title: [Application of the pin-hole marker measurement of the irregular silicone impression accuracy].
abstract: OBJECTIVE
  To investigate the feasibility of the pin-hole marker measurement of the irregular silicone dental impression accuracy.
  
  
  METHODS
  The metal model simulating abutment preparations had triangle-formed circular needles on the surface. Two silicone impressions were made by the metal model with the corresponding pin-hole markers. The dimensional change of the markers was evaluated by stereomicroscope. The records were output by the software which could simulate the centre of a circle to measure the displacement and dimensional accuracy.
  
  
  RESULTS
  The outline of pin-hole marker was clear and shape was stable. Values of center coordinates were repeated well. The percentage of linear dimensional change of two impression samples was 0.023% and 0.042% at 48h respectively. Between two abutment preparations, the percentage of linear dimensional change of Zhermeck silicone impression increased 0.214% (45.1μm) at 1h and decreased 0.019% (4.0μm) at 48h while 3M silicone impression increased 0.087%(18.2μm) at 1h and decreased 0.09% (18.8μm) at 48h.
  
  
  CONCLUSIONS
  The pin-hole marker measurement of the irregular silicone impression accuracy was feasible.
authors.affiliation: Department of Orthodontics, Ninth People's Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, China. gongyao0328@hotmail.com
authors.forename: Yao
authors.initials: Y
authors.lastname: Gong
authors.forename: Jie
authors.initials: J
authors.lastname: Chen
authors.forename: Ye-kan
authors.initials: YK
authors.lastname: Li
authors.forename: Bin
authors.initials: B
authors.lastname: Wei
authors.forename: Gang
authors.initials: G
authors.lastname: Shen
mesh_terms: D003760:Dental Impression Materials; D003761:Dental Impression Technique; D003765:Models, Dental; D012828:Silicones
chemical_list: D003760:Dental Impression Materials; D012828:Silicones