Synthesis and characterization of mesoporous zinc oxide nanoparticles and evaluation of their biocompatibility in L929 fibroblasts

OBJECTIVES

This study aimed to synthesize and characterize mesoporous zinc oxide nanoparticles (ZnO NPs) and also to evaluate the cytotoxicity of mesoporous ZnO NPs on L929 mouse fibroblast cell lines using 3-(4,5- dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay.

MATERIALS AND METHODS

The synthesized mesoporous ZnO NPs were extensively characterized using X-ray diffraction analysis (XRD), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) analysis, field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectra (EDAX), Fourier-transform infrared spectroscopy (FTIR), and dynamic light scattering (DLS). The cytotoxicity of mesoporous ZnO NPs was assessed by MTT assay. The study groups for cytotoxicity assay were normal saline, 0.1% calcined mesoporous ZnO NP solution, 1% calcined mesoporous ZnO NP solution, 0.1% noncalcined mesoporous ZnO NP solution, 1% noncalcined mesoporous ZnO NP solution, 0.1% ZnO NP solution, 1% ZnO NP solution, 2% chlorhexidine, and phosphate-buffered saline (PBS). The percentages of mean ± standard deviation of viable cells were analyzed.

RESULTS

Characterization of mesoporous ZnO NPs revealed that all the particles were in a more or less spherical shape with a wide particle size distribution of 70-100 nm. TEM image showed the uniformed and aggregated ZnO NPs with a typical size of 10-15 nm. BET analysis showed a mesoporous structure for the prepared mesoporous ZnO NPs. According to the MTT assay, chlorhexidine had the lowest cell viability percentage. Cell viability percentages of 0.1% mesoporous ZnO NP solutions (calcined and noncalcined) were statistically, significantly higher than 0.1% ZnO NP solution (p < .05). Cell viability percentages of 0.1% calcined and noncalcined mesoporous ZnO NP solutions and 0.1% ZnO NP solution were statistically, significantly higher than the 1% solutions (p < .05).

CONCLUSION

Mesoporous ZnO NPs exhibited less cytotoxicity against L929 mouse fibroblast cell lines compared to CHX and ZnO NPs, hence are safe to use.

Evaluation of the Effects of Different Types of Resin Cement Systems on the Push-Out Bond Strength of the Fiber Post to Intracanal Dentin in Anterior Primary Teeth

Background

This study aimed to evaluate the effects of using three different resin cements on push-out bond strength (PBS) of fiber posts to root canal dentin of primary teeth.

Methods

Fifty primary canines were randomly divided into five experimental groups according to the type of the luting agent used for fiber post cementation after endodontic treatment and post space preparation as the following: Group 1: glass ionomer cement (GIC), Group 2: flowable resin composite, Group 3: etch and rinse (E&R) resin cement, Group 4: self-etch (SE) resin cement, Group 5: self-adhesive (SA) resin cement. The PBS values of the cemented fiber posts to root canals were measured. The data were statistically analyzed using a one-way analysis of variance, followed by Tukey's post hoc test.

Results

The highest mean PBS value was observed in Group 4 (SE resin cement), followed by Group 3 (E&R resin cement), and the lowest PBS value belonged to Group 1 (GIC), followed by Group 5 (p-values < 0.05). The mean PBS of Group 3 (E&R resin cement) was significantly higher than those of Groups 1 (GIC), 2 (flowable resin composite), and 5 (SA resin cement) (p-values < 0.05). However, no significant difference was found between the mean PBS of GIC and SA resin cement (p-value >0/05).

Conclusion

Using SE resin cement for fiber post cementation in primary anterior teeth showed the best results, followed by E&R resin cement. The lowest PBS was observed for GIC, followed by SA resin cement.

Assessment of knowledge, attitude, and behavior related to children's oral health in pediatricians and students in the pediatric field in Iran: a cross-sectional study

Background

Pediatricians have an important role to play in motivating and instructing parents on oral health in children. The aim of this study was to assess knowledge of, attitude to, and behavior regarding oral health care in children among pediatricians and students in the pediatric field in Iran.

Methods

This cross-sectional study included all students in the pediatric field (those who had started a residency or fellowship) and practicing pediatricians in provincial centers and universities (61 setting centers) throughout Iran in the course of 2021. Participants completed an online questionnaire assessing details of the parameters of knowledge of, attitude to, and behavior toward oral health for each individual. A convenience sampling technique was used to gather the study sample. All data were coded for each of the parameters. The data were analyzed by one-way ANOVA (Analysis of Variance)/Tukey and Pearson's correlation tests and path analysis.

Results

Out of 582 participants who visited the website, a total of 217 completed the entire questionnaire (participation rate of 37.2%). On the attitude parameter, 84.8% of participants scored above 75% of the possible attainable score, while only 37.9% and 48.1% of them had adequate knowledge and behavior for the possible score, respectively. Specialists had a higher mean score on behavior and knowledge than residents (P=0.001). There was a significant correlation between the scores on attitude and behavior (r=0.42, P<0.001), attitude and knowledge (r=0.19, P=0.005), and behavior and knowledge (r=0.25, P<0.001). Nearly all of the participants, 216 (99.5%), felt the need for the principles of dentistry to be included in the curriculum.

Conclusions

Pediatricians showed a favorable attitude to oral health, but their knowledge of and behavior in the field was inadequate. Improvement of pediatricians' interest and performance in oral health in children should be encouraged through the inclusion of these parameters in the curriculum for students of the pediatric field. Implementing training programs for practical pediatricians or incorporating independent theoretical and clinical courses offered by pediatric dentists in dental school departments into the field curriculum of the students in the pediatric field is recommended.

The Effect of Silver, Zinc Oxide, and Titanium Dioxide Nanoparticles Used as Final Irrigation Solutions on the Fracture Resistance of Root-Filled Teeth

Aim

This study was conducted to evaluate the effect of three nanoparticle solutions used as final root canal irrigants on the fracture resistance of endodontically treated roots.

Materials and Methods

Sixty intact single-rooted premolar teeth were used after removing the crowns below the cementum–enamel junction to standardize the length of the remaining roots to 13 mm. After instrumenting the roots using ProTaper Universal rotary instruments up to size F4, the roots were randomly divided into six groups (n=10) according to the final irrigating solutions: Group 1: normal saline; Group 2: 2% chlorhexidine (CHX); Group 3: 17% EDTA+2.5% NaOCl; Group 4: 17% EDTA+0.1% silver nanoparticle (SNP) solution; Group 5: 17% EDTA+0.1% titanium dioxide nanoparticle (TNP) solution; Group 6: 17% EDTA+0.1% zinc oxide nanoparticle (ZNP) solution. After filling the root canals with gutta-percha and AH Plus sealer, the fracture resistance (FR) values were measured. The data were subjected to the one-way analysis of variance and the Tamhane post hoc test (p=0.05).

Results

EDTA + NaOCl had the lowest FR value, followed by normal saline and CHX (p values < 0.05). No significant difference was found between the FR of roots irrigated with CHX and normal saline (p > 0.05). The application of nanoparticles (SNP, TNP, and ZNP) was associated with a significantly greater FR than that of other irrigation solutions (p values < 0.05).

Conclusion

The final irrigation of root canals with nanoparticles enhanced the fracture resistance of the endodontically treated roots. The lowest FR value was observed for NaOCl.

Cutaneous Wound Healing after Topical Application of Pistacia atlantica Gel Formulation in Rats

Objectives

This study has been undertaken to investigate the antioxidant activity of the gel formulation from Pistacia atlantica oil extraction on enzymatic antioxidants in experimental wound created in rats.

Materials and Methods

Under anesthesia, a square-shaped skin defect (2x2 cm) was created aseptically by surgical incision. Then, animals were randomly allocated to four groups (I- untreated controls, II- topically treated with base gel, III- topically treated with 5% gel, IV- topically treated with 10% gel).

Results

The results suggest that topical application of Pistacia atlantica oil gels improved reepithelialization with continuous stratum basalis and a mature granulation tissue and adnexa (hair follicles and sweat gland) compared with control and base gel groups. Treatment with 10% oil gel significantly enhanced the tensile strength, ultimate stress, yield strength and stiffness in this group compared with the control and base gel groups at 21 days post injury. The collagen fibers showed a more organized pattern and the tissue alignment was greater as compared to the control and base gel-treated groups at the same stage.

Conclusion

The results suggest that topical application of Pistacia atlantica oil gel improved the morphological, biochemical and biomechanical properties of experimentally-induced wound defects in rats.

Asthma and pulmonary arterial hypertension: do they share a key mechanism of pathogenesis?

Although largely distinct and seemingly unrelated, asthma and pulmonary arterial hypertension (PAH) have important pathological features in common, including inflammation, smooth muscle contraction and remodelling. We hypothesised that these common features could be explained by one shared mechanism of pathogenesis: activation of the transcription factor NFAT (nuclear factor of activated T-cells). If this concept is validated, it could lead to the introduction of novel therapeutic strategies against both lung disorders. In several experimental models, airway remodelling is accompanied by remodelling of smaller pulmonary arteries, validating the hypothesis of their similar pathogenesis. In addition, lungs of vasoactive intestinal peptide (VIP) knockout mice express airway hyperresponsiveness with airway inflammation and PAH with vascular remodelling, with both sets of pathological findings being reversible with VIP treatment. Preliminary data suggest that absence of the VIP gene leads to activation of the calcineurin-NFAT pathway, and that VIP is probably a physiological inhibitor of this pathway. Enough evidence exists to support the views that asthma and PAH share important pathological features, probably related to NFAT activation, and that VIP may be a physiological modulator of this mechanism.

Enhancement of pulmonary vascular remodelling and inflammatory genes with VIP gene deletion

The pathogenesis of idiopathic pulmonary arterial hypertension (PAH) remains poorly understood. The present authors recently reported that mice with vasoactive intestinal peptide (VIP) gene disruption show a spontaneous phenotype of PAH, with pulmonary vascular remodelling and lung inflammation. To explore the underlying molecular mechanisms in this model, it was examined whether absence of the VIP gene might alter the expression of additional genes involved in the pathogenesis of PAH, as single-gene deletions, in the absence of hypoxia, rarely result in significant pulmonary vascular remodelling. Lung tissue from mice with targeted disruption of the vasoactive intestinal peptide gene (VIP(-/-) mice) and from control mice was subjected to whole-genome gene microarray analysis, and the results validated with quantitative, real-time PCR. Lungs from VIP(-/-) mice showed a wide range of significant gene expression alterations, including overexpression of genes that promote pulmonary vascular smooth muscle cell proliferation, underexpression of antiproliferative genes and upregulation of pro-inflammatory genes. In conclusion, vasoactive intestinal peptide is a pivotal modulator of genes controlling the pulmonary vasculature, its deficiency alone resulting in gene expression alterations that can readily explain both the vascular remodelling and associated inflammatory response in pulmonary arterial hypertension. The present findings shed more light on the molecular mechanisms of pulmonary arterial hypertension, and could lead to better understanding of the pathogenesis of human pulmonary arterial hypertension, and hence to improved therapy.

Clues to VIP function from knockout mice

We have taken advantage of the availability of vasoactive intestinal polypeptide (VIP) knockout (KO) mice to examine the possible influence of deletion of the VIP gene on: (a) airway reactivity and airway inflammation, as indicators of bronchial asthma; (b) mortality from endotoxemia, a model of septic shock; and (c) the pulmonary circulation. VIP KO mice showed: (a) airway hyperresponsiveness to the cholinergic agonist methacholine, as well as peribronchial and perivascular inflammation; (b) a greater susceptibility to death from endotoxemia; and (c) evidence suggestive of pulmonary hypertension.

Association of red blood cell 5-methyltetrahydrofolate folate with bone mineral density in postmenopausal Iranian women

Recent studies have suggested that hyperhomocysteinemia and low plasma folate are associated with fracture and also bone mineral density (BMD) and that they may contribute to the pathogenicity of osteoporosis in postmenopausal women. However, as plasma total homocysteine (tHcy) and plasma folate can be regarded as short-term markers when compared to a long-term variable such as BMD, in this study we tested the hypothesis that low red blood cell 5-methyltetrahydrofolate (RBC 5-MTHFR) as a long-term marker of the folate status may be a better predictor of BMD than plasma 5-MTHF, and its deficiency may contribute to the pathogenicity of osteoporosis in postmenopausal Iranian women. The BMD at the femoral neck and lumbar spine (measured by dual-energy X-ray absorptiometry, DXA) together with anthropometric and biochemical components of the homocysteine re-methylation pathway including plasma tHcy, 5-MTHF and vitamin B12, RBC 5-MTHF and creatinine were determined in 366 postmenopausal women. RBC 5-MTHF was more highly correlated with BMD at the lumbar spine (r=0.21, P=0.001) and femoral neck (r=0.19, P=0.004) than was plasma 5-MTHF (lumbar spine; r=0.14, P=0.03 and femoral neck; r=0.17, P=0.006). Stepwise multiple linear regression analyses revealed that RBC 5-MTHF was one of the predictors of BMD explaining 4.3 and 4.0% variance of BMD at the lumbar spine and femoral neck, respectively, whereas plasma 5-MTHF was excluded in the model and not determined to be a predictor of BMD at both the lumbar spine and femoral neck when adjusted for age, BMI, years since menopause and RBC 5-MTHF. This study suggests that RBC 5-MTHF is a better predictor of BMD than plasma 5-MTHFR when compared to a long-term marker such as BMD, and its deficiency is associated with low BMD that may contribute to the pathogenicity of osteoporosis in postmenopausal women.