Acetyl tri-n-butyl citrate (ATBC) and poly-(ethyleneglycol)s (PEGs) with different molecular weights (from 400 to 10000) were used in this study to plasticize poly(L-lactic acid) (PLA). The thermal and mechanical properties of the plasticized polymer are reported. Both ATBC and PEG are effective in lowering the glass transition (T g ) of PLA up to a given concentration, where the plasticizer reaches its solubility limit in the polymer (50 wt % in the case of ATBC; 15-30 wt %, depending on molecular weight, in the case of PEG). The range of applicability of PEGs as PLA plasticizers is given in terms of PEG molecular weight and concentration. The mechanical properties of plasticized PLA change with increasing plasticizer concentration. In all PLA/plasticizer systems investigated, when the blend T g approaches room temperature, a stepwise change in the mechanical properties of the system is observed. The elongation at break drastically increases, whereas tensile strength and modulus decrease. This behavior occurs at a plasticizer concentration that depends on the T g -depressing efficiency of the plasticizer.

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After tooth extraction, the immediate wound treatment by implanting an exact copy of the root could prevent alveolar bone atrophy. The implant should have an interconnected porosity in order to promote tissue in-growth. This communication reports a novel method to realize such net-shaped porous scaffolds fabricated within a few minutes. Porosity and micro-architecture are evaluated by Hg-porosimetry and by image analysis of electron and light microscopy as well as by computed micro-tomography. The total porosity of the scaffold corresponds to (63 +/- 3)%, mainly related to open interconnected porosity. Micro-tomography, as a noninvasive 3D method, is best suited to uncover pores of about 100 microm, a diameter especially important for tissue in-growth. The differentiation between open and closed porosity, however, depends on the method chosen. This effect is attributed to the spherical pores with an orifice only detected in the 3D analysis. Consequently, the closed porosity is overestimated by 8% evaluating 2D images. Finally, the mean pore diameter is found to be 106 and 100 microm for 2D and 3D analysis, respectively. Although the porosity of the scaffold needs to be further optimized for clinical applications, the procedure proposed is a promising route in manufacturing open porous implants without the use of any organic solvent.

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