title: Dense hydroxyapatite inserted into postextraction sockets: a histologic and histomorphometric 20-year case report.
abstract: BACKGROUND
  The biologic behavior, i.e., the degradation of hydroxyapatite (HA) in the human body, is of relevance for clinicians. The present investigation is a long-term (20-year) histologic and histomorphometric evaluation of dense HA used in postextraction sockets.
  
  
  METHODS
  Dense HA particles were used in a patient in postextraction alveolar sockets to maintain the alveolar ridge height. The patient returned after 20 years for implant treatment. A ridge remodeling was necessary during implant insertion surgery, and the HA/bone tissue was harvested with bone-cutting forceps from the canine and premolar area. The specimen was processed for histology and histomorphometry at the Implant Retrieval Centre, Dental School, University of Chieti-Pescara.
  
  
  RESULTS
  Most of the particles (56%) were surrounded partially by bone, whereas some particles (39%) were surrounded completely. At higher magnification, bone was in close contact with the particles, and neither gaps nor fibrous tissues were present at the bone-biomaterial interface. Microscopically, the particles had a dense appearance. In only a few fields, it was possible to observe that the outer part of some particles had detached from the original particles' surface. Histomorphometry showed that bone represented 25.4% +/- 3.2%, marrow spaces represented 41.3% +/- 5.2%, and residual HA particles represented 38.1% +/- 4.1%.
  
  
  CONCLUSIONS
  Intimate binding between bone and HA particles was present after a long-term implantation period (20 years). The fact that HA particles were surrounded closely by bone is very promising for the long-term stability of the augmentation.
authors.affiliation: Department of Biomaterials Science, Dental School, University of Varese, Varese, Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Mangano
authors.forename: Adriano
authors.initials: A
authors.lastname: Piattelli
authors.forename: Vittoria
authors.initials: V
authors.lastname: Perrotti
authors.forename: Giovanna
authors.initials: G
authors.lastname: Iezzi
mesh_terms: D020341:Absorbable Implants; D001861:Bone Regeneration / Q000502:physiology*; D018786:Bone Substitutes / Q000378:metabolism* / Q000627:therapeutic use; D017886:Durapatite / Q000378:metabolism* / Q000627:therapeutic use; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D016348:Osseointegration / Q000187:drug effects / Q000502:physiology*; D012086:Reoperation; D014081:Tooth Extraction; D020390:Tooth Socket / Q000187:drug effects / Q000378:metabolism*; D016896:Treatment Outcome
chemical_list: D018786:Bone Substitutes; D017886:Durapatite