Characteristics of Dental Follicle Stem Cells and Their Potential Application for Treatment of Craniofacial Defects

Utilization of patient-specific stem cells in regenerative medicine provides a novel treatment approach for diseases and disorders. Embryonic stem cells and induced pluripotent stem cells can differentiate into any cells found within the body; however, ethical, technical and safety concerns have to be overcome before they can be used in clinics. Patient-specific stem cells can be isolated from adult tissues with no ethical, fewer technical, and safety concerns. Obtaining tissues for stem cell isolation usually requires invasive procedures, but impacted teeth are often extracted in the clinics and can be used for isolation of dental follicle stem cells (DFSCs). The overall goal of this dissertation is to characterize the osteogenic potential of DFSCs and to explore the possibility of using DFSCs for the treatment of craniofacial defects. In this regard, we first showed that DFSCs can be induced to differentiate primarily toward the osteoblast lineage. Our experiments showed that DFSCs at passages 3 to 5 have a strong osteogenic capability that is reduced during in vitro expansion. Comparing DFSCs with non-stem cell dental follicle cells (DFCs), we determined that dentin matrix protein 1 (DMP1) is highly expressed in DFSCs. Further study suggests that DMP1 is likely necessary to maintain the osteogenic differentiation capability of DFSCs via regulating expression of osteogenic genes. Given that adult stem cells exist in a quiescent state under normal physiological conditions, we attempted to activate DFSCs with heat-stress. Culturing DFSCs under mild heat-stress (39ºC-40ºC) could effectively promote their proliferation and osteogenic differentiation. In the final part of this project, in vivo transplantation experiments were conducted to evaluate the osteogenic potential of DFSCs for treatment of calvarial critical-size defects using a rat model. Bone regeneration was assessed by micro-computed tomography (micro-CT) and histological analysis at 4 and 8 weeks post-transplantation. The results showed that transplantation of DFSCs seeded into PCL scaffold significantly improved bone regeneration. An average of 50% bone recovery was observed with treatment of PCL-DFSC transplantation at 8 weeks. In conclusion, this study found that DFSCs are valuable tissue stem cells possessing strong osteogenic potential that can be used for repairing craniofacial defects

Cytotoxicity of a New Nano Zinc-Oxide Eugenol Sealer on Murine Fibroblasts

Introduction: The aim of this study was to evaluate the cytotoxicity of a new nano zinc-oxide eugenol (NZOE) sealer in comparison with AH-26 and Pulpdent root canal sealers. Methods and Materials: The L929 mouse fibroblast cells were cultivated and incubated for 24, 48 or 72 h with different dilutions (1/1, 1/2, 1/4, 1/8, 1/16 and 1/32) of culture media previously exposed to either of the test sealers naming NZOE, AH-26 or Pulpdent. At the end of incubation period, the effect of sealers on cell viability was evaluated using Mosmann’s Tetrazolium Toxicity (MTT) colorimetric assay. The data was compared using the one-way analysis of variance (ANOVA) followed by the Tukey’s post hoc test for multiple comparisons. Results: After 24, 48 or 72 h, both NZOE and Pulpdent sealers inhibited cell viability at 1/1, 1/2 and 1/8 dilutions. Within the 24 and 48 h, the AH-26 sealer reduced the cell viability at all dilutions except the 1/32 solution; however after 72 h even the 1/32 dilution was cytotoxic. Conclusion: The biocompatibility of the nano zinc-oxide eugenol sealer was comparable to Pulpdent sealer and lower than AH-26.Keywords: Cytotoxicity; MTT Assay; Nanoparticles; Root Canal Sealer; Zinc-Oxide Eugenol

Evaluation of X-ray protective shielding used in dental offices in Kerman, Iran, in 2014

BACKGROUND AND AIM: Protective equipment, such as lead aprons and thyroid shields, is effective in reducing patient radiation. This study was conducted for evaluation the use of thyroid shields and lead aprons in dental offices, in Kerman, Iran, in June 2014. METHODS: In this descriptive-analytical study, 106 dental offices with active X-ray machines were evaluated in Kerman. The information was recorded on a data sheet consisting of eight questions in three fields of the rate of the use of lead aprons, thyroid shields and taking part in radiation protection courses. Data were evaluated using frequency distribution and chi-squared test. RESULTS: In this study, 12.3% of clinics were equipped with lead aprons but only 5.7% used them for all the patients. Only 10.4% of Kerman Dental Clinics had thyroid shields. Approximately, 9.7% of Kerman dentists had participated in continuous retraining courses on radiation protection. There was a significant relationship between clinics equipped with lead aprons with more job experience. CONCLUSION: The results showed that the rate of the use of lead aprons and thyroid shields in dental clinics equipped with X-ray machines in Kerman is not sufficient and is far from the international standards. Therefore, it is suggested that radiation protection equipment be promoted and oral and dental radiologists be responsible for the use of such equipment in their clinics. KEYWORDS: Patient Protection; Radiation; Dentist

Tooth Discoloration Resulting from a Nano Zinc Oxide-Eugenol Sealer

Introduction: A desirable quality of any endodontic sealer is its ability to be tooth color friendly. Therefore the aim of the present study was to evaluate the tooth discoloration potential of a nano zinc oxide-eugenol (NZOE) sealer. Methods and Materials: In order to evaluate tooth discoloration, the pulp chamber of 60 human maxillary central and lateral incisors were filled with one of the sealers, naming AH-26 (resin-based sealer), Pulpdent sealer (ZOE-based) and a NZOE experimental sealer. Color measurements was assessed at the baseline (before placement of sealers) (T0), 24 h (T1) and 72 h (T2) h, 1-week (T3), and 1-month (T4) after the placement of sealers using the Easy Shade spectrophotometer. Data were analyzed in SPSS software using one-way ANOVA, and repeated measured ANOVA. Results: No significant differences were observed when the paired comparison test was performed (P>0.05). Conclusion: The tested nZOE sealer had similar tooth discoloration potential in comparison with AH-26 and ZOE sealer.Keywords: Nano Particle; Root Canal Sealer; Tooth Discoloration; Spectrophotometry; Zinc-Oxide Eugenol

Sample Size Calculation of Clinical Trials Published in Two Leading Endodontic Journals

Introduction: The purpose of this article was to evaluate the quality of sample size calculation reports in published clinical trials in Journal of Endodontics and International Endodontic Journal in years 2000-1 and 2009-10. Materials and Methods: Articles fulfilling the inclusion criteria were collected. The criteria were: publication year, research design, types of control group, reporting sample size calculation, the number of participants in each group, study outcome, amount of type I (α) and II (β) errors, method used for estimating prevalence or standard deviation, percentage of meeting the expected sample size and considering clinically importance level in sample size calculation. Data were extracted from all included articles. Descriptive analyses were conducted. Inferential statistical analyses were done using independent T-test and Chi-square test with the significance level set at 0.05. Results: There was a statistically significant increase in years between 2009 and 10 compared to 2000-1 in terms of reporting sample size calculation (P=0.002), reporting clinically importance level (P=0.003) and in samples size of clinical trials (P=0.01). But there was not any significant difference between two journals in terms of reporting sample size calculation, type of control group, frequency of various study designs and frequency of positive and negative clinical trials in different time periods (P>0.05). Conclusion: Sample size calculation in endodontic clinical trials improved significantly in 2009-10 when compared to 2000-1; however further improvements would be desirable

In Vitro Cytotoxicity of a New Nano Root Canal Sealer on Human Gingival Fibroblasts

Introduction: The aim of this in vitro study was to evaluate the cytotoxicity of a new nano zinc-oxide eugenol (NZOE) sealer on human gingival fibroblasts (HGFs) compared with Pulpdent (micro-sized ZOE sealer) and AH-26 (resin-based sealer). Methods and Materials: The Pulpdent, AH-26, and NZOE sealers were prepared and exposed to cell culture media immediately after setting, and 24 h and one week after setting. Then, the primary cultured HGFs were incubated for 24 h with different dilutions (1:1 to 1:32) of each sealer extract. Cell viability was evaluated by methyl thiazolyl diphenyl tetrazolium bromide (MTT) assay. The results were compared using two-way analysis of variance followed by Tukey’s post hoc test. The level of significance was set at 0.05. Results: All sealer extracts, up to 32 times dilutions, showed cytotoxicity when exposed to HGF immediately after setting. The extracts obtained 24 h or one week after setting showed lower cytotoxicity than extracts obtained immediately after setting. At all setting times, NZOE showed lower cytotoxicity than Pulpdent and AH-26. While one-week extracts of NZOE had no significant effect on the viability of HGF at dilutions 1:4 to 1:32, both Pulpdent and AH-26 decreased the cell viability at dilutions of 1:4 and 1:8. Conclusion: NZOE exhibited lower cytotoxicity compared to Pulpdent and AH-26 on HGF and has the potential to be considered as a new root canal filling material.Keywords: Cytotoxicity; Human Gingival Fibroblast; MTT assay; Nano; Seale

Detection of extended-spectrum beta-lactamase genes among Escherichia coli isolates from urinary tract infection in Mashhad

Urinary tract infections (UTIs) are known as one of the most important infections around the world, and Escherichia coli is the most important cause of UTI. Also, the empiric treatment and misusing of antimicrobial agents has led to increasing multi-drug resistance around the world which is a worldwide concern. Extended-spectrum beta-lactamase (ESBLs) is an enzyme group that is produced by the Enterobacteriaceae family. The three main ESBLs enzyme are as follow: blaCTX-M, blaTEM, and blaSHV, additionally, there are several types of each of them by the same mechanism. This study was conducted to evaluate the prevalence of ESBL genes among E. coli isolated from UTI patients. A total of 105 isolates were collected from UTI patients at two hospitals in Mashhad from 2017 to 2019. Bacterial identification was performed by standard microbiologic methods. The assessment of antimicrobial susceptibility was accomplished by the disk diffusion method. The presence of ESBL genes was investigated by multiplex-PCR. The prevalence of UTI, among females, was identified more than males. Furthermore, the blaTEM and blaCTX-M genes were detected in all isolates, but only six isolates (5.7%) were harboring blaSHV. The considerable role of E. coli in UTI infection, as well as the presence of ESBL genes in E. coli strains, emphasize the need for surveillance of antimicrobial therapy to prevent the extension of resistance among clinical strains

Creating a Future for an Ancient Sustainable City, Yazd

Abstract Sustainable architecture attempts to find a way to minimize the negative environmental impact of buildings by improving the use of energy and the efficiency of material used. As new and more affordable technologies emerge, solar-generated electricity and hot water, as well as passive and active systems of natural heating and cooling are becoming more widespread. Although advanced technology can provide some solutions, it may also be worth learning from energy-saving approaches of the past. This author believes that vernacular architecture can give us some clues to improve the environmental performance of tomorrow’s architecture. A combination of our current understanding of ancient techniques in addition to current knowledge about building science may help us find unique and powerful solutions. Ancient architecture used natural resources of energy to enhance the interior conditions of a building in the absence of modern cooling/heating systems. In this study, we review samples of architecture designed by such strategies; then, we move further to a specific example of sustainable features such as windcatchers, qanats, etc. located in Yazd, Iran. Windcatchers are the most remarkable well-adapted passive natural cooling and ventilation systems used in the harsh conditions in hot zones. In fact, the use of local materials and renewable energy resources in the most prominent feature of Yazd, the windcatchers, illustrate the harmony of human built-environments and nature. This thesis focuses on hot, hot-arid and hot-humid climates in Iran and some of the Arab countries in the Persian Gulf region. It uses the vernacular architecture of Yazd as an excellent example of the area, both culturally and climatically. Although this region is the focus of this study, the fundamental approaches can be manipulated for use in other hot-climate locations as a method of sustainable design. Literature reviews and analysis of case studies show that current Iranian designs do not achieve the best performance from an environmental aspect. It is proposed in this study that implementing vernacular architectural principles results in significant performance improvements over the current methods and offers a new architectural design language. In conclusion, a series of guidelines and successful strategies are presented to aid the designer of tomorrow’s buildings

A systematic review of questionnaires used on oral health knowledge, attitude, and practice in 12-year-olds

BACKGROUND AND AIM: National oral health knowledge, attitude, and practice (KAP) data among 12-year-old children need nation-wide programs to help promote oral health. In most countries, oral epidemiologic data are collected by selfadministered structured questionnaires. The aim of this study was to undertake a systematic review of the existing literature about questionnaires used for analyzing the oral health knowledge, attitude, and behavior profile of the 12- year-old children. METHODS: The search was conducted in PubMed and Google Scholar search engines. The Medical Subject Heading (MeSH) search was performed applying singularly and by combining the following terms retrieved from the MeSH browser provided by MEDLINE: “Knowledge, awareness, attitude, practice, behavior, 12-year-old children, oral health.” RESULTS: Of 176 records found, 29 evaluated oral health KAP in 12-year-old children by structured questionnaires. The most important questions on knowledge (23 of 29 questionnaires) included some items which are focused on the importance of preserving natural teeth, effects of brushing, and sweets and soft drinks on the dentition. The most common questions on practice (28 questionnaires) were brushing activity and dental visits. The attitudes were evaluated by questions about fear of dental treatment, opinion about dentists and dental care (10 questionnaires). CONCLUSION: Considering differences in the available questionnaires showed that despite the importance of promotion of oral health by increasing knowledge, and improving attitudes and practice in 12-year-old children, more work is needed to form a standard questionnaire. KEYWORDS: Oral Health; Knowledge; Attitude; Behavior; Revie