title: The mucosal barrier at implant abutments of different materials.
abstract: OBJECTIVE
  The aim of the present study was to analyze the soft tissue barrier formed to implant abutments made of different materials.
  
  
  METHODS
  Six Labrador dogs, about 1 year old, were used. All mandibular premolars and the first, second and third maxillary premolars were extracted. Three months later four implants (OsseoSpeed, 4.5 x 9 mm, Astra Tech Dental, Mölndal, Sweden) were placed in the edentulous premolar region on one side of the mandible and healing abutments were connected. One month later, the healing abutments were disconnected and four new abutments were placed in a randomized order. Two of the abutments were made of titanium (Ti), while the remaining abutments were made of ZrO(2) or AuPt-alloy. A 5-months plaque control program was initiated. Three months after implant surgery, the implant installation procedure and the subsequent abutment shift were repeated in the contra-lateral mandibular region. Two months later, the dogs were euthanized and biopsies containing the implant and the surrounding soft and hard peri-implant tissues were collected and prepared for histological analysis.
  
  
  RESULTS
  It was demonstrated that the soft tissue dimensions at Ti- and ZrO(2) abutments remained stable between 2 and 5 months of healing. At Au/Pt-alloy abutment sites, however, an apical shift of the barrier epithelium and the marginal bone occurred between 2 and 5 months of healing. In addition, the 80-mum-wide connective tissue zone lateral to the Au/Pt-alloy abutments contained lower amounts of collagen and fibroblasts and larger fractions of leukocytes than the corresponding connective tissue zone of abutments made of Ti and ZrO(2).
  
  
  CONCLUSIONS
  It is suggested that the soft tissue healing to abutments made of titanium and ZrO(2) is different to that at abutments made of AuPt-alloy.
authors.affiliation: Department of Periodontology, The Sahlgrenska Academy at Göteborg University, Göteborg, Sweden. maria.welander@odontologi.gu.se
authors.forename: Maria
authors.initials: M
authors.lastname: Welander
authors.forename: Ingemar
authors.initials: I
authors.lastname: Abrahamsson
authors.forename: Tord
authors.initials: T
authors.lastname: Berglundh
mesh_terms: D000818:Animals; D002516:Ceramics; D003238:Connective Tissue / Q000033:anatomy & histology; D000044:Dental Abutments; D003758:Dental Implantation, Endosseous; D015921:Dental Implants; D003764:Dental Materials; D017267:Dental Prosthesis Design; D004285:Dogs; D004848:Epithelium / Q000033:anatomy & histology; D005881:Gingiva / Q000033:anatomy & histology*; D006047:Gold Alloys; D020007:Implants, Experimental; D009061:Mouth Mucosa / Q000033:anatomy & histology*; D011897:Random Allocation; D014025:Titanium; D014945:Wound Healing / Q000502:physiology; D015040:Zirconium
chemical_list: D015921:Dental Implants; D003764:Dental Materials; D006047:Gold Alloys; D015040:Zirconium; D014025:Titanium; C028541:zirconium oxide