title: Partial generation of periodontal ligament on endosseous dental implants in dogs.
abstract: OBJECTIVE
  The objective of this pilot study was to investigate the feasibility of periodontal ligament (PDL) generation on an implant surface by approximating a tooth-to-implant contact using orthodontics.
  
  
  METHODS
  Maxillary second premolars of six beagle dogs were extracted bilaterally. After 2 weeks of healing, hydroxyapatite (HA) coated titanium implants, 5 mm in length and 3.3 mm in diameter, were placed in the extraction sites. One side of the arch was used as control. Orthodontic tooth movement was initiated following implant placement to tip the first premolar roots into contact with the implant. This was achieved in 4-6 weeks as confirmed radiographically. Tooth-to-implant contact was maintained for further 6 weeks after which time, teeth were separated from implant contact orthodontically. After further 2 weeks of stabilization, the animals were sacrificed. Samples were analyzed by Faxitron radiographs before histology. Histology samples were prepared with Stevenel's Blue and Van Gieson stain and were subjected to polarized light microscopy.
  
  
  RESULTS
  Histologic analysis revealed transfer and formation of PDL-like structure with formation of cellular cementum on the implant surfaces, in four out of six animals, where tooth-to-implant contact had been achieved. Direct bone-to-implant contact was noted in the areas coronal to the PDL-like tissue, an important sign to distinguish between PDL-like tissue and connective tissue that could originate from the coronal portion of a failing implant. Additionally, at the site of contact, the implant surface revealed some resorption of the HA coating.
  
  
  CONCLUSIONS
  An animal model was established in which the proximity of tooth-to-implant contact lead to partial generation of PDL on a bioactive implant surface in four out of six animals.
authors.affiliation: Louis Blatterfein Department of Prosthodontics, New York University College of Dentistry, New York, NY 10010, USA. lj14@nyu.edu
authors.forename: Leila
authors.initials: L
authors.lastname: Jahangiri
authors.forename: Ramin
authors.initials: R
authors.lastname: Hessamfar
authors.forename: John L
authors.initials: JL
authors.lastname: Ricci
mesh_terms: D000818:Animals; D001641:Bicuspid / Q000502:physiology; D025021:Cementogenesis / Q000502:physiology; D020099:Coated Materials, Biocompatible / Q000737:chemistry; D003238:Connective Tissue / Q000033:anatomy & histology; D003739:Dental Cementum / Q000033:anatomy & histology; D015921:Dental Implants; D004285:Dogs; D017886:Durapatite / Q000737:chemistry; D005240:Feasibility Studies; D023421:Models, Animal; D016348:Osseointegration / Q000502:physiology; D010513:Periodontal Ligament / Q000033:anatomy & histology / Q000502:physiology*; D010865:Pilot Projects; D012038:Regeneration / Q000502:physiology; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry; D014087:Tooth Movement Techniques; D014092:Tooth Root / Q000502:physiology; D020390:Tooth Socket / Q000601:surgery
chemical_list: D020099:Coated Materials, Biocompatible; D015921:Dental Implants; D017886:Durapatite; D014025:Titanium