title: Cement thickness at implant-supported single-tooth Lava assemblies: a scanning electron microscopic investigation.
abstract: OBJECTIVE
  The fit of implant-supported single-tooth Lava zirconia assemblies was investigated in this study. The implant-abutment interface, the interface between the metallic and the zirconia portion of the abutment and the interface between Lava abutments and copings were evaluated. The adaptation of titanium abutments to implants and Lava copings was investigated as a control.
  
  
  METHODS
  Twenty implants were randomly assigned and connected to Lava abutments (group 1) or titanium abutments (group 2). All specimens were subjected to scanning electron microscopy (SEM) analysis of the fixture/abutment fit. Afterwards, specimens were luted to Lava copings and subjected to a SEM evaluation of the marginal external adaptation of the abutments with the copings. Finally, the samples were embedded in resin, sectioned and subjected to SEM analysis of the following interfaces; group 1: titanium/zirconia interface (between the constitutive components of the Lava abutment) and the zirconia/zirconia interface (between the Lava abutment and the coping); group 2: the titanium/zirconia interface (between the titanium abutment and the Lava coping). Non-parametric analysis of variance and a post hoc test were used for statistical analysis.
  
  
  RESULTS
  Significant differences emerged in the cement thickness between titanium and zirconia components of the Lava abutments as compared with the thickness measured at the interface between Lava copings and the abutments investigated. No differences were found in cement thickness between Lava copings and the two different abutments.
  
  
  CONCLUSIONS
  When Lava abutments are used, the most critical cement thickness is the internal interface between its titanium and zirconia components. Lava coping adaptation for both Lava and titanium abutments is within the clinical acceptable range.
authors.affiliation: Department of Dental Materials and Fixed Prosthodontics, University of Siena, Siena, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Apicella
authors.forename: M
authors.initials: M
authors.lastname: Veltri
authors.forename: N
authors.initials: N
authors.lastname: Chieffi
authors.forename: P
authors.initials: P
authors.lastname: Balleri
authors.forename: M
authors.initials: M
authors.lastname: Ferrari
mesh_terms: D000704:Analysis of Variance; D002484:Cementation; D003442:Crowns; D000044:Dental Abutments; D019250:Dental Implants, Single-Tooth; D018772:Dental Marginal Adaptation; D003776:Dental Porcelain; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D003799:Dental Stress Analysis; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D011897:Random Allocation; D019279:Resin Cements; D013499:Surface Properties; D014025:Titanium; D015040:Zirconium
chemical_list: C483701:Rely X Unicem; D019279:Resin Cements; D003776:Dental Porcelain; D015040:Zirconium; D014025:Titanium; C028541:zirconium oxide