Table 2 Definitions of the measurements used in the study

Quantitative basal measurements

MBW

The maxillary first molar basal width dimension was measured along the nasal floor reference plane, following the line created by the outside corners of the right and left sides of the maxillary base (lateral limits)

PMBW

The maxillary first premolar basal width dimension was measured at the nasal floor reference plane along a line formed by the outside edges of the right and left sides of the maxillary base (lateral limits)

AD

Arch depth was equally distant between the inter-molar line (right /left buccal cusps at the centre of the maxillary first molars) and the mid-palatal point

Quantitative Dentoalveolar measurements

MAW

The maxillary first molar alveolar width measure was measured on the first molar coronal slice between the most occlusal sites of the maxillary alveolar process

PMAW

The maxillary first premolar alveolar width was measured on the first premolar coronal slice between the most occlusal sites of the maxillary alveolar process

IMW

The inter-molar width was determined by measuring the width between the right and left mesiobuccal cusp at the centre of the maxillary first molars

IPW

The inter-premolar width was determined by measuring the width between a set position in the right and left buccal cusps at the centre of the maxillary first premolars

ICW

The inter-canine width was determined by measuring the width between the right and left centre of the maxillary canines

AL

The arch length defined as the distance between the mesial contact point of the incisors and the inter-molar plane perpendicular to the midline

AP

The arch perimeter was measured from one side's mesiobuccal cusp of the first permanent molar to the other side's mesiobuccal cusp of the molar

Quantitative Dental measurements

CL

The canine length was determined by measuring from the edge of the incisal to the root apex

CW

The canine width was measured from the mesial point of contact to the distal point of contact