title: A systematic review of screw- versus cement-retained implant-supported fixed restorations.
abstract: OBJECTIVE
  To systematically evaluate the survival and success of screw- versus cement-retained implant crowns.
  
  
  METHODS
  The authors performed an electronic search of nine databases using identical MeSH phrases. Systematic evaluation and data extraction of the articles from 1966 through 2007 were completed by three reviewers and two clinical academicians. The major outcome variable was implant or crown loss, and the minor outcome variables were screw loosening, decementation, and porcelain fracture. Random effects Poisson models were used to analyze the failure and complication rates.
  
  
  RESULTS
  The initial search produced 26,582 articles. Of these, 577 titles and subsequently 295 abstracts were available for evaluation, with 81 full texts meeting the criteria for review. Data were extracted from 23 level one and two research studies. Fleiss' kappa interevaluator agreement ranged from almost perfect to moderate. Major failures included 0.71 screw-retained and 0.87 cement-retained failures per 100 years. Minor failures included 3.66 screw loosenings, 2.54 decementations, and 0.46 porcelain fractures per 100 years.
  
  
  CONCLUSIONS
  There is no significant difference between cement- and screw-retained restorations for major and minor outcomes with regard to implant survival or crown loss. This is important data, as clinicians use both methods of restoration, and neither is a form of inferior care.
authors.affiliation: Harvard School of Dental Medicine, Boston, MA; Private Practice, London, United Kingdom.
authors.forename: Sami
authors.initials: S
authors.lastname: Sherif
authors.forename: Harlyn K
authors.initials: HK
authors.lastname: Susarla
authors.forename: Theodoros
authors.initials: T
authors.lastname: Kapos
authors.forename: Deborah
authors.initials: D
authors.lastname: Munoz
authors.forename: Brian M
authors.initials: BM
authors.lastname: Chang
authors.forename: Robert F
authors.initials: RF
authors.lastname: Wright
mesh_terms: D002484:Cementation / Q000379:methods*; D003442:Crowns; D003776:Dental Porcelain / Q000737:chemistry; D017267:Dental Prosthesis Design; D017268:Dental Prosthesis Retention / Q000295:instrumentation / Q000379:methods*; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D006801:Humans
chemical_list: D003776:Dental Porcelain
keywords: Systematic review; cement-retained restorations; crown failure; decementation; implant failure; porcelain fracture; screw loosening; screw-retained restorations