Cementable implant crowns composed of cast superstructure frameworks luted to electroformed primary copings: an in vitro retention study Roberto Di Felice Giorgio Rappelli Emanuele Camaioni Maria Cattani Jean-Marc Meyer Urs C. Belser Authors’ affiliation: Roberto Di Felice, Giorgio Rappelli, Department of Prosthodontics, School of Dentistry, University of Ancona, Ancona, Italy Emanuele Camaioni, Private Practice, San Benedetto del Tronto, Ascoli Piceno, Italy Maria Cattani, Jean-Marc Meyer, Division of Dental Materials, School of Dental Medicine, University of Geneva, Geneva, Switzerland Urs C. Belser, Division of Fixed Prosthodontics and Occlusion, School of Dental Medicine, University of Geneva, Geneva, Switzerland Correspondence to: Prof. Giorgio Rappelli Department of Prosthodontics School of Dentistry University of Ancona Via Tronto 10, I–60020 Ancona Italy Tel.: þ 39 071 2206227 Fax: þ 39 071 2206221 e-mail: g.rappelli@univpm.it Key words: auro-galva crowns, casting retention, ITI implants, solid titanium abutments 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. Materials and 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 371 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 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. An important objective in the implant prosthodontic procedure is to achieve pas- sive fit and marginal precision of the frame- work (Taylor et al. 2000; Bra ¨gger et al. 2001). The difficulty of routinely and consis- tently achieving a passive and precise fit between an implant and a lost-wax frame- work is well documented in the dental literature (Jemt 1995, 1996; Jemt & Book 1996; Wee et al. 1998; Jemt et al. 1999; Watanabe et al. 2000; Ortorp et al. 2003; Takahashi & Gunne 2003; Yoko et al. 2003; Karl et al. 2004). Potentially detrimental tensile, bending or compressive forces are introduced into an implant-supported rehabilitation through misfitting and consequential lack of passive fit (Jemt 1991; Clelland et al. 1995; Smedberg et al. 1996; Pietrabissa et al. 2000; Watanabe et al. 2000; Kunavi- sarut et al. 2002; Karl et al. 2004). Copyright r Blackwell Munksgaard 2006 Date: Accepted 12 December 2005 To cite this article: Di Felice R, Rappelli G, Camaioni E, Cattani M, Meyer J-M, Belser UC. Cementable implant crowns composed of cast superstructure frameworks luted to electroformed primary copings: an in vitro retention study. Clin. Oral Impl. Res. 18, 2007; 108–113 doi: 10.1111/j.1600-0501.2006.01299.x 108