title: Marginal and internal fit of nano-composite CAD/CAM restorations.
abstract: OBJECTIVE
  The purpose of this study was to compare the marginal and internal fit of nano-composite CAD-CAM restorations.
  
  
  METHODS
  A full veneer crown and an mesio-occluso-distal (MOD) inlay cavity, which were prepared on extracted human molars, were used as templates of epoxy resin replicas. The prepared teeth were scanned and CAD-CAM restorations were milled using Lava Ultimate (LU) and experimental nano-composite CAD/CAM blocks (EB) under the same milling parameters. To assess the marginal and internal fit, the restorations were cemented to replicas and were embedded in an acrylic mold for sectioning at 0.5 mm intervals. The measured gap data were pooled according to the block types and measuring points for statistical analysis.
  
  
  RESULTS
  Both the block type and measuring point significantly affected gap values, and their interaction was significant (p = 0.000). In crowns and inlays made from the two blocks, gap values were significantly larger in the occlusal area than in the axial area, while gap values in the marginal area were smallest (p < 0.001). Among the blocks, the restorations milled from EB had a significantly larger gap at all measuring points than those milled from LU (p = 0.000).
  
  
  CONCLUSIONS
  The marginal and internal gaps of the two nano-composite CAD/CAM blocks differed according to the measuring points. Among the internal area of the two nano-composite CAD/CAM restorations, occlusal gap data were significantly larger than axial gap data. The EB crowns and inlays had significantly larger gaps than LU restorations.
authors.affiliation: Seoul National University Dental Hospital, Seoul, Korea.
authors.forename: So-Hyun
authors.initials: SH
authors.lastname: Park
authors.affiliation: Department of Conservative Dentistry, Seoul National University School of Dentistry and Dental Research Institute, Seoul, Korea.
authors.forename: Yeon-Jee
authors.identifier: 0000-0002-3931-7668
authors.initials: YJ
authors.lastname: Yoo
authors.affiliation: Department of Conservative Dentistry, Seoul National University School of Dentistry and Dental Research Institute, Seoul, Korea.
authors.forename: Yoo-Jin
authors.initials: YJ
authors.lastname: Shin
authors.affiliation: Department of Conservative Dentistry, Seoul National University School of Dentistry and Dental Research Institute, Seoul, Korea.
authors.forename: Byeong-Hoon
authors.identifier: 0000-0001-9641-5507
authors.initials: BH
authors.lastname: Cho
authors.affiliation: Department of Conservative Dentistry, Seoul National University School of Dentistry and Dental Research Institute, Seoul, Korea.
authors.forename: Seung-Ho
authors.identifier: 0000-0003-2594-2283
authors.initials: SH
authors.lastname: Baek
keywords: Internal gap; Lava ultimate; Marginal gap; Nano-composite CAD/CAM blocks