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The aim of this study was to evaluate the technical procedural iatrogenic errors, especially to determine the frequency of dental perforation made by undergraduate students in Sofia, Faculty of Dentistry, Bulgaria, in the school years of 2014/2015 and 2015/2016. The assessment was by examination of periapical radiographs of completed endodontically treated teeth, performed by last year dental students. A total of 748 teeth were evaluated and 30 perforations were found. From 285 treated in 2015, 10 perforations were found. From 493 teeth treated in 2016, 20 perforations were found. The overall frequency of perforations was 3.9% for 2015 and 4.1% for 2016. The frequency of perforations made by postgraduate Bulgarian students established by us is low and it is similar to that made by general practitioners and found by other Bulgarian researches. Perforation frequency found in this study is due to the large number of retreatments (36% of all cases) and the prevailing number of elderly patients with calcified canals that come to be treated in our facility. And yet it is not significantly different from other published data.

β-Tricalcium phosphate (β-TCP) is a well-established biomaterial for bone regeneration, highly regarded for its biocompatibility and osteoconductivity. However, its clinical efficacy is often compromised by susceptibility to bacterial infections. In this study, we address this limitation by integrating femtosecond (fs)-laser processing with the concurrent synthesis of silver nanoparticles (AgNPs) mediated by Azorean green tea leaf extract (GTLE), which is known for its rich antioxidant and anti-inflammatory properties. The fs laser was employed to modify the surface of β-TCP scaffolds by varying scanning velocities, fluences, and patterns. The resulting patterns, formed at lower scanning velocities, display organized nanostructures, along with enhanced roughness and wettability, as characterized by Scanning Electron Microscopy (SEM), optical profilometry, and contact angle measurements. Concurrently, the femtosecond laser facilitated the photoreduction of silver ions in the presence of GTLE, enabling the efficient synthesis of small, spherical AgNPs, as confirmed by UV–vis spectroscopy, Transmission Electron Microscopy (TEM), and Fourier Transform Infrared Spectroscopy (FTIR). The resulting AgNP-embedded β-TCP scaffolds exhibited a significantly improved cell viability and elongation of human bone marrow mesenchymal stem cells (hBM-MSCs), alongside significant antibacterial activity against Staphylococcus aureus (S. aureus). This study underscores the transformative potential of combining femtosecond laser surface modification with GTLE-mediated AgNP synthesis, presenting a novel and effective strategy for enhancing the performance of β-TCP scaffolds in bone-tissue engineering. [ABSTRACT FROM AUTHOR]

Bone substitutes are widely employed for applications in orthopedic surgery for the replacement of injured bone. Among the diverse methods that are used to design 3D bioceramic matrices, Freeze Foaming has gained attention, since it provides the ability to tune the shape of the created structures. One of the major problems related to these constructs is the lack of porosity at the outwards sides (holder) of the scaffold, thus reducing the cellular affinity and creating a rejection of the implant. In this research, we aimed to develop a bone scaffold with enhanced surface properties and improved cellular affinity. The main aim was to alter the biocompatibility characteristics of the 3D bioceramic constructs. We have produced three-dimensional, complex-shaped hollow shell structures, manufactured by Additive Manufacturing processes and as a second step, filled with a ceramic suspension by the Freeze-Foaming process. 3D constructs from HAP-derived TCP and TCP/ZrO2 were synthesized by freezefoaming method and subsequently irradiated with a fs-laser (λ = 800 nm) spanning a range of parameters for achievement of optimal surface processing conditions. The designed scaffolds demonstrated enhanced topographical properties with improved porosity examined by SEM, EDX, and 3D profilometry after laser treatment. Wettability and computer tomography (CT) evaluation was also performed. The results from X-ray diffraction (XRD) and micro-Raman analysis did not show photochemical and surface or volume defects and changes after laser processing of the ceramic samples. Preliminary results from MG-63 osteoblast-like cell tests showed good cell affinity on the processed surfaces and no cytotoxic effect on the cells. [ABSTRACT FROM AUTHOR]

Traditional chemical modification techniques used to alter the surface properties of diverse biomaterials possess drawbacks, such as leaving additional chemical toxicity from the solvents used and altering the mechanical stability. As an alternative approach for surface treatment, ultra-short pulsed laser processing (Fig. 1) is a non-contact method that enables a unique route to manipulate diverse biomaterial surfaces without severe thermal damage leading to heat-affected zones. Application of ultra-short laser radiation induces precise surface modification of scaffolds and allows the creation of multifunctional geometries with the potential to affect the biomimetic and antimicrobial properties of the constructs. By finely tuning the laser processing parameters (scanning velocity (V), laser fluence (F), and a number of applied laser pulses (N), it is possible to influence the surface roughness, thus altering the wettability of the materials without disrupting their chemical composition. The conducted research was performed on a number of materials and has demonstrated that surface topography has a great influence on the biomimetic and antimicrobial behavior of materials used in biomedicine and in everyday life. [ABSTRACT FROM AUTHOR]

Objective: To investigate the influence of citric acid on the osteogenic and angiogenic potential of stem cells from apical papillae (SCAPs)., Materials and Methods: Stem cells from apical papillae were isolated from freshly extracted third permanent molars. These cells were treated with 20 and 100 μM citric acid. Alizarin red staining was used to evaluate mineral deposition. The secreted levels of vascular endothelial growth factor (VEGF) were assessed by ELISA on days 18, 24 and 28. Immunofluorescence analysis was performed to assess the expression of surface markers after exposure to 20 and 100 μM citric acid., Results: Different mineralisation patterns were observed. Supplemented with citric acid, media showed more diffuse and less dense crystals. On day 18, most VEGF was secreted from the cells with no added citric acid. On day 24, there was a significant increase (p < 0.05) in the levels of VEGF secreted from cells treated with 20 μM citric acid. On day 28, cells from the control group did not secrete VEGF. There was a reduction in the levels of VEGF secreted by cells treated with 20 μM citric acid and a significant increase in the cells exposed to 100 μM citric acid (p < 0.05)., Conclusion: Citric acid can promote the differentiation of SCAPs and angiogenesis.