title: Clinical marginal and internal fit of metal ceramic crowns fabricated with a selective laser melting technology.
abstract: BACKGROUND
  Selective laser melting (SLM) technology has been introduced to fabricate dental restorations. However, the fit of these restorations still needs further study.
  
  
  OBJECTIVE
  The purpose of this in vivo investigation was to compare the marginal and internal fit of SLM metal ceramic crowns with 2 lost-wax cast metal ceramic crowns and to evaluate the influence of tooth type on the marginal and internal fit of these crowns.
  
  
  METHODS
  A total of 330 metal ceramic crowns were evaluated. The metal copings were fabricated with SLM Co-Cr, cast Au-Pt, and cast Co-Cr alloy (n=110). The marginal and internal gaps of crowns were recorded by using a replica technique. The anterior and premolar replicas were sectioned 2 times, and molar replicas were sectioned 4 times. The marginal and internal gap width of each cross section was examined by stereomicroscope at ×30 magnification. Two-way analysis of variance was performed to identify the statistical difference among the groups.
  
  
  RESULTS
  The marginal fit of the SLM Co-Cr group (75.6 ±32.6 μm) was not different from the cast Au-Pt group (76.8 ±32.1 μm) (P>.05) but was better than the cast Co-Cr group (91.0 ±36.3 μm) (P<.01). No significant difference was found among the SLM Co-Cr group (127.3 ±45.8 μm), cast Au-Pt group (129.9 ±61.1 μm). and cast Co-Cr group (142.5 ±63.7 μm) (P>.05). The mean occlusal gap width of the SLM Co-Cr group (309.8 ±106.6 μm) was significantly higher than that of the cast Au-Pt group (254.6 ±109.6 μm) and the cast Co-Cr group (249.6 ±110.4 μm) (P<.005). No significant difference was found in the marginal fit among the anterior group (84.4 ±35.1 μm), the premolar group (80.6 ±26.3 μm), and the molar group (82.7 ±38.0 μm) (P>.05). Also, no significant difference was found in the axial fit among the anterior group (138.3 ±52.5 μm), the premolar group (132.9 ±50.4 μm), and the molar group (134.4 ±52.5 μm) (P>.05). The anterior group (267.6 ±110.2 μm) did not differ from the premolar group (270.2 ±112.8 μm) and the molar group (268.6 ±110.5 μm) in occlusal fit (P>.05).
  
  
  CONCLUSIONS
  The marginal fit of SLM Co-Cr metal ceramic crowns was similar to that of the cast Au-Pt metal ceramic crowns and was better than that of the cast Co-Cr metal ceramic crowns. The SLM Co-Cr metal ceramic crowns were not significantly different from the 2 cast metal ceramic crowns in axial fit but were less accurate in occlusal fit. Tooth type did not influence the marginal and internal fit of the metal ceramic crowns.
authors: Resident, Department of Prosthodontics, 9th People's Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, P.R. China.
authors: Zhuoli
authors: Z
authors: Huang
authors: Former graduate student, Department of Prosthodontics, 9th People's Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, P.R. China.
authors: Lu
authors: L
authors: Zhang
authors: Resident, Department of Prosthodontics, 9th People's Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, P.R. China.
authors: Jingwei
authors: J
authors: Zhu
authors: Professor, Department of Prosthodontics, 9th People's Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, P.R. China. Electronic address: xiuyinzhangxyz@163.com.
authors: Xiuyin
authors: X
authors: Zhang
mesh_terms: D002858:Chromium Alloys / Q000737:chemistry; D017076:Computer-Aided Design; D003442:Crowns; D003734:Dental Casting Investment / Q000737:chemistry; D003735:Dental Casting Technique; D045662:Dental Etching / Q000379:methods; D018772:Dental Marginal Adaptation; D003776:Dental Porcelain / Q000737:chemistry; D017267:Dental Prosthesis Design; D003801:Dental Veneers; D006047:Gold Alloys / Q000737:chemistry; D006801:Humans; D007834:Lasers; D008422:Materials Testing; D016876:Metal Ceramic Alloys / Q000737:chemistry*; D010984:Platinum / Q000737:chemistry; D016628:Replica Techniques; D013499:Surface Properties; D013674:Technology, Dental
chemical_list: D002858:Chromium Alloys; D003734:Dental Casting Investment; D006047:Gold Alloys; D016876:Metal Ceramic Alloys; D003776:Dental Porcelain; D010984:Platinum