Three-Dimensional \u3cem\u3eIn Vitro\u3c/em\u3e Oral Mucosa Models of Fungal and Bacterial Infections

Oral mucosa is the target tissue for many microorganisms involved in periodontitis and other infectious diseases affecting the oral cavity. Three-dimensional (3D) in vitro and ex vivo oral mucosa equivalents have been used for oral disease modeling and investigation of the mechanisms of oral bacterial and fungal infections. This review was conducted to analyze different studies using 3D oral mucosa models for the evaluation of the interactions of different microorganisms with oral mucosa. In this study, based on our inclusion criteria, 43 articles were selected and analyzed. Different types of 3D oral mucosa models of bacterial and fungal infections were discussed in terms of the biological system used, culture conditions, method of infection, and the biological endpoints assessed in each study. The critical analysis revealed some contradictory reports in this field of research in the literature. Challenges in recovering bacteria from oral mucosa models were further discussed, suggesting possible future directions in microbiomics, including the use of oral mucosa-on-a-chip. The potential use of these 3D tissue models for the evaluation of the effects of antiseptic agents on bacteria and oral mucosa was also addressed. This review concluded that there were many aspects that would require optimization and standardization with regard to using oral mucosal models for infection by microorganisms. Using new technologies—such as microfluidics and bioreactors—could help to reproduce some of the physiologically relevant conditions and further simulate the clinical situation. Impact statement Tissue-engineered or commercial models of the oral mucosa are very useful for the study of diseases that involve the interaction of microorganisms and oral epithelium. In this review, challenges in recovering bacteria from oral mucosa models, the potential use of these three-dimensional tissue models for the evaluation of the effects of antiseptic agents, and future directions in microbiomics are discussed

Investigating Strategic Processes of L2 Reading Comprehension Among Collegiate Iranian ESP Learners Across Three Academic Fields of Study

The current study has aimed to explore strategic processes of English reading comprehension among Iranian ESP learners across three academic fields of medicine, computer engineering and law. To this end, 90 intermediate ESP learners were selected from a population of 180 volunteers, based on their performance on a standard placement test (Edwards, 2007). Afterwards, participants completed Survey of Reading Strategies (SORS) (Mokhtari & Sheorey, 2002). The results of the statistical analysis uncovered the individual reading strategy preferences and weaknesses of ESP learners and also indicated that intermediate ESP learners moderately perceived the use of reading strategies while reading academic texts in English. Also, an attempt has been made to identify whether there are significant differences regarding the frequency of perceived individual and overall reading strategy use across the three disciplines. The findings of the study would help ESP teachers to gain a more profound understanding of ESP learners’ strategic processes of L2 reading.Key words: ESP; Reading; Strategy; Reading strategies; Metacognitive awareness of reading strategiesRésumé L'étude actuelle a eu pour objectif d'explorer les processus stratégiques de la compréhension en lecture chez les apprenants en anglais ESP iranienne à travers trois champs théoriques de la médecine, le génie informatique et en droit. À cette fin, 90 intermédiaires apprenants ESP ont été sélectionnés parmi une population de 180 bénévoles, en fonction de leur performance sur un test de placement standard (Edwards, 2007). Ensuite, les participants ont rempli Enquête sur les stratégies de lecture (SORS) (Mokhtari & Sheorey, 2002). Les résultats de l'analyse statistique mis au jour les préférences individuelles stratégie de lecture et les faiblesses des apprenants ESP et a également indiqué que les apprenants intermédiaires ESP modérément perçu l'utilisation de stratégies de lecture en lisant des textes académiques en anglais. En outre, une tentative a été faite afin d'identifier s'il existe des différences significatives concernant la fréquence de l'utilisation perçue stratégie de lecture individuelle et globale dans les trois disciplines. Les résultats de l'étude pourrait aider les professeurs ESP pour acquérir une compréhension plus profonde des processus apprenants ESP de stratégique de la lecture en L2. Mots clés: ESP; lecture; Stratégie; Stratégies de lecture; Conscience Métacognitive des stratégies de lectur

Dental Residents’ Knowledge and Attitude towards Stem Cells and Regenerative Dentistry

Objectives: Success of regenerative dental procedures highly depends on their acceptance by the clinicians; yet, little is known about dental residents’ attitudes regarding this new technology. The purpose of this study was to assess the knowledge and attitude of post-graduate dental students towards stem cells and regenerative dentistry as part of future dental treatments.Methods: This cross-sectional survey was conducted on 84 third-year residents of various dental specialties. The questionnaire included demographics and professional status of the respondents, questions regarding their ethical beliefs and their clinical practice.Results: Eighty-four completed questioners were returned anonymously. The majorities of the participants were female, and had practiced for ≤ 5 years. The survey showed that 76.2% of the participants had not received any continuing education or training courses on stem cells or regenerative dentistry. The majority of the participants (82.1%) believed that regenerative treatments should be included in dental practice. Of all, 76.2% had no umbilical cord or stem cell banking for themselves or a relative and 63.1% thought that dental pulp stem cell banking would be useful to regenerate dental tissues. Most of the participants (65.5%) had never performed regenerative therapy of any kind in their clinical practice and 51.2% of the participants were not sure whether regenerative procedures would be successful.Conclusion: Although more evidence on the efficacy and safety of regenerative dentistry is required, postgraduate training in this regard seems necessary

In Vitro Study of Surface Alterations to Polyetheretherketone and Titanium and their Effect Upon Human Gingival Fibroblasts

Statement of problem Soft-tissue attachment to different surfaces may play a pivotal role in the long-term success of dental implants. However, studies on the issue, especially on newer materials, are sparse. Purpose The purpose of this in vitro study was to evaluate the viability and adhesion of human gingival fibroblasts (HGFs) on different implant abutment materials with specific surface modifications. Material and methods One hundred and fifty specimens in 6 experimental groups were evaluated: smooth-machined titanium alloy (Ti), laser-modified titanium (TiL), smooth-machined polyetheretherketone (PEEK) (P), laser-modified PEEK (PL), plasma-treated PEEK (PP), laser- and plasma-treated PEEK (PLP). Machined Ti was considered as the control group. Surface roughness (Sa), water contact angle (WCA), and X-ray photoelectron spectroscopy (XPS) were measured. HGF attachment and proliferation were observed at 1, 3, and 7 days after cell seeding. Comparison of the means among the groups was performed with 1-way analysis of variance (ANOVA) with post hoc comparison using the Tukey test (α=.05). Results Sa values of the laser modified groups were significantly higher than those of the nonmodified (smooth-machined) groups (P\u3c.001). WCAs were significantly different among PEEK groups, and plasma-sprayed groups had the lowest WCAs. XPS analysis of both Ti and PEEK groups showed laser treatment did not have any significant effect on the surface composition of the PEEK as the same bonds with similar ratio/fraction were detected in the spectrum of the modified specimens. Scanning electron microscopy (SEM) revealed more functionally oriented HGF cells on the laser-grooved surfaces. On the first, third, and seventh day of proliferation, the titanium groups showed no significant differences (P\u3e.05). On the first and third days of proliferation, the plasma sprayed groups (PP, PLP) showed significantly greater proliferation than all experimental groups (P\u3c.001). On the seventh day of proliferation, statistically significant differences were observed between all PEEK groups and between all PEEK groups and the Ti group (P\u3c.001), with the exception of the PL and P groups and the PLP and Ti groups (P\u3e.05). Conclusions Laser-modified titanium and PEEK surfaces led to guided gingival fibroblast attachment. Plasma treatment of PEEK surfaces increased the wettability of this polymer and improved proliferation of HGF

Evaluation of Chemical and Physical Properties of an Experimental Endodontic Sealer in Comparison with AH-26 and AH-Plus

Introduction: This study aimed to assess the physical and chemical properties of an experimental endodontic resin sealer (Resil) compared with AH-26 and AH-Plus.  Methods and Materials: In this in vitro experimental study, dimensional stability (by measurement of length; n=5), pH (using a pH meter; n=5), and antibacterial activity (by agar diffusion test; n=8) of Resil, AH-26 and AH-Plus were evaluated and compared using one-way ANOVA and Tukey’s test. Results: All three groups showed significant expansion from day 1 to day 30 (P<0.05). The difference in the mean dimensional changes between the AH-Plus and experimental sealer was significant (P=0.020). Two hours after mixing, the pH of experimental sealer (Resil) was significantly lower than that of AH-Plus (P<0.001) and higher than that of AH-26 (P<0.001). Antibacterial activity of the experimental sealer before and after setting was significantly higher than that of the other two sealers (P<0.001). Conclusion: The results of this in vitro study showed that the experimental sealer had dimensional changes greater than the other two sealers. It had an alkaline pH, and showed superior antibacterial activity compared with AH-26 and AH-Plus. It may be possible to use this sealer in the clinic after animal studies because an epoxy resin based sealer with lower price and more appropriate properties is favorable

Comparison of the Antimicrobial Efficacy of Calcium Hydroxide and Photodynamic Therapy Against Enterococcus faecalis and Candida albicans in Teeth With Periapical Lesions; An In Vivo Study

Introduction: Elimination of pathological microflora of root canal systems is a major goal in endodontic treatment. This study aimed to compare the antimicrobial efficacy of calcium hydroxide as an intracanal medication and antibacterial photodynamic therapy (aPDT) against Enterococcus faecalis and Candida albicans in teeth with periapical (PA) lesions.Methods: This in vivo study was conducted on 20 patients with single-rooted mandibular premolar with previously failed endodontic treatment. This study was performed as a clinical trial (IRCTID: IRCT2016090429686N1). After conventional chemo-mechanical root canal preparation (hand and rotary instruments and 2.5% NaOCl), microbiological samples were obtained using sterile paper points, then stored in thioglycolate solution and transferred to a microbiology laboratory. Group 1 (n = 10) specimens underwent aPDT (diode laser 808 nm + 50 mg/mL methylene blue), while creamy calcium hydroxide paste was used in group 2 for a duration of 1 week. A control sample was taken with sterile paper points and F3 Protaper rotary file. The samples were dispersed in transport medium, serially diluted, and cultured on selective mediums to determine the number of colony forming units (CFUs). Data were analyzed by Mann-Whitney U test at 5% significance level. The significance level for all analyses was set at P<0.05.Results: Number of CFU significantly decreased in both groups after the interventions (P<0.001); however, there was no significant difference in the colony count between the 2 groups.Conclusion: aPDT and calcium hydroxide therapy showed the same antimicrobial efficacy on E. faecalis and C. albicans

Manufacturing And Characterization of Mechanical, Biological and Dielectric Properties of Hydroxyapatite-Barium Titanate Nanocomposite Scaffolds

In this research, hydroxyapatite (HA)-based ceramics were produced as suitable ceramic implants for orthopedic applications. To improve the physical, mechanical, electrical and biological properties of pure HA, we developed composite scaffolds of HA-barium titanate (BT) by cold isostatic pressing and sintering. Microstructure, crystal phases, and molecular structure were analyzed by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR), respectively. Bulk density values were measured using the Archimedes method. The effect of different percentages of BT on cell proliferation, viability, and ALP activity of dental pulp stem cells (DPSCs) was assessed by ProstoBlue assay, Live/Dead staining, and p-NPP assay. The obtained results indicate that the HA-BT scaffolds possess higher compressive strength, toughness, density, and hardness compared with pure HA scaffolds. After immersing the scaffold in SBF solution, more deposited apatite appeared on the HA-BT, which results in rougher surface on this scaffold thanpure HA. Electrical properties of HA in the presence of BT are improved. Based on the results of cell culture experiments, composites containing 40, 50 and 60 %wt of BT have excellent biocompatibility, with the best results occurring for the sample with 50 %wt BT

Comparison of the Antibacterial Effect of 810 nm Diode Laser and Photodynamic Therapy in Reducing the Microbial Flora of Root Canal in Endodontic Retreatment in Patients With Periradicular Lesions

Introduction: The aim of this study was to compare the antibacterial efficacy of diode laser 810nm and photodynamic therapy (PDT) in reducing bacterial microflora in endodontic retreatment of teeth with periradicular lesion.Methods: In this in vivo clinical trial, 20 patients who needed endodontic retreatment were selected. After conventional chemo mechanical preparation of root canals, microbiological samples were taken with sterile paper point (PP), held in thioglycollate broth, and then were transferred to the microbiological lab. In the first group, PDT with methylene blue (MB) and diode laser (810 nm, 0.2 W, 40 seconds) was performed and in the second group diode laser (810 nm, 1.2 W, 30 seconds) was irradiated. Then second samples were taken from all canals.Results: CFU/ml amounts showed statistically significant reduction in both groups (P < 0.001). CFU/ml amounts were compared between the two groups and there was no statistical difference.Conclusion: PDT and diode laser 810 nm irradiation are effective methods for root canal disinfection. PDT is a suitable alternative for diode laser 810 nm irradiation, because of lower thermal risk on root dentin

Comparison of Propolis and Calcium Hydroxide in terms of Mineralization and Cytotoxicity Using Dental Pulp Stem Cells

Objectives: This study aimed to compare the in vitro cytotoxic activity of propolis, a bioactive material made by the honeybee, and calcium hydroxide (CH) and their effect on formation of mineralized nodules by human dental pulp stem cells (HDPSCs).Methods: In this in vitro study, HDPSCs were obtained from the Cellular and Molecular Oral Biology Laboratory of School of Dentistry, Shahid Beheshti University of Medical Sciences. In order to evaluate the proliferative effect of propolis and CH, HDPSCs were incubated with different concentrations of propolis (0-32mg/mL) and CH (0-4.8 mg/mL). Twenty-four and 48 hours later, the methylthiazolyl diphenyl-tetrazolium bromide (MTT) assay was carried out to evaluate the proliferation potential and viability of HDPSCs treated with propolis and CH. The effect of propolis and CH on mineralization of HDPSCs was assessed by alizarin red staining.Results: The MTT assay revealed that propolis at its highest concentration caused the greatest proliferation after 24 and 48 hours. Alizarin test showed that the lowest concentrations of CH and propolis at 14 days induced the formation of calcium nodules but at 21 days, propolis was deposited on the cells and calcification was not well recognizable.Conclusion: Propolis led to higher cell vitality at all concentrations in comparison to CH. However, due to its deposition on the cells, its effects on mineralization at 48 hours could not be determined

Culture of Dental Pulp Stem Cells on Nanoporous Alumina Substrates Modified by Carbon Nanotubes

Purpose: Alumina substrates are one of the commonly used scaffolds applied in cell culture, but in order to prevent formation of biofilm on the alumina substrate, these substrates are modified with carbon nanotube. Methods: The alumina substrate was made by a two-step anodization method and was then modified with carbon nanotubes by simple chemical reaction. The substrates were characterized with FTIR, SEM, EDX, 3D laser scanning digital microscope, contact angle (CA) and surface free energy (SFE). To determine how this modification influences the reduction of biofilm, biofilm of two various bacteria, Escherichia coli (E.coli) and Staphylococcus aureus (S. aureus), were investigated. Results: The biofilm on the modified substrate decreased due to the presence of carbon nanotubes and increased antibacterial properties. Dental pulp stem cells (DPSCs) were cultured onto flat alumina (FA) and nanoporous alumina-multiwalled carbon nanotubes (NAMC) substrates to examine how the chemical modification and surface topography affects growth of DPSCs. Conclusion: Cell attachment and proliferation were investigated with SEM and Presto Blue assay, and the findings show that the NAMC substrates are suitable for cell culture