title: Influence of preparation design on fit and ceramic thickness of CEREC 3 partial ceramic crowns after cementation.
abstract: OBJECTIVE
  This study investigated the influence of preparation design on the marginal and internal gap and ceramic thickness of partial ceramic crowns (PCCs) fabricated with the CEREC 3 system.
  
  
  METHODS
  Sixteen extracted human mandibular molars were prepared according to two different preparation designs (n = 8): a retentive preparation design with traditional cusp capping (Group I) and a non-retentive preparation design with horizontal reduction of cusps (Group II). PCCs were fabricated from IPS Empress CAD with the CEREC 3 system. The parameters for luting space and minimum occlusal ceramic thickness were set to 30 μm and 1.5 mm, respectively. The fabricated PCCs were cemented to their corresponding teeth with self-adhesive resin cement and were then scanned by micro-computed tomography. The marginal and internal gaps were measured at pre-determined measuring points in five bucco-lingual and three mesio-distal cross-sectional images. The ceramic thicknesses of the PCCs were measured at the measuring points for cusp capping areas.
  
  
  RESULTS
  Group II (167.4 ± 76.4 μm) had a smaller overall mean gap, which included the marginal and internal gap measurements, than that of Group I (184.8 ± 89.0 μm). The internal gaps were larger than the marginal gaps, regardless of preparation design. Group I presented a thinner ceramic thickness in the cusp capping areas than the minimum occlusal ceramic thickness parameter of 1.5 mm. CONCLUSION. Preparation design had an influence on fit, particularly the internal gap of the PCCs. Ceramic thickness could be thinner than the minimum ceramic thickness parameter.
authors.affiliation: Department of Conservative Dentistry and Dental Research Institute, School of Dentistry, Seoul National University , Seoul , Republic of Korea.
authors.forename: Jae-Hoon
authors.initials: JH
authors.lastname: Kim
authors.forename: Byeong-Hoon
authors.initials: BH
authors.lastname: Cho
authors.forename: Jin-Hee
authors.initials: JH
authors.lastname: Lee
authors.forename: Soo-Jung
authors.initials: SJ
authors.lastname: Kwon
authors.forename: Young-Ah
authors.initials: YA
authors.lastname: Yi
authors.forename: Yooseok
authors.initials: Y
authors.lastname: Shin
authors.forename: Byoung-Duck
authors.initials: BD
authors.lastname: Roh
authors.forename: Deog-Gyu
authors.initials: DG
authors.lastname: Seo
mesh_terms: D002484:Cementation / Q000379:methods*; D002516:Ceramics / Q000737:chemistry*; D017076:Computer-Aided Design; D003442:Crowns / Q000145:classification; D018772:Dental Marginal Adaptation; D003776:Dental Porcelain / Q000737:chemistry*; D017267:Dental Prosthesis Design; D017268:Dental Prosthesis Retention; D006801:Humans; D008963:Molar; D011897:Random Allocation; D019279:Resin Cements / Q000737:chemistry; D013499:Surface Properties; D019231:Tooth Preparation, Prosthodontic / Q000379:methods; D055114:X-Ray Microtomography
chemical_list: D019279:Resin Cements; D003776:Dental Porcelain; C074543:Cerec
keywords: CAD/CAM; internal gap; luting space; marginal gap; micro CT