Reconstruction of bone defects represents a serious issue for orthopaedic and maxillofacial surgeons, especially in extensive bone loss. Adipose-derived mesenchymal stem cells (ADScs) with tri-calcium phosphates (tcp) are widely used for bone regeneration facilitating the formation of bone extracellular matrix to promote reparative osteogenesis. The present study assessed the potential of cell-scaffold constructs for the regeneration of extensive mandibular bone defects in a minipig model. Sixteen skeletally mature miniature pigs were divided into two groups: Control group and scaffolds seeded with osteogenic differentiated pADSCs (n = 8/group). TCP-PLGA scaffolds with or without cells were integrated in the mandibular critical size defects and fixed by titanium osteosynthesis plates. After 12 weeks, ADSCs seeded scaffolds (n = 7) demonstrated significantly higher bone volume (34.8% ± 4.80%) than scaffolds implanted without cells (n = 6, 22.4% ± 9.85%) in the micro-CT (p < 0.05). Moreover, an increased amount of osteocalcin deposition was found in the test group in comparison to the control group (27.98 ± 2.81% vs 17.10 ± 3.57%, p < 0.001). In conclusion, ADSCs seeding on ceramic/polymer scaffolds improves bone regeneration in large mandibular defects. However, further improvement with regard to the osteogenic capacity is necessary to transfer this concept into clinical use. Maxillofacial bone defects, which occur due to trauma, craniofacial deformities, tumour or infection can lead to facial deformities and severe maxillofacial dysfunctions provoking a dramatic decrease in the quality of life of the patients 1,2. The reconstruction of large bone defects poses many challenges in oral and maxillofacial surgery. Although autologous bone grafts are considered the gold standard in bone defect repair, there are some concerns related to the limited supply and donor site morbidity 3. Several alternatives as allografts, xenografts or synthetic bone substitutes have been brought by researchers and clinicians to restore the function and architecture of the defective bone but still cannot solve the problem due to various limitations. The search of new treatment alternatives has emerged enormously in the past few

Polyelectrolyte multilayers (PEMs) from poly(allylamine hydorchloride) (PAH) and sodium poly(styrenesulfonate) (PSS) are prepared at different conditions and investigated in air with X-ray reflectivity. Beyond a critical temperature the thickness per deposited polycation/polyanion bilayer and the surface roughness increase on heating the preparation solution. With increasing NaCl concentration that critical temperature decreases (40°C at 1 M down to 15°C at 3 M). Below the critical temperature the film thickness shows no dependence on the deposition temperature. Also, for ion concentrations up to 3 M, the surface roughness is constant (1-1.5 nm). However, for films prepared at 4 M the roughness increases on cooling, which is attributed to approaching the UCST at very high salt concentrations. AFM measurements in air show that the increased surface roughness is due to a random pattern of holes, whose separation is characterized by a single length scale, a behavior typical for spinodal decomposition. The length scale exceeds 100 nm and depends on the preparation conditions. Grains consisting of polyelectrolyte complexes with a size below 30 nm do not influence the surface roughness. It is suggested that the decomposition occurs during film drying since the film morphology in water shows no decomposition pattern, even when the film is cooled.

Smooth surfaces are becoming increasingly important in many industries, such as medical, chemical or food. In some industrial areas, the mechanical treatment of surfaces (grinding and polishing) does not fulfil desired specifications. Non-abrasive methods (chemical and electrochemical) have the advantage that even complex geometries and free-form shapes can be polished. In the context of this paper, electrochemical surface treatment is considered in more detail. Both electro polishing, which is state of the art, and the novel electrolytic plasma polishing (EPP) process are presented. This paper focusses on the electrolytic plasma polishing because it has many advantages compared to the process of electro polishing. The theoretical operation of the electrolytic plasma polishing is shown. A prototype system for plasma polishing of internal surfaces of pipes was installed and a polishing head was developed. Several parameters are investigated, such as the width of the adjustable polishing head gap and different velocities v or different applied potential differences U, and first results of the average surface roughness Sa as function of the various parameters were evaluated. It can be seen that a stable polishing process can be achieved at the highest potential difference of 320 V and that the average surface roughness Sa reaches a range from 0.065 to 0.090 µm. At the same time, it has been shown that with increasing potential difference, the average surface roughness becomes independent of the width of the adjustable polishing head gap.

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