title: Calcium phosphate/poly(D,L-lactic-co-glycolic acid) composite bone substitute materials: evaluation of temporal degradation and bone ingrowth in a rat critical-sized cranial defect.
abstract: OBJECTIVE
  The present study aimed to provide temporal information on material degradation and bone formation using composite (C) bone defect filler materials consisting of calcium phosphate cement (CaP) and poly(D,L-lactic-co-glycolic acid) (PLGA) microparticles (20 or 30 wt%) in rat critical-sized cranial defects.
  
  
  METHODS
  Critical-sized bicortical cranial defects were created in 48 rats and CaP/PLGA cement composites were implanted for 4, 8 and 12 weeks (n=8).
  
  
  RESULTS
  Histological analysis of the retrieved specimens revealed that implant degradation was significantly faster for C30% (remaining implant up to 89.4 ± 4.4% at 12 weeks) compared with C20% (remaining implant upto 94.8 ± 2.1% at 12 weeks), albeit that overall degradation was limited. Although bone formation was limited in both experimental groups (upto 685765.9 μm(2) for C20% vs. 917603.3 μm(2) for C30%), C30% showed a significant temporal increase of total bone formation. The percentage of defect bridging was comparable for C20% and C30% at all implantation periods (range 40 ± 25.5% at week 4 to 65 ± 20% at week 12 for C20%; range 51.8 ± 7.8% at week 4 to 70.5 ± 16.2% at week 12 for C30%).
  
  
  CONCLUSIONS
  The amount of PLGA-microparticles in the CaP/PLGA cement composites demonstrated acceleration of material degradation, while bone formation was found not to be influenced. Further optimization of the composite material is necessary to increase control over degradation and tissue ingrowth.
authors.affiliation: Department of Biomaterials (309), Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands.
authors.forename: Floor C J
authors.initials: FCJ
authors.lastname: van de Watering
authors.affiliation: Department of Biomaterials (309), Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands.
authors.forename: Jeroen J J P
authors.initials: JJJP
authors.lastname: van den Beucken
authors.affiliation: Department of Biomaterials (309), Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands.
authors.forename: X Frank
authors.initials: XF
authors.lastname: Walboomers
authors.affiliation: Department of Biomaterials (309), Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands.
authors.forename: John A
authors.initials: JA
authors.lastname: Jansen
mesh_terms: D020341:Absorbable Implants; D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry / Q000378:metabolism; D001861:Bone Regeneration / Q000187:drug effects*; D018786:Bone Substitutes / Q000737:chemistry / Q000378:metabolism*; D002130:Calcium Phosphates / Q000737:chemistry / Q000378:metabolism*; D019344:Lactic Acid / Q000737:chemistry / Q000378:metabolism*; D008297:Male; D008422:Materials Testing; D010316:Particle Size; D011100:Polyglycolic Acid / Q000737:chemistry / Q000378:metabolism*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D051381:Rats; D017208:Rats, Wistar; D012886:Skull / Q000378:metabolism* / Q000601:surgery*; D013997:Time Factors; D055114:X-Ray Microtomography
chemical_list: D001672:Biocompatible Materials; D018786:Bone Substitutes; D002130:Calcium Phosphates; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid