title: Clinical performance of two-piece zirconia implants in the posterior mandible and maxilla: a prospective cohort study over 2 years.
abstract: OBJECTIVE
  To assess the clinical performance of two-piece zirconium implants over a period of up to 2 years.
  
  
  METHODS
  A total of 52 patients with single-tooth gaps in the posterior mandible or maxilla received the same type of a two-piece zirconium implant system with customized heights of the transmucosal aspect. Fibreglass abutments were cemented and restored with fixed all-ceramic single crowns using a conventional loading protocol. The cumulative survival rate (primary outcome) was calculated according to the life table method, and Kaplan-Meier survival curves were used to estimate the survival function. Covariates (gender, implant position, implant diameter/length, oral surgeon) were tested using log-rank tests.
  
  
  RESULTS
  A total of two target implants in 2 patients were lost after a functioning time of 8 months. The cumulative survival rate was 95.8%, and the mean survival time amounted to 32.9 months. Log-rank tests revealed a significant association for the covariate "oral surgeon" (P = 0.047). The Kaplan-Meier estimates of mechanical/technical and biological complications amounted to 2.1% and 37.5%, respectively. All implant sites revealed a marked increase of the vestibular mucosal level and gain of keratinized tissue at 24 months.
  
  
  CONCLUSIONS
  Within the limitations of a prospective cohort study, it was concluded that this two-piece zirconium implant/fibreglass abutment system can be successfully used in the clinical indication investigated.
authors.affiliation: Department of Oral Surgery, Universitätsklinikum Düsseldorf, Düsseldorf, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Becker
authors.affiliation: Department of Oral Surgery, Universitätsklinikum Düsseldorf, Düsseldorf, Germany.
authors.forename: Gordon
authors.initials: G
authors.lastname: John
authors.affiliation: Department of Orthodontics, Universitätsklinikum Düsseldorf, Düsseldorf, Germany.
authors.forename: Kathrin
authors.initials: K
authors.lastname: Becker
authors.affiliation: Department of Oral Surgery, Universitätsklinikum Düsseldorf, Düsseldorf, Germany.
authors.forename: Saskia
authors.initials: S
authors.lastname: Mainusch
authors.affiliation: Department of Prosthodontics, Universitätsklinikum Düsseldorf, Düsseldorf, Germany.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Diedrichs
authors.affiliation: Department of Oral Surgery, Universitätsklinikum Düsseldorf, Düsseldorf, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Schwarz
mesh_terms: D000328:Adult; D000044:Dental Abutments; D003722:Dental Alloys; D019250:Dental Implants, Single-Tooth; D017267:Dental Prosthesis Design; D019232:Dental Restoration Failure; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D020784:Matrix Metalloproteinase 8 / Q000378:metabolism; D008875:Middle Aged; D011446:Prospective Studies; D015040:Zirconium
chemical_list: D003722:Dental Alloys; D015040:Zirconium; D020784:Matrix Metalloproteinase 8; C028541:zirconium oxide
keywords: cohort study; implant survival; zirconia implants