title: Back-scattered electron imaging and elemental microanalysis of retrieved bone tissue following maxillary sinus floor augmentation with calcium sulphate.
abstract: OBJECTIVE
  To investigate the presence and composition of residual bone graft substitute material in bone biopsies from the maxillary sinus of human subjects, following augmentation with calcium sulphate (CaS).
  
  
  METHODS
  Bone cores were harvested from the maxillary sinus of patients who had undergone a sinus lift procedure using CaS G170 granules 4 months after the initial surgery. Samples from seven patients, which contained residual biomaterial particles, were examined by field emission scanning electron microscopy and energy dispersive X-ray spectroscopy was used to determine the composition of the remaining bone graft substitute material.
  
  
  RESULTS
  Residual graft material occurred in isolated areas surrounded by bone and consisted of individual particles up to 1 mm in length and smaller spherical granules. On the basis of 187 separate point analyses, the residual material was divided into three categories (A, B and C) consisting of: A, mainly CaS (S/P atomic% ratio > or =2.41); B, a heterogeneous mixture of CaS and calcium phosphate (S/P=0.11-2.4) and C, mainly calcium phosphate (S/P< or =0.11; C), which had a mean Ca : P ratio of 1.63+/-0.2, consistent with Ca-deficient hydroxyapatite. Linescans and elemental maps showed that type C material was present in areas which appeared dense and surrounded, or were adjacent to, more granular CaS-containing material, and also occurred as spherical particles. The latter could be disintegrating calcium phosphate in the final stages of the resorption process.
  
  
  CONCLUSIONS
  CaS resorption in the human maxillary sinus is accompanied by CaP precipitation which may contribute to its biocompatibility and rapid replacement by bone.
authors.affiliation: School of Dentistry, University of Birmingham, Birmingham, UK.
authors.forename: Nicola
authors.initials: N
authors.lastname: Slater
authors.forename: Amir
authors.initials: A
authors.lastname: Dasmah
authors.forename: Lars
authors.initials: L
authors.lastname: Sennerby
authors.forename: Mats
authors.initials: M
authors.lastname: Hallman
authors.forename: Adriano
authors.initials: A
authors.lastname: Piattelli
authors.forename: Rachel
authors.initials: R
authors.lastname: Sammons
mesh_terms: D016301:Alveolar Bone Loss / Q000473:pathology / Q000601:surgery; D000539:Alveolar Process / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure*; D000540:Alveolar Ridge Augmentation / Q000379:methods; D001672:Biocompatible Materials / Q000737:chemistry / Q000378:metabolism* / Q000627:therapeutic use; D018786:Bone Substitutes / Q000737:chemistry / Q000378:metabolism* / Q000627:therapeutic use; D002133:Calcium Sulfate / Q000032:analysis / Q000378:metabolism*; D004577:Electron Probe Microanalysis; D006801:Humans; D008437:Maxilla / Q000601:surgery / Q000648:ultrastructure; D008443:Maxillary Sinus / Q000601:surgery / Q000648:ultrastructure; D008855:Microscopy, Electron, Scanning; D016348:Osseointegration / Q000502:physiology*
chemical_list: D001672:Biocompatible Materials; D018786:Bone Substitutes; D002133:Calcium Sulfate