Poly(L-lactide): a long-term degradation study in vivo. I. Biological results.
Three poly(L-lactides) with different molecular weights were synthesized. Small blocks (3 x 3 x 2 mm) and rods (25 x 3 x 2 mm) were produced either by injection moulding (amorphous parts, Mvis 200,000 and 120,000, respectively) or machined out of a solid aspolymerized polylactide block (crystalline parts, Mvis 429,000) and implanted into the dorsal muscle of rats. After 1 to 116 wk the rats were killed and the implants were recovered. Histological preparation was carried out using the cutting-grinding technique. All three polylactides had incorporated well, forming a collagenous fibrous layer. Crystalline block polylactide remained stable in form and structure over the whole observation period. Amorphous injection-moulded specimens developed a rough surface within weeks, then deep resorptive lacunae after ca. 1 yr and became totally degraded (Mvis 120,000) or nearly totally degraded (Mvis 200,000) after 2 yr. This velocity of biodegradation seems to meet the requirements for an absorbable material for osteosynthesis. Long-term implantation into rodents brings the problem of foreign-body tumorigenesis independent of the chemical nature of implants (the Oppenheimer effect). Observations in this study and in the literature are discussed.
Klinik und Poliklinik für Mund-, Kiefer-, Gesichtschirurgie, Universität Wüzburg, Germany.
H
H
Pistner
R
R
Gutwald
R
R
Ordung
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J
Reuther
J
J
Mühling
D000818:Animals; D001672:Biocompatible Materials / Q000493:pharmacokinetics* / Q000633:toxicity; D001673:Biodegradation, Environmental; D005549:Foreign-Body Reaction; D008297:Male; D008970:Molecular Weight; D009132:Muscles; D011091:Polyesters / Q000138:chemical synthesis / Q000493:pharmacokinetics* / Q000633:toxicity; D019736:Prostheses and Implants; D051381:Rats; D012513:Sarcoma, Experimental / Q000139:chemically induced
D001672:Biocompatible Materials; D011091:Polyesters; C033616:poly(lactide)