A partially demineralized allogeneic bone graft: in vitro osteogenic potential and preclinical evaluation in two different intramembranous bone healing models

Crestal approach for maxillary sinus augmentation in individuals with limited alveolar bone height: An observational study

In cases where the bone presence is <4 mm, the lateral approach is typically the first approach considered. Nevertheless, for patients who prefer minimally invasive procedures or wish to reduce postoperative discomfort, the crestal approach is a viable option. The objective of this study was to investigate the potential of crestal sinus augmentation for achieving adequate bone in individuals with residual bone measuring <3 mm. The study comprised 11 participants (63.6 ± 10.9 years of age) who were treated at Seoul St. Mary's Hospital between 2021 and 2023 and received crestal approach sinus augmentation due to insufficient bone density of <3 mm using the crestal approach kit. Pre-augmentation and post-augmentation cone-beam computed tomographic images were analyzed using the imaging software to measure vertical bone height, bucco-palatal width, and mesio-distal width. Before the intervention, the height of the vertical bone was 2.1 ± 0.5 mm, while the width from buccal to palatal was 10.6 ± 2.9 mm, and the width from mesial to distal was 9.9 ± 1.2 mm. Following the intervention, these measurements increased to 8.8 ± 0.9 mm, 12.2 ± 2.2 mm, and 10.2 ± 1.2 mm, respectively. The change in height of the vertical bone was 6.7 ± 1.0 mm, in bucco-palatal width was 1.6 ± 1.4 mm, and in mesio-distal width was 0.3 ± 0.4 mm. The results revealed a significant rise in the height of the vertical bone and bucco-palatal width. Crestal sinus augmentation has been demonstrated to be a highly effective approach for achieving an adequate quantity of bone in patients with residual bone <3 mm. Nonetheless, further observation is required to evaluate the long-term prognosis of the procedures.

Strategies of functionalized GelMA-based bioinks for bone regeneration: Recent advances and future perspectives

Gelatin methacryloyl (GelMA) hydrogels is a widely used bioink because of its good biological properties and tunable physicochemical properties, which has been widely used in a variety of tissue engineering and tissue regeneration. However, pure GelMA is limited by the weak mechanical strength and the lack of continuous osteogenic induction environment, which is difficult to meet the needs of bone repair. Moreover, GelMA hydrogels are unable to respond to complex stimuli and therefore are unable to adapt to physiological and pathological microenvironments. This review focused on the functionalization strategies of GelMA hydrogel based bioinks for bone regeneration. The synthesis process of GelMA hydrogel was described in details, and various functional methods to meet the requirements of bone regeneration, including mechanical strength, porosity, vascularization, osteogenic differentiation, and immunoregulation for patient specific repair, etc. In addition, the response strategies of smart GelMA-based bioinks to external physical stimulation and internal pathological microenvironment stimulation, as well as the functionalization strategies of GelMA hydrogel to achieve both disease treatment and bone regeneration in the presence of various common diseases (such as inflammation, infection, tumor) are also briefly reviewed. Finally, we emphasized the current challenges and possible exploration directions of GelMA-based bioinks for bone regeneration.

Bioprinted PDLSCs with high-concentration GelMA hydrogels exhibit enhanced osteogenic differentiation in vitro and promote bone regeneration in vivo

OBJECTIVES

We aimed to explore the osteogenic potential of periodontal ligament stem cells (PDLSCs) in bioprinted methacrylate gelatine (GelMA) hydrogels in vitro and in vivo.

MATERIALS AND METHODS

PDLSCs in GelMA hydrogels at various concentrations (3%, 5%, and 10%) were bioprinted. The mechanical properties (stiffness, nanostructure, swelling, and degradation properties) of bioprinted constructs and the biological properties (cell viability, proliferation, spreading, osteogenic differentiation, and cell survival in vivo) of PDLSCs in bioprinted constructs were evaluated. Then, the effect of bioprinted constructs on bone regeneration was investigated using a mouse cranial defect model.

RESULTS

Ten percent GelMA printed constructs had a higher compression modulus, smaller porosity, lower swelling rate, and lower degradation rate than 3% GelMA. PDLSCs in bioprinted 10% GelMA bioprinted constructs showed lower cell viability, less cell spreading, upregulated osteogenic differentiation in vitro, and lower cell survival in vivo. Moreover, upregulated expression of ephrinB2 and EphB4 protein and their phosphorylated forms were found in PDLSCs in 10% GelMA bioprinted constructs, and inhibition of eprhinB2/EphB4 signalling reversed the enhanced osteogenic differentiation of PDLSCs in 10% GelMA. The in vivo experiment showed that 10% GelMA bioprinted constructs with PDLSCs contributed to more new bone formation than 10% GelMA constructs without PDLSCs and constructs with lower GelMA concentrations.

CONCLUSIONS

Bioprinted PDLSCs with high-concentrated GelMA hydrogels exhibited enhanced osteogenic differentiation partially through upregulated ephrinB2/EphB4 signalling in vitro and promoted bone regeneration in vivo, which might be more appropriate for future bone regeneration applications.

CLINICAL RELEVANCE

Bone defects are a common clinical oral problem. Our results provide a promising strategy for bone regeneration through bioprinting PDLSCs in GelMA hydrogels.

Immunomodulatory fibrous hyaluronic acid-Fmoc-diphenylalanine-based hydrogel induces bone regeneration

AIM

To investigate the potential of an ultrashort aromatic peptide hydrogelator integrated with hyaluronic acid (HA) to serve as a scaffold for bone regeneration.

MATERIALS AND METHODS

Fluorenylmethyloxycarbonyl-diphenylalanine (FmocFF)/HA hydrogel was prepared and characterized using microscopy and rheology. Osteogenic differentiation of MC3T3-E1 preosteoblasts was investigated using Alizarin red, alkaline phosphatase and calcium deposition assays. In vivo, 5-mm-diameter calvarial critical-sized defects were prepared in 20 Sprague-Dawley rats and filled with either FmocFF/HA hydrogel, deproteinized bovine bone mineral, FmocFF/Alginate hydrogel or left unfilled. Eight weeks after implantation, histology and micro-computed tomography analyses were performed. Immunohistochemistry was performed in six rats to assess the hydrogel's immunomodulatory effect.

RESULTS

A nanofibrous FmocFF/HA hydrogel with a high storage modulus of 46 KPa was prepared. It supported osteogenic differentiation of MC3T3-E1 preosteoblasts and facilitated calcium deposition. In vivo, the hydrogel implantation resulted in approximately 93% bone restoration. It induced bone deposition not only around the margins, but also generated bony islets along the defect. Elongated M2 macrophages lining at the periosteum-hydrogel interface were observed 1 week after implantation. After 3 weeks, these macrophages were dispersed through the regenerating tissue surrounding the newly formed bone.

CONCLUSIONS

FmocFF/HA hydrogel can serve as a cell-free, biomimetic, immunomodulatory scaffold for bone regeneration.

Appropriate Implant Rehabilitation in Patients With Iatrogenic Oroantral Fistula and Odontogenic Maxillary Sinusitis

Oroantral fistula (OAF) is the most common etiology for odontogenic maxillary sinusitis that can be caused by tooth extractions, failed maxillary sinus lifts, bone grafts, and poor positioning of dental implant fixtures. A 52-year-old man presented with an OAF and maxillary sinusitis after implant placement and bone grafting. The authors treated the patient with modified endoscopic sinus surgery to obtain OAF closure and provided dental implant placement procedures afterward. The authors also treated 8 other similar cases with favorable outcomes. In this study, the authors report the know-how of implant placement procedures in patients with OAF and maxillary sinusitis.

An Extrudable Partially Demineralized Allogeneic Bone Paste Exhibits a Similar Bone Healing Capacity as the "Gold Standard" Bone Graft

Autologous bone grafts (BGs) remain the reference grafting technique in various clinical contexts of bone grafting procedures despite their numerous peri- and post-operative limitations. The use of allogeneic bone is a viable option for overcoming these limitations, as it is reliable and it has been widely utilized in various forms for decades. However, the lack of versatility of conventional allogeneic BGs (e.g., blocks, powders) limits their potential for use with irregular or hard-to-reach bone defects. In this context, a ready- and easy-to-use partially demineralized allogeneic BG in a paste form has been developed, with the aim of facilitating such bone grafting procedures. The regenerative properties of this bone paste (BP) was assessed and compared to that of a syngeneic BG in a pre-clinical model of intramembranous bone healing in critical size defects in rat calvaria. The microcomputed tridimensional quantifications and the histological observations at 7 weeks after the implantation revealed that the in vivo bone regeneration of critical-size defects (CSDs) filled with the BP was similar to syngeneic bone grafts (BGs). Thus, this ready-to-use, injectable, and moldable partially demineralized allogeneic BP, displaying equivalent bone healing capacity than the “gold standard,” may be of particular clinical relevance in the context of oral and maxillofacial bone reconstructions.