Inclusion criteria were the following: patients had to be Mexican born from Mexican parents, of both genders 37 male and 73 females, age ranking from 18 to 25 years. With no prior prosthetic or orthodontic treatment and presenting occlusion considered normal Angle's Class I in molar and canines, 1 to 2 mm horizontal overbite 1 to 3 mm vertical overbite, <1.5 crowding, as well as no clinical proof of temporomandibular articulation problems.
Los criterios de inclusión fueron: nacionalidad mexicana y de padres mexicanos, ambos sexos 37 hombres y 73 mujeres, de 18 a 25 años de edad, sin tratamientos protésicos u ortodóncicos previos y con oclusiones consideradas normales Clase I de molares y caninos, sobremordida horizontal entre 1 y 2 mm, sobremordida vertical entre 1 y 3 mm, apiñamiento < 1.5 mm y sin observarse clínicamente problemas de la articulación temporomandibular.