title: Digital assessment of preliminary impression accuracy for edentulous jaws: Comparisons of 3-dimensional surfaces between study and working casts.
abstract: OBJECTIVE
  The aim of this study was to compare 3-dimensional surfaces of study and working casts for edentulous jaws and to evaluate the accuracy of preliminary impressions with a view to the future application of digital dentistry for edentulous jaws.
  
  
  METHODS
  Forty edentulous volunteers were serially recruited. Nine dentists took preliminary and final impressions in a routine clinical work-up. The study and working casts were digitized using a dental 3-dimensional scanner. The two surface images were superimposed through a least-square algorithm using imaging software and compared qualitatively. Furthermore, the surface of each jaw was divided into 6 sections, and the difference between the 2 images was quantitatively evaluated.
  
  
  RESULTS
  Overall inspection showed that the difference around residual ridges was small and that around borders were large. The mean differences in the upper and lower jaws were 0.26mm and 0.45mm, respectively. The maximum values of the differences showed that the upward change mainly occurred in the anterior residual ridge, and the downward change mainly in the posterior border seal, and the labial and buccal vestibules, whereas every border of final impression was shortened in the lower jaw. The accuracy in all areas except the border, which forms the foundation, was estimated to be less than 0.25mm.
  
  
  CONCLUSIONS
  Using digital technology, we here showed the overall and sectional accuracy of the preliminary impression for edentulous jaws. In our clinic, preliminary impressions have been made using an alginate material while ensuring that the requisite impression area was covered.
authors.affiliation: Department of Oral and Maxillofacial Prosthodontics, Institute of Biomedical Sciences, Tokushima University Graduate School, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Matsuda
authors.affiliation: Department of Oral and Maxillofacial Prosthodontics, Institute of Biomedical Sciences, Tokushima University Graduate School, Japan. Electronic address: tak510@tokushima-u.ac.jp.
authors.forename: Takaharu
authors.initials: T
authors.lastname: Goto
authors.affiliation: Department of Oral and Maxillofacial Prosthodontics, Institute of Biomedical Sciences, Tokushima University Graduate School, Japan.
authors.forename: Kosuke
authors.initials: K
authors.lastname: Kurahashi
authors.affiliation: Department of Oral and Maxillofacial Prosthodontics, Institute of Biomedical Sciences, Tokushima University Graduate School, Japan.
authors.forename: Toshiya
authors.initials: T
authors.lastname: Kashiwabara
authors.affiliation: Department of Oral and Maxillofacial Prosthodontics, Institute of Biomedical Sciences, Tokushima University Graduate School, Japan.
authors.forename: Megumi
authors.initials: M
authors.lastname: Watanabe
authors.affiliation: Oral Implant Center, Tokushima University Hospital, Japan.
authors.forename: Yoritoki
authors.initials: Y
authors.lastname: Tomotake
authors.affiliation: Department of Oral and Maxillofacial Prosthodontics, Institute of Biomedical Sciences, Tokushima University Graduate School, Japan.
authors.forename: Kan
authors.initials: K
authors.lastname: Nagao
authors.affiliation: Department of Oral and Maxillofacial Prosthodontics, Institute of Biomedical Sciences, Tokushima University Graduate School, Japan.
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Ichikawa
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003734:Dental Casting Investment; D003761:Dental Impression Technique; D006801:Humans; D021621:Imaging, Three-Dimensional; D007575:Jaw, Edentulous; D012984:Software
chemical_list: D003734:Dental Casting Investment
keywords: Complete denture; Digital dentistry; Edentulous; Impression; Scanner