title: Fractographic ceramic failure analysis using the replica technique.
abstract: OBJECTIVE
  To demonstrate the effectiveness of in vivo replicas of fractured ceramic surfaces for descriptive fractography as applied to the analysis of clinical failures.
  
  
  METHODS
  The fracture surface topography of partially failed veneering ceramic of a Procera Alumina molar and an In-Ceram Zirconia premolar were examined utilizing gold-coated epoxy poured replicas viewed using scanning electron microscopy. The replicas were inspected for fractographic features such as hackle, wake hackle, twist hackle, compression curl and arrest lines for determination of the direction of crack propagation and location of the origin.
  
  
  RESULTS
  For both veneering ceramics, replicas provided an excellent reproduction of the fractured surfaces. Fine details including all characteristic fracture features produced by the interaction of the advancing crack with the material's microstructure could be recognized. The observed features are indicators of the local direction of crack propagation and were used to trace the crack's progression back to its initial starting zone (the origin). Drawbacks of replicas such as artifacts (air bubbles) or imperfections resulting from inadequate epoxy pouring were noted but not critical for the overall analysis of the fractured surfaces.
  
  
  CONCLUSIONS
  The replica technique proved to be easy to use and allowed an excellent reproduction of failed ceramic surfaces. It should be applied before attempting to remove any failed part remaining in situ as the fracture surface may be damaged during this procedure. These two case studies are intended as an introduction for the clinical researcher in using qualitative (descriptive) fractography as a tool for understanding fracture processes in brittle restorative materials and, secondarily, to draw conclusions as to possible design inadequacies in failed restorations.
authors.affiliation: Department of Prosthodontics-Biomaterials, University of Geneva, School of Dental Medicine, 19, Barthélemy-Menn, 1205 Geneva, Switzerland. susanne.scherrer@medicine.unige.ch
authors.forename: Susanne S
authors.initials: SS
authors.lastname: Scherrer
authors.forename: Janet B
authors.initials: JB
authors.lastname: Quinn
authors.forename: George D
authors.initials: GD
authors.lastname: Quinn
authors.forename: H W Anselm
authors.initials: HW
authors.lastname: Wiskott
mesh_terms: D000537:Aluminum Oxide; D003760:Dental Impression Materials; D003761:Dental Impression Technique; D003776:Dental Porcelain; D019232:Dental Restoration Failure; D019544:Equipment Failure Analysis / Q000379:methods; D008855:Microscopy, Electron, Scanning; D011145:Polyvinyls; D016628:Replica Techniques; D012833:Siloxanes; D013499:Surface Properties; D015040:Zirconium
chemical_list: D003760:Dental Impression Materials; D011145:Polyvinyls; D012833:Siloxanes; C480691:aquasil; D003776:Dental Porcelain; D015040:Zirconium; D000537:Aluminum Oxide; C028541:zirconium oxide