Comparison of space analysis evaluations with digital models and plaster dental casts.
BACKGROUND
Diagnostic measurements have traditionally been made on plaster dental casts. Now, 3-dimensional digital dental models can be used. The purpose of this study was to compare space analysis measurements made on digital models with those from plaster dental casts.


METHODS
Two sets of 25 alginate impressions were taken of patients who had a permanent Class I crowded dentition. Each impression was made into a plaster cast and a 3-dimensional virtual orthodontic model (OrthoCad, Cadent, Fairview, NJ). Measurements of tooth widths at their greatest mesiodistal dimension and arch length were recorded for both types of models. Tooth widths were measured on the plaster models with a digital caliper, and arch length was measured with a piece of brass wire and a millimeter ruler. The virtual models were measured by using OrthoCad's dedicated software. The space analysis measurements were calculated for both types of models, and the extrapolated amount of crowding for each type of model was accessed. All measurements were made by 2 examiners. The resulting values were compared with nonparametric statistics, and method errors were calculated.


RESULTS
When comparing digitized models with conventional plaster dental study models, we found a slight (0.4 mm) but statistically significant difference in the space analysis measurements on the maxillary models; measurements on the mandibular models were not significantly different. No significant difference was found between the measurements of the 2 examiners.


CONCLUSIONS
The accuracy of the software for space analysis evaluation on digital models is clinically acceptable and reproducible when compared with traditional plaster study model analyses.
Leifert
Michael F
MF
Division of Orthodontics, College of Dental Medicine, Columbia University, New York, NY 10032, USA.
Leifert
Melvyn M
MM
Efstratiadis
Stella S
SS
Cangialosi
Thomas J
TJ
D002133:Calcium Sulfate; D002508:Cephalometry / Q000379:methods*; D003724:Dental Arch / Q000473:pathology*; D003734:Dental Casting Investment; D003761:Dental Impression Technique; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008311:Malocclusion, Angle Class I / Q000473:pathology; D008334:Mandible / Q000473:pathology; D008437:Maxilla / Q000473:pathology; D003765:Models, Dental; D015588:Observer Variation; D009811:Odontometry / Q000379:methods; D015203:Reproducibility of Results; D012984:Software; D014070:Tooth / Q000473:pathology; D014584:User-Computer Interface
D003734:Dental Casting Investment; D002133:Calcium Sulfate