Table 3.

Comparison of Open Gingival Embrasure Spaces Between the Nonoccurrence and Occurrence Groups in the Maxilla and Mandible^a

Measurement	Maxilla			Mandible
	Nonoccurrence	Occurrence	Significance	Nonoccurrence	Occurrence	Significance
	(n = 78)	(n = 22)		(n = 64)	(n = 36)
Treatment duration, mo	23.10 ± 2.00	28.12 ± 2.31	NS	24.67 ± 3.51	24.10 ± 1.41	NS
Age, y	23.91 ± 7.30	27.77 ± 8.63	NS	23.97 ± 6.04	26.17 ± 10.07	NS
Δ U1 to SN/Δ IMPA, °	−6.60 ± 9.33	−10.45 ± 9.43	NS	−2.21 ± 6.29	−6.75 ± 6.43	*
Horizontal movement of U1/L1, mm	−2.74 ± 3.70	−4.94 ± 3.80	*	−2.18 ± 3.60	−3.51 ± 3.11	NS
Vertical movement of U1/L1, mm	−0.29 ± 1.66	−0.80 ± 1.97	NS	−0.37 ± 2.66	−1.66 ± 1.84	*
Crown ratio (tooth shape)	1.24 ± 0.12	1.28 ± 0.10	NS	1.25 ± 0.14	1.33 ± 0.09	*
Root angulation at T2, °	−2.21 ± 6.12	−3.55 ± 6.03	NS	−2.26 ± 4.63	−2.71 ± 5.19	NS
Right CEJ–left CEJ distance at T2, mm	1.60 ± 0.49	1.70 ± 0.40	NS	1.45 ± 0.36	1.59 ± 0.43	NS
Distance from ICP to ABC at T1, mm	4.67 ± 0.80	5.04 ± 0.91	NS	4.42 ± 0.63	4.90 ± 0.87	*
Distance from ICP to ABC at T2, mm	5.06 ± 0.79	5.51 ± 0.95	*	4.97 ± 0.53	5.85 ± 1.05	***
Δ Distance from ICP to ABC, mm	−0.39 ± 0.61	−0.47 ± 0.84	NS	−0.56 ± 0.49	−0.95 ± 1.03	*
Crowding
A-P overlapped distance, mm	0.55 ± 0.66	0.91 ± 0.71	*	0.30 ± 0.58	0.31 ± 0.50	NS
Transverse overlapped distance, mm	0.21 ± 0.09	0.21 ± 0.78	NS	0.38 ± 0.43	0.63 ± 0.88	NS
Rotation, °	8.43 ± 6.00	9.23 ± 8.53	NS	10.96 ± 4.97	10.25 ± 7.47	NS

^aIndependent t-tests were used to compare between the nonoccurrence and occurrence groups, and Bonferroni correction was performed. Regarding root angulation, a negative value indicates that the two roots diverge apically.

NS indicates not significant; U1, maxillary incisor; L1, mandibular incisor; SN, Sella-Nasion; IMPA, incisor mandibular plane angle; T1, before treatment; T2, after treatment; Δ, T2-T1; CEJ, cementoenamel junction; ICP, interproximal contact point; ABC, alveolar bone crest; A-P, antero-posterior.

^*P < .05; *** P < .001.