Table 2 Definition on dental anomalies and characteristics

 Hypoplasia

Quantitative macroscopic defect of the enamel, reduced thickness of enamel. The borders of the defect should be rounded and smooth [9, 10]. The pits should be of significant size or appear more than once on the surface of the tooth.

 Invagination

A clear outline of enamel inside the second maxillary incisors [16] (4.24)^a.

 Short root

Short root is when the root appears distinctly shortened compared to mean root length [16] (4.29)^a.

 Blunting of root apex

Root ends with a clear blunting of apex [7].

 Obliteration of pulp canal

The pulp canal is not visible on radiographs, because of deposits occluding the root canal [16] (4.47)^a.

 Pulp calcification

Foci of calcification in the dental pulp. Radiographically visible opaque structures in the pulp chambers. They may occur as a single dense mass or as several small radioopacities [8]. Pulp calcification was assessed on molars only.

 Root flexion

A minimum of a 45 degrees bend between the axis for the apical respective the coronal part of the root.

 Impaction

Absence of tooth eruption due to an obstacle in the eruption path or ectopic position of the tooth germ [11].

 Primary retention

Absence of tooth eruption without an obstacle in the eruption path or ectopic position of the tooth germ before gingival emergence [11].

 Secondary retention

Arrested eruption after gingival emergence [11].

 Hypodontia

Congenital absence of at least one permanent tooth or tooth germ, seen as persistence of primary teeth [15].

 Hyperdontia

Teeth present in addition to the normal tooth set, seen in the permanent dentition [14].

 Sagittal molar occlusion

(if first molar is missing the canine and premolar relationship are the guide [15])

 Class I

The mesiobuccal cusp of the upper first molars occludes in the mesiobuccal fossa of lower first molar [12].

 Class II

The mesiobuccal cusp of the upper first molar occludes ≥ ½ width mesial to the mesiobuccal sulcus of lower first molar [12].

 Class III

The mesiobuccally cusp of the upper first molar occludes ≥ ½ premolar width distal to the mesiobuccal sulcus of lower first molar [12].

 Lateral cross bite

The buccal cusp of the maxillary tooth occludes lingually to the buccal cusp of the mandibular tooth; minimum two teeth in one side (M, P, C) [16] (4.62)^a.

 Open bite

Vertical distance between incisal edges of incisors perpendicular to occlusal plane > 0 [46] (4.61)^a.

 Overbite, increased

Maxillary anterior teeth cover the crown of the mandibular teeth totally [16] (4.63)^a.

 Crowding of teeth

Deficit of space in the dental arch visible by severely rotated teeth and/or buccally or lingually displaced teeth [16] (4.57)^a

Midline diastema

Space between the upper central incisors > 1 mm.

 Spaced teeth

Diastema in multiple places (≥4) in the lower or the upper dental arch [16] (4.58)^a.

 Ectopic position

Tooth totally displaced outside the normal position in the dental arch [13].