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Background: One-visit apexification is a treatment of choice in necrotic immature open apex teeth. Calcium silicate base materials are suitable for this method. The purpose of this study was to investigate and compare the sealing efficiency of Biodentine, mineral trioxide aggregate (MTA) ProRoot, and calcium-enriched mixture (CEM) cement orthograde apical plug using bacterial leakage method. Materials and Methods: In this in vitro study a total of 70 extracted maxillary incisors were cleaned and shaped. A 1.1-mm standardized artificially open apex was created in all samples. The teeth were randomly divided into three experimental groups of 20, and two negative and positive control groups of 5. In experimental groups, 4-mm thick apical plugs of ProRoot MTA, CEM cement, or Biodentine were placed in an orthograde manner. Negative control samples were completely filled with MTA while positive control samples were left unfilled. Sealing efficiency was measured by bacterial leakage method, and results were analyzed by Kaplan–Meier and Chi-square tests. The level of significance was set at 0.05. Results: The highest number of turbidity was recorded for ProRoot MTA samples, while the lowest for Biodentine. There was a significant difference in the number of turbidity between ProRoot MTA and Biodentine groups (P < 0.001), but there was no significant difference between CEM cement and Biodentine (P = 0.133) and ProRoot MTA (P = 0.055). Conclusion: Within the limitation of this in vitro study, Biodentine showed promising results as a substance with good-sealing efficiency.

Background: Bacteria and their by-products are etiological factors for the failure of endodontic treatment. Reduction of root canal bacterial contamination is one of the chief aims of root canal therapy. The aim of this study was to compare the effects of different rotary file tapers and two irrigation fluids on Enterococcus faecalis counts. Materials and Methods: In this ex vivo study Root canals of 72 human upper lateral incisors were enlarged to ISO #20 K-file. Then, the samples were sterilized and inoculated with E. faecalis for 72 h, divided into six experimental groups and prepared with #30 Flexmaster files with 0.02, 0.04, and 0.06 tapers and two different irrigation solutions such as normal saline and sodium hypochlorite. The control group (n = 10) was subdivided into two groups with or without bacterial inoculation and no mechanical instrumentation. Cleaning efficacy was evaluated in terms of the reduction of colony forming units (CFUs). T-test, ANOVA, Duncan, and Tukey tests were applied to the groups. A significant level of α = 0.05 was set for comparison between the groups. Results: The canals instrumented with 0.06 taper exhibited greater significant reduction in CFUs compared to canals instrumented with 0.04 and 0.02 taper (P < 0.05); 0.04 taper also resulted in greater significant reduction in CFUs than 0.02 taper (P < 0.05). In addition, no significant differences were observed in E. faecalis counts between the two irrigation fluids (P > 0.05). Conclusion: Under the conditions of this study, root canal preparation with greater taper resulted in canal cleanliness and better debridement.

Background: The aim of this study was to compare the cytotoxicity and the biocompatibility of three different nanofibers scaffolds after seeding of stem cells harvested from human deciduous dental pulp. Given the importance of scaffold and its features in tissue engineering, this study demonstrated the construction of polyhydroxybutyrate (PHB)/chitosan/nano-bioglass (nBG) nanocomposite scaffold using electrospinning method. Materials and Methods: This experimental study was conducted on normal exfoliated deciduous incisors obtained from 6-year-old to 11-year-old healthy children. The dental pulp was extracted from primary incisor teeth which are falling aseptically. After digesting the tissue with 4 mg/ml of type I collagenase, the cells were cultured in medium solution. Identification of stem cells from human exfoliated deciduous teeth was performed by flowcytometry using CD19, CD14, CD146, and CD90 markers. Then, 1 × 104 stem cells were seeded on the scaffold with a diameter of 10 mm × 0.3 mm. Cell viability was evaluated on days 3, 5, and 7 through methyl thiazol tetrazolium techniques (P < 0.05) on different groups that they are groups included (1) PHB scaffold (G1), (2) PHB/chitosan scaffold (G2), (3) the optimal PHB/chitosan/nBG scaffold (G3), (4) mineral trioxide aggregate (MTA), and (5) the G3 + MTA scaffold (G3 + MTA). Data were analyzed with two-way ANOVA at significance level of P < 0.05. Results: The results indicated that the PHB/chitosan/nBG scaffold and PHB/chitosan/nBG scaffold + MTA groups showed significant difference compared with the PHB/chitosan scaffold and PHB scaffold groups on the 7th day (P < 0.05). Conclusion: Thus, it can be concluded that the scaffold with nBG nanoparticles is more biocompatible than the other scaffolds and can be considered as a suitable scaffold for growth and proliferation of stem cells.

An ideal material used for filling root canal system and in periapical surgery should completely seal the pathway connecting root canals and their surrounding tissues.Materials applied for this purpose must neither be toxic nor carcinogenic. They are also expected to be highly biocompatible and dimensionally stable. They should additionally resist dissolving in tissue fluids.Mineral Trioxide Aggregate (MTA); first used as a retrofilling material in root–end surgery to substitute traditional materials which could not seal the apical area completely.Currently MTA is used for pulp capping, pulpotomy, apexogenesis as an apical plug in non-vital open apex teeth, root perforation repair, treatment of root resorption and fracture and for filling the root canal system. Besides its antibacterial and antifungal activity, MTA is highly biocompatible, not soluble in tissue fluids, stimulates hard tissue formation and has a high pH. However, MTA causes tooth color change and shows low compressive strength. Furthermore, lack of a suitable solvent along side its long setting time and high price have limited the widespread application of MTA. Key words: Clinical applications, MTA, Root end filling