin fibers without negatively affecting the overall performance of the matrices. More importantly, CaO incorporation enhanced cell viability as well as differentiation capacity, as demonstrated by an increased ALP expression.

Clinical Significance: CaO-loaded electrospun matrices show potential for applications in bone tissue engineering.
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http://dx.doi.org/10.1007/s00784-015-1671-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4884177PMC
November 2016

Tetracycline-incorporated polymer nanofibers as a potential dental implant surface modifier.

J Biomed Mater Res B Appl Biomater 2017 10 13;105(7):2085-2092. Epub 2016 Jul 13.

Department of Biomedical and Applied Sciences, Division of Dental Biomaterials, Indiana University School of Dentistry (IUSD), Indianapolis, Indiana, 46202.

This study investigated the antimicrobial and osteogenic properties of titanium (Ti) disks superficially modified with tetracycline (TCH)-incorporated polymer nanofibers. The experiments were carried out in two phases. The first phase dealt with the synthesis and characterization (i.e., morphology, mechanical strength, drug release, antimicrobial activity, and cytocompatibility) of TCH-incorporated fibers. The second phase was dedicated to evaluating both the antimicrobial and murine-derived osteoprecursor cell (MC3T3-E1) response of Ti-modified with TCH-incorporated fibers. TCH was successfully incorporated into the submicron-sized and cytocompatible fibers. All TCH-incorporated mats presented significant antimicrobial activity against periodontal pathogens. The antimicrobial potential of the TCH-incorporated fibers-modified Ti was influenced by both the TCH concentration and bacteria tested. At days 5 and 7, a significant increase in MC3T3-E1 cell number was observed for TCH-incorporated nanofibers-modified Ti disks when compared to that of TCH-free nanofibers-modified Ti-disks and bare Ti. A significant increase in alkaline phosphatase (ALP) levels on the Ti disks modified with TCH-incorporated nanofiber on days 7 and 14 was seen, suggesting that the proposed surface promotes early osteogenic differentiation. Collectively, the data suggest that TCH-incorporated nanofibers could function as an antimicrobial surface modifier and osteogenic inducer for Ti dental implants. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2085-2092, 2017.
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http://dx.doi.org/10.1002/jbm.b.33743DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5540804PMC
October 2017

Effects of Simulated Gastric Juice on CAD/CAM Resin Composites-Morphological and Mechanical Evaluations.

J Prosthodont 2017 Jul 18;26(5):424-431. Epub 2015 Dec 18.

Department of Biomedical and Applied Sciences, Division of Dental Biomaterials, Indiana University School of Dentistry (IUSD), Indianapolis, IN.

Purpose: To evaluate the effects of simulated gastric juice on CAD/CAM resin composites by means of morphological and mechanical (i.e., hardness) evaluations.

Materials And Methods: Fourteen specimens of each resin composite (Lava Ultimate and Paradigm MZ100) were prepared according to the manufacturer's instructions. They were submitted to erosive challenges in a simulated gastric juice (pH = 1.2) solution for 6 and 24 hours. Vickers microhardness and surface roughness (R , R ) evaluations were taken before (baseline) and after acid exposure. Morphological analysis was obtained using scanning electron microscopy (SEM). Statistical analysis was performed using two-way repeated measures ANOVA and Student-Newman-Keuls's test (α = 0.05).

Results: Paradigm MZ100 demonstrated higher microhardness than Lava Ultimate regardless of the storage time period (p ≤ 0.001), and microhardness was not affected by the acidic challenge (p = 0.58). After 6 hours of acid exposure, a significant decrease in R and R was seen for Paradigm MZ100 when compared to the baseline (R p = 0.032; R p = 0.013); however, for Lava Ultimate only Rq decreased (p = 0.021), while R remained unchanged (p = 0.38). After 24 hours of acid exposure, while Paradigm MZ100 exhibited no additional changes in surface roughness (p ≥ 0.75), Lava Ultimate became rougher (R p = 0.041; R p = 0.014), as confirmed by SEM imaging.

Conclusions: The acidic scenario tested in the present study changed the surface roughness of the resin composites but not their Vickers microhardness. Moreover, both resin composites seem suitable for use under acidic scenarios, although Paradigm MZ100 showed enhanced stability compared to Lava Ultimate.
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http://dx.doi.org/10.1111/jopr.12420DOI Listing
July 2017

Effects of Novel 3-dimensional Antibiotic-containing Electrospun Scaffolds on Dentin Discoloration.

J Endod 2016 Jan 23;42(1):106-12. Epub 2015 Oct 23.

Department of Biomedical and Applied Sciences, Indiana University School of Dentistry, Indianapolis, Indiana. Electronic address:

Introduction: Although intracanal application of the triple antibiotic paste (TAP) may offer advantages (eg, disinfection), this practice has been associated with significant drawbacks, including tooth discoloration. In this study, the color change of dentin was monitored during treatment with distinct TAP pastes and novel tubular-shaped 3-dimensional electrospun scaffolds containing minocycline (MINO) or doxycycline (DOX).

Methods: Two TAP pastes (TAPMINO [MINO, metronidazole, and ciprofloxacin] and TAPDOX [DOX, metronidazole, and ciprofloxacin]), 4 scaffold-based groups containing MINO or DOX at distinct concentrations, 1 antibiotic-free scaffold, and 1 untreated group (control) were investigated. Human canines were sectioned at the cementoenamel junction and tubular-shaped scaffolds or paste were placed into the root canals and sealed. Color measurements (CIEL(*)a(*)b(*) parameters) were performed at baseline and after 1, 3, 7, 14, 21, and 28 days. Color changes were expressed as ΔE(*) values. In addition, scanning electron microscopy and energy-dispersive X-ray spectroscopy were also performed on the specimens after treatment. Data were analyzed using repeated measures analysis of variance (alpha = 0.05).

Results: All antibiotic-containing groups led to greater discoloration than the antibiotic-free groups. A severe discoloration occurred after 1 day. At the end of the experiment, antibiotic-treated samples exhibited crusts/agglomerates over the dentin surface, which totally or partially obliterated the dentinal tubules. The presence of MINO resulted in a greater color change than DOX.

Conclusions: Scaffolds containing MINO or DOX produced similar color change to dentin when compared with their respective TAP systems, although DOX-related discoloration was less pronounced.
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http://dx.doi.org/10.1016/j.joen.2015.09.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4913479PMC
January 2016

Synthesis and characterization of novel halloysite-incorporated adhesive resins.

J Dent 2015 Nov 31;43(11):1316-22. Epub 2015 Aug 31.

Department of Biomedical and Applied Sciences, Division of Dental Biomaterials, Indiana University School of Dentistry (IUSD), Indianapolis, IN 46202, USA. Electronic address:

Objective: To investigate the effects of Halloysite® aluminosilicate clay nanotubes (HNTs) addition on selected physical, mechanical, and biological properties of experimental adhesive resins.

Methods: Experimental dentin adhesive resins were prepared by mixing Bis-GMA, TEGDMA, HEMA (50/25/25wt.%), and photo-initiators. As-received HNTs were then incorporated into the resin mixture at distinct concentrations: 0 (HNT-free, control), 1, 2.5, 5, 7.5, 10, and 20wt.%. The degree of conversion (DC), radiopacity (RP), Knoop hardness (KHN), flexural strength (FS), and cytotoxicity analyses were carried out for each adhesive formulation. The adhesive resin of Adper Scotchbond Multi-Purpose (SBMP) was used as the commercially available reference for both the RP and cytotoxicity tests. Data were statistically analyzed using One-Way ANOVA and Tukey's test (p≤0.05).

Results: All adhesives exhibited similar DC (p=0.1931). The RP of adhesives was improved with the addition of up to 5wt.% of HNTs (p<0.001). Adhesives containing 5-10wt.% of HNTs led to greater KHN when compared to the control (p<0.001). The FS was reduced only when 20wt.% of HNTs was added (p≤0.001). None of the prepared adhesives was cytotoxic.

Conclusion: The incorporation of up to 10wt.% of HNTs into the adhesive resins did not jeopardize the tested physical and biological properties.

Clinical Significance: When using HNTs as carriers of drugs/bioactive compounds, the amount of the former added into adhesive resin materials should not exceed 10wt.%; otherwise, a significant reduction in physicomechanical properties may be expected.
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http://dx.doi.org/10.1016/j.jdent.2015.08.014DOI Listing
November 2015

Development and characterization of novel ZnO-loaded electrospun membranes for periodontal regeneration.

Dent Mater 2015 Sep 24;31(9):1038-51. Epub 2015 Jun 24.

Department of Restorative Dentistry, Division of Dental Biomaterials, Indiana University School of Dentistry (IUSD), Indianapolis, IN 46202, USA. Electronic address:

Objectives: This study reports on the synthesis, materials characterization, antimicrobial capacity, and cytocompatibility of novel ZnO-loaded membranes for guided tissue/bone regeneration (GTR/GBR).

Methods: Poly(ɛ-caprolactone) (PCL) and PCL/gelatin (PCL/GEL) were dissolved in hexafluoropropanol and loaded with ZnO at distinct concentrations: 0 (control), 5, 15, and 30wt.%. Electrospinning was performed using optimized parameters and the fibers were characterized via scanning and transmission electron microscopies (SEM/TEM), energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), contact angle (CA), mechanical testing, antimicrobial activity against periodontopathogens, and cytotoxicity test using human dental pulp stem cells (hDPSCs). Data were analyzed using ANOVA and Tukey (α=5%).

Results: ZnO nanoparticles were successfully incorporated into the overall submicron fibers, which showed fairly good morphology and microstructure. Upon ZnO nanoparticles' incorporation, the PCL and PCL/GEL fibers became thicker and thinner, respectively. All GEL-containing membranes showed lower CA than the PCL-based membranes, which were highly hydrophobic. Overall, the mechanical properties of the membranes were reduced upon ZnO incorporation, except for PCL-based membranes containing ZnO at the 30wt.% concentration. The presence of GEL enhanced the stretching ability of membranes under wet conditions. All ZnO-containing membranes displayed antibacterial activity against the bacteria tested, which was generally more pronounced with increased ZnO content. All membranes synthesized in this study demonstrated satisfactory cytocompatibility, although the presence of 30wt.% ZnO led to decreased viability.

Significance: Collectively, this study suggests that PCL- and PCL/GEL-based membranes containing a low content of ZnO nanoparticles can potentially function as a biologically safe antimicrobial GTR/GBR membrane.
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http://dx.doi.org/10.1016/j.dental.2015.06.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4527962PMC
September 2015

Effect of Diamond Bur Grit Size on Composite Repair.

J Adhes Dent 2015 Jun;17(3):257-63

Purpose: This study investigated the effect of diamond bur grit size on the repair bond strength of fresh and aged resin composites.

Materials And Methods: Blocks of microhybrid composite (Opallis, FGM) were stored in distilled water at 37°C for 24 h (fresh composite) or subjected to 5000 thermal cycles (aged composite). The surfaces were roughened using diamond-coated, flame-shaped carbide burs with medium grit (#3168), fine grit (#3168F), or extra-fine grit (#3168FF). The control group underwent no surface treatment. Surface roughness, water contact angle, and surface topography by scanning electron microscopy (SEM) were evaluated (n = 3). Samples were restored with resin composite and sectioned into beam-shaped specimens, which were subjected to microtensile bond testing. Failure modes were classified using a stereomicroscope. Data were statistically analyzed using the Student- Newman-Keuls test and two-way ANOVA, with significance set at p < 0.05.

Results: Higher surface roughness was observed for groups treated with the medium- and fine-grit burs; aged composites were rougher than fresh composites. The water contact angle formed on the aged composite was lower than that on the fresh composite. The highest repair bond strength was observed for the fine-grit bur group, and the lowest was recorded for control. Interfacial failures were more predominant. SEM images showed that the surfaces treated with fine- and extra-fine-grit burs had a more irregular topography.

Conclusion: Surface roughening of fresh or aged resin composites with diamond burs improved retention of the repair material. Fine-grit burs generally performed better than medium- and extra-fine-grit burs.
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http://dx.doi.org/10.3290/j.jad.a34398DOI Listing
June 2015

Effect of random/aligned nylon-6/MWCNT fibers on dental resin composite reinforcement.

J Mech Behav Biomed Mater 2015 Aug 1;48:134-144. Epub 2015 Apr 1.

Indiana University School of Dentistry - Department of Restorative Dentistry/Division of Dental Biomaterials 1121 W. Michigan Street, Indianapolis, IN 46202, USA. Electronic address:

The aims of this study were (1) to synthesize and characterize random and aligned nanocomposite fibers of multi-walled carbon nanotubes (MWCNT)/nylon-6 and (2) to determine their reinforcing effects on the flexural strength of a dental resin composite. Nylon-6 was dissolved in hexafluoropropanol (10 wt%), followed by the addition of MWCNT (hereafter referred to as nanotubes) at two distinct concentrations (i.e., 0.5 or 1.5 wt%). Neat nylon-6 fibers (without nanotubes) were also prepared. The solutions were electrospun using parameters under low- (120 rpm) or high-speed (6000 rpm) mandrel rotation to collect random and aligned fibers, respectively. The processed fiber mats were characterized by scanning (SEM) and transmission (TEM) electron microscopies, as well as by uni-axial tensile testing. To determine the reinforcing effects on the flexural strength of a dental resin composite, bar-shaped (20×2×2 mm(3)) resin composite specimens were prepared by first placing one increment of the composite, followed by one strip of the mat, and one last increment of composite. Non-reinforced composite specimens were used as the control. The specimens were then evaluated using flexural strength testing. SEM was done on the fractured surfaces. The data were analyzed using ANOVA and the Tukey׳s test (α=5%). Nanotubes were successfully incorporated into the nylon-6 fibers. Aligned and random fibers were obtained using high- and low-speed electrospinning, respectively, where the former were significantly (p<0.001) stronger than the latter, regardless of the nanotubes׳ presence. Indeed, the dental resin composite tested was significantly reinforced when combined with nylon-6 fibrous mats composed of aligned fibers (with or without nanotubes) or random fibers incorporated with nanotubes at 0.5 wt%.
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http://dx.doi.org/10.1016/j.jmbbm.2015.03.019DOI Listing
August 2015

Antimicrobial Effects of Novel Triple Antibiotic Paste-Mimic Scaffolds on Actinomyces naeslundii Biofilm.

J Endod 2015 Aug 25;41(8):1337-43. Epub 2015 Apr 25.

Division of Dental Biomaterials, Department of Restorative Dentistry, Indiana University School of Dentistry, Indianapolis, Indiana. Electronic address:

Introduction: Actinomyces naeslundii has been recovered from traumatized permanent teeth diagnosed with necrotic pulps. In this work, a triple antibiotic paste (TAP)-mimic scaffold is proposed as a drug-delivery strategy to eliminate A. naeslundii dentin biofilm.

Methods: Metronidazole, ciprofloxacin, and minocycline were added to a polydioxanone (PDS) polymer solution and spun into fibrous scaffolds. Fiber morphology, mechanical properties, and drug release were investigated by using scanning electron microscopy, microtensile testing, and high-performance liquid chromatography, respectively. Human dentin specimens (4 × 4 × 1 mm(3), n = 4/group) were inoculated with A. naeslundii (ATCC 43146) for 7 days for biofilm formation. The infected dentin specimens were exposed to TAP-mimic scaffolds, TAP solution (positive control), and pure PDS (drug-free scaffold). Dentin infected (7-day biofilm) specimens were used for comparison (negative control). Confocal laser scanning microscopy was done to determine bacterial viability.

Results: Scaffolds displayed a submicron mean fiber diameter (PDS = 689 ± 312 nm and TAP-mimic = 718 ± 125 nm). Overall, TAP-mimic scaffolds showed significantly (P ≤ .040) lower mechanical properties than PDS. Within the first 24 hours, a burst release for all drugs was seen. A sustained maintenance of metronidazole and ciprofloxacin was observed over 4 weeks, but not for minocycline. Confocal laser scanning microscopy demonstrated complete elimination of all viable bacteria exposed to the TAP solution. Meanwhile, TAP-mimic scaffolds led to a significant (P < .05) reduction in the percentage of viable bacteria compared with the negative control and PDS.

Conclusions: Our findings suggest that TAP-mimic scaffolds hold significant potential in the eradication/elimination of bacterial biofilm, a critical step in regenerative endodontics.
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http://dx.doi.org/10.1016/j.joen.2015.03.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4519366PMC
August 2015

Effect of acidic solutions on the surface degradation of a micro-hybrid composite resin.

Braz Dent J 2014 ;25(4):321-6

Department of Operative Dentistry, School of Dentistry, UFPEL - Federal University of Pelotas, Pelotas, RS, Brazil.

Composite resins may undergo wear by the action of chemical substances (e.g., saliva, alcohol, bacterial acids) of the oral environment, which may affect the material's structure and surface properties. This study evaluated the effect of acidic substances on the surface properties of a micro-hybrid composite resin (Filtek Z-250). Eighty specimens were prepared, and baseline hardness and surface roughness (KMN0 and Ra0, respectively) were measured. The specimens were subjected to sorption (SO) and solubility (SL) tests according to ISO 4049:2009, but using different storage solutions: deionized water; 75/25 vol% ethanol/water solution; lactic acid; propionic acid; and acetic acid. The acids were used in two concentrations: PA and 0.02 N. pH was measured for all solutions and final hardness (KMN1) and surface roughness (Ra1) were measured. Data were analyzed with paired t-tests and one-way ANOVA and Tukey's test (a=5%). All solutions decreased hardness and increased the Ra values, except for the specimens stored in water and 0.02 N lactic acid, which maintained the hardness. All solutions produced similar SO and SL phenomena, except for the 0.02 N lactic acid, which caused lower solubility than the other solutions. Ethanol showed the highest pH (6.6) and the 0.02 N lactic acid the lowest one (2.5). The solutions affected negatively the surface properties of the composite resin; in addition, an acidic pH did not seem to be a significant factor that intensifies the surface degradation phenomena.
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http://dx.doi.org/10.1590/0103-6440201300058DOI Listing
August 2016

1,3-Diethyl-2-thiobarbituric acid as an alternative coinitiator for acidic photopolymerizable dental materials.

J Biomed Mater Res B Appl Biomater 2013 Oct 6;101(7):1217-21. Epub 2013 Apr 6.

Department of Operative Dentistry, School of Dentistry, Federal University of Pelotas, Rio Grande do Sul, Brazil.

The ethyl-4-dimethylaminobenzoate (EDAB) is widely used as a coinitiator of the camphorquinone (CQ), but in acidic circumstances it might present some instability, reducing the polymerization efficiency of the material. Considering this, new coinitiators are being evaluated. Hence, this study evaluated the kinetic of polymerization (KP), the degree of conversion (DC), and the rate of polymerization (RP ) of experimental resin adhesives containing 1,3-diethyl-2-thiobarbituric acid (TBA) as a coinitiator of the CQ. The experimental monomeric blend was prepared with bisphenol A glycidyl dimethacrylate, 2-hydroxyethyl methacrylate, and acidic monomers. CQ was added at 1 mol % as photoinitiator. Six groups were formulated: four containing concentrations of 0.1, 0.5, 1, and 2 mol % of TBA, one without coinitiator, and the last one containing 1 mol % of EDAB (control group). The KP and the RP were performed using real-time Fourier Transform infrared spectroscopy. The group without coinitiator has not formed a polymer, whereas the addition of TBA resulted in the conversion of monomers in polymer. The DC of the adhesives was as higher as the increase in the TBA content. The group with 2 mol % of TBA presented improved DC and reactivity (RP ) than the other groups and the control one. Hence, the TBA has performed as a coinitiator of the CQ for the radical polymerization of methacrylate resin adhesives and it has improved the DC and the reactivity of the materials. Thus, it is a potential coinitiator for the photopolymerization of dental materials.
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http://dx.doi.org/10.1002/jbm.b.32933DOI Listing
October 2013