Effects of rhBMP-2/7 Heterodimer and RADA16 Hydrogel Scaffold on Bone Formation During Rabbit Mandibular Distraction.

PURPOSE: The effects of a recombinant human bone morphogenetic protein-2/7 (rhBMP-2/7) heterodimer and a RADA16 (Ac-RADARADARADARADA-CONH2) hydrogel scaffold on bone formation during distraction osteogenesis were evaluated. MATERIALS AND METHODS: Forty New Zealand white rabbits, which underwent mandibular lengthening, were randomly divided into 5 groups. One group served as the control group. The others received 2 µg of rhBMP-2 homodimer, 2 µg of rhBMP-2/7 heterodimer, 100 µL of RADA16, or 100 µL of RADA16 plus 2 µg of rhBMP-2/7 heterodimer in the mandibular distraction gap at the beginning of distraction. Fluorine-18-labeled fluoride positron emission tomography was used to assess osteogenesis both after distraction and at the end of consolidation. Dual-energy x-ray absorptiometry (DEXA) examination and bone histologic findings were also evaluated. RESULTS: At the end of distraction, the radioactivity concentration in the distracted area was significantly greater in the RADA16 plus rhBMP-2/7 heterodimer group than in the other groups (P < .01). The differences among the other 4 groups were also statistically significant in the following order: rhBMP-2/7 heterodimer group greater than the rhBMP-2 homodimer group, which was greater than the RADA16 group (or control group; P < .05). However, the radioactivity concentration of the RADA16 group was slightly greater than that of the control group with a nonsignificant difference (P > .05). By the end of consolidation, the activity in the control group, RADA16 group, rhBMP-2 homodimer group, and rhBMP-2/7 heterodimer group had significantly diminished (P < .05). However, the activity in the RADA16 plus rhBMP-2/7 heterodimer group remained at the same level (P > .05). The DEXA results and bone histologic findings indicated that more callus regeneration was noted in the RADA16 plus rhBMP-2/7 heterodimer group than in any other group. CONCLUSIONS: The use of rhBMP-2/7 heterodimer and RADA16 hydrogel scaffold significantly promoted mandibular distraction osteogenesis.

Effect of heat treatment on H2O2/HCl etched pure titanium dental implant: an in vitro study.

BACKGROUND: Surface chemistry of dental implant plays an important role in osseointegration. Heat treatment might alter surface chemistry and result in different biological response. The aim of this study was to investigate the roles of heat treatment of H2O2/HCl-treated Ti implants in cell attachment, proliferation and osteoblastic differentiation. MATERIAL/METHODS: Sandblasted, dual acid-etched and H2O2/HCl heat-treated discs were set as the control group and sandblasted, dual acid-etched H2O2/HCl-treated discs were the test group. Both groups' discs were sent for surface characterization. MC3T3-E1 cells were seeded on these 2 groups' discs for 3 hours to 14 days, and then cell attachment, cell proliferation and cell differentiation were evaluated. RESULTS: Scanning electron microscope analysis revealed that the titanium discs in the 2 groups shared the same surface topography, while x-ray diffraction examination showed an anatase layer in the control group and titanium hydride diffractions in the test group. The cell attachment of the test group was equivalent to that of the control group. Cell proliferation was slightly stimulated at all time points in the control group, but the alkaline phosphatase (ALP) activity and osteocalcin (OC) production increased significantly in the test group compared with those in the control group at every time point investigated (p<0.05 or p<0.01). Moreover, the osteoblastic differentiation-related genes AKP-2, osteopontin (OPN) and OC were greatly up-regulated in the test group (p<0.05 or p<0.01). CONCLUSIONS: The results implied that surface chemistry played an important role in cell response, and H2O2/HCl etched titanium surface without subsequent heat treatment might improve osseointegration response.

Enhanced attachment, proliferation, and differentiation of human gingival fibroblasts on titanium surface modified with biomolecules.

Surface modification of dental implants with biomolecules is of particularly interest recently. To mimic the structure and function of native extracellular matrix (ECM), a derivative of hyaluronic acid (HA), HA-GRGDSP, was synthesized, Arg-Gly-Asp (RGD)-containing collagen (Col)/HA multilayer polyelectrolyte films (MPFs) coating was fabricated on titanium (Ti) through alternate deposition of Col and HA-GRGDSP with 4.5 assembly cycles; moreover, bioactive molecule, basic fibroblast growth factor (bFGF), was also incorporated into such coating. This coating was then carefully characterized using scanning electronic microscope (SEM) and scanning force microscopy (SFM); bFGF release from the coating was also evaluated. (Col + bFGF)/HA-RGD coating was successfully deposited on Ti surface, and about 300 pg of bFGF could be slowly released from this coating for a week. This coating significantly promoted the initial cell attachment of human gingival fibroblasts (HGFs) compared with other groups (p < 0.05), and HGFs adhered and spread better on this coating than other groups (p < 0.05). Regarding cell proliferation and differentiation of HGFs, they were greatly stimulated when cultured on this coating (p < 0.05). These results indicated that surface modification of Ti using biomolecules might improve the sealing between the neck section of a dental implant and the soft tissue.

H2O2/HCl and heat-treated Ti-6Al-4V stimulates pre-osteoblast proliferation and differentiation.

The purpose of the present study was to evaluate the bioactivity of chemical treatment of titanium alloy (Ti-6Al-4V) in vitro. Smooth-surface discs of Ti-6Al-4V were used in this study. Sandblasted, dual acid-etched and H(2)O(2)/HCl heat-treated discs were set as test group, and sandblasted, dual acid-etched discs as control group. SEM and XRD analysis revealed a porous anatase gel layer on rough surface in the test group and a rough surface in the control group. Mouse pre-osteoblasts (MC3T3-E1 cells) were cultured on these 2 group discs, and then cell proliferation and differentiation were examined 4 days, 7 days, and 14 days after cell seeding. Cell proliferation was greatly stimulated at all time points when cultured in test group (P < .05). The alkaline phosphatase (ALP) activity and osteocalcin (OC) production were much higher in the test group compared with the control group at every time point investigated (P < .05). Furthermore, in the test group, the expressions of alkaline phosphatase-2, osteocalcin, and collagen type I alpha 1 mRNAs were significantly up-regulated as compared with those in the control group (P < .05 or P < .01). The results suggested that H(2)O(2)/HCl and heat-treatment might facilitate better integration of Ti-6Al-4V implants with bone.