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Abstract

Authors studied two degradable and resorbable polymers derived from lactic acid: poly-L-Lactic acid (PLLA), with a relatively long time of degradation (longer than 6 months, PL10 Purac NL); poly-DL-Lactic acid (PDLLA), with a relatively short time of degradation (shorter than 6 months, PDL Purac NL). The animal species was the young adult New Zealand White rabbit. The in-vivo study was performed by implantation of small cylinders of 10 x 3 mm in size (length x diameter) in the distal metaepiphysis of the femur; 34 cylinders have been implanted. Retrievals of PLLA specimens took place at 3, 6, 9, 12 and 24 months; for PDLLA specimens at 1, 2, 4 months. Polarized light microscopy of undecalcified tissue sections was performed. The analysis for PLLA and PDLLA has shown a favorable response of bone tissue: alterations in the bone repair, growth and remodeling have not been observed. PLLA is persistent at the times studied; there is never a tight apposition between bone and PLLA implant and an intervening fibrous layer has often been observed. PDLLA is not persistent at the times studied and it degrades quite fast; bone repair of the empty implantation's hole occurs by bony growth from the endosteal trabeculae. The newly formed bone covers the hole's walls with an elongation parallel to them. For both polymers, whether the degradation is fast or slow, the material's substitution by newly formed bone never starts from the walls of the implantation hole. Only after the complete disappearance of the polymeric material newly formed bone begins to fill the hole.

Anatomy into Interior Lamellar Assembly in Nuclei-Dependent Diversified Morphologies of Poly(l-lactic acid)

“…All those properties are highly correlated to the crystallization behavior of the polyester. In addition to mechanical and physical properties, biomedical compatibility with living cells is one of the main concerns for PLLA to be suited for intended purposes. , Blends of PLLA with other polymers have been intensively investigated for miscibility and phase behavior, such as poly­( l -lactic acid) (PLLA)/poly­( d -lactic acid) (PDLA), , PLLA/poly­(methyl methacrylate) (PMMA), PLLA/poly­(( R )-3-hydroxybutyrate) (PHB), , HMW-PLLA/poly­(ethylene oxide) (PEO), low-molecular-weight poly­( l -lactic acid) (LMW-PLLA)/poly­(ethylene adipate) (PEA), LMW-PLLA/poly­(trimethylene adipate) (PTA), etc.…”

Guided Tissue and Bone Regeneration Membranes: A Review of Biomaterials and Techniques for Periodontal Treatments

“…Additionally, it has a hybrid form (PDLLA) [ 93 ]. Because of its nature as an amorphous crystal, PDLLA degrades quicker than other forms of PLLA, in less than half a year [ 94 , 95 ].…”