Combined Treatment with Low-Level Laser and rhBMP-2 Promotes Differentiation and Mineralization of Osteoblastic Cells under Hypoxic Stress

BACKGROUND: The aim of this study was to evaluate the combined effect of low-level laser treatment (LLLT) and recombinant human bone morphological protein-2 (rhBMP-2) applied to hypoxic-cultured MC3T3-E1 osteoblastic cells and to determine possible signaling pathways underlying differentiation and mineralization of osteoblasts under hypoxia. METHODS: MC3T3-E1 cells were cultured under 1% oxygen tension for 72 h. Cell cultures were divided into four groups: normoxia control, low-level laser (LLL) alone, rhBMP-2 combined with LLLT, and rhBMP-2 under hypoxia. Laser irradiation was applied at 0, 24, and 48 h. Cells were treated with rhBMP-2 at 50 ng/mL. Alkaline phosphatase activity was measured at 3, 7, and 14 days to evaluate osteoblastic differentiation. Cell mineralization was determined with Alizarin red S staining at 7 and 14 days. Western blot assays were performed to evaluate whether p38/protein kinase D (PKD) signaling was involved. RESULTS: The results indicate that LLLT and rhBMP-2 synergistically increased alkaline phosphatase (ALP) activity and mineralization. Western blot analyses showed that expression of type I collagen, runt-related transcription factor 2 (RUNX2), and Osterix (Osx), increased and expression of hypoxia-inducible factor 1-alpha (HIF-1α), decreased more in the LLLT and rhBMP-2 combined group than in the rhBMP-2 or LLL alone groups. Moreover, LLLT and rhBMP-2 stimulated p38 phosphorylation and rhBMP-2 and LLLT increased Prkd1 phosphorylation. CONCLUSION: Combined treatment with rhBMP-2 and LLL induced differentiation and mineralization of hypoxiccultured MC3T3-E1 osteoblasts by activating p38/PKD signaling in vitro.

Osseointegration of Magnesium-Incorporated Sand-Blasted Acid-Etched Implant in the Dog Mandible: Resonance Frequency Measurements and Histomorphometric Analysis

The aim of this pilot study was to investigate the bone responses of novel magnesium (Mg)–incorporated sand-blasted and acid-etched (SLA) titanium (Ti) implant in an experimental animal model. Novel Mg-incorporated SLA Ti implant was obtained via vacuum arc source ion implantation method and Mg-ions were implanted into the SLA implant surface. Control group consisted of two commercial implants; resorbable blasting media (RBM) and SLA. Twelve implants from each group were placed into the mandibles of 6 mongrel dogs. Experimental animals were divided into 2 groups of 3 animals, with 4 weeks and 8 weeks healing time points. Resonance frequency analysis was performed at the time of fixture installation, 1, 2, 4, and 8 weeks after installation. Bone to implant contact (BIC) measurements were assessed at the 4 and 8 weeks healing time points. The overall implant survival rate was 97.2%. The Mg-incorporated SLA Ti implants showed more rapid osseointegration than control group implants at follow-up periods of 4 weeks. Histomorphometric analysis showed a tendency for BIC% values of Mg-incorporated SLA Ti implant to be higher than that of other the implant groups. The results of this study suggest that Mg-incorporated SLA Ti implant may be effective in enhancing the bone responses by rapid osseointegration in early healing periods.

Clinical study on malignant melanoma in oral cavity

The prognosis of oral malignant melanoma is poor compared with cutaneous melanoma. It may be related to the difficulty of wide enough resection, the early hematogenous matastases, higher stage at initial diagnosis, and tendency to growth vertically. In the view of histological differences between oral mucosa and skin, it is impossible use Clark's and Breslow's classifications for prognosis. The great problem is that there is still no consensus on the treatment due to rarity. Because data collection from case reports is considered to be the best source of information and should be pooled to analyze key determinants of outcome, We analysed 6 cases of primary malignant melanoma of the oral cavity which were diagnosed and treated in Pusan National University Hospital on recent 7 years and reviewed the literatures. Immunohistochemical study on S 100 Protein, GP 100 (HMB-45) with biopsy was usable to confirm the melanoma. Three patients who were treated by surgery, chemotherapy are alive, but a patients who couldn't received benefit care surgically due to poor condition was died of distant metastasis, and two patients who refused to surgery are still alive. Neck dissection including wide excision is recommended if lymph node involvement is suspected. Additionally, adjuvant chemotherapy could be considered as supporting therapy for malignant melanoma.