Cone beam computed tomographic evaluation of pharyngeal airway in North Indian children with different skeletal patterns

Table 1 Sample characteristics

	Group IANB < 4		Group II ANB > 4		Total
	Male	Female	Male	Female
Subjects (n)	26	30	28	36	120
Age (yr)	13-17	13-17	13-17	13-17	15.19 ± 1.28

ANB: The angle formed between point A, Nasion and point B.

Table 2 Two-dimensional cephalometric variables, cross-sectional planes and volumes of the 3-dimensional pharyngeal airway

Two-dimensional cephalometric variables
(1) Gonial angle: Angle formed between line drawn tangent to the lower border of the mandible and another line tangent to the distal border of the ascending ramus and the condyle on both sides; (2) Anterior facial height (AFH): Distance between the Nasion and Menton (Me); (3) Posterior facial height (PFH): Distance between Sella (S) to Gonion(Go); (4) PFH/AFH: Ratio of AFH and the PFH; (5) FMA: Frankfurt Mandibular Plane Angle formed by the intersection of the Frankfort horizontal plane and the mandibular plane; (6) ANB: The angle formed between point A, Nasion and Point B; (7) Facial convexity: Formed by the intersection of line from Nasion to point A, to point A to pogonion(Po); (8) Condylion to point A (Co-PtA); (9) Condylion to gnathion (Co-Gn); and (10) Mandibular body length (Mand-BL): Distance from gonion to pogonion
Cross-sectional planes and volumes of the 3D pharyngeal airway
Anterior nasal plane (Ana plane)	Plane passing through anterior nasal spine (ANS) and perpendicular to FH
Posterior nasal plane (Pna plane)	Plane passing through posterior nasal spine (PNS)and perpendicular to FH
Upper pharyngeal plane (Uph plane)	Plane passing through PNS parallel to FH
Middle pharyngeal plane (Mph plane)	Plane passing through lower margin of the soft palate and parallel to FH
Lower pharyngeal plane (Lph plane)	Plane passing through superior margin of the epiglottis and parallel to FH
Volume
Nasal airway	Airway formed by the planes between Ana and Pna
Superior pharyngeal airway	Airway formed by the planes between Pna and Uph
Middle pharyngeal airway	Airway formed by the planes between Uph and Mph
Inferior pharyngeal airway	Airway formed by the planes between Mph and Lph planes
Total airway	Airway extending between Ana plane to Lph plane

FH: Frankfurt horizontal; 3D: Three-dimensional.

Table 3 Correlations of sections of the airway with each other

	Nasal airway	Superior airway	Middle airway	Inferior airway	Totalairway
Nasal airway
Pearson correlation	1	0.085	0.471a	0.386	0.879b
Sig.(2-tailed)		0.722	0.036	0.093	0
n	120	120	120	120	120
Superior airway
Pearson correlation	0.85	1	0.494a	0.651b	0.4623a
Sig.(2-tailed)	0.722	-	0.027	0.002	0.04
n	120	120	120	120	120
Middle airway
Pearson correlation	0.471a	0.494a	1	0.763b	0.779b
Sig.(2-tailed)	0.036	0.027	-	0	0
n	120	120	120	120	120
Inferior airway
Pearson correlation	0.386	0.651b	0.763b	1	0.744b
Sig.(2-tailed)	0.093	0.002	0	-	0
n	120	120	120	120	120
Totalairway
Pearson correlation	0.879b	0.4623a	0.779b	0.744b	1
Sig.(2-tailed)	0	0.04	0	0	-
n	120	120	120	120	120

^aCorrelation is significant at 0.05 level.

^bCorrelation is significant at 0.01 level.

Table 4 Descriptive statistics of groups I and II

Group	Group I ANB < 4		Group II ANB > 4		P value
	mean	SD	mean	SD
Ana height	29.63	4.69	30.06	6.73	0.871
Ana width	13.81	1.98	15.24	3.61	0.273
Ana C. area	194.41	13.93	218.14	52.41	0.22
Pna height	29.95	7.85	28.73	8.70	0.744
Pna width	23.88	3.06	24.14	4.84	0.884
Pna C. area	257.85	74.25	284.32	78.01	0.448
Uph length	19.28	6.61	17.54	4.19	0.503
Uph width	26.01	4.81	24.14	7.87	0.522
Uph C. area	293.37	71.56	314.97	99.76	0.58
Mph length	11.67	3.47	11.54	3.60	0.935
Mph width	22.66	5.87	20.16	8.26	0.439
Mph C. area	226.32	85.90	213.25	102.48	0.76
Lph length	14.77	7.93	11.88	3.07	0.286
Lph width	24.44	5.19	28.90	6.76	0.111
Lph C. area	231.31	83.23	199.84	78.36	0.399
Gonial angle	126.37	7.79	125.24	7.55	0.748
AFH	108.38	6.08	112.12	4.86	0.152
PFH	73.06	5.42	71.81	7.58	0.672
PFH/AFH, %	67.47	4.49	64.02	5.83	0.152
FMA	25.06	3.61	27.48	6.02	0.281
ANB	2.85	1.56	6.14	1.02	< 0.001b
MAND-BL	66.94	3.74	61.61	4.27	0.008b
Facial convexity	5.17	3.57	10.76	4.56	0.007b
Co-pt A	82.10	6.09	82.68	3.44	0.802
Co-pt GN	109.83	5.54	103.72	6.42	0.035a
Nasal airway	36407.36	2526.59	30446.00	7060.88	0.037a
Superior airway	5563.27	1350.80	4559.67	1263.62	0.106
Middle airway	5322.45	2124.81	4213.89	1291.90	0.188
Inferior airway	5487.82	2018.25	5077.67	1521.36	0.621
Total airway	52780.91	6435.84	44297.22	8662.49	0.022a

^aCorrelation is significant at 0.05 level.

^bCorrelation is significant at 0.01 level.

ANB: The angle formed between point A, Nasion and point B; Ana: Anterior nasal; Pna: Posterior nasal; Uph: Upper pharyngeal; Mph: Middle pharyngeal; Lph: Lower pharyngeal; AFH: Anterior facial height; PFH: Posterior facial height; FMA: Frankfurt Mandibular Plane Angle; Mand-BL: Mandibular body length; Co-PtA: Condylion to point; GN: Gnathion; SD: Standard deviation.

Table 5 Correlations between the 2-dimensional cephalometric variables and the 3-dimensional volumetric measurements of the airway

	Nasal airway	Superior airway	Middle airway	Inferior airway	Total airway
Gonial angle
Pearson correlation	-0.021	0.135	0.098	-0.019	0.024
Sig.(2-tailed)	0.928	0.571	0.681	0.937	0.918
n	120	120	120	120	120
AFH
Pearson correlation	0.055	0.201	0.057	0.342	0.154
Sig.(2-tailed)	0.818	0.395	0.811	0.14	0.517
n	120	120	120	120	120
PFH
Pearson correlation	0.159	0.172	0.124	0.319	0.23
Sig.(2-tailed)	0.503	0.47	0.602	0.171	0.329
n	120	120	120	120	120
PFH/AFH, %
Pearson correlation	0.133	0.057	0.086	0.113	0.142
Sig.(2-tailed)	0.576	0.813	0.717	0.636	0.55
n	120	120	120	120	120
FMA
Pearson correlation	-0.372	-0.314	-0.377	-0.411	-0.473a
Sig.(2-tailed)	0.106	0.178	0.102	0.072	0.035
n	120	120	120	120	120
ANB
Pearson correlation	-0.364	-0.408	-0.197	-0.152	-0.389
Sig.(2-tailed)	0.115	0.034a	0.405	0.522	0.22a
n	120	120	120	120	120
Mand-BL
Pearson correlation	0.136	0.523a	0.038	0.184	0.225
Sig.(2-tailed)	0.567	0.018	0.874	0.436	0.341
n	120	120	120	120	120
Facial convexity
Pearson correlation	-0.362	-0.306	-0.221	-0.22	-0.391
Sig.(2-tailed)	0.116	0.189	0.349	0.351	0.088
n	120	120	120	120	120
Co-pt A
Pearson correlation	0.127	0.324	0.289	0.469a	0.3
Sig.(2-tailed)	0.594	0.163	0.217	0.037	0.199
n	120	120	120	120	120
Co-pt GN
Pearson correlation	0.301	0.296	0.012	0.225	0.303
Sig.(2-tailed)	0.197	0.204	0.959	0.34	0.194
n	120	120	120	120	120

^aCorrelation is significant at 0.05 level. AFH: Anterior facial height.

PFH: Posterior facial height; FMA: Frankfurt Mandibular Plane Angle; Co-PtA: Condylion to point; GN: Gnathion; ANB: The angle formed between point A, Nasion and point B; Mand-BL: Mandibular body length.