Ahmed Final.doc J Bagh College Dentistry Vol. 26(3), September 2014 Pharyngeal airway Orthodontics, Pedodontics and Preventive Dentistry 98 Pharyngeal airway volume and its relationship to the facial morphology in nasal breathing and mouth breathing subjects (A comparative computerized tomography study) Ahmed M. Al-Mayali, B.D.S. (1) Iman I. Al-Sheakli, B.D.S., M.Sc. (2) ABSTRACT Background: The value of lateral cephalometric radiographs to evaluate the pharyngeal airway is limited because it provided 2-dimensional (2D) images of complex 3-dimensional (3D) anatomic structures. Three dimensional analyses of the airway volumes are required to understand oral and pharyngeal adaptations in mouth breathing and nasal breathing subjects. The aim of this study was to measure the pharyngeal airway volume and the size of the face, then compare between pharyngeal airway volume in mouth breathing and nasal breathing subjects and find the gender difference in each group, also to study the relation between pharyngeal airway volume and the size of the face. Material and Methods: Fifty patients including 28 males and 22 females with an age ranged between 18-35 years suffered from clinical symptoms of nasal obstruction and mouth breathing was detected by otolaryngologist and sent to be imaged by Brilliance™ 64, Philips multi-detector computed tomography. Twenty normal subjects (10 males and 10 females) were selected as control. Angular and linear variables were measured in addition to the size of the face and the pharyngeal airway volume. Results: A statistically significant relationship between the pharyngeal airway volume and the mode of respiration and between pharyngeal airway volume and genders were detected. The pharyngeal airway volume was larger in nasal breathers than in mouth breathers and it was larger in males than in females. The size of the face was larger in males than females. Conclusion: CT volumetric images provide more reliable and accurate information for measurement of the pharyngeal airway volume, so the changes in the pharyngeal airway volume can be studied before and after surgery and this will aid in selection of the best treatment option in addition to control the relapse after orthodontic treatment with mouth breathing patients. Keyword: Pharyngeal airway volume, size of the face, mouth breathing, computerized tomography. (J Bagh Coll Dentistry 2014; 26(3):98-107). INTRODUCTION After more than a century of conjecture and heated argument, the orthodontic relevance of nasal obstruction and its assumed effect on facial growth continues to be debated. Oral respiration disrupts those muscle forces exerted by tongue, cheek and lips upon the maxillary arch. The main characteristics of the respiratory obstruction syndrome are mouth breathing, open-bite, cross- bite, excessive anterior face height, incompetent lip posture, excessive appearance of maxillary anterior teeth, narrow external nares and "V" shaped maxillary arch (1). Cone-Beam Computed Tomography (CBCT) was developed in the 1990 as an evolutionary process resulting from the demand for 3- dimensional (3D) information obtained by conventional computed tomography (CT) scans (2). The upper airway analysis, orthodontic and orthognathic surgical planning for patients with significant facial asymmetry has been increasingly performed based on 3D volumes (3-6). (1) Master student, Department of Orthodontics, College of Dentistry, University of Baghdad. (2) Assist. Professor, Department of Orthodontics, College of Dentistry, University of Baghdad. Most previous studies of the pharyngeal airway, head posture, malocclusion, as well as facial morphology have been carried out using a two dimensional lateral cephalograms (7,8) . Superimposition of the left and right images in the 2D plane projection of a three-dimensional (3D) structure leads to errors and the left-to-right width of the upper airway is not visible in 2D film. For these reasons, it is difficult to obtain precise volume of the pharyngeal airway and to reproduce the soft tissue structures accurately from lateral cephalograms alone (9,10). CBCT provides 3D-reconstructed image from multiple sequential planar projection images. It is possible to visualize sites of interest by adjusting the image orientation and rotation. CBCT has different gray-level intensities that allow visualization of soft tissue as well as hard tissue with different tissue densities. It also allows visualization of internal anatomic structures such as the airway independently by eliminating external structures (11,12). Furthermore, CBCT allows linear, angular, and planar as well as volumetric analyses (13). J Bagh College Dentistry Vol. 26(3), September 2014 Pharyngeal airway Orthodontics, Pedodontics and Preventive Dentistry 99 MATERIALS AND METHODS Sample The sample is composed of CT images for Iraqi adult patients who were attending Al-Sader medical city in Al-Najaf governorate- ENT department from March 2013 till August 2013. Only 50 subjects out of 427 individuals (28 males and 22 females with an age ranged between 18-35years were selected when met a special criteria. They sent by otolaryngologist specialist with a special sending request to the Al-Furat center for neuromedicine science / Computerized Tomography department because of clinical symptoms of nasal obstruction and mouth breathing to be imaged by high resolution computerized tomography scanning of the paranasal sinuses that extended to hyoid bone to visualize pharyngeal air way space. The control group was 20 subjects out of 98 in the same age group and also had been examined and identified by the otolaryngologist specialist in Al-Sader medical city as having no nasal obstruction, All the control group had class I molar relationship according to Angle's classification and class I canine relationship. Also they were class I skeletally through the clinical examination was determined by two fingers method (14). Method Each patient attained to the otolaryngology consultant clinic examined by the otolaryngologist specialist to include or exclude any nasal obstruction. This was done by the same otolaryngologist specialist by using head mirror, speculum and flexible nasofibroscopy. The orthodontist asked each subject about name, age, origin, nationality, occupation, address, past medical history, family history and past dental history. Each patient from the control group was examined to diagnose the skeletal relationship of the upper and lower jaws and the molar and canine relationship. Each patient had a written request with appropriate clinical history. The patients were informed about the study and consent to participate in this study was taken. The chronological age was determined accurately by the period from the birth date to the radiographic exposure date. All these information were documented in formulated case sheet, then a clinical examination was executed to confirm the special sample criteria. Mouth or nose breathing is recorded subjectively by holding a cold dental mirror in front of the nose and mouth as the patient sits in relaxed position to observe a misting pattern on a cold surface of dental mirror (15). Then the patients were sent with a written request to the CT scan department to taking CT scan image. During that, the subject was asked to swallow to bring the dentitions into maximum interdigitation, informed not to move his head to either side and to cut breathing and swallowing during the acquisition to minimize measurement errors. After that, a topogram and a lateral view of the head show the vertex to the 4th cervical vertebrae was obtained and followed by selecting the desired scan range of the sinuses. Angular Measurements The following angular measurements were done on 2D cephalogram (16): • SNA: Anteroposterior position of maxilla in relation to the anterior cranial base. • SNB: Anteroposterior position of mandible in relation to the anterior cranial base. • ANB: Relative anteroposterior position of the maxilla to the mandible. • Saddle angle (N-S-Ar): The Angle between the anterior &posterior cranial base. Size of the Face The size of the face was established from the P-A and lateral synthetic cephalograms as a rectangular prism encompassing the facial bones. (A) with edges as cube, (B) the bizygomatic width projected on x-axis, (C) the N-Me distance projected on the y-axis and (D) the Ba-ANS distance projected on the z-axis (18) (Figure1). J Bagh College Dentistry Vol. 26(3), September 2014 Pharyngeal airway Orthodontics, Pedodontics and Preventive Dentistry 100 (A) (C) (B) (D) Figure 1: Establishment the size of the face Three dimensional Model of the pharyngeal Airway volume The limits for airway analysis are (4): • Anterior: a vertical plane through posterior nasal spine perpendicular to the sagittal plane at the lowest border of the vomer. • Posterior: the posterior wall of the pharynx. • Lateral: the lateral walls of the pharynx, including the full extensions of the lateral projections. • Lower: a plane tangent to the most caudal medial projection of the third cervical vertebra perpendicular to the sagittal plane. • Upper: the highest point of the nasopharynx, coinciding with the posterior choanae and consistent with the anterior limit. Once segmented, airways were refined to obtain the true shape of the airway by eliminating the projections that did not belong to the airway then the volumes were measured in cm3 with the measuring tool (Figure 2). Figure 2: Three dimensional Model of the pharyngeal Airway volume RESULTS Angular measurements The mean differences between males and females nasal breather subjects expressed significant difference in SNA and SNB, female higher than male (Table 1). J Bagh College Dentistry Vol. 26(3), September 2014 Pharyngeal airway Orthodontics, Pedodontics and Preventive Dentistry 101 There are No significant correlation between Pharyngeal Airway volume & the angular measurements in both groups and gender except in female mouth breather that show significant correlation in SNA and ANB angle (Table 6). Linear measurements The mean differences between males and females nasal breather subjects expressed significant differences between genders in Bi- zygomatic width, Ba-ANS ,N-Me and UAFH, male higher than female (Table 1) . The mean differences between males and females mouth breather subjects expressed significant differences between genders in Bi- zygomatic width, Ba-ANS, N-Me, UAFH and LAFH, male higher than female (Table 2). The mean differences between nasal and mouth breather male subjects expressed significant differences in N-Me and LAFH, Mouth breather higher than Nasal breather, (Table 3). The mean differences between nasal and mouth breather female subjects expressed significant differences in LAFH, Mouth breather higher than Nasal breather (Table 4). The mean differences between nasal and mouth breather total sample expressed significant differences between two groups in N-Me, UAFH and LAFH. It was shown that mouth breathers are higher than nasal breather in N-me and LAFH and nasal breathers are higher than mouth breathers in UAFH, (Table 5). There are significant correlation between Pharyngeal Airway & the linear measurements in both groups and gender (Table 6). Size of the face The mean differences between males and females nasal breather subjects expressed highly significant differences between genders in the size of the face, male higher than female (Table 1) . The mean differences between males and females mouth breather subjects expressed highly significant differences between genders in the size of the face, male higher than female (Table 2). The mean differences between nasal and mouth breather male subjects expressed significant differences in the size of the face, Mouth breather higher than Nasal breather (Table 3). There are significant correlation between pharyngeal airway & size of the face in male nasal and mouth breather and in the total sample (Table 6). Pharyngeal Air way Volume The mean differences between males and females nasal breather subjects expressed highly significant differences in Pharyngeal Air way Volume, male higher than female (Table 1) . The mean differences between males and females mouth breather subjects expressed significant differences between genders in Pharyngeal Air way Volume, male higher than female (Table 2). The mean differences between nasal and mouth breather male subjects expressed significant differences in Pharyngeal Air way volume Nasal breather higher than Mouth breather (Table 3) The mean differences between nasal and mouth breather female subjects expressed significant differences in Pharyngeal Air way volume, Nasal breather higher than Mouth breather (Table 4). The mean differences between nasal & mouth breather total sample expressed significant differences in Pharyngeal Air way volume, Nasal breather higher than Mouth breather (Table 5). DISCUSSION Angular measurements For the SNA and SNB angles, the female nasal breathers had a higher value than male nasal breathers. The SNA angle was highly significant at P < 0.006 and the SNB angle was significant at P < 0.029. The possible difference in the mean of SNA between males and females is the more anterior position of point N in males than females. The anterior position of point N in males was reported by previous studies (17,18). The results expressed no significant genders differences in mouth breathers also there were no significant differences between nasal and mouth breathers. This result is in agreement with previous studies that concern with the relationship between facial prognathism and respiratory resistance and found no correlation between nasal respiratory resistance and SNA or SNB angles (19,20). Since the maxilla is a fixed bone and attached to two cranial bones (frontal and ethmoid bones) and seven facial bones (nasal, zygoma, lacrimal, inferior turbinate, palate, vomer and it fellow on the opposite side). The effect of muscular imbalance on the maxilla is decreased (21). The result disagrees with the finding of Sassouni et al. study that found the reduction in airway space will be associated with retrognathic maxilla (22). The result showed no significant differences between genders in ANB angle in nasal breather J Bagh College Dentistry Vol. 26(3), September 2014 Pharyngeal airway Orthodontics, Pedodontics and Preventive Dentistry 102 & mouth breather group. This comes in agreement with Trask et al. study (23). Also the result is in agreement with a Solow et al. study that found no significant correlation between airway adequacy and maxillary prognathism (24). On the other hand, the reduction of the nasopharyngeal airway has no effect on the sagittal jaw relationship. This result agrees with previous studies (19,25,26). The most probable explanation is that reduced nasopharyngeal airway and the possible subsequent mouth breathing affect both jaw, thus the ANB angle is not affected. But the result disagrees with Ung et al. who found that ANB angle had a higher value in the nasally obstructed sample than the normal group (27). Regarding the saddle angle, there was no significant gender difference in nasal and mouth breathers; this result agrees with Ali (28) and Al- Sahaf (29). Linear measurements Males and females nasal breather and mouth breather results expressed significant gender differences in Bi-zygomatic width, Ba-ANS, N- Me, UAFH and LAFH being males higher than females. These results indicated that the males possessed larger facial dimensions than females. This finding was supported by Al-Sahaf who found significant gender differences in all dimensional measurement and in all skeletal classes (29). There are significant differences between nasal breather & mouth breather group in N-Me, UAFH and LAFH, Nasal breather higher than Mouth breather in UAFH, Mouth breather higher than Nasal breather in N-Me and LAFH. For the facial height the results showed that for the UAFH for the nasal breather group had a higher mean than mouth breather groups in which it was significant at P < 0.002 for the comparison between nasal breather and mouth breather group; this comes in agreement with Kesso that found the UAFH for the nasal breather group had a higher mean than the mouth breather group (30). But this result disagreement with Trask et al. who found no difference in upper facial height between long faces and control subjects (31) For the LAFH and total AFH, the mean was higher for the mouth breather group than in the nasal breather group. This may be due to the backward rotation of the mandible (31,32) . On the other hand, the present result comes in agreement with Kesso, Tourne and Zain Al- Abedin who found an increase in the lower facial height (30,33,34) The higher mean value of these measurements in mouth breather group subjects is more than that in nasal breather group may be due to the fact that the increased mandibular plane and maxilla- mandibular planes angles in mouth breathing subject lead to increase in AFH and LFH (16). The finding of this study disagrees with Martin et al. who reported that a lack of a consistent relationship between nasal resistance and dentofacial morphology (35). Theoretically, the maintenance of vital pharyngeal airway necessitates lowering of the tongue, the soft palate and the mandible. This brings for the dorsal rotation of the mandible or at least ramus resulting in increasing anterior facial height (36). The prolonged buccal respiration is followed by increase in extrusion of the posterior teeth causing increased anterior facial height (37). Size of the face The size of the face was established as a rectangular prism encompassing the facial bones. The average size of the face was statistically significantly larger in the males than in the females. The size of the face was significantly correlated with gender. These result come in agreement with Al-Sahaf, Trenouth et al. and Genecov et al. (29,38,39). Pharyngeal airway volume was significantly correlated with face size. Subjects with larger faces would be expected to have larger airway volumes and this comes in agreement with Gruer et al. (4) . Pharyngeal air way volume There was significant gender difference in both groups being males had higher mean values than females. Linder-Aronson and Leighton and Martin et al. found sexual dimorphism during growth of the posterior wall of the pharynx (40,41) . Airway volume differed significantly for male and female being the female volume smaller which came in agreement with Gruer et al.(4) . The mean volume of the pharyngeal airway in males, females and total sample was higher in nasal breathers than mouth breathers. The mean of the pharyngeal airway volume in nasal breather was 20.4 cm3 and the mean of the pharyngeal airway volume in mouth breather was 15.9 cm3. This result comes in agreement with Vandana et al. (42). It is quite likely that 3-D images of the airway will allow an improved evaluation of sites of airway obstruction and an improved understanding of the physiologic response to pharyngeal stenosis. It already is possible to use the cranial base surface to superimpose 3-D J Bagh College Dentistry Vol. 26(3), September 2014 Pharyngeal airway Orthodontics, Pedodontics and Preventive Dentistry 103 models for different time points within the same patient, so that changes in airway volume and orientation relative to this stable reference can be studied before and after surgery (43). REFERENCES 1. Lopatiene' K, Babarskas. A malocclusion and upper airway obstruction. 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Table 1: Descriptive statistics and genders difference in nasal breathers group Variables Genders Descriptive statistics Gender difference N Mean S.D. S.E. t-test p-value A ngular m easurem ents (º) SNA Males 10 83.70 1.25 0.40 -3.111 0.006 (HS) Females 10 85.90 1.85 0.59 Total 20 84.80 1.91 0.43 SNB Males 10 80.80 1.75 0.55 -2.368 0.029 (S) Females 10 82.60 1.65 0.52 Total 20 81.70 1.89 0.42 ANB Males 10 2.90 0.88 0.28 -1.144 0.268 (NS) Females 10 3.30 0.67 0.21 Total 20 3.10 0.79 0.18 Saddle angle Males 10 119 3.65 1.15 0 1 (NS) Females 10 119 4.71 1.49 Total 20 119 4.10 0.92 L inear m easurem ents (m m .) Bi-zygomatic width Males 10 126.74 5.97 1.89 3.251 0.004 (HS) Females 10 119.32 4.06 1.28 Total 20 123.03 6.26 1.40 Ba-ANS Males 10 98.63 4.89 1.55 2.606 0.018 (S) Females 10 93.03 4.72 1.49 Total 20 95.83 5.49 1.23 N-Me Males 10 115.50 6.19 1.96 2.383 0.028 (S) Females 10 109.11 5.79 1.83 Total 20 112.31 6.69 1.50 UAFH Males 10 56.49 3.30 1.04 2.742 0.013 (S) Females 10 52.95 2.40 0.76 Total 20 54.72 3.35 0.75 LAFH Males 10 59.01 3.39 1.07 1.803 0.088 (NS) Females 10 56.16 3.67 1.16 Total 20 57.59 3.74 0.84 Size (cm3) Size of the face Males 10 1450.93 188.11 59.49 3.230 0.005 (HS) Females 10 1213.82 136.01 43.01 Total 20 1332.38 200.79 44.89 Volume (cm3) PA Males 10 22.49 2.88 0.91 4.436 0.000 (HS) Females 10 18.30 0.77 0.24 Total 20 20.40 2.97 0.67 J Bagh College Dentistry Vol. 26(3), September 2014 Pharyngeal airway Orthodontics, Pedodontics and Preventive Dentistry 105 Table 2: Descriptive statistics and genders difference in mouth breathers group Variables Genders Descriptive statistics Gender difference N Mean S.D. S.E. t-test p-value A ngular m easurem ents (º) SNA Males 28 85.68 3.01 0.57 0.634 0.529 (NS) Females 22 85.14 3.00 0.64 Total 50 85.44 2.98 0.42 SNB Males 28 81.86 3.03 0.57 -0.067 0.947 (NS) Females 22 81.91 2.31 0.49 Total 50 81.88 2.71 0.38 ANB Males 28 3.82 2.92 0.55 0.687 0.495 (NS) Females 22 3.23 3.18 0.68 Total 50 3.56 3.02 0.43 Saddle angle Males 28 118.04 4.44 0.84 0.444 0.659 (NS) Females 22 117.50 3.96 0.84 Total 50 117.80 4.20 0.59 L inear m easurem ents (m m .) Bi-zygomatic width Males 28 128.87 6.11 1.15 5.882 0.000 (HS) Females 22 119.44 4.94 1.05 Total 50 124.72 7.31 1.03 Ba-ANS Males 28 100.15 4.90 0.93 8.009 0.000 (HS) Females 22 88.87 5.00 1.07 Total 50 95.19 7.48 1.06 N-Me Males 28 123.93 8.21 1.55 5.550 0.000 (HS) Females 22 112.33 6.03 1.29 Total 50 118.83 9.30 1.32 UAFH Males 28 53.08 4.18 0.79 3.854 0.000 (HS) Females 22 49.14 2.64 0.56 Total 50 51.34 4.07 0.58 LAFH Males 28 70.86 6.55 1.24 4.464 0.000 (HS) Females 22 63.17 5.33 1.14 Total 50 67.47 7.12 1.01 Size (cm3) Size of the face Males 28 1599.85 151.32 28.59 9.533 0.000 (HS) Females 22 1196.23 145.06 30.93 Total 50 1422.26 250.19 35.38 Volume (cm3) PA Males 28 17.40 5.61 1.06 2.614 0.012 (S) Females 22 14.04 2.45 0.52 Total 50 15.92 4.77 0.67 J Bagh College Dentistry Vol. 26(3), September 2014 Pharyngeal airway Orthodontics, Pedodontics and Preventive Dentistry 106 Table 3: Descriptive statistics and group difference in male group Variables Groups Descriptive statistics Group difference N Mean S.D. S.E. t-test p-value A ngular m easurem ents (º) SNA NB 10 83.70 1.25 0.40 -2.005 0.052 (NS) MB 28 85.68 3.01 0.57 SNB NB 10 80.80 1.75 0.55 -1.038 0.306 (NS) MB 28 81.86 3.03 0.57 ANB NB 10 2.90 0.88 0.28 -0.975 0.336 (NS) MB 28 3.82 2.92 0.55 Saddle angle NB 10 119.00 3.65 1.15 0.615 0.543 (NS) MB 28 118.04 4.44 0.84 L inear m easurem ents (m m .) Bi-zygomatic width NB 10 126.74 5.97 1.89 -0.953 0.347 (NS) MB 28 128.87 6.11 1.15 Ba-ANS NB 10 98.63 4.89 1.55 -0.842 0.405 (NS) MB 28 100.15 4.90 0.93 N-Me NB 10 115.50 6.19 1.96 -2.952 0.006 (HS) MB 28 123.93 8.21 1.55 UAFH NB 10 56.49 3.30 1.04 2.327 0.026 (S) MB 28 53.08 4.18 0.79 LAFH NB 10 59.01 3.39 1.07 -5.435 0.000 (HS) MB 28 70.86 6.55 1.24 Size (cm3) Size of the face NB 10 1450.93 188.11 59.49 -2.506 0.017 (S) MB 28 1599.85 151.32 28.59 Volume (cm3) PA NB 10 22.49 2.88 0.91 2.727 0.010 (HS) MB 28 17.40 5.61 1.06 Table 4: Descriptive statistics and group difference in female group Variables Groups Descriptive statistics Group difference N Mean S.D. S.E. t-test p-value A ngular m easurem ents (º) SNA NB 10 85.90 1.85 0.59 0.740 0.465 (NS) MB 22 85.14 3.00 0.64 SNB NB 10 82.60 1.65 0.52 0.850 0.402 (NS) MB 22 81.91 2.31 0.49 ANB NB 10 3.30 0.67 0.21 0.071 0.944 (NS) MB 22 3.23 3.18 0.68 Saddle angle NB 10 119.00 4.71 1.49 0.936 0.357 (NS) MB 22 117.50 3.96 0.84 L inear m easurem ents (m m .) Bi-zygomatic width NB 10 119.32 4.06 1.28 -0.068 0.947 (NS) MB 22 119.44 4.94 1.05 Ba-ANS NB 10 93.03 4.72 1.49 2.221 0.034 (S) MB 22 88.87 5.00 1.07 N-Me NB 10 109.11 5.79 1.83 -1.417 0.167 (NS) MB 22 112.33 6.03 1.29 UAFH NB 10 52.95 2.40 0.76 3.886 0.001 (HS) MB 22 49.14 2.64 0.56 LAFH NB 10 56.16 3.67 1.16 -3.753 0.001 (HS) MB 22 63.17 5.33 1.14 Size (cm3) Size of the face NB 10 1213.82 136.01 43.01 0.324 0.748 (NS) MB 22 1196.23 145.06 30.93 Volume (cm3) PA NB 10 18.30 0.77 0.24 5.337 0.000 (HS) MB 22 14.04 2.45 0.52 J Bagh College Dentistry Vol. 26(3), September 2014 Pharyngeal airway Orthodontics, Pedodontics and Preventive Dentistry 107 Table 5: Descriptive statistics and group difference in total sample Variables Groups Descriptive statistics Group difference N Mean S.D. S.E. t-test p-value A ngular m easurem ents (º) SNA NB 20 84.80 1.91 0.43 -0.887 0.378 (NS) MB 50 85.44 2.98 0.42 SNB NB 20 81.70 1.89 0.42 -0.271 0.787 (NS) MB 50 81.88 2.71 0.38 ANB NB 20 3.10 0.79 0.18 -0.670 0.505 (NS) MB 50 3.56 3.02 0.43 Saddle angle NB 20 119.00 4.10 0.92 1.086 0.281 (NS) MB 50 117.80 4.20 0.59 L inear m easurem ents (m m .) Bi-zygomatic width NB 20 123.03 6.26 1.40 -0.910 0.366 (NS) MB 50 124.72 7.31 1.03 Ba-ANS NB 20 95.83 5.49 1.23 0.349 0.728 (NS) MB 50 95.19 7.48 1.06 N-Me NB 20 112.31 6.69 1.50 -2.849 0.006 (HS) MB 50 118.83 9.30 1.32 UAFH NB 20 54.72 3.35 0.75 3.290 0.002 (HS) MB 50 51.34 4.07 0.58 LAFH NB 20 57.59 3.74 0.84 -5.879 0.000 (HS) MB 50 67.47 7.12 1.01 Size (cm3) Size of the face NB 20 1332.38 200.79 44.89 -1.431 0.157 (NS) MB 50 1422.26 250.19 35.38 Volume (cm3) PA NB 20 20.40 2.97 0.67 3.894 0.000 (HS) MB 50 15.92 4.77 0.67 Table 6: Correlation between PA and other variables in both groups and genders Variables NB MB Males Females Total Males Females Total A ngular m easurem ents (º) SNA r 0.156 0.317 -0.342 -0.359 0.509 -0.090 p-value 0.667 (NS) 0.372 (NS) 0.140 (NS) 0.061 (NS) 0.016 (S) 0.536 (NS) SNB r 0.312 0.383 -0.179 -0.053 -0.093 -0.059 p-value 0.380 (NS) 0.274 (NS) 0.451 (NS) 0.790 (NS) 0.681 (NS) 0.684 (NS) ANB r -0.401 -0.064 -0.399 -0.315 0.547 -0.036 p-value 0.251(NS) 0.861(NS) 0.081 (NS) 0.103 (NS) 0.008 (HS) 0.806 (NS) Saddle angle r -0.188 -0.213 -0.107 -0.095 0.177 -0.006 p-value 0.603 (NS) 0.555 (NS) 0.654 (NS) 0.630 (NS) 0.432 (NS) 0.967 (NS) L inear m easurem ents (m m .) Bi-zygomatic width r 0.971 0.484 0.903 0.402 -0.129 0.427 p-value 0.000 (HS) 0.157 (NS) 0.000 (HS) 0.034 (S) 0.567 (NS) 0.002 (HS) Ba-ANS r 0.626 0.558 0.694 0.113 0.490 0.387 p-value 0.053 (NS) 0.094 (NS) 0.001 (HS) 0.568 (NS) 0.021(S) 0.006 (HS) N-Me r 0.761 -0.147 0.661 0.232 0.134 0.373 p-value 0.011 (S) 0.685 (NS) 0.001 (HS) 0.235 (NS) 0.552 (NS) 0.008 (HS) UAFH r 0.546 -0.172 0.625 0.311 0.570 0.460 p-value 0.103 (NS) 0.636 (NS) 0.003 (HS) 0.108 (NS) 0.006 (HS) 0.001 (HS) LAFH r 0.858 -0.120 0.625 0.092 -0.130 0.224 p-value 0.002 (HS) 0.741 (NS) 0.003 (HS) 0.643 (NS) 0.565 (NS) 0.117 (NS) Size (cm3) Size of the face r 0.880 0.349 0.846 0.407 0.238 0.476 p-value 0.001 (HS) 0.323 (NS) 0.000 (HS) 0.032 (S) 0.286 (NS) 0.000 (HS) P > 0.05 Non-significant , 0.05 ≥ P > 0.01 Significant , P ≤ 0.01 Highly significant