title: A comparison of the accuracy of two methods used by pre-doctoral students to measure vertical dimension.
abstract: BACKGROUND
  Measuring vertical dimension is a soft-tissue measurement. Therefore, inaccuracy may occur.
  
  
  OBJECTIVE
  The purpose of this study is to compare the accuracy of the Willis gauge method with the caliper method.
  
  
  METHODS
  The Willis gauge measures the distance between the septum of the nose and the chin. The caliper method measures the distance between reference points on the tip of the nose and the chin. Twenty predoctoral students applied both methods 10 times in measuring the rest vertical dimension (RVD) and the occlusal vertical dimension (OVD) of a single edentulous patient. The measurements obtained from one experienced clinician were selected as controls for the interocclusal distances (IOD) for the Willis and the caliper methods, respectively. One-sided t tests and a 1-sided nonparametric test were used to determine significant differences between the 2 methods (alpha=.05).
  
  
  RESULTS
  The variances in the RVD values for the Willis gauge method were higher than for the caliper method for most students. A Wilcoxon signed rank test showed that the accuracy of the OVD measurements for the caliper method was significantly better than for the Willis gauge method (P=.001). This was not the case for the RVD measurements (P=.073). The average IOD for the Willis method was significantly higher than the control IOD (P=.026). The average IOD for the caliper method was not significantly larger than the control (P=.1303).
  
  
  CONCLUSIONS
  This study showed that the use of the caliper method by predoctoral students was a significantly more reliable method of measuring the OVD for the patient evaluated.
authors.affiliation: Division of Prosthodontics, School for Oral Health Sciences, University of Stellenbosch, Tygerberg, South Africa. gavmg@sun.ac.za
authors.forename: G A V M
authors.initials: GA
authors.lastname: Geerts
authors.forename: M E
authors.initials: ME
authors.lastname: Stuhlinger
authors.forename: D G
authors.initials: DG
authors.lastname: Nel
mesh_terms: D002680:Chin / Q000033:anatomy & histology; D006801:Humans; D007574:Jaw Relation Record / Q000295:instrumentation / Q000379:methods*; D009066:Mouth, Edentulous / Q000473:pathology; D009666:Nose / Q000033:anatomy & histology; D011476:Prosthodontics / Q000193:education; D015203:Reproducibility of Results; D018709:Statistics, Nonparametric; D013335:Students, Dental; D014716:Vertical Dimension