The effect of electromagnetic fields on survival and proliferation rate of dental pulp stem cells.

Aims: Extremely low-frequency electromagnetic fields (ELF-EMF) can affect biological systems and alter some cell functions like proliferation rate. Dental pulp tissue is known as a source of multipotent stromal stem cells (MSCs), which can be obtained by a less invasive and more available process compared to bone marrow-derived stem cells (BMSCs). This study aimed to consider the effect of ELF-EMF on proliferation rates of human dental pulp stem cells (hDPSCs).Material and methods: ELF-EMF was generated by a system including autotransformer, multi-meter, solenoid coils, teslameter and its probe. The effect of ELF-EMF with the intensity of 0.5 and 1 mT and 50 Hz on the proliferation rate of hDPSCs was assessed in 20 and 40 min per day for 7 days. MTT assay and DAPI test were used to determine the growth and proliferation of DPSCs.Results: Based on MTT, ELF-EMF has maximum effect with the intensity of 1 mT for 20 min/day on the proliferation of hDPSCs. The survival and proliferation rate in all exposure groups were significantly higher than the control group. Based on the data obtained from MTT and DAPI assay, the number of viable cells in the group exposed to 1 mT for 20 min/day was higher than other groups (p < .05).Conclusions: Regarding to the results of this study, 0.5 and 1 mT ELF-EMF can enhance survival and proliferation rates of hDPSCs.

Dental care provision for people with neurodevelopmental disorders in Iran; a qualitative study of barriers.

INTRODUCTION: One of the most underserved populations among dental patients is the people with Neurodevelopmental Disorders (PNDs). This study aimed to explore the barriers to dental care provision for PNDs from the viewpoint of stakeholders in provision in Iran. METHODS: We arranged a qualitative study based on an individual in-depth, semi-structured interview between October 2019 and February 2020. We interviewed 30 participants using a snowball sampling strategy with three groups: dentists who provided dental care for PNDs, dental public health professionals, and policymakers/managers in dental care provision in Iran. The interviewer used an interview framework based on Levesque's model of patient-centered access. The main question was: "How do you assess the barriers to the provision of dental services to PNDs in Iran?" The data were analyzed by the qualitative content analysis method described by Graneheim and Lundman. RESULTS: From the 30 interviewees (11 women), there were 11 dentists, nine dental public health professionals, and 10 participants who worked as policymakers/managers. They were aged 35-62 years and had working experience between 4 and 25 years. In the content analysis, 60 meanings units were extracted, and later classified into 14 subthemes, and four main themes. CONCLUSION: Four main barriers were traced regarding access, financial, competency-related, and policy-making aspects.

Scanning Electron Microscopy and Energy-Dispersive X-Ray Microanalysis of Set CEM Cement after Application of Different Bleaching Agents.

INTRODUCTION: The present study evaluated the element distribution in completely set calcium-enriched mixture (CEM) cement after application of 35% carbamide peroxide, 40% hydrogen peroxide and sodium perborate as commercial bleaching agents using an energy-dispersive x-ray microanalysis (EDX) system. The surface structure was also observed using the scanning electron microscope (SEM). METHODS AND MATERIALS: Twenty completely set CEM cement samples, measuring 4×4 mm2, were prepared in the present in vitro study and randomly divided into 4 groups based on the preparation technique as follows: the control group; 35% carbamide peroxide group in contact for 30-60 min for 4 times; 40% hydrogen peroxide group with contact time of 15-20 min for 3 times; and sodium perborate group, where the powder and liquid were mixed and placed on CEM cement surface 4 times. Data were analyzed at a significance level of 0.05 through the one Way ANOVA and Tukey's post hoc tests. RESULTS: EDX showed similar element distribution of oxygen, sodium, calcium and carbon in CEM cement with the use of carbamide peroxide and hydroxide peroxide; however, the distribution of silicon was different (P<0.05). In addition, these bleaching agents resulted in significantly higher levels of oxygen and carbon (P<0.05) and a lower level of calcium (P<0.05) compared to the control group. SEM of the control group showed plate-like and globular structure. Sodium perborate was similar to control group due to its weak oxidizing properties. Globular structures and numerous woodpecker holes were observed on the even surface on the carbamide peroxide group. CONCLUSION: The mean elemental distribution of completely set CEM cement was different when exposed to sodium perborate, carbamide peroxide and hydrogen peroxide.