Metformin-Incorporated Gelatin/Nano-Hydroxyapatite Scaffolds Promotes Bone Regeneration in Critical Size Rat Alveolar Bone Defect Model

In this study, we fabricated gelatin/nano-hydroxyapatite/metformin scaffold (GHMS) and compared its effectiveness in bone regeneration with extraction-only, Sinbone, and Bio-Oss Collagen® groups in a critical size rat alveolar bone defect model. GHMS was synthesized by co-precipitating calcium hydroxide and orthophosphoric acid within gelatin solution, incorporating metformin, and cross-linked by microbial transglutaminase. The morphology, characterization, and biocompatibility of scaffold were examined. The in vitro effects of GHMS on osteogenic gene and protein expressions were evaluated. In vivo bone formation was assessed in a critical size rat alveolar bone defect model with micro-computed tomography and histological examination by comparing GHMS with extraction-only, Sinbone, and Bio-Oss Collagen®. The synthesized GHMS had a highly interconnected porous structure with a mean pore size of 81.85 ± 13.8 µm. GHMS exhibited good biocompatibility; promoted ALPL, RUNX2, SP7, BGLAP, SPARC and Col1a1 gene expressions; and upregulated the synthesis of osteogenic proteins, including osteonectin, osteocalcin, and collagen type I. In critical size rat alveolar bone defects, GHMS showed superior bone regeneration compared to extraction-only, Sinbone, and Bio-Oss Collagen® groups as manifested by greater alveolar ridge preservation, while more bone formation with a lower percentage of connective tissue and residual scaffold at the defect sites grafted with GHMS in histological staining. The GHMS presented in this study may be used as a potential bone substitute to regenerate alveolar bone. The good biocompatibility, relatively fast degradation, interconnected pores allowing vascularization, and higher bioactivity properties of the components of the GHMS (gelatin, nHA, and metformin) may contribute to direct osteogenesis.

Metformin-loaded β-TCP/CTS/SBA-15 composite scaffolds promote alveolar bone regeneration in a rat model of periodontitis

Periodontitis is a progressive infectious inflammatory disease, which leads to alveolar bone resorption and loss of periodontal attachment. It is imperative for us to develop a therapeutic scaffold to repair the alveolar bone defect of periodontitis. In this study, we designed a new composite scaffold loading metformin (MET) by using the freeze-drying method, which was composed of β-tricalcium phosphate (β-TCP), chitosan (CTS) and the mesoporous silica (SBA-15). The scaffolds were expected to combine the excellent biocompatibility of CTS, the good bioactivity of β-TCP, and the anti-inflammatory properties of MET. The MET-loaded β-TCP/CTS/SBA-15 scaffolds showed improved cell adhesion, appropriate porosity and good biocompatibility in vitro. This MET composite scaffold was implanted in the alveolar bone defects area of rats with periodontitis. After 12 weeks, Micro-CT and histological analysis were performed to evaluate different degrees of healing and mineralization. Results showed that the MET-loaded β-TCP/CTS/SBA-15 scaffolds promoted alveolar bone regeneration in a rat model of periodontitis. To our knowledge, this is the first report that MET-loaded β-TCP/CTS/SBA-15 scaffolds have a positive effect on alveolar bone regeneration in periodontitis. Our findings might provide a new and promising strategy for repairing alveolar bone defects under the condition of periodontitis.

Biphasic Calcium Phosphate/Chitosan/Polyacrylonitrile/Polylactic Acid-Glycolic Acid (PLGA) Nanocomposite Stent for Repair and Osteogenesis of Oral Alveolar Bone Defect

ABSTRACTThe ability of sol-gel micro-nano biphasic calcium stent to repair oral alveolar bone defects was investigated in this study, and its osteogenesis performance was also analyzed. Biphasic calcium phosphate (BCP) was synthesized by wet method, which was combined with chitosan (CS), polyacrylonitrile (PAN), and polylactic acid-glycolic acid (PLGA). Then, the BCP/CS/PAN/PLGA nanocomposite stent was prepared by vacuum freeze-drying technology. The micro-nano composite stent was combined with the bone morphogenetic protein-2 (BMP-2) gene, so as to obtain the sol-gel micro-nano biphasic calcium BMP-2/BCP/CS/PAN/PLGA composite stent. Besides, the composite stent should be measured in terms of compressive strength, porosity, structure, and morphological features. The healthy female rhesus monkeys were taken as the research animals, and the iliac bone marrow was extracted by puncture. The mesenchymal stem cells (MSCs) were obtained by density gradient centrifugation, and their osteogenic differentiation ability was observed. The MSCs were cultured in vitro with BMP-2/BCP/CS/PAN/PLGA composite stent, methylthiazolyldiphenyl-tetrazolium bromide (MTT) was applied to detect cell adhesion and proliferation, and the alkaline phosphatase (ALP) activity was employed to analyze its osteogenic properties on stent materials. In addition, the expression of BMP-2 was detected by Western blot. The alveolar bone defect models were established and divided into group A (MSCs + BMP-2/BCP/CS/PAN/PLGA), group B (BMP-2/BCP/CS/PAN/PLGA), group C (BCP/CS/PAN/PLG), and group D (control group, reposition of gingival flap and suture) according to different implant materials. The changes of bone defect area in different groups were detected by gross examinations and X-ray, so that the new bone density was analyzed. The results showed that the BCP/CS/PAN/PLGA composite stent exhibited a porous structure combining multiple pores/small pores, with an average pore diameter (PD) of 400–500 µm, maximum compressive strength of 6.02 Mpa, and porosity of 86.82%. MSCs differentiated into osteoblasts under osteogenic induction conditioned medium, and the optical density (OD) of CS + MSCs/BMP-2/BCP/CS/PAN/PLGA cells was greater in contrast to that of MSCs/BMP-2/BCP/CS/PAN/PLGA cells on the 1st and 7th day of culture, showing a statistical difference (P < 0.05). The gross examination and X-ray of bone defect area in group A showed that its bone structure and density were very close to those of normal bone (all materials were absorbed, and newly formed bone cells were active); the CT value of alveolar bone in groups A, B, C, and D was 1,092.45± 15.87 g/cm3, 932.26± 16.75 g/cm3, 859.51 ±17.86 g/cm3, and 787.96± 16.54 g/cm3, respectively. There was no marked difference in CT values between group A and normal alveolar bone (P > 0.05), while the CT value of alveolar bone in group A was higher obviously than the value of groups C and D (P < 0.05). It indicated that the composite stent based on sol–gel micro-nano biphasic calcium BMP-2/BCP/CS/PAN/PLGA could promote the repair of oral alveolar bone defect and its osteogenesis, thereby providing a reference for the oral clinical treatment of periodontal bone defects.

Effects of DSPP Gene Mutations on Periodontal Tissues

Dentin sialophosphoprotein (DSPP) gene mutations cause autosomal dominantly inherited diseases. DSPP gene mutations lead to abnormal expression of DSPP, resulting in a series of histological, morphological, and clinical abnormalities. A large number of previous studies demonstrated that DSPP is a dentinal-specific protein, and DSPP gene mutations lead to dentin dysplasia and dentinogenesis imperfecta. Recent studies have found that DSPP is also expressed in bone, periodontal tissues, and salivary glands. DSPP is involved in the formation of the periodontium as well as tooth structures. DSPP deficient mice present furcation involvement, cementum, and alveolar bone defect. We speculate that similar periodontal damage may occur in patients with DSPP mutations. This article reviews the effects of DSPP gene mutations on periodontal status. However, almost all of the research is about animal study, there is no evidence that DSPP mutations cause periodontium defects in patients yet. We need to conduct systematic clinical studies on DSPP mutation families in the future to elucidate the effect of DSPP gene on human periodontium.

A Synthetic Biodegradable Polymer Membrane for Guided Bone Regeneration in Bone Defect

Guided bone regeneration (GBR) technique is most commonly used to treat alveolar bone defect. Polylactic acid (PLA) attracts much attention to utilize as a GBR membrane because it has relatively high mechanical strength and biodegradability. However, randomized controlled trials of PLA as a GBR membrane in animals were rare. The aim of this work is to observe the efficacy of polylactic acid membrane in guiding bone regeneration in Beagle canine alveolar bone defect restoration and to compare efficacy with the collagen membrane, providing an experimental basis for further clinical use of the polylactic acid membrane. The tests of physical and chemical properties showed that the PLA membrane has well mechanical strength to maintenance the space for the new bone, and has proper aperture for the attachment of osteoblasts. Through X-ray and histopathological examination of the different time points, the bone grafting material covered with PLA membrane can form similar mature bone compared to collagen membrane ones. Meanwhile, biodegradable speed of the PLA membrane was slower. Thus, this study showed that polylactic acid membrane as synthetic biodegradable polymer was reliably effective in guiding bone regeneration of alveolar bone defects, showed the favorable osteogenic capability and forecasts well applications in bone augmentation.

Leucocyte- and Platelet-Rich Fibrin Block: Its Use for the Treatment of a Large Cyst with Implant-Based Rehabilitation

The management of critical-size bone defects is still demanding. Recently, autologous platelet concentrates in combination with bone substitute have been applied and reported in a few studies. Our aim is to report the healing of a critical-size alveolar bone defect treated with a new bone regeneration technique by means of L-PRF and L-PRF blocks. A 45-year-old woman presented a large cystic lesion; the extraction of three teeth, a cyst removal procedure, and bone regeneration procedures with L-PRF and L-PRF blocks were planned. The L-PRF block was prepared by mixing a bone substitute with a piece of L-PRF membrane and liquid fibrinogen. Additionally, after bone healing an implant-based rehabilitation was optimally performed. On the basis of the positive results, in terms of bone healing and tissue regeneration in a large bone defect, the application of L-PRF and L-PRF blocks, in agreement with the scarce literature, is suggested as a feasible procedure in selected cases.

Alveolar bone defects in adults reporting for orthodontic treatment - A CBCT study

Identifying alveolar bony fenestration and dehiscence preceding orthodontic treatment, especially arch expansion, is needed. An unrevealed and undiagnosed buccal alveolar bone defect leads to treatment relapse and further loss of bony support. The aim of this study was to determine the extent of posterior alveolar bony dehiscence and fenestration in adults undergoing orthodontic treatment. A total of 20 subjects in the age range 18-35 years were selected for this study randomly and their CBCT records were retrieved from the Department of Orthodontics, Saveetha dental college. All statistical analysis was performed using SPSS. Chi-square test was used to determine the association of extent of fenestrations and dehiscence between males and females. Females presented with wider and extensive dehiscence defects than males (p=0.019, p<0.05). On the other hand, there was a statistically non-significant association of fenestration severity between males and females. (p=0.178, p>0.05) Within the limits of this study, it was observed that females presented with more severe bony alveolar dehiscence than males.