[Two procedures for ridge preservation of molar extraction sites affected by severe bone defect due to advanced periodontitis]

CGF-HLC-I repaired the bone defect repair of the rabbits mandible through tight junction pathway

Background: The human-like collagen I (HLC-I) combined concentrated growth factors was used to construct CGF-HLC-I composite biomaterials to repair the critical bone defect disease model of rabbit mandible. This study aimed to research the repair mechanism of CGF-HLC-I/Bio-Oss in rabbit mandibular critical bone defect, to provide a new treatment direction for clinical bone defect repair.

Methods: The optimal concentration of HLC-I (0.75%) was selected in this study. Nine New Zealand white rabbits were randomly divided into 3 groups, normal control group, Bio-Gide/Bio-Oss and CGF-0.75%HLC-I/Bio-Oss group (n = 3, each group). CGF-0.75%HLC-I/Bio-Oss and Bio-Gide/Bio-Oss were implanted into rabbit mandibles, then X-ray, Micro-CT, HE and Masson staining, immunohistochemical staining and biomechanical testing were performed with the bone continuity or maturity at 4, 8 and 12 weeks after surgery. The repair mechanism was studied by bioinformatics experiments.

Results: As the material degraded, the rate of new bone formation in the CGF-0.75% HLC-I/Bio-Oss group was better than that the control group by micro-CT. The biomechanical test showed that the compressive strength and elastic modulus of the CGF-0.75%HLC-I/Bio-Oss group were higher than those of the control group. HE and Masson staining showed that the bone continuity or maturity of the CGF-0.75%HLC-I/Bio-Oss group was better than that of the control group. Immunohistochemical staining showed significantly higher bone morphogenetic protein 2 (BMP2) and Runt-related transcription factor 2 (RUNX2) in the CGF-0.75%HLC-I/Bio-Oss group than the control group at 8 and 12 W and the difference gradually decreased with time. There were 131 differentially expressed proteins (DEPs) in the Bio-Gide/Bio-Oss and CGF-0.75%HLC-I/Bio-Oss groups, containing 95 up-regulated proteins and 36 down-regulated proteins. KEGG database enrichment analysis showed actinin alpha 1 (ACTN1) and myosin heavy-Chain 9 (MYH9) are the main potential differential proteins related to osteogenesis, and they are enriched in the TJs pathway.

Conclusion: CGF-0.75%HLC-I/Bio-Oss materials are good biomaterials for bone regeneration which have strong osteoinductive activity. CGF-0.75%HLC-I/Bio-Oss materials can promote new bone formation, providing new ideas for the application of bone tissue engineering scaffold materials in oral clinics.

Buccal periosteal inversion (BUPI) for defect closure and keratinized gingiva width preservation after tooth extraction - technique modification

Introduction

Several techniques and methods have been proposed to cover alveolar bone after tooth extraction when soft tissue is lacking. Some authors recommend soft tissue flap techniques, and others advocate different types of materials for socket covering. In this article, the authors use a modified buccal inversion technique for adequate coverage of the alveolar ridge to ensure its preservation and to minimize soft tissue shrinkage and loss of keratinized gingiva after tooth extraction. This local mucogingival-periosteal plastic procedure was named by the authors the “Buccal Periosteal Inversion technique” or simply BUPI.

Materials and Methods

After extraction of a fractured, endodontically compromised lower right first molar, the BUPI technique was performed to cover the alveolus. After reflecting the two-sided full-thickness flap, the periosteum was split in the cranial direction. The inverted periosteum is used to provide tension-free defect closure of the postextractional defect. Detailed technique implementation and patient postoperative healing are presented here in detail.

Results

Postoperative evaluation at six weeks was presented with photos showing adequate surgical site healing, no signs of infection or dehiscence, and no crestal shift of the keratinized gingiva.

Conclusion

The buccal periosteal inversion (BUPI) technique is a modified technique that allows full socket coverage, avoiding a keratinized gingiva shift in the crestal direction using only the periosteum as a cover material. By inverting the buccal ridge periosteum alone from its normal position, the osteoclastic effect on the buccal bony wall will be eliminated, and this procedure abolishes the need for additional alveolar coverage materials.

[Biocompatibility and effect on bone formation of a native acellular porcine pericardium: Results of in vitro and in vivo]

OBJECTIVE

To examine the morphology and biocompatibility of a native acellular porcine pericardium (APP) in vitro and to evaluate its barrier function and effects on osteogenesis when used in guided bone regeneration (GBR) in vivo.

METHODS

First, the morphology of APP (BonanGen^Ⓡ) was detected using a scanning electron microscope (SEM). Next, for biocompatibility test, proliferation of human bone marrow mesenchymal stem cells (hBMSCs) were determined using cell counting kit-8 (CCK-8) after being seeded 1, 3 and 7 days. Meanwhile, the cells stained with phalloidine and 4, 6-diamidino-2-phenylindole (DAPI) were observed using a confocal laser scanning microscopy (CLSM) to view the morphology of cell adhesion and pattern of cell proliferation on day 5. A 3-Beagle dog model with 18 teeth extraction sockets was used for the further research in vivo. These sites were randomly treated by 3 patterns below: filled with Bio-Oss^Ⓡand coverd by APP membrane (APP group), filled with Bio-Oss^Ⓡand covered by Bio-Gide^Ⓡmembrane (BG group) and natural healing (blank group). Micro-CT and hematoxylin-eosin (HE) were performed after 4 and 12 weeks.

RESULTS

A bilayer and three-dimensional porous ultrastructure was identified for APP through SEM. In vitro, APP facilitated proliferation and adhesion of hBMSCs, especially after 7 days (P < 0.05). In vivo, for the analysis of the whole socket healing, no distinct difference of new bone ratio was found between all the three groups after 4 weeks (P>0.05), however significantly more new bone regeneration was detected in APP group and BG group in comparison to blank group after 12 weeks (P < 0.05). The radio of bone formation below the membrane was significantly higher in APP group and BG group than blank group after 4 and 12 weeks (P < 0.05), however, the difference between APP group and BG group was merely significant in 12 weeks (P < 0.05). Besides, less resorption of buccal crest after 4 weeks and 12 weeks was observed in APP group of a significant difference compared in blank group (P < 0.05). The resorption in BG group was slightly lower than blank group (P>0.05).

CONCLUSION

APP showed considerable biocompatibility and three-dimentional structure. Performing well as a barrier membrane in the dog alveolar ridge preservation model, APP significantly promoted bone regeneration below it and reduced buccal crest resorption. On the basis of this study, APP is a potential osteoconductive and osteoinductive biomaterial.