Effects of twin-block appliance on the anatomy of pharyngeal airway passage (PAP) in class II malocclusion subjects

Progress in Orthodontics

Table 2 Changes in the skeletal tissue among treatment and control group subjects

Variables	Groups						Comparison of mean difference among treatment and control groups (P-value)
	Treatment group			Control group
	Pre-treatment (T₀)	6 months post-treatment (T₁)	Significance (P-value)	Pre-follow-up (T₀)	6 months post-follow-up (T₁)	Significance (P-value)
	Mean ± SD	Mean ± SD	Significance (P-value)	Mean ± SD	Mean ± SD	Significance (P-value)
SNA (°)	81.10 ± 1.80	81.43 ± 1.86	0.097^NS	81.28 ± 1.71	81.47 ± 1.87	0.049*	0.547 ^NS
Maxillary length (mm) (ANS-PNS)	48.21 ± 3.56	48.70 ± 3.43	0.089^NS	48.50 ± 3.46	49.17 ± 3.50	0.000***	0.275^NS
Effective maxillary length (mm) (Co-A)	80.27 ± 5.37	80.56 ± 5.14	0.303^NS	81.19 ± 5.41	82.36 ± 5.04	0.002**	0.040*
SNB (°)	73.95 ± 1.91	75.85 ± 1.66	0.000***	73.94 ± 1.73	74.33 ± 1.75	0.069^NS	0.000***
Mandibular length (mm) (Go-Pog ⊥ MP)	63.21 ± 3.99	64.39 ± 4.14	0.000***	63.35 ± 4.09	63.82 ± 4.36	0.135^NS	0.004**
Effective mandibular length (mm) (Co-Gn)	96.55 ± 5.23	99.90 ± 5.54	0.000***	96.39 ± 6.84	98.52 ± 6.42	0.002**	0.007**
FMA(°)	25.48 ± 2.15	26.55 ± 2.44	0.000***	24.03 ± 2.76	24.22 ± 2.71	0.0130^NS	0.004**

SD indicates standard deviation; NS, nonsignificant; *P < .05; **P < .01; ***P < .001.
SNA, angle between ‘S,’ ‘N,’ and ‘A’; it represents the antero-posterior position of the maxilla in relation to the anterior cranial base; maxillary length, the linear distance between ‘ANS’ and ‘PNS’ points; effective maxillary length, the linear distance between ‘Co’ and ‘point A’; SNB, angle between ‘S,’ ‘N,’ and ‘B’; it represents the antero-posterior position of the mandible in relation to the anterior cranial base; mandibular length, the linear distance between ‘Go’ and the intersection of the perpendicular drawn from ‘Pog’ on mandibular plane (Go-Me); effective mandibular length, the linear distance between the ‘Co’ and ‘Gn’; FMA indicates Frankfort mandibular plane angle.