title: Implant adaptation of stock abutments versus CAD/CAM abutments: a radiographic and Scanning Electron Microscopy study.
abstract: BACKGROUND
  The study evaluated a null-hypothesis of no differences of fit between stock abutments and CAD/CAM titanium, gold sputtered and zirconia abutments when examined for radiographic adaptation and Scanning Electron Microcopy (SEM) at their inner aspect. The agreement between microscopic and radiographic fit was also assessed.
  
  
  METHODS
  Implants (Osseospeed, Astra Tech, Mölndal, Sweden) were connected to titanium abutments (Ti-design, Astra Tech, Mölndal, Sweden) (control group n=12), to stock zirconia abutments (Zir-design, Astra Tech) (group 1 n=12) and to third party zirconia abutments (Aadva Zr abutment, GC, Tokyo, Japan) as observed under SEM (JEOL JSM-6060LV, Tokyo, Japan). Two independent operators blindly evaluated the images, according to a three-score scale: perfect adaptation, no complete adaptation, and clear evidence of no adaptation. A Kruskal-Wallis test was applied to assess significant differences in adaptation scores between the groups.
  
  
  RESULTS
  All specimens showed precise SEM adaptation at all tested interfaces and no radiographically apparent gaps. No significant differences were found and therefore the null-hypothesis tested was accepted. Radiographic and SEM scores were in agreement.
  
  
  CONCLUSIONS
  CAD/CAM titanium, gold sputtered and zirconia abutments and third-part CAD/CAM zirconia abutments show an adaptation to Astra Tech implants that is comparable to that of stock titanium and zirconia abutments. Clinicians might be able to verify such adaptation with an x-ray. In-vivo studies would be needed to evaluate the clinical outcome of CAD/CAM abutments.
authors.affiliation: University of Florence and Siena, Italy, Tuscan School of Dental Medicine, Department of Prosthodontics and Dental Materials of Siena.
authors.forename: Davide
authors.initials: D
authors.lastname: Apicella
authors.forename: Mario
authors.initials: M
authors.lastname: Veltri
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Chieffi
authors.forename: Antonella
authors.initials: A
authors.lastname: Polimeni
authors.forename: Agostino
authors.initials: A
authors.lastname: Giovannetti
authors.forename: Marco
authors.initials: M
authors.lastname: Ferrari