title: Marginal and internal fit of CAD/CAM and slip-cast made zirconia copings.
abstract: OBJECTIVE
  CAD/CAM systems facilitate the use of zirconia substructure materials for all-ceramic copings. This in vitro study investigated the marginal and internal fit of zirconia copings made with CAD/CAM system and slip-casting method.
  
  
  METHODS
  Sixteen CAD/CAM made zirconia copings and 16 slip-cast made zirconia copings were fabri-cated and cemented with glass-ionomer cement to their respective master abutment models, and thickness of the cement layer was measured at specific measuring points with stereomicroscope.
  
  
  RESULTS
  In the left wall, the mean axial internal gap was greater in group one than group two (62.49 vs. 48.14) (P =0.007), in the right wall the mean axial internal gap was greater in group one than group two (44.87 vs. 40.91) (P = 0.465). The oc-clusal internal gap was greater in group one than group two (118.81 vs. 102.11) (P =0.423). The mean marginal gap also was greater in group one than group two (46.67 vs. 44.29) (P = 0.863). The differences in marginal fit between these two methods were not statistically significant, except for left axial internal gap that was significantly greater in the CAD/CAM system than conventional slip-cast technique (P =0.007).
  
  
  CONCLUSIONS
  It was concluded that this CAD/CAM system can compete well with conventional systems for clinical fit, and can achieve good in vitro marginal fit.
authors.affiliation: Associate Professor, Department of Prosthodontics, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Kianoosh
authors.initials: K
authors.lastname: Torabi Ardekani
authors.forename: Ahmad Hassan
authors.initials: AH
authors.lastname: Ahangari
authors.forename: Leila
authors.initials: L
authors.lastname: Farahi