Impact of Hyperbaric Oxygen on the Healing of Teeth Extraction Sockets and Alveolar Ridge Preservation.

OBJECTIVES: The purpose of this study was to investigate the role of hyperbaric oxygen (HBO) in the healing of teeth extraction sockets and in alveolar ridge preservation. This may provide an experimental basis for the widespread application of HBO in oral implantation. METHODS: A total of 32 beagle dogs were included in the study and randomly divided equally between an HBO group treated with hyperbaric oxygen (100% O2, 2.4 atm, 90 min/day, 5 times/week, 6 weeks) and a normobaric oxygen (NBO) group treated with normal air in the same chamber. The lateral incisors of the maxillary and mandible of each dog were extracted, and the right upper and lower incisor extraction sockets (A2C2) were allowed to heal naturally, while left upper and lower incisor sockets (B2D2) received implants of a commercial bone substitute. At 4 and 8 weeks after surgery, clinical observation, cone-beam computerized tomography (CBCT), histomorphology observation, and expression levels of vascular endothelial growth factor (VEGF) and bone morphogenetic protein 2 (BMP-2) were analyzed to evaluate new bone formation, mineralization, and reconstruction. RESULTS: After 4 and 8 weeks, bone width and lip contour of the extraction socket in the NBO group were significantly reduced and collapsed in comparison with the HBO group. CBCT showed that the difference in vertical height between the alveolar crest of the labial tongue and palatal side of the extraction sockets was smaller in the HBO than NBO group. There was a significant difference in new bone formation (P < 0.05) and bone mineral density (P < 0.05) between the HBO and NBO groups, and the HBO group showed significantly greater new bone and bone reconstruction based on histology. Furthermore, the expression levels of VEGF and BMP-2 were higher in the HBO group. CONCLUSION: HBO reduced bone resorption and promoted early bone formation, bone mineralization, and reconstruction in the extraction sockets. HBO greatly reduced the healing time of the extraction sockets and promoted alveolar ridge preservation, thus showing promise for the clinic.

Impact of Hyperbaric Oxygen on Tissue Healing around Dental Implants in Beagles.

BACKGROUND The impact of hyperbaric oxygen (HBO) on the healing of soft tissues around dental implants was studied in a beagle model. MATERIAL AND METHODS Beagle dogs were randomized to receive implants, followed by postoperative HBO therapy or not (n=10 per group). On postoperative days 3, 7, and 14, tissue specimens were paraffin-embedded and analyzed by hematoxylin-eosin and Masson staining, as well as immunohistochemistry against CD31. RESULTS Scores for inflammation pathology based on hematoxylin-eosin staining and mean optical density of collagen fibers were significantly different between the HBO and control groups on postoperative days 3 and 7 (P<0.05), but not on day 14. Mean optical density due to anti-CD31 staining was significantly higher in the HBO group on postoperative days 3, 7, and 14 (P<0.05). CONCLUSIONS These results suggest that HBO may promote early osteogenesis and soft tissue healing after implantation.

ADCY6 is a potential prognostic biomarker and suppresses OTSCC progression via Hippo signaling pathway.

Oral tongue squamous cell carcinoma (OTSCC) is a malignant tumor. Recently, studies have found that adenylate cyclase 6 (ADCY6) plays a pivotal role in many lethal tumors formation processes. The role of ADCY6 in OTSCC remains unknown. The expression of ADCY6 in OTSCC tissue samples was detected. The clinical significance of ADCY6 in OTSCC was analyzed by statistical methods. OTSCC cell lines were selected to analyze the biological function of ADCY6. Meanwhile, the effect of ADCY6 on the growth of OTSCC in vivo was explored using subcutaneous tumorigenesis assay. WB assay was used to detect the underlying signaling pathway. Cell function recovery test used to investigate the mechanism of ADCY6-promoting OTSCC malignant biological behavior via Hippo signaling pathway. We report that ADCY6 was obviously downregulated in OTSCC tissue samples and cell lines. Importantly, lower expression of ADCY6 indicates a poorer prognosis in patients with OTSCC, and its expression is significantly correlated with TNM stage and tumor size. Functionally, forced expression of ADCY6 can significantly inhibit the proliferation, migration, invasion, and promote apoptosis of OTSCC cells. Mechanistically, we demonstrated that ADCY6 upregulation impaired Hippo signaling pathway to reduce the malignant biological behavior of OTSCC. Generally, our findings suggest that ADCY6 suppressed Hippo signaling pathway to regulate malignant biological behavior in OTSCC, which provide new cues for further exploring the mechanism of occurrence and development of OTSCC.

Development and characterization of a mouse floxed Bmp2 osteoblast cell line that retains osteoblast genotype and phenotype.

Bone morphogenetic protein 2 (Bmp2) is essential for osteoblast differentiation and osteogenesis. Generation of floxed Bmp2 osteoblast cell lines is a valuable tool for studying the effects of Bmp2 on osteoblast differentiation and its signaling pathways during skeletal metabolism. Due to relatively limited sources of primary osteoblasts, we have developed cell lines that serve as good surrogate models for the study of osteoblast cell differentiation and bone mineralization. In this study, we established and characterized immortalized mouse floxed Bmp2 osteoblast cell lines. Primary mouse floxed Bmp2 osteoblasts were transfected with pSV3-neo and clonally selected. These transfected cells were verified by PCR and immunohistochemistry. To determine the genotype and phenotype of the immortalized cells, cell morphology, proliferation, differentiation and mineralization were analyzed. Also, expression of osteoblast-related gene markers including Runx2, Osx, ATF4, Dlx3, bone sialoprotein, dentin matrix protein 1, osteonectin, osteocalcin and osteopontin were examined by quantitative RT-PCR and immunohistochemistry. These results showed that immortalized floxed Bmp2 osteoblasts had a higher proliferation rate but preserved their genotypic and phenotypic characteristics similar to the primary cells. Thus, we, for the first time, describe the development of immortalized mouse floxed Bmp2 osteoblast cell lines and present a useful model to study osteoblast biology mediated by BMP2 and its downstream signaling transduction pathways.

Immortalized mouse floxed Bmp2 dental papilla mesenchymal cell lines preserve odontoblastic phenotype and respond to BMP2.

Bone morphogenetic protein 2 (Bmp2) is essential for odontogensis and dentin mineralization. Generation of floxed Bmp2 dental mesenchymal cell lines is a valuable application for studying the effects of Bmp2 on dental mesenchymal cell differentiation and its signaling pathways during dentinogenesis. Limitation of the primary culture of dental mesenchymal cells has led to the development of cell lines that serve as good surrogate models for the study of dental mesenchymal cell differentiation into odontoblasts and mineralization. In this study, we established and characterized immortalized mouse floxed Bmp2 dental papilla mesenchymal cell lines, which were isolated from 1st mouse mandibular molars at postnatal day 1 and immortalized with pSV40 and clonally selected. These transfected cell lines were characterized by RT-PCR, immunohistochemistry, and analyzed for alkaline phosphatase activity and mineralization nodule formation. One of these immortalized cell lines, iBmp2-dp, displayed a higher proliferation rate, but retained the genotypic and phenotypic characteristics similar to primary cells as determined by expression of tooth-specific markers as well as demonstrated the ability to differentiate and form mineralized nodules. In addition, iBmp2-dp cells were inducible and responded to BMP2 stimulation. Thus, we for the first time described the establishment of an immortalized mouse floxed Bmp2 dental papilla mesenchyma cell line that might be used for studying the mechanisms of dental cell differentiation and dentin mineralization mediated by Bmp2 and other growth factor signaling pathways.

Multilayered pore-closed PLGA microsphere delivering OGP and BMP-2 in sequential release patterns for the facilitation of BMSCs osteogenic differentiation.

Bone tissue regeneration may be more effectively administrated by controlled release of multiple biofactors, given that bone healing comprises a cascade of biological events controlled by numerous cytokines and growth factors (GFs). Here, we propose a novel microcarrier with the capability to sequentially deliver dual biofactors for better controlling the bone regeneration process. First, osteogenic growth peptide (OGP) was incorporated in porous poly(lactic-co-glycolic) acid (PLGA) microspheres by a simple solution dipping method and subsequent pore-closing treatment. Then, a multilayered polyelectrolyte coating ((HA-CS)2 -Hep-BMP-2-Hep-(CS-HA)2 ) was prepared on the surface of such OGP-loaded pore-closed PLGA microspheres by layer-by-layer assembly. Results showed that the OGP release was minimal (<17.1%) in the first 15 days but accelerated remarkably thereafter, while at least 60.3% of the bone morphogenetic protein-2 (BMP-2) load was released in the first 15 days and only very slow release was observed subsequently. Further in vitro cell experiments showed that the dual-biomolecule-loaded microspheres elicited more cells with extremely elongated cellular morphology, much higher alkaline phosphatase level and upregulated expression of osteocalcin. Such a dual loading of OGP and BMP-2 had a more positive impact on bone marrow mesenchymal stem cells proliferation and osteogenic differentiation compared with either OGP or BMP-2 alone, suggesting potential synergistic benefit of the sequential release of multiple peptide-based biofactors in a coordinated manner. Overall, this dual delivery system may provide a therapeutic strategy sequentially targeting multiple events (or mechanisms) during bone healing, which is believed to benefit the regenerative repair of bone defects. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 95-105, 2018.

Enhanced osteogenesis of multilayered pore-closed microsphere-immobilized hydroxyapatite scaffold via sequential delivery of osteogenic growth peptide and BMP-2.

Since many complex physiological processes are controlled by multiple biomolecules, comprehensive regulation of bone tissue regeneration may be more effectively achieved by administering more than one type of biofactor. Thus, we propose a novel bone tissue engineering scaffold incorporating a multiple peptide-based drug delivery vehicle for accelerated bone regeneration. Pore-closed poly(lactic-co-glycolic acid) (PLGA) microspheres with a surface structure of multilayer polyelectrolytes ((Ha-Cs)2-Hep-BMP-2-Hep-(Cs-Ha)2) were prepared as multi-barrier microcarriers for osteogenic growth peptide (OGP). In addition, BMP-2 loading was achieved via a pore-closing process and layer-by-layer (LbL) assembly technique, followed by immobilization on the surface of a highly interconnected porous hydroxyapatite (HA) scaffold. On the basis of such a construction, sequential delivery of OGP and BMP-2 occurred in a coordinated manner through an orchestrated sequence of spatial changes, targeting different bone healing stages. The in vitro studies showed that OGP release was minimal (<11.7%) in the first 15 d but accelerated remarkably thereafter, while at least 56.3% of BMP-2 payload was released at this time and subsequent release was only marginal. In addition, scaffolds carrying dual-biofactor exhibited a stronger ability to induce bone marrow mesenchymal stem cell (BMSC) differentiation toward osteoblasts than those incorporating OGP or BMP-2 alone and factor-free scaffolds in terms of alkaline phosphatase (ALP) activity and osteogenic gene and protein (Runx2, COL I, and OCN) expression. The results of in vitro cell culturing demonstrated the roles of BMP-2 in osteogenic differentiation early as well as the effect of OGP on accelerated proliferation and maturation of osteoblast precursors at a later stage. Further in vivo osteogenesis studies also revealed that the dual biofactor-loaded scaffold manifested the best repair efficacy due to a potential synergistic effect of BMP-2 and OGP. Collectively, our findings suggested that such a dual delivery system may provide a therapeutic strategy sequentially targeting multiple events or mechanisms during bone healing and was proved to be a promising therapeutic scaffold for future use in bone tissue regeneration.

[Clinical study on the abutment periodontal condition with extracoronal attachment denture].

OBJECTIVE: To evaluate the abutment periodontium condition after restored with the distal-extension extracoronal attachment dentures. METHODS: 20 mandibular distal-extension cases were followed up, to measure the gingival index (GI) and plaque index (PLI) of the distant-abutments before restored with attachment dentures and after restored for one month, six months and one year; to compare the length of distant alveolar bone before restored with that after restored one year by taking digital stomatology tomogram photos. RESULTS: There were not significantly different in the PLI of distant-abutment between before repaired and after repaired one month, six months, one year (P > 0.05). There were not significantly different in the GI of distant-abutment between before repaired and after repaired one month, six months (P > 0.05), but the GI of distant-abutment after repaired one year was significantly higher than that before repaired (P < 0.05). There were no significant differences on the length of distant alveolar bone in distant-abutment before repaired and after repaired one year(P > 0.05). CONCLUSION: It is important to protect the periodontal health of the abutment when restored with distal-extension extracoronal attachment dentures. It is necessary to examine periodically after restored in order to keep the periodontal health of the abutment.