Publications by authors named "Vinicius Rosa"

55 Publications

Characterization, Antimicrobial Effects, and Cytocompatibility of a Root Canal Sealer Produced by Pozzolan Reaction between Calcium Hydroxide and Silica.

Materials (Basel) 2021 May 27;14(11). Epub 2021 May 27.

Department of Conservative Dentistry, School of Dentistry and Institute of Oral Bioscience, Jeonbuk National University, Jeonju 54896, Korea.

This study aimed to evaluate a newly developed pozzolan-based bioceramic sealer (PZBS) regarding setting time, radiopacity, antibacterial effect, and cytocompatibility. The PZBS was manufactured by mixing calcium hydroxide and silica. The pozzolan reaction was verified by identification of calcium silicate hydrate (C-S-H) using X-ray diffraction analysis. The initial setting time and radiopacity were measured using the ISO 6876/2012 protocol in comparison with other commercially available calcium silicate (CS) sealers. The antibacterial effect of PZBS on biofilms cultured in the bovine root canal was evaluated by measurement of colony-forming units and volume of biofilms in comparison with other calcium hydroxide pastes. The morphological features of the biofilms were observed by scanning electron microscopy (SEM). The cytocompatibility of PZBS was assessed by the viability of bone marrow-derived mesenchymal stem cells and scratch wound healing rate in comparison with other CS sealers. The morphology of the cells cultured on the tested sealers was observed by SEM. The detection of the CS peak confirmed the formation of C-S-H. The initial setting time of PZBS was around 11 h, which was twice as long as the other tested sealers. The radiopacity of PZBS was 4.3 mm/Al, which satisfied the ISO criteria. The antibacterial effect and cytocompatibility of PZBS were comparable to those of the commercially available intracanal medicaments and CS endodontic sealers, respectively. The PZBS has the potential to be used for root canal obturation, and is expected to exert a favorable antibacterial effect.
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http://dx.doi.org/10.3390/ma14112863DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8199352PMC
May 2021

Concentration of essential and toxic elements as a function of the depth of the soil and the presence of fulvic acids in a wetland in Cerrado, Brazil.

Environ Monit Assess 2021 Mar 4;193(4):157. Epub 2021 Mar 4.

Geosciences and Exact Sciences Institute, São Paulo State University (UNESP), 24-A Avenue, 1515, Bela Vista, Rio Claro, SP, 13506-900, Brazil.

The protection of wetlands is essential for sustainable development. The particular hydrology of wetlands creates conditions for the formation of hydric soils. Hydric soils are formed in oxide-reducing environments and perform important removal and re-oxidation of Fe and Mn oxides and hydroxides. They are also characterized by the formation of a superficial horizon enriched by the accumulation of organic matter. The objective of this study was to determine the concentration of essential (Co, Cu, Fe, Mn, Ni, Zn) and toxic (Al, Cd, Pb) elements in the soil solution in a wetland, surrounded by an intense agricultural activity area. The concentrations of the elements were evaluated according to the level of hydromorphy (border to the center) and the depth of the soil. The physical fractionation of these elements was also assessed (total and < 30 kDa), and the results were compared with the chemical speciation of these elements. Despite the high total concentrations of Al and Fe, the concentration of these elements was very low in the < 30 kDa fraction, which suggests that these elements are complexed with organic matter, in the form of hydroxides. Evidence of removal of Fe and Mn from the surface horizon was observed at the center of the wetland, where the highest level of hydromorphy is found. The results showed that the concentration of metals in the fraction < 30 kDa is insignificant, suggesting that the mechanisms of precipitation and/or adsorption to soil colloids play an important role in the regulation of this ecosystem.
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http://dx.doi.org/10.1007/s10661-021-08945-yDOI Listing
March 2021

Fighting viruses with materials science: Prospects for antivirus surfaces, drug delivery systems and artificial intelligence.

Dent Mater 2021 03 10;37(3):496-507. Epub 2021 Jan 10.

Division of Dentistry, School of Medical Sciences, University of Manchester, United Kingdom. Electronic address:

Objective: Viruses on environmental surfaces, in saliva and other body fluids represent risk of contamination for general population and healthcare professionals. The development of vaccines and medicines is costly and time consuming. Thus, the development of novel materials and technologies to decrease viral availability, viability, infectivity, and to improve therapeutic outcomes can positively impact the prevention and treatment of viral diseases.

Methods: Herein, we discuss (a) interaction mechanisms between viruses and materials, (b) novel strategies to develop materials with antiviral properties and oral antiviral delivery systems, and (c) the potential of artificial intelligence to design and optimize preventive measures and therapeutic regimen.

Results: The mechanisms of viral adsorption on surfaces are well characterized but no major breakthrough has become clinically available. Materials with fine-tuned physical and chemical properties have the potential to compromise viral availability and stability. Emerging strategies using oral antiviral delivery systems and artificial intelligence can decrease infectivity and improve antiviral therapies.

Significance: Emerging viral infections are concerning due to risk of mortality, as well as psychological and economic impacts. Materials science emerges for the development of novel materials and technologies to diminish viral availability, infectivity, and to enable enhanced preventive and therapeutic strategies, for the safety and well-being of humankind.
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http://dx.doi.org/10.1016/j.dental.2020.12.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7834288PMC
March 2021

Persistent inhibition of Candida albicans biofilm and hyphae growth on titanium by graphene nanocoating.

Dent Mater 2021 02 25;37(2):370-377. Epub 2020 Dec 25.

Faculty of Dentistry, National University of Singapore, 9 Lower Kent Ridge Road, Singapore; Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore; NUS Craniofacial Research and Innovation Center, National University of Singapore, Singapore. Electronic address:

Objectives: Candida albicanscolonizes biomaterial surfaces and are highly resistant to therapeutics. Graphene nanocoating on titanium compromises initial biofilm formation. However, its sustained antibiofilm potential is unknown. The objective of this study was to investigate the potential of graphene nanocoating to decrease long-term fungal biofilm development and hyphae growth on titanium.

Methods: Graphene nanocoating was deposited twice (TiGD) or five times (TiGV) on grade 4 titanium with vacuum assisted technique and characterized with Raman spectroscopy and atomic force microscope. The biofilm formation and hyphae growth of C. albicans was monitored for seven days by CFU, XTT, confocal, mean cell density and scanning electronic microscopy (SEM). Uncoated titanium was the Control. All tests had three independent biological samples and were performed in independent triplicates. Data was analyzed with one- or two-way ANOVA and Tukey's HSD (α = 0.05).

Results: Both TiGD and TiGV presented less biofilms at all times points compared with Control. The confocal and SEM images revealed few adhered cells on graphene coated samples, absence of hyphae and no features of a mature biofilm architecture. The increase in number of layers of graphene nanocoating did not improve its antibiofilm potential.

Significance: The graphene nanocoating exerted a long-term persistent inhibitory effect on the biofilm formation on titanium. The fewer cells that were able to attach on graphene coated titanium were scattered and unable to form a mature biofilm with hyphae elements. The findings open opportunities to prevent microbial attachment and proliferation on implantable materials without the use of antibiotics.
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http://dx.doi.org/10.1016/j.dental.2020.11.028DOI Listing
February 2021

Characterization of Enterococcus faecalis in different culture conditions.

Sci Rep 2020 12 14;10(1):21867. Epub 2020 Dec 14.

Department of Conservative Dentistry, Jeonbuk National University, 567 Baekje-daero, Jeonju-si, 54896, Korea.

The aim of this study was to investigate how carbohydrates (glucose or sucrose) affect the characteristics of Enterococcus faecalis (E. faecalis) planktonic and biofilm in vitro. For this study, E. faecalis was cultured in tryptone-yeast extract broth with 0% glucose + 0% sucrose, 0.5% glucose, 1% glucose, 0.5% sucrose, or 1% sucrose. Viability of E. faecalis was examined by colony forming unit counting assays. Biofilm formation was assessed by measuring extracellular DNA (eDNA), a component of the biofilm matrix. Quantitative real-time PCR (qRT-PCR) was performed to investigate the expression of virulence-associated genes. Field emission scanning electron microscopy analysis, confocal laser scanning microscopy analysis, and crystal violet colorimetric assay were conducted to study E. faecalis biofilms. E. faecalis showed the highest viability and eDNA levels in 1% sucrose medium in biofilms. The result of qRT-PCR showed that the virulence-associated genes expressed highest in 1% sucrose-grown biofilms and in 1% glucose-grown planktonic cultures. E. faecalis showed highly aggregated biofilms and higher bacteria and exopolysaccharide (EPS) bio-volume in sucrose than in 0% glucose + 0% sucrose or glucose. The results indicate that the production of eDNA and EPS and expression of virulence-associated genes in E. faecalis are affected by the concentration of carbohydrates in biofilm or planktonic culture.
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http://dx.doi.org/10.1038/s41598-020-78998-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7736865PMC
December 2020

Zika virus testing of asymptomatic patients undergoing assisted reproduction in Curitiba, Brazil.

JBRA Assist Reprod 2021 02 2;25(1):128-130. Epub 2021 Feb 2.

Conceber Reproductive Medicine Center, Curitiba, PR, Brazil.

Objective: The objective is to report recent data on the infection and detection of Zika virus in infertile couples and to discuss the need to make disease surveillance compulsory in this population in order to decrease the burden on the healthcare system and expedite treatment onset.

Methods: We collected and analyzed the results of Zika virus infection screening tests of infertile couples in a private clinic in the low-incidence region of Curitiba - Brazil.

Results: Among the 1189 serologies performed, 98.5% were negative for Zika virus, 0.75% were positive, and 0.75% were inconclusive. The twenty-one reverse transcription polymerase chain reaction tests performed for confirmation of infection were negative.

Conclusion: Zika virus infection screening for asymptomatic patients may lead to delayed fertility treatment initiation in addition to excessive expenses for the patients. Based on our results, we challenge the validity of mandatory screening, especially in low-incidence regions.
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http://dx.doi.org/10.5935/1518-0557.20200063DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7863094PMC
February 2021

Sodium Hypochlorite Treatment Post-Etching Improves the Bond Strength of Resin-Based Sealant to Hypomineralized Enamel by Removing Surface Organic Content.

Pediatr Dent 2020 Sep;42(5):392-398

Hu is an assistant professor, Orthodontics and Paediatric Dentistry, Faculty of Dentistry, National University of Singapore, Singapore, Singapore;, Email:

he purpose of this study was to evaluate in vitro the effect of 5.25 percent sodium hypochlorite (NaOCl) on the bond strength of resin sealant to hypomineralized enamel. Sound (S) and hypomineralized (H) enamel specimens were subjected to three different treatments: (1) etch only (E); (2) 5.25 percent NaOCl treatment (60 seconds) after (Post) etching; and (3) 5.25 percent NaOCl treatment (60 seconds) before (Pre) etching. A sealant rod was bonded for microshear bond strength (μSBS) testing. DIAGNOdent™ and spectrophotometry were used to detect changes in surface organic content and verify the amount of organic material removed. Ninety S and 90 H specimens were randomly grouped into SE, SPost, SPre, HE, HPost, HPre groups. The average μSBS of hypomineralized enamel in etch only (HE) and NaOCl pre-etch (HPre) were significantly lower (9.2 MPa). NaOCl after etching significantly increased the μSBS of hypominineralized enamel (HPost) to 14.5 MPa, similar to sound enamel. DIAGNOdent™ readings were significantly lower in NaOCl Post versus E and NaOCl Pre, suggesting lower surface organic content. Spectrophotometry confirmed that NaOCI significantly removed more organic material in hypomineralized enamel. Applying 5.25 percent sodium hypochlorite for 60 seconds after etching (32 percent phosphoric acid) increased the bond strength of resin sealant to hypomineralized enamel comparable to that of sound enamel, as a result of surface organic content removal.
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September 2020

Main and Accessory Canal Filling Quality of a Premixed Calcium Silicate Endodontic Sealer According to Different Obturation Techniques.

Materials (Basel) 2020 Oct 1;13(19). Epub 2020 Oct 1.

Department of Conservative Dentistry, School of Dentistry and Institute of Oral Bioscience, Jeonbuk National University, Jeonju 54896, Korea.

The present study aimed to investigate the effects of different obturation techniques on the main and accessory canal filling quality of a premixed calcium silicate endodontic sealer (Endoseal TCS). We also highlighted the validity of the methods used for evaluating the canal filling quality. Thirty single-rooted premolars were used for the main canal filling and 75 were used for accessory canal filling. The canals were instrumented and randomly divided into three groups according to the filling techniques: (1) single-cone technique (SC), (2) single-cone with ultrasonic activation (SU), and (3) warm vertical compaction (WV). Voids in relation to the root canal fillings were assessed using cross-section images from microcomputed tomography (μCT) scans or transversely sectioned tooth specimens ( = 10). After demineralization and clearing of the teeth, the incidence, number, and completeness of the accessory canal fillings were evaluated ( = 25). One-way analysis of variance (ANOVA) and Tukey's post hoc test was used for the evaluation of the voids in the main root canal and the incidence and number of filled accessory canals. Pearson's chi-squared (χ) test was used for the evaluation of the filling completeness (α = 0.05). In the stereomicroscopic evaluation of the sectioned specimen, the SC group had significantly higher void occurrence than the other groups ( < 0.05), although there was no difference between groups in the μCT evaluation. However, there was no difference between the SU and WV. There was no difference between all the groups regarding the incidence, number, and completeness of the accessory canal fillings. When the premixed calcium silicate sealer is used with SC, the ultrasonic activation is recommended to obtain a better main canal filling quality. In contrast, the obturation techniques did not affect the accessory canal filling. We also recommend using the sectioning method when the void formation in the root canal filling materials is evaluated.
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http://dx.doi.org/10.3390/ma13194389DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7579472PMC
October 2020

New Surgical Model for Bone-Muscle Injury Reveals Age and Gender-Related Healing Patterns in the 5 Lipoxygenase (5LO) Knockout Mouse.

Front Endocrinol (Lausanne) 2020 11;11:484. Epub 2020 Aug 11.

Department of Basic Sciences, School of Dentistry, São Paulo State University (UNESP), Araçatuba, Brazil.

Signaling lipid mediators released from 5 lipoxygenase (5LO) pathways influence both bone and muscle cells, interfering in their proliferation and differentiation capacities. A major limitation to studying inflammatory signaling pathways in bone and muscle healing is the inadequacy of available animal models. We developed a surgical injury model in the (VL) muscle and femur in 129/SvEv littermates mice to study simultaneous musculoskeletal (MSK) healing in male and female, young (3 months) and aged (18 months) WT mice compared to mice lacking 5LO (5LOKO). MSK defects were surgically created using a 1-mm punch device in the VA muscle followed by a 0.5-mm round defect in the femur. After days 7 and 14 post-surgery, the specimens were removed for microtomography (microCT), histopathology, and immunohistochemistry analyses. In addition, non-injured control skeletal muscles along with femur and L5 vertebrae were analyzed. Bones were microCT phenotyped, revealing that aged female WT mice presented reduced BV/TV and trabecular parameters compared to aged males and aged female 5LOKO mice. Skeletal muscles underwent a customized targeted lipidomics investigation for profiling and quantification of lipid signaling mediators (LMs), evidencing age, and gender related-differences in aged female 5LOKO mice compared to matched WT. Histological analysis revealed a suitable bone-healing process with osteoid deposition at day 7 post-surgery, followed by woven bone at day 14 post-surgery, observed in all young mice. Aged WT females displayed increased inflammatory response at day 7 post-surgery, delayed bone matrix maturation, and increased TRAP immunolabeling at day 14 post-surgery compared to 5LOKO females. Skeletal muscles of aged animals showed higher levels of inflammation in comparison to young controls at day 14 post-surgery; however, inflammatory process was attenuated in aged 5LOKO mice compared to aged WT. In conclusion, this new model shows that MSK healing is influenced by age, gender, and the 5LO pathway, which might serve as a potential target to investigate therapeutic interventions and age-related MSK diseases. Our new model is suitable for bone-muscle crosstalk studies.
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http://dx.doi.org/10.3389/fendo.2020.00484DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7431610PMC
June 2021

Combined Effect of Melittin and DNase on Biofilms and Its Susceptibility to Sodium Hypochlorite.

Materials (Basel) 2020 Aug 24;13(17). Epub 2020 Aug 24.

Department of Conservative Dentistry, School of Dentistry and Institute of Oral Bioscience, Jeonbuk National University, Jeonju 54896, Korea.

Biofilm communities are tolerant to antimicrobials and difficult to eradicate. This study aimed to investigate the effect of melittin, an antimicrobial peptide, either alone or in combination with deoxyribonuclease (DNase), an inhibitor of extracellular deoxyribonucleic acid (eDNA), against () biofilms, and biofilm susceptibility to sodium hypochlorite (NaOCl). Biofilms of were developed in root canals of bovine teeth. The biofilms were treated with distilled water (control), melittin, DNase, or DNase+melittin. The antibiofilm effects of the treatments were analyzed using colony forming unit (CFU) assay, crystal violet staining, confocal laser scanning microscopy (CLSM), and field emission scanning electron microscope (FE-SEM). The susceptibility of DNase+melittin-treated biofilms to NaOCl (0%, 2.5% and 5%) was investigated by the CFU assay. The data were statistically analyzed using one-way analysis of variance, followed by Tukey's test. A -value of <0.05 was considered significant. Specimens treated with DNase+melittin showed a more significant decrease in the CFUs, eDNA level, and biofilm formation rate than those treated only with melittin or DNase ( < 0.05). CLSM analysis showed DNase+melittin treatment significantly reduced the volume of biofilms and extracellular polymeric substance compared to either treatment alone ( < 0.05). FE-SEM images showed a high degree of biofilm disruption in specimens that received DNase+melittin. 2.5% NaOCl in specimens pretreated with DNase+melittin showed higher antibacterial activity than those treated only with 5% NaOCl ( < 0.05). This study highlighted that DNase improved the antibiofilm effects of melittin. Moreover, DNase+melittin treatment increased the susceptibility of biofilms to NaOCl. Thus, the complex could be a clinical strategy for safer use of NaOCl by reducing the concentration.
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http://dx.doi.org/10.3390/ma13173740DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7503955PMC
August 2020

Effect of a calcium hydroxide-based intracanal medicament containing N-2-methyl pyrrolidone as a vehicle against Enterococcus faecalis biofilm.

J Appl Oral Sci 2020 27;28:e20190516. Epub 2020 Mar 27.

Chonbuk National University, School of Dentistry and Institute of Oral Bioscience, Department of Conservative Dentistry, Jeonju, Korea.

Introduction: This study investigated the effect of a calcium hydroxide (CH) paste (CleaniCal®) containing N-2-methyl pyrrolidone (NMP) as a vehicle on Enterococcus faecalis (E. faecalis) biofilms compared with other products containing saline (Calasept Plus™) or propylene glycol (PG) (Calcipex II®).

Methodology: Standardized bovine root canal specimens were used. The antibacterial effects were measured by colony-forming unit counting. The thickness of bacterial microcolonies and exopolysaccharides was assessed using confocal laser scanning microscopy. Morphological features of the biofilms were observed using field-emission scanning electron microscopy (FE-SEM). Bovine tooth blocks covered with nail polish were immersed into the vehicles and dispelling was observed. The data were analyzed using one-way analysis of variance and Tukey tests (p<0.05).

Results: CleaniCal® showed the highest antibacterial activity, followed by Calcipex II® (p<0.05). Moreover, NMP showed a higher antibacterial effect compared with PG (p<0.05). The thickness of bacteria and EPS in the CleaniCal® group was significantly lower than that of other materials tested (p<0.05). FE-SEM images showed the specimens treated with Calasept Plus™ were covered with biofilms, whereas the specimens treated with other medicaments were not. Notably, the specimen treated with CleaniCal® was cleaner than the one treated with Calcipex II®. Furthermore, the nail polish on the bovine tooth block immersed in NMP was completely dispelled.

Conclusions: CleaniCal® performed better than Calasept Plus™ and Calcipex II® in the removal efficacy of E. faecalis biofilms. The results suggest the effect might be due to the potent dissolving effect of NMP on organic substances.
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http://dx.doi.org/10.1590/1678-7757-2019-0516DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7105290PMC
April 2020

Biomechanics of alloplastic mandible reconstruction using biomaterials: The effect of implant design on stress concentration influences choice of material.

J Mech Behav Biomed Mater 2020 03 23;103:103548. Epub 2019 Nov 23.

Faculty of Dentistry, National University Centre for Oral Health, National University of Singapore, 9 Lower Kent Ridge Road, 119085, Singapore. Electronic address:

Introduction: Mandibular endoprostheses have been explored extensively as potential methods of alloplastic reconstruction. Studies, however, have demonstrated that for segmental mandibular defects, there are challenges associated with loosening. Another method recently introduced in clinical settings is popular as a design for patient-specific implants for segmental mandibular defect and involves a tray (filled with bone) over the defect with wings on both sides secured with screws. Our aim was to investigate which design better withstands the forces of function since studies have presented favourable results with regard to the wing design.

Materials And Methods: Two designs, an endoprosthesis with stems and wings were modelled. Finite element analysis was performed, and geometric data obtained from a human-sized mandible. A continuity defect of 20 mm was created digitally at the right mandibular molar region and the modelled segments combined with the endoprosthesis. Boundary conditions were set, and 300-N vertical loads applied in the incisor region. The stress concentrations and displacements were evaluated for the titanium alloy (Group 1-Stem) (Group 2-Wing) and the polycaprolactone (PCL) (Group 3 with stem, Group 4 wing design).

Results: For the titanium stem (Group 1), the stress values were in the 557-803 MPa range. The titanium wing (Group 2) design showed markedly reduced stress values in the 20-68 MPa range. The stresses observed for the PCL(Group 3) were in the 66-110 MPa range, and the stress concentration in the PCL wing (Group 4) was observed in the wing and body regions of the scaffolds in the 8-42 MPa range.

Conclusion: The wing design decreased the areas of stress concentrations significantly compared to an endoprosthesis. PCL alone did not have adequate strength to withstand forces applied even in a design that reduced stress concentrations significantly.
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http://dx.doi.org/10.1016/j.jmbbm.2019.103548DOI Listing
March 2020

Comparative study of xeno-free induction protocols for neural differentiation of human dental pulp stem cells in vitro.

Arch Oral Biol 2020 Jan 25;109:104572. Epub 2019 Sep 25.

Faculty of Dentistry, National University of Singapore, Singapore; National University Centre For Oral Health Singapore, National University Hospital System, Singapore. Electronic address:

Objective: To compare three different xeno-free protocols for neural differentiation of human dental pulp stem cells (DPSC).

Methods: DPSC were treated with three different media to induce neural differentiation namely N1 (DMEM for 5 days), N2 (PSC neural induction media for 7 days) and N3 (neural media with B27 supplement, 40 ng/ml bFGF and 20 ng/ml EGF for 21 days). Cell proliferation (MTS assay), morphology, gene (qPCR for NESTIN, VIMENTIN, TUB-3, ENO2, NF-M and NF-H) and protein expression (flow cytometry) of neurogenic markers were assessed at different time points and compared to untreated cells (DMEM supplemented with 10% FBS). Statistical analysis was performed with global significance level of 5%.

Results: N1 and N2 formulations increased the genetic expression of two out of six genes TUB-3, NF-M and TUB-3, NF-H, respectively, whereas N3 elevated the expression of all genes by the late stage. N3 also stimulated protein expression for NESTIN, TUB-3 and NF-H. Cells treated with both N2 and N3 presented neuron-like morphology, decreased proliferation and expression of stemness genes at protocol end point.

Conclusion: N3 was the most effective formulation in promoting a neurogenic shift in gene and protein expression. Cells provided with the N3 formulation exhibited neuron-like morphology, elaborating axonal-like projections concomitant with cell cycle withdrawal and reduced expression of stemness genes indicating greater commitment to a neurogenic lineage.
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http://dx.doi.org/10.1016/j.archoralbio.2019.104572DOI Listing
January 2020

Antibiotics Used in Regenerative Endodontics Modify Immune Response of Macrophages to Bacterial Infection.

J Endod 2019 Nov 19;45(11):1349-1356. Epub 2019 Sep 19.

Faculty of Dentistry, National University of Singapore, Singapore. Electronic address:

Introduction: Ciprofloxacin, amoxicillin, and metronidazole are antibiotics used in regenerative endodontic therapy (RET). Although their antimicrobial properties are well-documented, there is a lack of information on the effects of these antibiotics on the immune response by host macrophages and periapical healing. Thus, this study had 2 objectives: (1) to determine the immune response of macrophages to bacterial infection in response to the combination of ciprofloxacin or amoxicillin and metronidazole and (2) using conditioned media produced by these macrophages to simulate the periapical microenvironment, to determine the impact on the expression of extracellular matrix (ECM) components by periodontal fibroblasts.

Methods: Macrophages were treated with ciprofloxacin and metronidazole or amoxicillin and metronidazole at 10-1000 μg/mL. The treated macrophages were exposed to lipopolysaccharide, and the pro- and anti-inflammatory cytokines produced were quantified with enzyme-linked immunosorbent assay. Periodontal fibroblasts were treated with conditioned media from these treated macrophages, and the expression of ECM genes was determined by quantitative polymerase chain reaction.

Results: Lipopolysaccharides elicited the production of proinflammatory cytokines interleukin 1 beta and tumor necrosis factor alpha by macrophages, but this was suppressed by ciprofloxacin and metronidazole. Moreover, only conditioned media from macrophages treated with ciprofloxacin and metronidazole rescued microbial-induced down-regulation of ECM genes by periodontal fibroblasts. Specifically, ciprofloxacin was the antibiotic responsible for these observations. In contrast, these effects were not observed with amoxicillin and metronidazole.

Conclusions: Apart from disinfection of the root canal system, the combination of ciprofloxacin and metronidazole also exerts an immunomodulatory effect, which may aid in periapical healing.
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http://dx.doi.org/10.1016/j.joen.2019.08.001DOI Listing
November 2019

Translucency, hardness and strength parameters of PMMA resin containing graphene-like material for CAD/CAM restorations.

J Mech Behav Biomed Mater 2019 12 3;100:103388. Epub 2019 Aug 3.

Faculty of Dentistry, National University of Singapore, Singapore; Department of Materials Science and Engineering, National University of Singapore, Singapore; Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore. Electronic address:

CAD/CAM restorations can be produced from several ceramic and hybrid materials. The moderate mechanical properties of PMMA based resin have hindered its use for permanent restorations. Recently, a graphene reinforced PMMA namely G-CAM has been introduced for permanent CAD/CAM restorations. Although graphene family materials have been successfully used as a reinforcement phase in a variety of polymers, the properties and mechanical behavior of PMMA resin containing graphene-like materials remain unknown. Herein, we have evaluated the translucency, hardness and strength parameters (flexural strength, Weibull modulus and characteristic strength) of G-CAM A1 (GA1) and G-CAM B2 (GB2) and benchmarked it against a unmodified PMMA resin (PM), two polymer/ceramic hybrid materials [Vita Enamic (VE) and Lava Ultimate (LU)] and one ceramic (e.max, EX) for CAD/CAM restorations. The trends for the translucency parameter were similar for all materials at all thickness tested. The hardness for GA1, GB2 and PM were significantly lower than VE, LU and EX. The biaxial flexural strengths of GA1, GB2, PM and VE were approximately 150 MPa but significantly lower than LU and EX (201 and 313 MPa). All materials presented Weibull modulus higher than 10, except EX (m = 8) The stresses required to fracture 5% and 63.2% of specimens (σ and σ) were similar for GA1, GB2, PM and VE but significantly lower than LU and EX. Overall, the PMMA modified by graphene-like materials presented properties comparable with unmodified PM and VE.
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http://dx.doi.org/10.1016/j.jmbbm.2019.103388DOI Listing
December 2019

Role of extracellular DNA in Enterococcus faecalis biofilm formation and its susceptibility to sodium hypochlorite.

J Appl Oral Sci 2019 Aug 12;27:e20180699. Epub 2019 Aug 12.

Chonbuk National University, School of Dentistry and Institute of Oral Bioscience, Department of Conservative Dentistry, Jeonju, Korea.

Objective: This study investigated the role of extracellular deoxyribonucleic acid (eDNA) on Enterococcus faecalis ( E. faecalis ) biofilm and the susceptibility of E. faecalis to sodium hypochlorite (NaOCl).

Methodology: E. faecalis biofilm was formed in bovine tooth specimens and the biofilm was cultured with or without deoxyribonuclease (DNase), an inhibitor of eDNA. Then, the role of eDNA in E. faecalis growth and biofilm formation was investigated using colony forming unit (CFUs) counting, eDNA level assay, crystal violet staining, confocal laser scanning microscopy, and scanning electron microscopy. The susceptibility of E. faecalis biofilm to low (0.5%) or high (5%) NaOCl concentrations was also analyzed by CFU counting.

Results: CFUs and biofilm formation decreased significantly with DNase treatment (p<0.05). The microstructure of DNase-treated biofilms exhibited less structured features when compared to the control. The volume of exopolysaccharides in the DNase-treated biofilm was significantly lower than that of control (p<0.05). Moreover, the CFUs, eDNA level, biofilm formation, and exopolysaccharides volume were lower when the biofilm was treated with DNase de novo when compared to when DNase was applied to matured biofilm (p<0.05). E. faecalis in the biofilm was more susceptible to NaOCl when it was cultured with DNase (p<0.05). Furthermore, 0.5% NaOCl combined with DNase treatment was as efficient as 5% NaOCl alone regarding susceptibility (p>0.05).

Conclusions: Inhibition of eDNA leads to decrease of E. faecalis biofilm formation and increase of susceptibility of E. faecalis to NaOCl even at low concentrations. Therefore, our results suggest that inhibition of eDNA would be beneficial in facilitating the efficacy of NaOCl and reducing its concentration.
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http://dx.doi.org/10.1590/1678-7757-2018-0699DOI Listing
August 2019

Taguchi's methods to optimize the properties and bioactivity of 3D printed polycaprolactone/mineral trioxide aggregate scaffold: Theoretical predictions and experimental validation.

J Biomed Mater Res B Appl Biomater 2020 04 21;108(3):629-637. Epub 2019 May 21.

Faculty of Dentistry, National University of Singapore, Singapore, Singapore.

Mineral trioxide aggregate (MTA) can provide bioactivity to poly-caprolactone (PCL), which is an inert polymer used to print scaffolds. However, testing all combinations of scaffold characteristics (e.g., composition, pore size, and distribution) to optimize properties of scaffolds is time-consuming and costly. The Taguchi's methods can identify characteristics that have major influences on the properties of complex designs, hence decreasing the number of combinations to be tested. The objective was to assess the potential of Taguchi's methods as a predictive tool for the optimization of bioactive scaffold printed using electro-hydro dynamic jetting. A three-level approach assessed the influence of PCL/MTA proportion, pore size, fiber dimension and number of layers in pH, degradation rate, porosity, yield strength, and Young's modulus. Data were analyzed using Tukey's honest significant difference test, analysis of mean and signal-to-noise ratio (S/N) test. Cytocompatibility and differentiation potential were assessed for 5 and 30 days using dental pulp stem cells and analyzed with one-way analysis of variance (proliferation) or Mann-Whitney (qPCR). The S/N ratio and analysis of mean showed that fiber diameter and composition were the most influential characteristics in all properties. The experimental data confirmed that the addition of MTA to PCL increased the pH and scaffold degradation. Only PCL and PCL with 4% MTA allowed cell proliferation. The latter increased the genetic expression of ALP, COL-1, OCN, and MSX-1. The theoretical predictions were confirmed by the experiments. The Taguchi's identified the inputs that can be disregarded to optimize 3D printed meshed bioactive scaffolds.
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http://dx.doi.org/10.1002/jbm.b.34417DOI Listing
April 2020

Intrauterine insemination as a primary viable option to infertile couples: evaluation of patients in a private center.

JBRA Assist Reprod 2019 10 14;23(4):328-332. Epub 2019 Oct 14.

Conceber Reproductive Medicine Center. Curitiba - PR - Brazil.

Objective: This study aimed to identify which parameters positively affect the clinical pregnancy rates of IUI cycles and find which couples should opt for IUI.

Methods: This retrospective observational study included 261 patients submitted to 381 IUI cycles with fresh or cryopreserved partner semen (IU-H) from January 2012 to February 2017 in a private center in Curitiba-PR, Brazil.

Results: Idiopathic infertility was the most frequent finding (35.9%). Patients younger than 40 years accounted for 87.9% of the IUI cycles (n=335) and 16.1% of the clinical pregnancies (n=54). The pregnancy rate was three times higher in patients with an endometrium thickness ≥8 mm compared to patients with endometrium thickness <8mm. Sperm motility >55% was linked to higher pregnancy rates (p=0.002). Concerning gonadotropins, 159 (48.4%) took rFSH, 127 (38.7%) hMG, and 42 (12.8%) uFSH, with pregnancy rates of 21.3%, 10.4% and 10.5%, respectively.

Conclusion: Patients under 40 years of age with endometrium thickness ≥8 mm, sperm motility >55%, and on rFSH had significantly higher pregnancy rates (p<0.05).
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http://dx.doi.org/10.5935/1518-0557.20190014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6798586PMC
October 2019

Graphene-Induced Osteogenic Differentiation Is Mediated by the Integrin/FAK Axis.

Int J Mol Sci 2019 Jan 29;20(3). Epub 2019 Jan 29.

Faculty of Dentistry, National University of Singapore, 9 Lower Kent Ridge Road, Singapore 119085, Singapore.

Graphene is capable of promoting osteogenesis without chemical induction. Nevertheless, the underlying mechanism(s) remain largely unknown. The objectives here were: (i) to assess whether graphene scaffolds are capable of supporting osteogenesis in vivo and; (ii) to ascertain the participation of the integrin/FAK mechanotransduction axis during the osteogenic differentiation induced by graphene. MSC-impregnated graphene scaffolds ( = 6) were implanted into immunocompromised mice (28 days). Alternatively, MSCs were seeded onto PDMS substrates (modulus of elasticity = 130, 830 and 1300 kPa) coated with a single monomolecular layer of graphene and cultured in basal medium (10 days). The ensuing expressions of FAK-p397, integrin, ROCK1, F-actin, Smad p1/5, RUNX2, OCN and OPN were evaluated by Western blot ( = 3). As controls, MSCs were plated onto uncoated PDMS in the presence of mechanotransduction inhibitors (echistatin, Y27632 and DMH1). MSC-impregnated graphene scaffolds exhibited positive immunoexpression of bone-related markers (RUNX2 and OPN) without the assistance of osteogenic inducers. In vitro, regardless of the stiffness of the underlying PDMS substrate, MSCs seeded onto graphene-coated PDMS substrates demonstrated higher expressions of all tested osteogenic and integrin/FAK proteins tested compared to MSCs seeded onto PDMS alone. Hence, graphene promotes osteogenesis via the activation of the mechanosensitive integrin/FAK axis.
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http://dx.doi.org/10.3390/ijms20030574DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6387117PMC
January 2019

Hydrophobicity of graphene as a driving force for inhibiting biofilm formation of pathogenic bacteria and fungi.

Dent Mater 2019 03 21;35(3):403-413. Epub 2019 Jan 21.

Faculty of Dentistry, National University of Singapore, Singapore; Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore. Electronic address:

Objective: To evaluate the surface and wettability characteristics and the microbial biofilm interaction of graphene coating on titanium.

Methods: Graphene was deposited on titanium (Control) via a liquid-free technique. The transfer was performed once (TiGS), repeated two (TiGD) and five times (TiGV) and characterized by AFM (n=10), Raman spectroscopy (n=10), contact angle and SFE (n=5). Biofilm formation (n=3) to Streptococcus mutans, Enterococcus faecalis, Pseudomonas aeruginosa and Candida albicans was evaluated after 24h by CV assay, CFU, XTT and confocal microscopy. Statistics were performed by one-way Anova, Tukey's tests and Pearson's correlation analysis at a pre-set significance level of 5 %.

Results: Raman mappings revealed coverage yield of 82 % for TiGS and ≥99 % for TiGD and TiGV. Both TiGD and TiGV presented FWHM>44cm and I/I ratio<0.12, indicating multiple graphene layers and occlusion of defects. The contact angle was significantly higher for TiGD and TiGV (110° and 117°) comparing to the Control (70°). The SFE was lower for TiGD (13.8mN/m) and TiGV (12.1mN/m) comparing to Control (38.3mN/m). TiGD was selected for biofilm assays and exhibited significant reduction in biofilm formation for all microorganisms compared to Control. There were statistical correlations between the high contact angle and low SFE of TiGD and decreased biofilm formation.

Significance: TiGD presented high quality and coverage and decreased biofilm formation for all species. The increased hydrophobicity of graphene films was correlated with the decreased biofilm formation for various species.
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http://dx.doi.org/10.1016/j.dental.2018.09.016DOI Listing
March 2019

Author Correction: Enhanced Skin Permeation of Anti-wrinkle Peptides via Molecular Modification.

Sci Rep 2018 Apr 20;8(1):6500. Epub 2018 Apr 20.

Department of Pharmacy, Faculty of Science, National University of Singapore, Singapore, 117543, Singapore.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.
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http://dx.doi.org/10.1038/s41598-018-24806-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5910389PMC
April 2018

Thermo-setting glass ionomer cements promote variable biological responses of human dental pulp stem cells.

Dent Mater 2018 06 9;34(6):932-943. Epub 2018 Apr 9.

Hematopoietic Transplant and Cellular Therapy Unit, Instituto Murciano de Investigación Biosanitaria-Arrixaca, Virgen de la Arrixaca University Hospital, University of Murcia, Murcia, Spain; School of Dentistry, Faculty of Medicine, University of Murcia, Murcia, Spain. Electronic address:

Objective: To evaluate the in vitro cytotoxicity of Equia Forte (GC, Tokyo, Japan) and Ionostar Molar (Voco, Cuxhaven, Germany) on human dental pulp stem cells (hDPSCs).

Methods: hDPSCs isolated from third molars were exposed to several dilutions of Equia Forte and Ionostar Molar eluates (1/1, 1/2 and 1/4). These eluates were obtained by storing material samples in respective cell culture medium for 24h (n=40). hDPSCs in basal growth culture medium were the control. Cell viability and cell migration assays were performed using the MTT and wound-healing assays, respectively. Also, induction of apoptosis and changes in cell phenotype were evaluated by flow cytometry. Changes in cell morphology were analysed by immunocytofluorescence staining. To evaluate cell attachment to the different materials, hDPSCs were directly seeded onto the material surfaces and analyzed by scanning electron microscopy (SEM). The chemical composition of the materials was determined by energy dispersive X-ray (EDX) and eluates were analyzed by inductively coupled plasma-mass spectrometry (ICP-MS). Statistical analysis was performed with analysis of variance (ANOVA) and Student's t-test (α<0.05).

Results: Undiluted Equia Forte extracts led to a similar cell proliferation rates than the control group from 72h onwards. There were no significance differences between Equia Forte and Ionostar Molar in terms of cell apoptosis and phenotype. However, in presence of Equia extracts the migration capacity of hDPSCs was higher than in presence of Ionostar Molar (p<0.05). Also, SEM studies showed a higher degree of cell attachment when Equia Forte extracts were used. Finally, EDX analysis pointed to different weight percentages of C, O and Ca ions in glass ionomer cements, while other elements such as La, Al, Si, W, Mo and F were also detected.

Significance: In summary, Equia Forte promoted better biological responses in hDPSCs than Ionostar Molar.
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http://dx.doi.org/10.1016/j.dental.2018.03.015DOI Listing
June 2018

Graphene onto medical grade titanium: an atom-thick multimodal coating that promotes osteoblast maturation and inhibits biofilm formation from distinct species.

Nanotoxicology 2018 05 6;12(4):274-289. Epub 2018 Feb 6.

a Faculty of Dentistry , National University of Singapore , Singapore , Singapore.

The time needed for the osseointegration of titanium implants is deemed too long. Moreover, the bacterial colonization of their surfaces is a major cause of failure. Graphene can overcome these issues but its wet transfer onto substrates employs hazardous chemicals limiting the clinical applications. Alternatively, dry transfer technique has been developed, but the biological properties of this technique remain unexplored. Here, a dry transfer technique based on a hot-pressing method allowed to coat titanium substrates with high-quality graphene and coverage area >90% with a single transfer. The graphene-coated titanium is cytocompatible, did not induce cell membrane damage, induced human osteoblast maturation (gene and protein level), and increased the deposition of mineralized matrix compared to titanium alone. Moreover, graphene decreased the formation of biofilms from Streptococcus mutans, Enterococcus faecalis and even from whole saliva on titanium without killing the bacteria. These findings confirm that coating of titanium with graphene via a dry transfer technique is a promising strategy to improve osseointegration and prevent biofilm formation on implants and devices.
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http://dx.doi.org/10.1080/17435390.2018.1434911DOI Listing
May 2018

Enhanced Skin Permeation of Anti-wrinkle Peptides via Molecular Modification.

Sci Rep 2018 01 25;8(1):1596. Epub 2018 Jan 25.

Department of Pharmacy, Faculty of Science, National University of Singapore, Singapore, 117543, Singapore.

Wrinkles can have a negative effect on quality of life and Botox is one of the most effective and common treatments. Argireline (Arg0), a mimetic of Botox, has been found to be safer than Botox and effective in reducing wrinkles, with efficacies up to 48% upon 4 weeks of twice daily treatment. However, the skin permeation of Arg0 is poor, due to its large molecular weight and hydrophilicity. Arg0 exists in zwitterionic form and this charged state hindered its skin permeation. Chemical modification of the peptide structure to reduce the formation of zwitterions may result in increased skin permeability. We investigated a total of 4 peptide analogues (Arg0, Arg1, Arg2, Arg3), in terms of skin permeation and wrinkle reduction. The 4 peptides were dissolved in various propylene glycol and water co-solvents. Enhanced human skin permeation was demonstrated by both Arg2 and Arg3 in vitro. On the other hand, the abilities of the 4 analogues to reduce wrinkle formation were also compared using primary human dental pulp stem cells derived neurons. By measuring the inhibition of glutamate release from the neurons in vitro, it was shown that Arg3 was the most effective, followed by Arg1, Arg0 and Arg2.
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http://dx.doi.org/10.1038/s41598-017-18454-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5785486PMC
January 2018

Root Canal Filling Quality of a Premixed Calcium Silicate Endodontic Sealer Applied Using Gutta-percha Cone-mediated Ultrasonic Activation.

J Endod 2018 Jan 6;44(1):133-138. Epub 2017 Nov 6.

Department of Conservative Dentistry, School of Dentistry and Institute of Oral Bioscience, Chonbuk National University, Jeonju, Korea; Research Institute of Clinical Medicine, Chonbuk National University, Jeonju, Korea; Biomedical Research Institute of Chonbuk National University Hospital, Jeonju, Korea. Electronic address:

Introduction: The aim of this study was to investigate the filling quality of a recently developed premixed calcium silicate-based endodontic sealer (Endoseal MTA) with a single gutta-percha (GP) cone technique compared with a resin-based sealer (AH plus) with warm vertical compaction. We also explored the effect of GP cone-mediated ultrasonic activation on the filling quality of Endoseal MTA.

Methods: Thirty human single-rooted maxillary premolars with ribbon-shaped canals were prepared and assigned to 3 experimental groups according to filling method: EMS group was Endoseal MTA + single-cone; EMSU group was Endoseal MTA + single-cone with ultrasonic activation; and the APW group was AH plus + warm vertical compaction. Each tooth was scanned using micro-computed tomography (μ-CT), and the proportions of sections with void and the volume percentages of void were calculated. Then, the tooth was sectioned transversely, and the presence of void in the slices was scored under a stereomicroscope. The data were statistically analyzed using 1-way analysis of variance and Tukey tests to detect any significance (α = 0.05).

Results: In the μ-CT assessment, there was no significant difference among the groups regarding the proportion of sections with void and the void volume percentage (P > .05). However, in the stereomicroscopic evaluation, the EMS group showed a higher number of voids and a higher void score compared with the other groups (P < .05).

Conclusion: Endoseal MTA performs best when used with GP cone-mediated ultrasonic activation. Furthermore, stereomicroscopic observation of sections of the specimens should be performed when evaluating root canal filling quality.
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http://dx.doi.org/10.1016/j.joen.2017.07.023DOI Listing
January 2018

Graphene Nanosheets to Improve Physico-Mechanical Properties of Bioactive Calcium Silicate Cements.

Materials (Basel) 2017 May 31;10(6). Epub 2017 May 31.

Faculty of Dentistry, National University of Singapore, Singapore 119083, Singapore.

Bioactive calcium silicate cements are widely used to induce mineralization, to cement prosthetic parts, in the management of tooth perforations, and other areas. Nonetheless, they can present clinical disadvantages, such as long setting time and modest physico-mechanical properties. The objective of this work was to evaluate the potential of graphene nanosheets (GNS) to improve two bioactive cements. GNS were obtained via reduction of graphite oxide. GNS were mixed (1, 3, 5, and 7 wt %) with Biodentine (BIO) and Endocem Zr (ECZ), and the effects on setting time, hardness, push-out strength, pH profile, cell proliferation, and mineralization were evaluated. Statistics were performed with two-way ANOVA and Tukey test (α = 0.05). GNS has not interfered in the composition of the set cements as confirmed by Raman, FT-IR and XRD. GNS (1 and 3 wt %) shortened the setting time, increased hardness of both materials but decreased significantly the push-out strength of ECZ. pH was not affected but 1 wt % and 7 wt % to ECZ and 5 wt % to BIO increased the mineralization compared to the controls. In summary, GNS may be an alternative to improve the physico-mechanical properties and bioactivity of cements. Nonetheless, the use of GNS may not be advised for all materials when effective bonding is a concern.
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http://dx.doi.org/10.3390/ma10060606DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5553423PMC
May 2017

Applications of additive manufacturing in dentistry: A review.

J Biomed Mater Res B Appl Biomater 2018 07 24;106(5):2058-2064. Epub 2017 Jul 24.

Department of Mechanical Engineering, National University of Singapore, Singapore, 117608, Singapore.

Additive manufacturing (AM) or 3D printing has been hailed as the third industrial revolution as it has caused a paradigm shift in the way objects have been manufactured. Conventionally, converting a raw material to a fully finished and assembled, usable product comprises several steps which can be eliminated by using this process as functional products can be created directly from the raw material at a fraction of the time originally consumed. Thus, AM has found applications in several sectors including automotive, aerospace, printed electronics, and healthcare. AM is increasingly being used in the healthcare sector, given its potential to fabricate patient-specific customized implants with required accuracy and precision. Implantable heart valves, rib cages, and bones are some of the examples where AM technologies are used. A vast variety of materials including ceramics, metals, polymers, and composites have been processed to fabricate intricate implants using 3D printing. The applications of AM in dentistry include maxillofacial implants, dentures, and other prosthetic aids. It may also be used in surgical training and planning, as anatomical models can be created at ease using AM. This article gives an overview of the AM process and reviews in detail the applications of 3D printing in dentistry. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2058-2064, 2018.
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http://dx.doi.org/10.1002/jbm.b.33961DOI Listing
July 2018

Graphene for the development of the next-generation of biocomposites for dental and medical applications.

Dent Mater 2017 07 8;33(7):765-774. Epub 2017 May 8.

Faculty of Dentistry, National University of Singapore, Singapore; Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore. Electronic address:

Objective: Graphene and its derivatives, graphene oxide (GO) and reduced graphene oxide (rGO), are 2D carbon-based materials with remarkable physical, chemical and biological properties. Graphene sheets have high specific surface area and mechanical strength. Moreover, they have been shown to influence the differentiation of stem cells and to improve properties of biomaterials.

Methods: Here, we present the recent achievements on the use of graphene and its derivatives to improve properties and enhance bioactivity of biomaterials. We also discuss the biosafety constraints to be solved to translate these carbonaceous materials to the clinic.

Results: Graphene and its derivatives can be functionalized and further modified with several bioactive molecules. They can be combined with several biomaterials used in regenerative and reconstructive dentistry and medicine. The resultant graphene-modified composites often present improved physico-mechanical properties and enhanced bioactivity. Moreover, graphene-modified composites are promising candidates to deliver growth factors, drugs and others bioactive compounds.

Significance: Graphene can improve the physical, chemical and mechanical properties of biomaterials. As it can be functionalized and combined with several biomolecules, graphene holds enormous potential to be used as drug carriers or substrates and scaffolds for cell-based tissue engineering strategies.
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http://dx.doi.org/10.1016/j.dental.2017.04.008DOI Listing
July 2017

Streptococcus mutans forms xylitol-resistant biofilm on excess adhesive flash in novel ex-vivo orthodontic bracket model.

Am J Orthod Dentofacial Orthop 2017 Apr;151(4):669-677

Discipline of Oral Sciences, Faculty of Dentistry, National University of Singapore, Singapore. Electronic address:

Introduction: During orthodontic bonding procedures, excess adhesive is invariably left on the tooth surface at the interface between the bracket and the enamel junction; it is called excess adhesive flash (EAF). We comparatively evaluated the biofilm formation of Streptococcus mutans on EAF produced by 2 adhesives and examined the therapeutic efficacy of xylitol on S mutans formed on EAF.

Methods: First, we investigated the biofilm formation of S mutans on 3 orthodontic bracket types: stainless steel preadjusted edgewise, ceramic preadjusted edgewise, and stainless steel self-ligating. Subsequently, tooth-colored Transbond XT (3M Unitek, Monrovia, Calif) and green Grengloo (Ormco, Glendora, Calif) adhesives were used for bonding ceramic brackets to extracted teeth. S mutans biofilms on EAF produced by the adhesives were studied using the crystal violet assay and scanning electron microscopy. Surface roughness and surface energy of the EAF were examined. The therapeutic efficacies of different concentrations of xylitol were tested on S mutans biofilms.

Results: Significantly higher biofilms were formed on the ceramic preadjusted edgewise brackets (P = 0.003). Transbond XT had significantly higher S mutans biofilms compared with Grengloo surfaces (P = 0.007). There was no significant difference in surface roughness between Transbond XT and Grengloo surfaces (P >0.05). Surface energy of Transbond XT had a considerably smaller contact angle than did Grengloo, suggesting that Transbond XT is a more hydrophilic material. Xylitol at low concentrations had no significant effect on the reduction of S mutans biofilms on orthodontic adhesives (P = 0.016).

Conclusions: Transbond XT orthodontic adhesive resulted in more S mutans biofilm compared with Grengloo adhesive on ceramic brackets. Surface energy seemed to play a more important role than surface roughness for the formation of S mutans biofilm on EAF. Xylitol does not appear to have a therapeutic effect on mature S mutans biofilm.
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http://dx.doi.org/10.1016/j.ajodo.2016.09.017DOI Listing
April 2017

Effects of Epigallocatechin Gallate, an Antibacterial Cross-linking Agent, on Proliferation and Differentiation of Human Dental Pulp Cells Cultured in Collagen Scaffolds.

J Endod 2017 Feb;43(2):289-296

Department of Conservative Dentistry, School of Dentistry, Chonbuk National University, Jeonju, Korea; Biomedical Research Institute of Chonbuk National University Hospital, Jeonju, Korea. Electronic address:

Introduction: This study aimed to evaluate the efficacy of epigallocatechin gallate (EGCG), an antibacterial cross-linking agent, on the proliferation and differentiation of human dental pulp cells (hDPCs) cultured in hydrogel collagen scaffolds.

Methods: The odontogenic differentiation induced by EGCG was evaluated by alkaline phosphatase (ALP) activity and odontogenic-related gene expression using real-time polymerase chain reaction. The antibacterial effect of EGCG was investigated by a disc diffusion assay in comparison with glutaraldehyde. Proliferation was analyzed by cell number counting under both optical and confocal laser scanning microscopes. To assess the mechanical properties of collagen treated with EGCG, the setting time, surface roughness, and compressive strength were measured.

Results: EGCG itself did not up-regulate the odontogenic-related markers (P > .05) although ALP activity was slightly increased. The proliferation and differentiation of hDPCs cultured in collagen increased significantly in the presence of EGCG (P < .05). The antibacterial activity of EGCG was similar to that of glutaraldehyde. The setting time of collagen was significantly shortened when it was treated with EGCG (P < .05). The surface roughness and compressive strength of the cross-linked collagen were higher than those of collagen without EGCG (P < .05).

Conclusions: Our results showed that EGCG, the antibacterial cross-linking agent, promoted the proliferation and differentiation of hDPCs cultured in collagen scaffolds. Furthermore, the enhanced mechanical properties of collagen scaffolds induced by EGCG may play important roles in cell behavior. Consequently, the application of EGCG to collagen scaffolds might be beneficial for regenerative endodontic therapy.
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http://dx.doi.org/10.1016/j.joen.2016.10.017DOI Listing
February 2017