| 1. |
- Liljensten, E, et al.
(författare)
-
Hydroxyapatite granule/carrier composites promote new bone formation in cortical defects.
- 2000
-
Ingår i: Clinical implant dentistry and related research. - : Wiley. - 1523-0899 .- 1708-8208. ; 2:1, s. 50-9
-
Tidskriftsartikel (refereegranskat)abstract
- A great deal of interest has been focused on finding substitutes for autogenous bone grafts. Among the most interesting materials are different calcium phosphate compositions (e.g., hydroxyapatite [HA]), due to their biocompatible properties in hard and soft tissue.
|
|
| 2. |
- Jarmar, T., et al.
(författare)
-
Characterization of the surface properties of commercially available dental implants using scanning electron microscopy, focused ion beam, and high-resolution transmission electron microscopy
- 2008
-
Ingår i: Clinical Implant Dentistry and Related Research. - : Wiley. - 1523-0899 .- 1708-8208. ; 10:1, s. 11-22
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Since osseointegration of the respective implant is claimed by all manufacturing companies, it is obvious that not just one specific surface profile including the chemistry controls bone apposition. PURPOSE: The purpose was to identify and separate out a particular set of surface features of the implant surfaces that can contribute as factors in the osseointegration process. MATERIAL AND METHODS: The surface properties of several commercially available dental implants were extensively studied using profilometry, scanning electron microscopy, and transmission electron microscopy. Ultrathin sections prepared with focused ion beam microscopy (FIB) provided microstructural and chemical data which have not previously been communicated. The implants were the Nobel Biocare TiUnite (Nobel Biocare AB, Goteborg, Sweden), Nobel Biocare Steri-Oss HA-coated (Nobel Biocare AB, Yorba Linda, CA, USA), Astra-Tech OsseoSpeed (Astra Tech AB, Molndal, Sweden), Straumann SLA (Straumann AG, Waldenburg, Switzerland), and the Branemark Integration Original Fixture implant (Branemark Integration, Goteborg, Sweden). RESULTS: It was found that their surface properties had differences. The surfaces were covered with crystalline TiO(2) (both anatase and rutile), amorphous titanium oxide, phosphorus doped amorphous titanium oxide, fluorine, titanium hydride, and hydroxyapatite, respectively. CONCLUSION: This indicates that the provision of osseointegration is not exclusively linked to a particular set of surface features if the implant surface character is a major factor in that process. The studied methodology provides an effective tool to also analyze the interface between implant and surrounding bone. This would be a natural next step in understanding the ultrastructure of the interface between bone and implants.
|
|
| 3. |
- Malmström, Johan, 1975, et al.
(författare)
-
Bone response to free form-fabricated hydroxyapatite and zirconia scaffolds : A histological study in the human maxilla
- 2009
-
Ingår i: Clinical Oral Implants Research. - : John Wiley & Sons. - 0905-7161 .- 1600-0501. ; 20:4, s. 379-385
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives: Synthetic and biological materials are increasingly used to provide temporary or permanent scaffolds for bone regeneration. This study evaluated the effect of material chemistry and microporosity on bone ingrowth and osseointegration of zirconia (ZrO2) and hydroxyapatite (HA) scaffolds in the human maxilla.Material and methods: Twelve patients subjected to dental implant placement were enrolled in the study. Scaffolds of ZrO 2 and HA were placed in the maxilla of each subject, using a randomization protocol. After 3 months of healing, biopsies were harvested comprising the scaffolds and surrounding bone tissue. The biopsies were processed for histological evaluation and morphometric analysis (bone ingrowth and bone-to-scaffold contact).Results: Healing was uneventful in all cases. All scaffolds demonstrated a measurable bone response using light microscopy and scanning electron microscopy. Microporous HA scaffolds revealed four times larger bone ingrowth and seven times larger bone contact as compared with ZrO2 scaffolds.Conclusion: The results show that chemistry and microporosity of HA promote bone ingrowth and bone contact of ceramic scaffolds in human maxilla.
|
|
| 4. |
- Wermelin, Karin, 1977-, et al.
(författare)
-
Stainless steel screws coated with bisphosphonates gave stronger fixation and more surrounding bone. Histomorphometry in rats.
- 2008
-
Ingår i: Bone. - : Elsevier BV. - 8756-3282 .- 1873-2763. ; 42:2, s. 365-71
-
Tidskriftsartikel (refereegranskat)abstract
- Coating of stainless steel screws with bisphosphonate in a fibrinogen matrix leads to an enhancement of the pullout strength 2 weeks after insertion in rat tibiae. This effect then increases over time until at least 8 weeks. The pullout force reflects the mechanical properties of the bone within the threads, which acts as a screw nut. The aim of the present study was to find descriptive and morphometric histological correlates to the increased pullout strength. Because the bisphosphonates are applied via the implant surface, we also measured bone to implant contact and how far away from the surface any effects could be seen. Stainless steel screws underwent one of three treatments: uncoated control, controls coated with a layer of cross-linked fibrinogen, or screws further modified with bisphosphonates covalently linked and physically adsorbed to the fibrinogen layer. At 1 (n=33) and 8 (n=27) weeks, bone to implant contact and bone area density in the threads were measured, as well as bone area density at 250 and 500 microm from the outer edge of the threads. Additionally, removal torque for each screw treatment was measured at 2 weeks (n=28). At 8 weeks, the part of the bisphosphonate screw that was located in the marrow cavity had become surrounded with bone, whereas there was almost no bone surrounding the controls. The bone area density in the threads along the entire bisphosphonate screw was increased by 40% compared with uncoated controls, and at 250 microm distance it was more than doubled. At 1 week, coated screws had less implant-bone contact, but at 8 weeks there was no difference between uncoated and bisphosphonate-coated screws. The bisphosphonate screws had 50% increased removal torque at 2 weeks compared to uncoated screws. Howship's lacunae and osteoclasts were found near the screws with bisphosphonates at 8 weeks, suggesting that some bone remodeling took place near the implant, in spite of the presence of bisphosphonates.
|
|
| 5. |
|
|
| 6. |
- Adolfsson, E., et al.
(författare)
-
Evaluation of bone ingrowth in Free Form Fabricated scaffolds
- 2008
-
Ingår i: Key Engineering Materials. - 1662-9795.
-
Tidskriftsartikel (refereegranskat)abstract
- Colloidal processing was used to cast zirconia and hydroxyapatite materials. The cast materials reached densities around 99% when sintered at 1500°C and 1200°C respectively. By controlling the colloidal process the sintered density of hydroxyapatite was also reduced to around 80% when the same sintering condition was used. The casting process was combined with free form fabrication to prepare designed scaffolds with identical macroporosity. These scaffolds were used to evaluate the early bone tissue response in rabbit femur. After six weeks of implantation the bone area in scaffolds of zirconia and hydroxyapatite were compared. In scaffolds of hydroxyapatite the bone area was roughly three times larger compared to corresponding scaffolds of zirconia. When the scaffolds of hydroxyapatite also contained an open microporosity of around 20% the amount of bone was even more pronounced. The results showed the importance of the material composition and the microstructure on the bone regenerating performance of scaffolds.
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
- Almqvist, Sofia, 1980, et al.
(författare)
-
Ex Vivo Study of the Angiogenic Effect of the Extracellular Matrix Protein Amelogenin
- 2008
-
Ingår i: Abstract, The 9th New Jersey Symposium on Biomaterials Science and regenerative medicine, New Jersey, USA. ; 29-31 October
-
Konferensbidrag (refereegranskat)abstract
- Introduction: Angiogenesis is crucial for wound healing but is often impaired in chronic wounds. The process is dependent on the interaction of endothelial cells and the extracellular matrix (ECM), which is mediated by cell membrane integrins. Amelogenin is an extracellular matrix protein that has been reported to promote formation of granulation tissue and repair of chronic venous leg ulcers and elevate the pro-angiogenic vascular endothelial growth factor in dermal fibroblasts.1-3 This study investigated the effect of amelogenin on angiogenesis in an ex vivo sprouting assay and related the findings to the cell surface integrin expression. Methods: Chick aortic arch assay: Transverse sections of the aortic arch of 13-day-old chick embryos were attached and sealed with Matrigel to the bottom of a 48-well plate. Amelogenin was added (0.01 mg/ml, 0.1 mg/ml and 1 mg/ml) in serum-free endothelial basal growth medium. Porcine serum albumin was used as control for unspecific protein effects. The plates were incubated at 37°C and sprouting was assessed at 24 h and 48 h by microscopy and scored from 0 to 6 (arbitrary units) by a blinded observer. Integrin assay: Human dermal microvascular endothelial cells (Promocell) were seeded in complete cell growth medium alone or supplemented with 0.1 mg/ml, 1 mg/ml amelogenin or 20 µg/ml fibronectin. After 24 h incubation in 37°C, cells were gently harvested with the non-enzymatic buffer (EDTA/PBS). Upregulated integrins/subunits were detected by an Integrin-Mediated Cell Adhesion Array (Chemicon), where cells expressing specific integrins (α1, α2, α3, α4, α5, αv, β1, β2, β3, β4, β6, αvβ3, αvβ5 and α5b1) are captured by surface immobilized antibodies. Results and Discussion: Amelogenin at 0.1 mg/ml significantly (p = 0.001) increased micro-vessel outgrowth by 76 % from the explants compared with control explants after 48 h of incubation. No significant sprouting was observed with the non-specific protein control porcine serum albumin or medium only. The preliminary data from the integrin assay show that amelogenin at 0.1 mg/ml also displays a broad up-regulation of several integrins/subunits. This result is comparable to the positive control, fibronectin, an ECM protein involved in all phases of tissue repair. Taken together, the present observations suggest that the angiogenic effects might be explained by the cell binding properties of amelogenin. Conclusions: Amelogenin stimulated micro-vessel outgrowth in the chick aortic arch assay possibly through up-regulation of several integrins and subunits important for cell interaction with the ECM. The pro-angiogenic property may contribute to the beneficial effects reported after treatment of chronic ulcers with the novel ECM therapy containing amelogenin. Acknowledgements: The studies were supported by the Swedish Research Council (grant K2006-73X-09495-16-3), Mölnlycke Health Care AB, the VINNOVA VinnVäxt Program Biomedical Development in Western Sweden, and the Danish Medical Research Council (22-02-0287). References: 1. Mirastschijski U. et al. (2004) Wound Repair Regen. 12:100-108. 2. Vowden P. et al. (2006) Wound Repair Regen. 14:240-248. 3. Ågren M. S. et al. (2007) Wound Repair Regen. 15:A139.
|
|
