. Author manuscript; available in PMC: 2013 May 1.

Published in final edited form as: Angle Orthod. 2012 Oct 8;83(3):376–380. doi: 10.2319/071112-573.1

Table 1.

Characteristics of Subjects/Patients (N = 74) at Enrollment Grouped by Those With No Mandibular Premolars Removed (n = 24), Mandibular First Premolars Removed (n = 25), or Second Premolars Removed (n = 25) as Part of Orthodontic Treatment

	Subjects With No Premolars Removed	Subjects With First Premolars Removed	Subjects With Second Premolars Removed	P Value

	n (%)	n (%)	n (%)
Female	14 (58)	14 (56)	11 (44)	.56
Male	10 (42)	11 (44)	14 (56)
White	19 (80)	11 (44)	17 (68)	.17
African American	2 (8)	10 (40)	5 (20)
Other	3 (12)	4 (16)	3 (12)
Age at start of orthodontic treatment, y	Mean (SD)	Mean (SD)	Mean (SD)	.60
	12.8 (0.6)	13.2 (1.7)	12.8 (1.4)
Length of orthodontic treatment, y	Mean (SD)	Mean (SD)	Mean (SD)	.01
	2.3 (0.6)	2.5 (0.5)	2.7 (0.4)