title: Vertical discrepancy and microleakage of laser-sintered and vacuum-cast implant-supported structures luted with different cement types.
abstract: OBJECTIVE
  This study aimed to evaluate the vertical misfit and microleakage of laser-sintered and vacuum-cast cement-retained implant-supported frameworks.
  
  
  METHODS
  Three-unit implant-fixed structures were constructed with: (1) laser-sintered Co-Cr (LS); (2) vacuum-cast Co-Cr (CC); and (3) vacuum-cast Pd-Au (CP). Every framework was luted onto 2 prefabricated abutments under constant seating pressure. Each alloy group was randomly divided into three subgroups (n=10) according to the cement used: (1) Ketac Cem Plus (KC); (2) Panavia F 2.0 (PF); and (3) RelyX Unicem 2 Automix (RXU). After 30 days of water ageing, vertical discrepancy was measured by SEM, and marginal microleakage was scored using a digital microscope. Three-way ANOVA and Student-Newman-Keuls tests were run to investigate the effect of alloy/fabrication technique, FDP retainer, and cement type on vertical misfit. Data for marginal microleakage were analysed with Kruskal-Wallis and Dunn's tests (α=0.05).
  
  
  RESULTS
  Vertical discrepancy was affected by alloy/manufacturing technique and cement type (p<0.001). Despite the luting agent, LS structures showed the best marginal adaptation, followed by CP, and CC. Within each alloy group, KC provided the best fit, whilst the use of PF or RXU resulted in no significant differences. Regardless of the framework alloy, KC exhibited the highest microleakage scores, whilst PF and RXU showed values that were comparable to each other.
  
  
  CONCLUSIONS
  Laser-sintered Co-Cr structures achieved the best fit in the study. Notwithstanding the framework alloy, resin-modified glass-ionomer demonstrated better marginal fit but greater microleakage than did MDP-based and self-adhesive dual-cure resin cements. All groups were within the clinically acceptable misfit range.
  
  
  CONCLUSIONS
  Laser-sintered Co-Cr may be an alternative to cast base metal and noble alloys to obtain passive-fitting structures. Despite showing higher discrepancies, resin cements displayed lower microleakage than resin-modified glass-ionomer. Further research is necessary to determine whether low microleakage scores may guarantee a suitable seal that could compensate for misfit.
authors: Department of Buccofacial Prostheses, Faculty of Dentistry, Complutense University of Madrid (U.C.M.), Pza, Ramón y Cajal, s/n, 28040 Madrid, Spain. raquel.castillo@odon.ucm.es
authors: Raquel Castillo
authors: RC
authors: Oyagüe
authors: Andrés
authors: A
authors: Sánchez-Turrión
authors: José Francisco
authors: JF
authors: López-Lozano
authors: M Jesús
authors: MJ
authors: Suárez-García
mesh_terms: D002484:Cementation / Q000379:methods*; D002858:Chromium Alloys / Q000737:chemistry; D000044:Dental Abutments; D003735:Dental Casting Technique; D003738:Dental Cements / Q000737:chemistry*; D003763:Dental Leakage / Q000145:classification*; D018772:Dental Marginal Adaptation; D019094:Dental Prosthesis, Implant-Supported; D003781:Denture Retention; D003830:Denture, Partial, Fixed; D005899:Glass Ionomer Cements / Q000737:chemistry; D006047:Gold Alloys / Q000737:chemistry; D006801:Humans; D007834:Lasers; D008277:Magnesium Oxide / Q000737:chemistry; D008422:Materials Testing; D016876:Metal Ceramic Alloys / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D010165:Palladium / Q000737:chemistry; D011076:Polycarboxylate Cement / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D013499:Surface Properties; D013997:Time Factors; D014618:Vacuum; D014867:Water / Q000737:chemistry; D015034:Zinc Oxide / Q000737:chemistry
chemical_list: D002858:Chromium Alloys; D003738:Dental Cements; D005899:Glass Ionomer Cements; D006047:Gold Alloys; D016876:Metal Ceramic Alloys; C438843:Panavia-Fluoro; D011076:Polycarboxylate Cement; C483701:Rely X Unicem; D019279:Resin Cements; D014867:Water; D008277:Magnesium Oxide; D010165:Palladium; C040235:Ketac-cem; D015034:Zinc Oxide