title: Clinical Marginal and Internal Fit of Crowns Fabricated Using Different CAD/CAM Technologies.
abstract: OBJECTIVE
  The aims of this in vivo investigation were to compare the marginal and internal fit of single-unit crowns fabricated using a selective laser melting (SLM) procedure with two CAD/CAM grinding procedures, and to evaluate the influence of tooth type on the parameters measured.
  
  
  METHODS
  A total of 270 crowns were evaluated, including 90 SLM metal-ceramic crowns (group B), 90 zirconium-oxide-based ceramic crowns (group L), and 90 lithium disilicate ceramic crowns (group C). The marginal and internal gaps of the crowns were recorded using a replica technique with a silicone indicator paste stabilized with a light-body silicone. The gap replica specimen were sectioned buccolingually and mesiodistally and then examined using a stereomicroscope at 30× magnification. Ten reference points were measured on each anterior and premolar specimen, and 20 reference points were measured on each molar specimen. Two-way ANOVA was performed to identify the significant differences between the groups.
  
  
  RESULTS
  The mean marginal fit of group B was significantly better than those of group C and group L (p < 0.005), but a significant difference was not found between group C and group L (p > 0.05). The mean axial gap of group B was significantly smaller than those of group C and group L (p < 0.01), while group C was not different from group L (p > 0.05). The mean occlusal gap of group B was significantly higher than those of group C and group L (p < 0.05), and no difference was found between group C and group L (p > 0.05). The marginal and internal gaps of crowns varying according to tooth type were not significantly different (p > 0.05).
  
  
  CONCLUSIONS
  The SLM system demonstrated better marginal and internal fit compared to the two CAD/CAM grinding systems examined. Tooth type did not significantly influence the marginal or internal fit.
authors.affiliation: Department of Prosthodontics, 9th People's Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, P. R. China.
authors.forename: Zhuoli
authors.initials: Z
authors.lastname: Huang
authors.affiliation: Department of Prosthodontics, 9th People's Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, P. R. China.
authors.forename: Lu
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Prosthodontics, 9th People's Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, P. R. China.
authors.forename: Jingwei
authors.initials: J
authors.lastname: Zhu
authors.affiliation: Department of Prosthodontics, 9th People's Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, P. R. China.
authors.forename: Yiwei
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Department of Prosthodontics, 9th People's Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, P. R. China.
authors.forename: Xiuyin
authors.initials: X
authors.lastname: Zhang
mesh_terms: D017076:Computer-Aided Design; D003442:Crowns; D018772:Dental Marginal Adaptation; D003776:Dental Porcelain; D017267:Dental Prosthesis Design; D006801:Humans; D016628:Replica Techniques
chemical_list: D003776:Dental Porcelain
keywords: CAD/CAM grinding technology; Fit; crown; selective laser melting