title: An investigation of the Impac custom abutment for root form dental implants.
abstract: OBJECTIVE
  This study measured the tensile force required to separate a custom implant abutment fixture that had been cast onto a machined component using the Impac custom abutment system (Vident, Baldwin Park, CA). The characteristics of the interface between the cast and machined components were also investigated by scanning electron microscopy x-ray and energy-dispersive (JEOL T330A, Peabody, MA) analysis (Kevex Delta Level I, San Carlos, CA).
  
  
  METHODS
  A polycarbonate custom abutment component, attached to a gold alloy component of the abutment, was invested in a phosphate-bonded investment and cast in a type III gold alloy (Argenco, Argen Precious Metals, San Diego, CA). Eight samples were cast after a burn-out of 900 degrees F and 13 samples were cast after a burn-out at 1300 degrees F. The abutment components were pulled in tension in a universal Testing Machine (Instron 4204, Canton, MA) until failure. The interface of as-cast and failed samples were examined by electron microscopy.
  
  
  RESULTS
  Samples burned out at 1300 degrees F failed at a mean force of 2477 +/- 295 N (545 +/- 65 lb), and samples burned out at 900 degrees F failed at a mean force of 2182 +/- 91 N (484 +/- 20 lb). Electron microscopy of the interface between the cast and machined components showed retentive tags provided in the design of the machined components. There was also a zone of diffusion between components shown by a zone of void formation within the casting. Failure occurred at the interface of the cast and machined components for all samples.
  
  
  CONCLUSIONS
  The cast component was retained by a combination of mechanical and chemical mechanisms.
authors.affiliation: School of Dental Medicine, University of Pennsylvania, Philadelphia.
authors.forename: F K
authors.initials: FK
authors.lastname: Mante
authors.forename: R J
authors.initials: RJ
authors.lastname: Seckinger
authors.forename: D
authors.initials: D
authors.lastname: Purinton
authors.forename: S J
authors.initials: SJ
authors.lastname: Abreu
authors.forename: P
authors.initials: P
authors.lastname: Berthold
mesh_terms: D000044:Dental Abutments; D003722:Dental Alloys / Q000737:chemistry; D003735:Dental Casting Technique; D015921:Dental Implants; D003775:Dental Polishing; D017267:Dental Prosthesis Design; D004577:Electron Probe Microanalysis; D006047:Gold Alloys; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D011076:Polycarboxylate Cement; D016062:Porosity; D013499:Surface Properties; D013718:Tensile Strength
chemical_list: D003722:Dental Alloys; D015921:Dental Implants; D006047:Gold Alloys; D011076:Polycarboxylate Cement; C005506:polycarbonate