This study intended to determine the differences of space analysis in four groups each with a different
level of crowding severity using digital models of impressions and compared with the plaster models. One hundred
and twenty upper and lower plaster models were divided into four groups according to the crowding severity: group
1, no crowding; group 2, lack of space less than 2 mm; group 3, lack of space 2–4 mm; and group 4, more than 4
mm. These models were converted to digital models by impression scanning using the 3Shape R700™ scanner.
Tooth size and segmental arch length measurement were performed on the plaster models using a digital caliper
with a scale precision of 0.01 mm and digital models using the 3Shape OrthoAnalyzer™ software. Space discrepancy
of each study model was calculated. Independent t-test and Wilcoxon rank-sum test were used to compare sum
of tooth size, segmental arch length, and space discrepancy. No statistically significant differences were found between
the plaster and digital models for sum of tooth size, segmental arch length or space discrepancy measurement in
any group of crowding. The use of digital models obtained from the 3Shape R700™ scanner appears to be acceptable
in tooth size, segmental arch length, and space discrepancy measurements.