title: Marginal adaptation of ceramic crowns: a systematic review.
abstract: BACKGROUND
  After the development of a variety of ceramic restorative systems over the past 20 years, the fabrication of fixed dental prostheses has undergone considerable change. Esthetics and resistance to fracture are two of the main determinants of the success of a restoration; the third is marginal adaptation. Therefore, a systematic review of the literature dedicated to the marginal accuracy of ceramic systems is indicated.
  
  
  OBJECTIVE
  This study reviewed the current scientific literature that pertains to the marginal fit of ceramic crowns fabricated with different systems and investigated the factors that influence marginal adaptation.
  
  
  METHODS
  An electronic search was completed by using the PubMed and Scopus databases with the following combination of key words: (discrepancy or fit or gaps or adaptation) and (disilicate or ceramic) and (copings or crowns). The search was limited to English-language peer-reviewed articles published before April 15, 2012. Titles and abstracts were read to identify articles that fulfilled the inclusion criteria designed for this review.
  
  
  RESULTS
  Of 469 studies identified, 54 satisfied the selection criteria and were included in this review. All were published between 1994 and 2012. A total of 17 ceramic systems were tested in 48 in vitro and 6 in vivo studies. Of all the marginal gaps measured, 94.9% were in the range of clinical acceptability. Study heterogeneity made it impossible to conduct a proper meta-analysis of research findings and to compare and rank the various systems in terms of marginal fit. Four parameters were found to influence marginal adaptation: finish line configuration, value of the predefined cementing space, veneering process, and cementation.
  
  
  CONCLUSIONS
  The systems evaluated in the selected articles generally provide a clinically acceptable marginal fit. The current state of research does not allow for a proper comparison of the various systems in terms of marginal fit. The use of computer x-ray microtomography is recommended for further research on marginal adaptation.
authors.affiliation: Instructor, Department of Prosthodontics, Faculty of Dentistry, University of Bordeaux Segalen, Bordeaux, France. Electronic address: mathieu.contrepois@gmail.com.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Contrepois
authors.forename: Arnaud
authors.initials: A
authors.lastname: Soenen
authors.forename: Michel
authors.initials: M
authors.lastname: Bartala
authors.forename: Odile
authors.initials: O
authors.lastname: Laviole
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry; D002516:Ceramics / Q000737:chemistry; D003442:Crowns; D018772:Dental Marginal Adaptation; D003776:Dental Porcelain / Q000737:chemistry; D017267:Dental Prosthesis Design; D006801:Humans; D017640:Silicates / Q000737:chemistry; D015019:Yttrium / Q000737:chemistry; D015040:Zirconium / Q000737:chemistry
chemical_list: D000538:Aluminum Silicates; D017640:Silicates; C493120:lithia disilicate; C499362:yttria stabilized tetragonal zirconia; D003776:Dental Porcelain; C078519:leucite; C003784:zircon; D015019:Yttrium; C023506:Glass ceramics; D015040:Zirconium