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  Bioabsorbable materials were inventedto address issues with syntheticimplants includingmigrationgrowth disturbancerigidityradioopacityinfectionneed for implant removal operationsIndications include but are not limitedtopediatric orthopaedicstransphyseal SR PLGA 80/20screws only cause temporarygrowth arrest in rabbits (unlikenonbioabsorbable implants)osteomyelitisantibiotic eluting PLA carriers for growth factorsrhBMP2 and rhBMP7augmentation of bone healing at iliaccrest bone harvest site Types of Bioabsorbable Materials Polyglycolic acid (PGA)hydrophilic, crystallicglass transition temperature 36degC becomes malleable if thistemperature is exceededdisadvantagesearly degradation and strength losspotential postop complicationsintraoperatively, must be heated toadapt to implantation surface, andcooledincreased intraoperative timeconsumptionPolylactic acid (PLA)more hydrophobic than PGAL-isomer or poly-L-lactic acid(PLLA)hydrophobic and crystallichas prolonged degradation time(several years)  late adverse reactions in the finalstages of polymer degradationglass transition temperature57degCD-isomer amorphous, less stableuseful for building co-polymersCo-polymersP(L/D)LA copolymersmixture of D- and L-isomers of PLAhydrophobic and crystallicresistant to hydrolysis anddegradationadding D-isomers results in lesstightly packed polymer chainsless crystallic and more rapidlydegraded than PLLA aloneexample is P(L/D)LA 70/30 in oral-maxillofacial surgerysimple and self-reinforced formsPLGA copolymerscombination of PLA and PGAlow crystallinityused in oral-maxillofacial surgerysimple and self-reinforced formsSelf reinforcing (SR)composite structure made frompartially crystalline/amorphousmaterial made of orientatedfibers/fibrils and binding matrixbetter biomechanical propertiesimproved rigidity and strength along longitudinal axismalleable at room temperatureno need for heating-coolingcan withstand 4 times bendingminimal memory  (tendency toreturn to previous shape after bending)can be sterilized by gammairradiationgamma irradiation cannot be usedwith non-reinforced materials will reduce its molecular weightand adversely affect themechanical properties of the  implant
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