Table 1 Detailed explanation of the measurements carried out with the necessary reference points for standardising the digital and analogue measurement. The measurements were only carried out on permanent teeth

Tooth sizes (16–26, 36–46)

Maximal mesiodistal width of the respective tooth (perpendicular to tooth axis and parallel to occlusal plane)

Crown height (12–22, 32–42)

Respective distance between the most cervical to the most incisal point (parallel to the tooth axis)

Arch perimeter (= Available space) of the maxilla (15–25)

The two lateral segments, measured from the mesial approximal contact of the first molar to the distal point of the lateral incisor on each side, should be added to the two frontal segments. These segments are defined between the distal point of the lateral incisor and the mesial point of the central incisor.

Arch perimeter (= Available space) of the mandible (35–45)

The two lateral segments, measured from the mesial approximal contact of the first molar to the distal point of the lateral incisor on each side, should be added to the two frontal segments. These segments are defined between the distal point of the lateral incisor and the mesial point of the central incisor.

Anterior and posterior arch widths maxilla

Distance between the cusps of canines and distance between the mesiobuccal cusp tips of first molars

Anterior and posterior arch widths mandible

Distance between the cusps of canines and distance between the the most gingival extension of buccal grooves of the first molar

Arch length

Distance from contact point of central incisors perpendicular to a tangent applied to the distal surfaces of first molars

Overjet

the maximum horizontal overlap of incisors

Overbite

the maximum vertical overlap of incisors

Midline deviation maxilla

Midline deviation of the upper jaw in relation to the raphe median plane

Midline deviation mandibula

Midline deviation of the lower jaw in relation to the raphe median plane

Midline deviation of the upper to the lower jaw

Midline deviation of the upper jaw in relation to the midline of the lower jaw

Duration

Time required for the aforementioned measurements to be completed (time needed for computations not included)

Computations*

Bolton 3–3

Ratio of the sum of mesiodistal widths of teeth 33–43 and 13–33 (not applicable to early mixed dentitions)

Bolton 5–5

Ratio of the sum of mesiodistal widths of teeth 35–45 and 15–25 (not applicable to early mixed dentitions)

Upper crowding/spacing (Total difference maxilla)

Difference between the available space of the dental upper arch (arch perimeter of the maxilla) and the total sum of the mesiodistal widths of 15–25

Lower crowding/spacing (Total difference mandible)

Difference between the available space of the dental lower arch (Arch perimeter of the mandible) and the total sum of the mesiodistal widths of 35–45