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Objectives: The primary aim of this research was to find the effects of Normal saline injection rate and position on irrigation quality in curved root canals. Methods: Computational Fluid Dynamics (CFD) was used to simulate irrigation in root canals. Root canal geometries were obtained by considering the complete shaping of a rotary file in four root groups with 0, 10, 30, and 60° of curvatures. Fluid surface tension, bouncy, gravity, and air entrance were considered in the numerical simulation using Ansys-CFX software. For each root canal, the flow regime and wall shear stresses were calculated at three different syringe plunger speeds, and three different injection locations of a beveled open-ended needle and their effects on the irrigation quality were investigated in this paper. Results: Wall shear stress is considered the main parameter determining irrigation quality. It was calculated for all 36 test cases. Injection rate and normal saline accumulating near the apex and their effects on washed area ratio were shown for the test cases. Results showed significant effects of injection characteristics, incredibly faster injection, and deeper needle position on the irrigation quality of curved root canals. Conclusions: A higher injection rate and deeper needle position are required to achieve the best irrigation quality and a more washed area ratio in root canals with greater curvature.
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A systematic review and meta-analysis were conducted to evaluate the effect of endodontic irrigation on the mineral content of root canal dentine. A systematic search was performed in the following databases: PubMed, Web of Science, Scopus, Cochrane, ProQuest, and Wiley. The quality assessment of the articles was performed. The meta-analysis was carried out using the random effects model in the Stata 16 software (p<0.05). The results showed that Er: YAG Laser had a significant effect on the removal of the phosphorus content of dentine (Hedges' g=-0.49; 95% CI: -0.85, -0.13; I2=0.0%). In addition, the EDTA 5Min had a lower removal effect compared to the control group on the magnesium content of dentine (Hedges' g=0.58; 95% CI: 0.00, 1.16; I2=0.0%). Other irrigations had no significant effect on other on the mineral content of root canal dentine. Evidence was found to support that most root canal irrigation protocols did not have a significantly affected in terms of the mineral content of root dentine. (EEJ-2022-11-140).
Subject(s)
Dental Pulp Cavity , Root Canal Irrigants , Root Canal Therapy , Minerals , DentinABSTRACT
Cartilage lesions are common conditions, affecting elderly and non-athletic populations. Despite recent advances, cartilage regeneration remains a major challenge today. The absence of an inflammatory response following damage and the inability of stem cells to penetrate into the healing site due to the absence of blood and lymph vessels are assumed to hinder joint repair. Stem cell-based regeneration and tissue engineering have opened new horizons for treatment. With advances in biological sciences, especially stem cell research, the function of various growth factors in the regulation of cell proliferation and differentiation has been established. Mesenchymal stem cells (MSCs) isolated from different tissues have been shown to increase into therapeutically relevant cell numbers and differentiate into mature chondrocytes. As MSCs can differentiate and become engrafted inside the host, they are considered suitable candidates for cartilage regeneration. Stem cells from human exfoliated deciduous teeth (SHED) provide a novel and non-invasive source of MSCs. Due to their simple isolation, chondrogenic differentiation potential, and minimal immunogenicity, they can be an interesting option for cartilage regeneration. Recent studies have reported that SHED-derived secretome contains biomolecules and compounds that efficiently promote regeneration in damaged tissues, including cartilage. Overall, this review highlighted the advances and challenges of cartilage regeneration using stem cell-based therapies by focusing on SHED.
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Introduction: Lasers and optics have been used extensively in dental procedures in recent years, and realizing the optical properties of the tooth is also an essential in its successful applications. The aim of this study was to compare the absorption and transmission of applied wavelengths in the range of 190-1100 nm at different dentin thicknesses and the effect of changing the direction of radiation emission on the dentin tubules. Methods: There were fifteen dentin specimens with thicknesses of 300, 600, and 1000 mm, five specimens for each thickness, prepared through a transverse section of the coronal dentin over the pulpal roof area of human molars. Considering the coronal-apical and apical-coronal directions, we measured the absorption and transmission of parallel light rays perpendicular to the dentin samples in different thicknesses and two directions with a Cecil CE 7400 UV/Vis spectrometer. Data analysis was performed using SPSS software version 19. P value<0.05 was considered significant. Results: The absorption rate of the ultraviolet wavelength range was significantly higher than that of visible and infrared light irradiation from both directions at three thicknesses (P<0.001). The radiation shift direction had no significant differences in the absorption and transmission of wavelengths of ultraviolet, visible, and infrared light in any of the three thicknesses (P>0.05). Conclusion: Accordingly, attenuation or transmission losses of light in the ultraviolet to infrared range clearly depend on the wavelength of light and the optical properties of dental dentin, and the thickness of the dentin used in this study has a little effect.
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Background. This study assessed the antimicrobial effects of different concentrations of simvastatin versus triple antibiotic paste (TAP) on Enterococcus faecalis biofilms at different stages of development. Methods. In this in vitro study, 70 human single-rooted mature premolars were decoronated, instrumented, and autoclave-sterilized. Next, an E. faecalis suspension was prepared and inoculated into the canals to obtain 4- and 6-week biofilms. After ensuring biofilm formation, the samples in each group were randomly assigned to 5 subgroups (n=12): 1 mg/mL TAP, 10 mg/ mL TAP, 1 mg/mL simvastatin, 10 mg/mL simvastatin, and positive control (phosphate-buffered saline solution). The medicaments were applied in the canals, and the teeth were incubated for one week. Dentin samples were collected by a rotary file, cultured, and the number of E. faecalis colonies was counted. The Kruskal-Wallis, Mann-Whitney U, and Wilcoxon tests were used for data analysis (α=0.05). Results. There were significant differences in colony counts between the two concentrations of TAP and the control group against both 4- and 6-week biofilms (P<0.05). The antibacterial effect of 10 mg/mL TAP and simvastatin was stronger than that of 1 mg/mL concentration against the 4- and 6-week E. faecalis biofilms (P<0.05). Furthermore, 10 mg/mL TAP and simvastatin were more effective against the 4-week biofilms than the 6-week biofilms (P<0.05). Conclusion. According to the present results and since biofilms may remain viable in the root canal system for weeks to months, applying 10 mg/mL TAP and simvastatin might be more effective.
