title: Back-scattered electron imaging and elemental analysis of retrieved bone tissue following sinus augmentation with deproteinized bovine bone or biphasic calcium phosphate.
abstract: OBJECTIVE
  To compare resorption of a synthetic biphasic calcium phosphate (BCP) bone-graft substitute with deproteinized bovine bone (DBB) used for human maxillary sinus augmentation.
  
  
  METHODS
  Eleven patients underwent bilateral maxillary sinus floor augmentation with DBB in one side and a BCP (40%beta-tricalcium phosphate (beta-TCP) and 60% hydroxyapatite) in the contralateral side. Simultaneously, with the augmentation on each side a microimplant was placed vertically from the top of the alveolar crest penetrating the residual bone and the grafting material. Eight months after initial surgery the microimplants were retrieved with a surrounding bone core. The composition of residual graft material and surrounding bone was analysed by scanning electron microscopy and energy dispersive X-ray spectroscopy.
  
  
  RESULTS
  Residual graft material of both types was present as 10-500 mum particles in direct contact with, or completely surrounded by, newly formed bone; smaller particles were also present in non-mineralized tissue. In the case of BCP the bone-graft substitute interface showed evidence of superficial disintegration of particles into individual grains. Median Ca/P ratios (at.%), determined from >200 discreet sites within residual graft particles and adjacent bone, were: DBB: 1.61 (confidence interval [CI] 1.59-1.64); BCP: 1.5 (CI 1.45-1.52); DBB-augmented bone: 1.62 (CI 1.59-1.66); BCP-augmented bone: 1.52 (CI 1.47-1.55); P=0.028 for DBB vs. BCP and DBB- vs. BCP-augmented bone. The reduction in Ca/P ratio for BCP over the healing period is consistent with the dissolution of beta-TCP and reprecipitation on the surface of calcium-deficient hydroxyapatite.
  
  
  CONCLUSIONS
  The beta-TCP component of BCP may be gradually substituted by calcium-deficient hydroxyapatite over the healing period. This process and superficial degranulation of BCP particles may influence the progress of resorption and healing.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Linköping, Sweden.
authors.forename: Christer
authors.initials: C
authors.lastname: Lindgren
authors.forename: Mats
authors.initials: M
authors.lastname: Hallman
authors.forename: Lars
authors.initials: L
authors.lastname: Sennerby
authors.forename: Rachel
authors.initials: R
authors.lastname: Sammons
mesh_terms: D000368:Aged; D000540:Alveolar Ridge Augmentation / Q000379:methods*; D000818:Animals; D001672:Biocompatible Materials / Q000493:pharmacokinetics / Q000627:therapeutic use*; D001711:Biotransformation; D001857:Bone Matrix / Q000637:transplantation*; D018786:Bone Substitutes / Q000493:pharmacokinetics / Q000627:therapeutic use*; D002118:Calcium / Q000032:analysis; D002130:Calcium Phosphates / Q000493:pharmacokinetics / Q000627:therapeutic use*; D002417:Cattle; D011232:Chemical Precipitation; D003094:Collagen; D017886:Durapatite / Q000493:pharmacokinetics / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D008297:Male; D008437:Maxilla / Q000473:pathology / Q000601:surgery; D008443:Maxillary Sinus / Q000473:pathology / Q000601:surgery*; D008567:Membranes, Artificial; D008855:Microscopy, Electron, Scanning; D008875:Middle Aged; D008903:Minerals / Q000493:pharmacokinetics / Q000627:therapeutic use*; D016348:Osseointegration / Q000502:physiology; D010012:Osteogenesis / Q000502:physiology; D010758:Phosphorus / Q000032:analysis; D012542:Scattering, Radiation; D012995:Solubility; D013052:Spectrometry, X-Ray Emission; D013499:Surface Properties
chemical_list: C106416:Bio-Gide; C077540:Bio-Oss; D001672:Biocompatible Materials; D018786:Bone Substitutes; D002130:Calcium Phosphates; D008567:Membranes, Artificial; D008903:Minerals; C485817:beta-tricalcium phosphate; D010758:Phosphorus; D003094:Collagen; D017886:Durapatite; D002118:Calcium