6 PIO09_Salvato_48-53
26-10-2009
12:56
Pagina 48
1 Plaster and digital models reliability of measurements
Traditional plaster casts and dental digital models: intra-examiner reliability of measurements Rossella Mangiacapra* DDS, Andrea Carlo Butti** DDS, MSc, Antonino Salvato*** MD, DDS, MSc, Roberto Biagi**** MD, DDS, MSc Department of Orthodontics, School of Dentistry, University of Milan, Milan, Italy. Chairman: Prof. A. Salvato * ** *** ****
Postgraduate Student of Orthodontics Visiting Professor of Orthodontics Professor of Orthodontics Assistant Professor of Paediatric Dentistry
Correspondence to: Andrea Carlo Butti Unità Operativa di Ortognatodonzia Università degli Studi di Milano Istituto Stomatologico Italiano Via Pace 21, 20122 Milano, Italy E-mail:
[email protected]
Introduction Dental casts have always been a peculiar tool in the orthodontic diagnosis and, during or after the therapy, they are often used to evaluate the degree of results achieved. Dental models are useful in forensic procedures too. Lately, also dental digital models have become available. They are extremely easy to be stored and retrieved from databases, they take up little space and can be sent over the Internet. Digital models cannot be damaged by accidental falls, but of course it is important to back up often. If needed, a digital model could be transformed formed to a real a real one through different techniques1. No-
48
The aim of this study was to compare the intra-examiner reliability of measurements made on plaster cast and dental digital models. Material and methods. Five young patients with different occlusal patterns were selected and their dental casts and corresponding digital models were obtained. Twenty expert orthodontists were asked to measure two times both the traditional and digital models. The measurements taken included: lower inter-canine distance, lower inter-molar distance, lower right first molar mesio-distal length, lower right lateral incisor mesiodistal length and overbite. The absolute differences between the two sets of repeated measurements were computed for each of the five couples of parameters and compared with Student's paired T tests. Results. Four parameters showed no statistical difference when the error of measurement of the traditional models was compared to the error of measurement of the digital models. They where the lower inter-canine distance (p=0.11), the lower inter-molar distance (p=0.24), the lower right first molar mesio-distal length (p=0.4), the lower right lateral incisor mesio-distal length (p=0.39). On the contrary, the error of measurement for the overbite was lower (P
