title: Cementable implant crowns composed of cast superstructure frameworks luted to electroformed primary copings: an in vitro retention study.
abstract: OBJECTIVE
  The aim of this in vitro study was to investigate, on ITI solid abutments, the retention values of single crowns fabricated using an alternative prosthetic solution: secondary cast superstructure luted to an electroformed primary coping.
  
  
  METHODS
  Fifty standard 4.1 mm ITI implants and 5.5 mm high ITI machined abutments were assembled and mounted in acrylic resin. Implant/abutment assemblies were randomly divided into two groups. In the test group, primary galvanic caps were directly fabricated on implant abutments (A.G.C. Micro machine), and a secondary cast noble alloy superstructure was luted on each primary galvanic cap with a resin cement (Nimetic Cem). In the control group, prefabricated burn-out caps were used for casting the metal frameworks. Test and control crowns were cemented using a resin cement (Panavia 21). After storage at 37 degrees for 24 h, the specimens were subjected to a pull-out test using an Instron universal testing machine. The load required to dislodge each sample and the respective mode of failure were recorded. Means and standard deviations of loads at failure were analyzed using ANOVA. Statistical significance was set at P< or =0.05.
  
  
  RESULTS
  The retention values (+/-SD) of loads at failure were 67.26 (+/-16.61) for the test group and 44.03 (+/-9.45) for the control group. In the test group no separation occurred between the electroformed (galvanic) primary cap and the secondary superstructure.
  
  
  CONCLUSIONS
  The results showed that this prosthetic solution is superior on retentive performance than the conventional cast framework. An added clinical advantage of this novel method is its potential to provide a totally passive fit. Further in vitro and in vivo studies involving multiple-unit restorations are needed in order to more generally validate this prosthetic concept.
authors.affiliation: Department of Prosthodontics, School of Dentistry, University of Ancona, Ancona, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Di Felice
authors.forename: Giorgio
authors.initials: G
authors.lastname: Rappelli
authors.forename: Emanuele
authors.initials: E
authors.lastname: Camaioni
authors.forename: Maria
authors.initials: M
authors.lastname: Cattani
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Meyer
authors.forename: Urs C
authors.initials: UC
authors.lastname: Belser
mesh_terms: D002484:Cementation / Q000379:methods*; D003188:Composite Resins / Q000737:chemistry; D003442:Crowns; D000044:Dental Abutments; D003735:Dental Casting Technique; D015921:Dental Implants; D017267:Dental Prosthesis Design; D017268:Dental Prosthesis Retention; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis / Q000295:instrumentation; D004595:Electroplating; D006047:Gold Alloys / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D010710:Phosphates / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D013499:Surface Properties; D013696:Temperature
chemical_list: D003188:Composite Resins; D015921:Dental Implants; D006047:Gold Alloys; C093719:Panavia TPN-S; D010710:Phosphates; D019279:Resin Cements; C033051:Nimeticap