Change of Mandibular Position during Two-Phase Orthodontic Treatment of Skeletal Class II in the Chinese Population

Table 2

(a) Comparison of dentofacial morphology between the population normand the study sample at the start of treatment (T0) and after phase I (T1) and phase II (T2) treatment. (b) Comparison of dentofacial morphology with the population norm and the three subgroups at the start of treatment (T0).

(a)

Variables	Population norm		T0		T1		T2
	Mean	SD	Mean	SD	Mean	SD	Mean	SD
Sagittal
Overjet (mm)	4.3	1.76	9.8^***	3.13	0.6^***	2.91	3.9	0.88
Wits appraisal (mm)	−4.5	3.00	3.6^***	3.58	−4.3	3.34	0.2^***	3.06
Maxillary prognathism
OLp-A (mm)	76.1	3.86	80.2^**	4.25	82.4^***	4.22	83.1^***	4.25
S-N-A (°)	82.0	3.50	82.6	3.69	83.1	3.36	82.4	3.12
Mandibular prognathism
OLp-Pg (mm)	82.3	4.88	79.2^**	6.74	86.0^***	8.30	86.4^***	8.99
OLp-B (mm)	N/A	N/A	77.0	5.93	83.6	7.34	83.4	7.66
Ar-Gn	N/A	N/A	104.0	5.78	112.0	6.88	113.9	7.73
S-N-B (°)	79.0	3.00	75.1^***	3.45	77.7^*	3.93	77.1^**	4.31
Jaw base relationship
A-Pg (mm)	−6.2	3.38	1.1^***	3.76	−3.5^***	5.53	−3.3^***	5.99
A-N-B (°)	3.0	2.00	7.5^***	1.78	5.4^***	1.93	5.3^***	2.20
Maxillary incisor
OLp-is (mm)	88.1	4.54	91.8	4.89	93.0^***	5.30	93.7^***	5.40
Mandibular incisor
OLp-ii (mm)	83.8	4.44	82.0	4.75	92.4^***	5.79	89.7^***	5.13
Maxillary molar
OLp-ms (mm)	55.0	3.98	56.7	4.30	56.0	5.07	60.6^***	5.30
Mandibular molar
OLp-mi (mm)	57.7	4.26	54.6	4.95	64.6^***	6.02	64.0^***	5.88
Molar relationship
ms-mi (mm)	−2.7	1.62	2.1^***	1.77	−8.6^***	2.33	−3.4^*	2.04
Vertical
Overbite (mm)	2.2	1.51	3.2	2.60	−0.1^***	1.44	1.0	0.89
Upper face height
N-NL (mm)	54.0	3.50	57.2^***	3.48	59.7^***	3.89	60.7^***	3.55
Lower face height
NL-Me (mm)	64.0	4.00	65.5	4.54	71.0^***	5.34	72.7^***	5.52
Total face height
NSL-Me (mm)	N/A	N/A	117.8	6.50	126.4	7.23	129.0	7.16
Incisor position
is-NL (mm)	28.9	2.72	30.5	2.82	32.9^***	2.98	33.7^***	3.14
ii-ML (mm)	41.3	2.73	43.9^**	3.35	43.4^**	3.68	44.8^***	3.72
Molar position
msc-NL (mm)	21.9	2.22	23.7^*	2.25	23.1	2.74	26.0^***	3.03
mic-ML (mm)	31.8	2.41	33.2	2.25	35.9^***	2.54	37.8^***	3.09
Rotational changes
NL/NSL (°)	9.1	3.34	9.8	2.46	9.8	3.00	9.4	3.26
ML/NSL (°)	35.3	5.57	34.8	7.28	34.0	7.49	33.6	8.38

SD: Standard deviation.
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(b)

Variables	Population norm		Positive group		Stable group		Negative group
	Mean	SD	Mean	SD	Mean	SD	Mean	SD
Sagittal
Overjet (mm)	4.3	1.76	10.3^***	2.54	8.6^***	3.45	10.3^***	3.34
Wits appraisal (mm)	−4.5	3.00	3.7^***	2.60	3.4^***	2.85	3.7^***	5.13
Maxillary prognathism
OLp-A (mm)	76.1	3.86	80.6^***	3.90	78.2	4.30	81.9^***	4.04
SNA (°)	82.0	3.50	83.3	3.87	81.4	3.45	83.0	3.83
Mandibular prognathism
OLp-Pg (mm)	82.3	4.88	81.0	5.65	77.5^**	8.04	79.0^*	6.54
OLp-B (mm)	N/A	N/A	78.2	5.54	75.3	7.10	77.5	5.21
Ar-Gn	N/A	N/A	104.9	6.08	101.8	5.07	105.4	6.05
SNB (°)	79.0	3.00	76.4^***	4.26	74.2^***	3.07	74.7^***	2.83
Jaw base relationship
A-Pg (mm)	−6.2	3.38	−0.4^***	2.98	0.7^***	4.40	2.9^***	3.35
ANB (°)	3.0	2.00	6.9^***	2.03	7.2^***	1.50	8.3^***	1.65
Maxillary incisor
OLp-is (mm)	88.1	4.54	92.6^***	4.64	88.6	3.64	94.2^***	4.89
Mandibular incisor
OLp-ii (mm)	83.8	4.44	82.3	4.59	80.0	4.51	83.9	4.80
Maxillary molar
OLp-ms (mm)	55.0	3.98	56.4	4.53	56.0	4.68	57.7	3.93
Mandibular molar
OLp-mi (mm)	57.7	4.26	54.2	5.01	53.6	5.44	56.1	4.51
Molar relationship (mm)
ms-mi (mm)	−2.7	1.62	2.1^***	1.81	2.4^***	1.70	1.6^***	1.88
Vertical
Overbite (mm)	2.2	1.51	4.4^***	1.61	2.9	2.93	2.2	2.76
Upper face height
N-NL (mm)	54.0	3.50	56.4	2.68	56.0	2.27	59.2^***	4.48
Lower face height
NL-Me (mm)	64.0	4.00	64.3	4.07	64.1	2.70	68.0	5.63
Total face height
NSL-Me (mm)	N/A	N/A	116.6	5.17	114.7	4.52	122.2	7.40
Incisor position
is-NL (mm)	28.9	2.72	30.3	2.84	30.0	2.48	31.1^*	3.27
ii-ML (mm)	41.3	2.73	43.5^*	2.21	42.3	1.72	45.9^***	4.56
Molar position
msc-NL (mm)	21.9	2.22	23.5^*	2.38	23.6^*	1.96	23.9^**	2.59
mic-ML (mm)	31.8	2.41	32.8	2.22	32.8	1.98	34.1^**	2.51
Rotational changes
NL/NSL (°)	9.1	3.34	8.8	2.04	11.3^*	2.46	9.4	2.33
ML/NSL (°)	35.3	5.57	31.1^*	8.11	35.1	6.40	38.1	6.00

SD: Standard deviation.
.