Table 2 Study cast measurements

1

Spee's curve depth (mm)

Perpendicular distance from the line joining the mesial contact points of the lower first molars to the contact point of the lower central incisors

2

Overbite (mm)

Distance from the upper central incisor tip to the lower central incisor tip and perpendicular to the occlusal plane

3

Overjet (mm)

Distance from the upper central incisor tip to a plane tangential to the lower incisor labial surface and parallel to the occlusal plane

4

Molar relationship (mm)

Distance between the mesiobuccal cusp tip of the upper first molar and the buccal groove of the lower first molar

5

Lower anterior crowding (mm)

Discrepancy between arch length and tooth size and calculated by subtracting the arch length between distal contact points of the lower canines from the total width of lower anterior teeth

6

Bolton index 3-3 (%)

The percentage ratio of total lower anterior teeth width to total upper anterior teeth width

7

Bolton index 6-6 (%)

The percentage ratio of total lower teeth width of 6-6 to total upper teeth width of 6-6