Table 1 Data collected in the study

Data on malocclusion

Extra-oral features: Patients were seated in the natural head position and the following were recorded

1. Facial profile relationship in the antero-posterior dimension (Class I, II, and III): the deepest concavity of the anterior surface of the maxilla (soft tissue A point) relative to the deepest concavity of the anterior surface of the mandible (soft tissue B point) within the sagittal plane

2. Facial profile convexity: assessed using an imaginary line connecting the glabella, subnasale, and pogonion

3. Vertical proportions of the face assessed by soft tissue Frankfort-mandibular plane angle (FMPA): The angle between Frankfort plane and the line representing the lower border of the mandible was examined relative to the occipital area. This was classified into high, average or low (both lines meet anterior to the occipital, at the occipital, posterior to the occipital; respectively)

4. Nasolabial angle (NLA): classified into acute (< 90 degrees), average (90–110 degrees), or obtuse (> 110 degrees)

5. Lips at rest: competent (meet at rest), incompetent (separated > 2 mm at rest)

6. Upper and lower lips were described as prominent (everted), average, or retrusive (inverted) relative to the true vertical line extending from subnasale

Intra-oral features

1. Crowding in both arches: no crowding, mild (2–4 mm), moderate (4–8 mm), or severe (> 8 mm)

2. Spacing in both arches: no spacing, localized, or generalized

3. Contact point deflection: no displacement, < 1 mm, 1–2 mm, 2–4 mm, or > 4 mm

4. Centerlines (CL): Upper/lower dental centerlines were examined relative to the face centreline and recorded as centred, or shifted

5. The right/left molar and canine relationship was recorded to the nearest full unit and was classified into Class I, II, or III. If the first permanent molars and/or canines were missing, no registration was made

6. Crossbite: a transverse discrepancy in the buccal segment affecting two or more teeth (no crossbite, buccal, or lingual crossbite (scissor bite))

7. Mandibular displacement (no, anterior or lateral displacement) in the presence of anterior or posterior crossbite

8. Discrepancy of the position of the head of the condyle between retrusive contact position (RCP) and intercuspal position (ICP) was examined (no discrepancy or a discrepancy of < 1 mm, 1–2 mm, or > 2 mm)

9. Incisor relationship: classified in the maximum intercuspation as Class I, Class II division 1, Class II division 2, or Class III

10. Overjet (OJ): recorded as average (2–4 mm), increased (> 4 mm), reduced (0–2 mm), or reversed (on at least two incisors)

11. Overbite (OB): recorded as increased, average, decreased, or anterior open bite (AOB)

Orthodontic need

The DHC of the IOTN: grade 1 (no need), grade 2 (little need), grade 3 (moderate need), grade 4 (great need), or grade 5 (very great need)