dental materials 23 ( 2 0 0 7 ) 296–301 available at www.sciencedirect.com journal homepage: www.intl.elsevierhealth.com/journals/dema Fracture resistance of implant-supported screw- versus cement-retained porcelain fused to metal single crowns: SEM fractographic analysis Fernando Zarone a,* , Roberto Sorrentino a,b , Tonino Traini c , Donato Di lorio c , Sergio Caputi c a Department of Fixed Prosthodontics, School of Dentistry, University “Federico II”, Naples, Italy b Department of Dental Materials and Restorative Dentistry, University of Siena, Italy c Department of Applied Sciences of Oral and Dental Diseases, School of Dentistry, University “G.d’Annunzio”, Chieti-Pescara, Italy article info Article history: Received 19 April 2005 Accepted 25 October 2005 Keywords: Fracture Resistance Cement-retained Screw-retained Implant-supported prostheses Single crown Porcelain fused to metal abstract Objectives. The present in vitro study aimed at evaluating the fracture resistance of both implant-supported screw- and cement-retained porcelain fused to metal (PFM) single crowns. A scanning electron microscope (SEM) evaluation of the mode of failure of the spec- imens was also performed. Methods. Forty PFM premolar-shaped identical single crowns were realized. The restorations were divided into two groups: cement-retained (group 1) and screw-retained (group 2) pros- theses. Compressive loading tests and SEM fractographic analyses were performed. The data were statistically analysed by means of the Student’s t-test, with a confidence interval of 95%. Results. The mean fracture load value was 1657 (±725) N in group 1 and 1281 (±747) N in group 2; the statistical analysis pointed out no significant differences between the two groups (p = 0.115). The mean work at maximum load value was 0.775 (±0.619) J in group 1 and 0.605 (±0.526) J in group 2; the statistical analysis pointed out no significant differences between the two groups (p = 0.355). All the samples were affected by cohesive fractures of the porcelain. Screw-retained crowns showed microcracks at the level of the occlusal access to the screw and extensive fractures in the whole thickness of the ceramics. On the contrary, cement-retained restora- tions were affected by less wide paramarginal fractures of the porcelain. Significance. A stronger implant-prosthetic connection was noticed in cemented restora- tions group than in screw-retained single crowns. Even though negatively influenced by the presence of the occlusal access to the screw, the metal–ceramics bond can be considered predictable in both the implant-prosthetic connection systems analysed. © 2006 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved. 1. Introduction In implant-supported prosthetic treatments, the choice of the restorative components and the connectionsystem between ∗ Correspondce to: Dipartimento di Scienze Odontostomatologiche e Maxillo-Facciali, Ed. 14, Universita degli Studi di Napoli “Federico II”, School of Dentistry, Via Pansini, 5-80131 Naples, Italy. Tel.: +39 081 7463018; fax: +39 081 7463018. E-mail address: zarone@unina.it (F. Zarone). the implants and the restorations must be considered a paramount factor for long-term success. The majority of the implant systems available today offer different types of connection between prosthetic restorations 0109-5641/$ – see front matter © 2006 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.dental.2005.10.013