title: Clinical performance of screw- versus cement-retained fixed implant-supported reconstructions--a systematic review.
abstract: OBJECTIVE
  To assess the survival outcomes and reported complications of screw- and cement-retained fixed reconstructions supported on dental implants.
  
  
  METHODS
  A Medline (PubMed), Embase, and Cochrane electronic database search from 2000 to September 2012 using MeSH and free-text terms was conducted. Selected inclusion and exclusion criteria guided the search. All studies were first reviewed by abstract and subsequently by full-text reading by two examiners independently. Data were extracted by two examiners and statistically analyzed using a random effects Poisson regression.
  
  
  RESULTS
  From 4,324 abstracts, 321 full-text articles were reviewed. Seventy-three articles were found to qualify for inclusion. Five-year survival rates of 96.03% (95% confidence interval [CI]: 93.85% to 97.43%) and 95.55% (95% CI: 92.96% to 97.19%) were calculated for cemented and screw-retained reconstructions, respectively (P = .69). Comparison of cement and screw retention showed no difference when grouped as single crowns (I-SC) (P = .10) or fixed partial dentures (I-FDP) (P = .49). The 5-year survival rate for screw-retained full-arch reconstructions was 96.71% (95% CI: 93.66% to 98.31). All-ceramic reconstruction material exhibited a significantly higher failure rate than porcelain-fused-to-metal (PFM) in cemented reconstructions (P = .01) but not when comparing screw-retained reconstructions (P = .66). Technical and biologic complications demonstrating a statistically significant difference included loss of retention (P ≤ .01), abutment loosening (P ≤ .01), porcelain fracture and/or chipping (P = .02), presence of fistula/suppuration (P ≤ .001), total technical events (P = .03), and total biologic events (P = .02).
  
  
  CONCLUSIONS
  Although no statistical difference was found between cement- and screw-retained reconstructions for survival or failure rates, screw-retained reconstructions exhibited fewer technical and biologic complications overall. There were no statistically significant differences between the failure rates of the different reconstruction types (I-SCs, I-FDPs, full-arch I-FDPs) or abutment materials (titanium, gold, ceramic). The failure rate of cemented reconstructions was not influenced by the choice of a specific cement, though cement type did influence loss of retention.
authors.forename: Julia-Gabriela
authors.initials: JG
authors.lastname: Wittneben
authors.forename: Christopher
authors.initials: C
authors.lastname: Millen
authors.forename: Urs
authors.initials: U
authors.lastname: Brägger
mesh_terms: D001863:Bone Screws / Q000592:standards*; D002516:Ceramics / Q000592:standards; D003442:Crowns / Q000706:statistics & numerical data; D000044:Dental Abutments; D003738:Dental Cements; D015921:Dental Implants; D003776:Dental Porcelain; D017268:Dental Prosthesis Retention / Q000295:instrumentation / Q000379:methods*; D019094:Dental Prosthesis, Implant-Supported / Q000009:adverse effects / Q000592:standards*; D019232:Dental Restoration Failure / Q000706:statistics & numerical data*; D003830:Denture, Partial, Fixed; D006801:Humans
chemical_list: D003738:Dental Cements; D015921:Dental Implants; D003776:Dental Porcelain