title: Adaptation of all-ceramic fixed partial dentures.
abstract: OBJECTIVE
  To measure the marginal and internal fit of three-unit fixed partial dentures (FPDs) using the micro-CT technique, testing the null hypothesis that there is no difference in the adaptation between the ceramic systems studied.
  
  
  METHODS
  Stainless steel models of prepared abutments were fabricated to design the FPDs. Ten FPDs were produced from each framework ceramic (YZ - Vita In-Ceram YZ and IZ - Vita In-Ceram Zirconia) using CEREC inLab according to the manufacturer instructions. All FPDs were veneered using the recommended porcelain. Each FPD was seated on the original model and scanned using micro-CT. Files were processed using NRecon and CTAn software. Adobe Photoshop and Image J software were used to analyze the cross-sections images. Five measuring locations were used as follows: MG - marginal gap; CA - chamfer area; AW - axial wall; AOT - axio-occlusal transition area; OA - occlusal area. The horizontal marginal discrepancy (HMD) was evaluated in another set of images. Results were statistically analyzed using ANOVA and Tukey tests (α=0.05).
  
  
  RESULTS
  The mean values for MG, CA, AW, OA and HMD were significantly different for all tested groups (p<0.05). IZ exhibited greater mean values than YZ for all measuring locations except for AW and AOT. OA showed the greatest mean gap values for both ceramic systems. MG and AW mean gap values were low for both systems.
  
  
  CONCLUSIONS
  The ceramic systems evaluated showed different levels of marginal and internal fit, rejecting the study hypothesis. Yet, both ceramic systems showed clinically acceptable marginal and internal fit.
authors.affiliation: Post-Graduation Program in Dentistry, University of Passo Fundo, Passo Fundo, RS, Brazil.
authors.forename: Márcia
authors.initials: M
authors.lastname: Borba
authors.forename: Paulo F
authors.initials: PF
authors.lastname: Cesar
authors.forename: Jason A
authors.initials: JA
authors.lastname: Griggs
authors.forename: Álvaro
authors.initials: Á
authors.lastname: Della Bona
mesh_terms: D000704:Analysis of Variance; D017076:Computer-Aided Design; D003442:Crowns; D018772:Dental Marginal Adaptation; D003776:Dental Porcelain; D003779:Denture Design; D003830:Denture, Partial, Fixed; D006801:Humans; D003765:Models, Dental; D018709:Statistics, Nonparametric; D055114:X-Ray Microtomography; D015019:Yttrium; D015040:Zirconium
chemical_list: C499362:yttria stabilized tetragonal zirconia; D003776:Dental Porcelain; D015019:Yttrium; D015040:Zirconium; C028541:zirconium oxide