title: Can Tooth Preparation Design Affect the Fit of CAD/CAM Restorations?
abstract: OBJECTIVE
  The purpose of this study was to evaluate if the marginal fit of computer-aided design and computer-aided manufacturing (CAD/CAM) restorations manufactured with CAD/CAM systems can be affected by different tooth preparation designs.
  
  
  METHODS
  Twenty-six typodont (plastic) teeth were divided into two groups (n = 13) according to the occlusal curvature of the tooth preparation. These were the group 1 (control group) (flat occlusal design) and group 2 (curved occlusal design). Scanning of the preparations was performed, and crowns were milled using ceramic blocks. Blocks were cemented using epoxy glue on the pulpal floor only, and finger pressure was applied for 1 minute. On completion of the cementation step, poor fits between the restoration and abutment were measured by microphotography and the silicone replica technique using light-body silicon material on mesial, distal, buccal, and lingual surfaces.
  
  
  RESULTS
  Two-way ANOVA analysis did not reveal a statistical difference between flat (83.61 ± 50.72) and curved (79.04 ± 30.97) preparation designs. Buccal, mesial, lingual, and distal sites on the curved design preparation showed less of a gap when compared with flat design. No difference was found on flat preparations among mesial, buccal, and distal sites (P < .05). The lingual aspect had no difference from the distal side but showed a statistically significant difference from mesial and buccal (P < .05).
  
  
  CONCLUSIONS
  Difference in occlusal design did not significantly impact the marginal fit. Marginal fit was significantly affected by the location of the margin; lingual and distal locations exhibited greater margin gap values compared with buccal and mesial sites regardless of the preparation design.
authors.affiliation: Associate Professor, Case Western Reserve University, School of Dental Medicine, Cleveland, Ohio.
authors.forename: Renato Cassio
authors.initials: RC
authors.lastname: Roperto
authors.affiliation: Researcher, Case Western Reserve University, School of Dental Medicine, Cleveland, Ohio.
authors.forename: Marina Piolli
authors.initials: MP
authors.lastname: Oliveira
authors.affiliation: Researcher, Case Western Reserve University, School of Dental Medicine, Cleveland, Ohio.
authors.forename: Thiago Soares
authors.initials: TS
authors.lastname: Porto
authors.affiliation: Researcher, Case Western Reserve University, School of Dental Medicine, Cleveland, Ohio.
authors.forename: Lais Alaberti
authors.initials: LA
authors.lastname: Ferreira
authors.affiliation: Researcher, Case Western Reserve University, School of Dental Medicine, Cleveland, Ohio.
authors.forename: Lucas Simino
authors.initials: LS
authors.lastname: Melo
authors.affiliation: Assistant Professor, Case Western Reserve University, School of Dental Medicine, Cleveland, Ohio.
authors.forename: Anna
authors.initials: A
authors.lastname: Akkus
mesh_terms: D002484:Cementation / Q000379:methods; D002516:Ceramics; D017076:Computer-Aided Design; D003442:Crowns; D018772:Dental Marginal Adaptation; D017267:Dental Prosthesis Design; D006801:Humans; D019231:Tooth Preparation, Prosthodontic / Q000379:methods*