Accuracy of Dental Dimensions Measured in Plaster Models and Three-dimensional Print Outs of Cone-Beam Computer Tomography Images

Objectives: The purpose of this study was to determine and compare the accuracy of dental measurements obtained from conventional plaster models and the respective three-dimensional printout models of respective cone-beam computer tomographies (CBCT).
Methods: Seventeen patients had CBCTs and plaster models taken for diagnostic purposes. CBCTs were segmented to only keep the dental maxillary and mandibular structures. These segmentations were then sent to a custom milling laboratory and three-dimensional model print outs were obtained. The plaster models and the three-dimensional print outs were measured using a slide caliper rounded to the nearest 0.01 mm. 52 dental points were assessed: length and width of each tooth, upper and lower intercanine widths and intermolar widths. Reliability was assessed measuring 10 plaster models three times and analyzed using interclass correlation coefficient. Descriptive statistics and paired sample t-test was used to compare the differences between the plaster models and the three dimensional models measurements.
Results: Differences between measurements from both type of models were found. Although, some were statistically different, clinically were not significant. The largest differences between both models was a mean of -2.23824 and a standard deviation of 1.18055 for the height of the lateral incisor in quadrant one and a mean of -2.28294 and a standard deviation of 0.78473 for the height of the lateral incisor in quadrant 2.
Conclusions: Measurements on the three dimensional models printed from CBCTs were comparable with conventional plaster models. Height measurements in printed models were higher since they show bone level and not gingival level as plaster models.