Marija Živković

Critical-sized bone defects pose significant challenges in orthopedic surgery. The introduction of 3D printing technology in bone grafting offers a promising solution by creating customized grafts that mimic the natural bone structure. This study aimed to reconstruct long-segment bone defects in the rabbit radius using a 3D-printed material composed of hydroxyapatite (HAP) and poly(lactide-co-glycolide) (PLGA), referred to as ALBO-OS, and to evaluate its potential to support bone healing without the use of stem cells or growth factors. Six rabbits underwent computed tomography scanning to create patient-specific 3D models of the radius. Custom-designed ALBO-OS implants were 3D-printed and used to fill segmental defects corresponding to one-third of the bone length in each rabbit, created by osteotomy. Over a 12-week observation period, graft integration, osteointegration, and overall bone regeneration were assessed through histological and histomorphometric analyses. The implanted scaffolds demonstrated encouraging bone healing, with significant bone regeneration observed within the defect areas. Histological evaluation revealed significant new bone formation and vascularization, with minimal inflammatory response. The findings demonstrated the potential of 3D-printed HAP/PLGA-based materials as a promising strategy for the reconstruction of large bone defects, eliminating the need for exogenous biological agents.

Background/Objectives: A novel 3D-printed, bioresorbable bone graft, made of nanohydroxyapatite (nHAP) covered by poly(lactide-co-glycolide) (PLGA), showed strongly expressed osteoinductive properties in our previous investigations. The current study examines its application in the dual regeneration of bone and cartilage by combining with nHAP gel obtained by nHAP enrichment with hydroxyethyl cellulose, sodium hyaluronate, and chondroitin sulfate. Methods: In the in vitro part of the study, the mitochondrial activity and osteogenic and chondrogenic differentiation of stem cells derived from apical papilla (SCAPs) in the presence of nHAP gel were investigated. For the in vivo part of the study, three rabbits underwent segmental osteotomies of the lateral condyle of the femur, and defects were filled by 3D-printed grafts customized to the defect geometry. Results: In vitro study revealed that nHAP gel displayed significant biocompatibility, substantially increasing mitochondrial activity and facilitating the osteogenic and chondrogenic differentiation of SCAPs. For the in vivo part of the study, after a 12-week healing period, partial resorption of the graft was observed, and lamellar bone tissue with Haversian systems was detected. Histological and stereological evaluations of the implanted grafts indicated successful bone regeneration, marked by the infiltration of new bone and cartilaginous tissue into the graft. The existence of osteocytes and increased vascularization indicated active osteogenesis. The hyaline cartilage near the graft showed numerous new chondrocytes and a significant layer of newly formed cartilage. Conclusions: This study demonstrated that tailored 3D-printed bone grafts could efficiently promote the healing of substantial bone defects and the formation of new cartilage without requiring supplementary biological factors, offering a feasible alternative for clinical bone repair applications.

Background/Objectives: A novel 3D-printed, bioresorbable bone graft, made of nanohydroxyapatite (nHAP) covered by poly(lactide-co-glycolide) (PLGA), showed strongly expressed osteoinductive properties in our previous investigations. The current study examines its application in dual regeneration of bone and cartilage by its combining with nHAP gel obtained by nHAP enrichment with hydroxyethyl cellulose, sodium hyaluronate, and chondroitin sulfate. Methods: In the in vitro part of the study, mitochondral activity and osteogenic and chondrogenic differentiation of stem cells derived from apical papilla (SCAPs) in the presence of nHAP gel were investigated. For in vivo part of the study, three rabbits underwent segmental osteotomies of lateral condyle of the femur, and defects were filled by 3D-printed grafts customized to the defect geometry. Results: In vitro study revealed that nHAP gel displayed significant biocompatibility, substantially increasing mitochondrial activity and facilitating osteogenic and chondrogenic differentiation of SCAPs. For in vivo part of the study, after a 12-week healing period, partial resorption of the graft was observed, and lamellar bone tissue with Haversian systems was detected. Histological and stereological evaluations of the implanted grafts indicated successful bone regeneration, marked by the infiltration of new bone and cartilaginous tissue into the graft. The existence of osteocytes and increased vascularization indicated active osteogenesis. The hyaline cartilage near the graft showed numerous new chondrocytes and the significant layer of newly formed cartilage. Conclusions: This study demonstrated that tailored 3D-printed bone grafts could efficiently promote the healing of substantial bone defects and formation of new cartilage without requiring supplementary biological factors, offering a feasible alternative for clinical bone repair applications.

Nickel-titanium alloys are the most common shape memory alloys (SMA) widely used in dentistry. The attractive properties of Ni-Ti BioSMAs (shape memory effect, superelasticity, good corrosion, wear resistance, and good biocompatibility) make them highly desirable candidates for the design of implants, prosthetic components, orthodontic wires, and endodontic files. The aim of this chapter is to present the advantages of Ni-Ti alloy in dentistry through a selection of optimal chemical composition and various surface treatments (mechanical polishing, electrochemical polishing, chemical etching in acid solutions, heat treatment). The osteoconductivity of the Ni-Ti alloy on human bone cells and the anticorrosive and antibacterial effects of nanocoating orthodontic wires were tested. The results on human bone cells suggested good adhesion and proliferation of osteoblast-like cells to nickel-titanium surfaces, which could improve osseointegration of the potential dental implants. A study of magnetron sputtering method (MS) with TiN-Cu-nanocoatings on orthodontic archwires showed favorable results in corrosion resistance and antibacterial properties. Future improvement of mechanical properties is focused on applying various methods of surface modifications, especially applying coatings with antibacterial properties.

Background/Aim. Available face masks, used to protect the respiratory system from various types of pathogens, show unsatisfactory efficiency because the size of viruses like severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is much smaller than the void spaces in these masks. Difficult breathing through some masks quickly tires out, which makes ordinary people avoid wearing them. These facts suggest that a new strategy is desirable for designing protective face masks. The aim of the study was to present new filters for face masks to protect people exposed to high concentrations of bacteria and viruses, particularly SARS-CoV-2. Methods. Filters for these masks were manufactured of dense cotton fabric impregnated with silver quantum dots. The filters were characterized by scanning electron microscopy and ion-coupled plasma mass spectrometry. Wettability properties were determined by measuring contact angles with water, and a color fastness test was performed. Antibacterial assay was performed using Staphylococcus (S.) aureus. Viability quantitative polymerase chain reaction (qPCR) for virus integrity assay and reverse transcription qPCR (RT-qPCR) assay were used for antiviral activity assessment. Results. In vitro assays showed extremely high efficiency of these filters in destroying S. aureus and SARS-CoV-2 virus. The filters also showed high safety and easy breathing possibilities. Conclusion. The high efficiency of these masks against SARS-CoV-2 has been demonstrated through numerous tests, and they have been approved as anti-SARS-CoV-2 masks for the first time in the world. In the meantime, this solution has been applied in practice, and the data obtained about that are very encouraging.

The goal of this study was to examine the prevalence of WNT10A and RUNX2 mutations and assess their potential impact on the phenotype of non‐syndromic tooth agenesis. The study included 30 participants with non‐syndromic tooth agenesis, divided into hypodontia (n = 24) and oligodontia forms (n = 6), and 42 unaffected family members. Genomic DNA from buccal epithelial cells was used for polymerase chain reaction amplification of functionally important exons of the WNT10A and RUNX2 genes. Direct sequencing reactions were performed to confirm the presence of mutations. The trend of increasing prevalence of WNT10A mutations and a slight increase in the prevalence of RUNX2 mutations were revealed in tooth agenesis cases compared to unaffected family members. There was a higher prevalence of hypodontia than oligodontia, increased frequency of females over males with missing teeth, and a wide phenotypic variability was observed in individuals and families analyzed. The common missense mutations (p.Phe228Ile, p.Arg113Cys, p.Asp217Asn, and p.Gly165Arg) and c.114‐56T>C in the WNT10A gene and in‐frame‐deletion/insertions (11A, 24Q, 30Q), synonymous variant c.240G>A, and 424‐33dupC in the RUNX2 gene were identified. These findings highlight an important role of WNT10A and RUNX2 mutations in the genetic etiology of non‐syndromic tooth agenesis.

Introduction. Temporomandibular disorder (TMD) is a collective term for numerous symptoms, with the most common being masticatory muscle pain, pain in temporomandibular joints, limited mouth opening, irregular jaw movements, headaches and sound effects in TMJ. The aim was to determine the prevalence and severity of TMD in orthodontic patients determining whether the type of malocclusion affects the prevalence and severity of TMD. Material and Methods. The study was conducted in the form of Fonseca Anamnestic Index, which classifies TMD severity among examinees (no TMD, mild, moderate and severe TMD). The experimental group consisted of orthodontic patients with confirmed malocclusions, while the control group consisted of dental students with a Class I occlusion and no need for orthodontic treatment. Orthodontic patients were classified into the three subgroups based on malocclusions. Results. In the experimental group, 45.03% of orthodontic patients had some degree of TMD, while among students, that percentage was 56.41%. Compared to Class I, higher percentage of TMD was found among patients with distal and mesial occlusion in experimental group. In the experimental and control groups, the greatest percentage of participants showed mild TMD. The prevalence of TMD was greater in females than in males in the experimental group. Conclusion. The high prevalence of TMD in the control group speaks in favor of its complex etiology, with stress having an important role. Malocclusion is one of many factors which can contribute to the occurrence and severity of TMD, but it cannot be considered the most significant.