title: Maxillary sinus floor augmentation with injectable calcium phosphate cements: a pre-clinical study in sheep.
abstract: OBJECTIVE
  The aim of this pre-clinical study was to evaluate the biological performance of two injectable calcium phosphate cement (CPC) composite materials containing poly(D,L-lactic-co-glycolic)acid (PLGA) microspheres with different properties in a maxillary sinus floor elevation model in sheep.
  
  
  METHODS
  PLGA microspheres were made of either low molecular weight (~17 kDa) acid-terminated PLGA (PLGA(L-AT) ) or high molecular weight (~44 kDa) end-capped PLGA (PLGA(H-EC) ) and incorporated in CPC. Eight female Swifter sheep underwent a bilateral maxillary sinus floor elevation procedure via an extra-oral approach. All animals received both materials, alternately injected in the left and right sinus (split-mouth model) and a time point of 12 weeks was used. Analysis of biological performance was based on histology, histomorphometry, and evaluation of sequential fluorochrome labeling.
  
  
  RESULTS
  Both types of CPC-PLGA composites showed biocompatibility and direct bone-cement contact. CPC-PLGA(L-AT)  showed a significantly higher degradation distance compared to CPC-PLGA(H-EC)  (1949 ± 1295 μm vs. 459 ± 267 μm; P = 0.0107). Further, CPC-PLGA(L-AT)  showed significantly more bone in the region of interest (26.4 ± 10.5% vs. 8.6 ± 3.9% for PLGA(H-EC) ; P = 0.0009) and significantly less remaining CPC material (61.2 ± 17.7% vs. 81.9 ± 10.9% for PLGA(H-EC) ; P = 0.0192).
  
  
  CONCLUSIONS
  Both CPC-PLGA(L-AT)  and CPC-PLGA(H-EC)  demonstrated to be safe materials for sinus floor elevation procedures in a large animal model, presenting biocompatibility and direct bone contact. In view of material performance, CPC-PLGA(L-AT)  showed significantly faster degradation and a significantly higher amount of newly formed bone compared to CPC-PLGA(H-EC) .
authors.affiliation: Department of Biomaterials, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands.
authors.forename: Jan Willem M
authors.initials: JW
authors.lastname: Hoekstra
authors.forename: Reinoud J
authors.initials: RJ
authors.lastname: Klijn
authors.forename: Gert J
authors.initials: GJ
authors.lastname: Meijer
authors.forename: Jeroen J J P
authors.initials: JJ
authors.lastname: van den Beucken
authors.forename: John A
authors.initials: JA
authors.lastname: Jansen
mesh_terms: D000818:Animals; D001843:Bone Cements / Q000494:pharmacology*; D002130:Calcium Phosphates / Q000494:pharmacology*; D005260:Female; D019344:Lactic Acid / Q000494:pharmacology*; D008863:Microspheres; D011100:Polyglycolic Acid / Q000494:pharmacology*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D034561:Sheep, Domestic; D059546:Sinus Floor Augmentation / Q000379:methods*
chemical_list: D001843:Bone Cements; D002130:Calcium Phosphates; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid