Three-dimensional assessment of teeth first-, second- and third-order position in Caucasian and African subjects with ideal occlusion

Progress in Orthodontics

Table 1 Inclusion criteria

Adult age (not less than 18 years)	No previous orthodontic treatment
Regular arch form with little or no crowding	Complete dentition to second molars
No bridges or implants	Centred midlines
No gingival recession	No joint or muscle pathologies
No ectopic teeth	No supernumerary teeth or tooth agenesis
At least four of Andrews’ six keys with bilateral molar and canine class I occlusion always present	Presence of minimal diastems and/or small premolar rotation or little irregularity (Little’s index less than 3) at incisors in some individuals
Overbite and overjet within normal limits 2 mm ± 1 mm	No anterior or posterior cross-bite
No markedly visible intra-oral or extra-oral symmetry