Relationship between malocclusion, soft tissue profile, and pharyngeal airways: A cephalometric study Original Research Article Relationship between malocclusion, soft tissue profile, and pharyngeal airways: A cephalometric study Kristina Lopatienė *, Antanas Šidlauskas, Arūnas Vasiliauskas, Lina Čečytė, Vilma Švalkauskienė, Mantas Šidlauskas Department of Orthodontics, Medical Academy, Lithuanian University of Health Sciences, Kaunas, Lithuania m e d i c i n a 5 2 ( 2 0 1 6 ) 3 0 7 – 3 1 4 a r t i c l e i n f o Article history: Received 27 April 2016 Received in revised form 10 July 2016 Accepted 26 September 2016 Available online 11 October 2016 Keywords: Soft tissue profile Cephalometric analysis Pharyngeal airway Malocclusion a b s t r a c t Background and objective: The recent years have been marked by a search for new interrela- tions between the respiratory function and the risk of the development of malocclusions, and algorithms of early diagnostics and treatment have been developed. The aim of the study was to evaluate the relationships between hard and soft tissues and upper airway morphol- ogy in patients with normal sagittal occlusion and Angle Class II malocclusion according to gender. Materials and methods: After the evaluation of clinical and radiological data, 114 pre-ortho- dontic patients with normal or increased ANB angle, were randomly selected for the study. The cephalometric analysis was done by using the Dolphin Imaging 11.8 computer soft- ware. Results: Comparison of the cephalometric values of soft tissue and airway measurements performed statistically significant negative correlation between the width of the upper pharynx and the ANB angle was found: the ANB angle was decreasing with an increasing width of the upper pharynx. The airways showed a statistically significant negative correlation between the width of the lower pharynx and the distance from the upper and the lower lips to the E line. Logistic regression analysis was performed to evaluate significant factors that could predict airway constriction. The upper pharynx was influ- enced by the following risk factors: a decrease in the SNB angle, an increase in the nose tip angle, and younger age; while the lower pharynx was influenced by an increase in the distance between the upper lip and the E line and by an increase in the upper lip thickness. Conclusions: During critical period of growth and development of the maxillofacial system, the patients with oral functional disturbances should be monitored and treated by a multidisciplinary team consisting of a dentist, an orthodontist, a pediatrician, an ENT Available online at www.sciencedirect.com ScienceDirect journal homepage: http://www.elsevier.com/locate/medici Peer review under the responsibility of the Lithuanian University of Health Sciences. * Corresponding author at: Department of Orthodontics, Medical Academy, Lithuanian University of Health Sciences, J. Lukšos-Daumanto 6, 50106 Kaunas, Lithuania. E-mail addresses: klopatiene@zebra.lt (K. Lopatienė). http://dx.doi.org/10.1016/j.medici.2016.09.005 1010-660X/# 2016 The Lithuanian University of Health Sciences. Production and hosting by Elsevier Sp. z o.o. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). http://dx.doi.org/10.1016/j.medici.2016.09.005 mailto:klopatiene@zebra.lt http://www.sciencedirect.com/science/journal/00000000 http://www.elsevier.com/locate/medici http://dx.doi.org/10.1016/j.medici.2016.09.005 http://creativecommons.org/licenses/by-nc-nd/4.0/ specialist, and an allergologist. Cephalometric analysis applied in our study showed that Angle Class II patients with significantly decreased facial convexity angle, increased naso- mental, upper lip-chin, and lower lip-chin angles, and upper and lower lips located more proximally to the E line more frequently had constricted airways. # 2016 The Lithuanian University of Health Sciences. Production and hosting by Elsevier Sp. z o.o. This is an open access article under the CC BY-NC-ND license (http://creative- commons.org/licenses/by-nc-nd/4.0/). m e d i c i n a 5 2 ( 2 0 1 6 ) 3 0 7 – 3 1 4308 1. Introduction The functions of the maxillofacial system affect the growth of the face and jaws as well as tooth eruption [1]. Prolonged mouth breathing is associated with impaired speech, maxil- lofacial deformities, tooth malposition, abnormal posture, and even cardiovascular, respiratory, or endocrine dysfunc- tions [2,3]. The discussion on the relationship between maxillofacial morphology and upper airway size and resis- tance has been continuing over a century. Narrowing of the pharyngeal airway passage caused by various etiological factors – especially in the nasopharyngeal area – results in mouth breathing [2,4]. According to various authors, the main features of upper airway obstruction include: increased excessive anterior face height, narrowed upper dental arch, high palatal vault, steep mandibular plane angle, protruding maxillary teeth, and incompetent lip postures [2,5–7]. Basheer et al. found that the facial profile of patients who had mouth- breathing pattern was more convex than in those who were breathing through the nose [2]. Other authors determined a relationship between the size of the upper airways and the severity of malocclusion [6]. Obstruction of the upper airways is associated with Angle Class II malocclusion and vertical facial growth impairment [6,8]. Some studies have shown that in patients with Angle Class II malocclusion, the width of the upper pharynx is smaller than in those with Angle Class I or III malocclusion. However, other researchers provided contra- dicting conclusions and did not find any association between the width of the upper or lower pharynx and malocclusion [6,9,10]; some authors associate this with genetic and environmental factors [11]. The importance of lateral cephalometric radiographs in the evaluation of the morphology of soft and skeletal maxillofacial tissues and the diagnostics of airway pathology is unques- tionable [1,12–14]. This cephalometric analysis is a simple, cheap, and sufficiently informative diagnostic technique, and the generated 2D images along with evaluation results are sufficiently reliable and may be an alternative to 3D imaging in the evaluation of soft tissue and upper airway morphology [1,15]. The recent years have been marked by a search for new interrelations between the respiratory function and the risk of the development of malocclusions, and algorithms of early diagnostics and treatment have been developed. The aim of the study was to evaluate the relationships between hard and soft tissues and upper airway morphology in patients with normal sagittal occlusion and Angle Class II malocclusion according to gender. 2. Materials and methods After the evaluation of clinical and radiological data, 114 pre- orthodontic patients (aged 14–16 years) were randomly recruited for the study from the Clinical Department of Orthodontics, Lithuanian University of Health Sciences. The study was conducted with the permission of the Kaunas Regional Biomedical Research Ethics Committee (February 9, 2015, No. BE-2-12). The inclusion criteria were the following: patients' age, sagittal jaw relationship angle ANB > 18, and no previous maxillofacial trauma or surgery, syndromes, clefts, or orthodontic treatment. The study included 114 patients: there were 71 girls (62.3%), and 43 boys (37.7%). The subjects' mean age was 14.42 � 0.58 years. The study sample was divided into two groups according to the ANB angle: the first group consisted of subjects with normal skeletal sagittal jaw relationship (ANB 28 � 18, Class I), and the second group consisted of patients with sagittal skeletal malocclusion, (ANB > 48, Class II). Group 1 consisted of 57 subjects, namely 37 girls (64.9%) and 20 boys (35.1%); group 2, 57 patients, namely 34 girls (59.6%), and 23 boys (40.4%). Lateral cephalometric radiography was performed in fixed head position. To minimize radiation doze digital panoramic systems were used and ALARA radiation safety principle was followed. The analysis was done by using the Dolphin Imaging 11.8 (Dolphin Imaging and Management Solution) computer software. Soft tissue analysis was performed manually, using the ‘‘Annotations and measurements’’ function of the Dolphin Imaging software. Cephalometric parameters used for this study are shown in Fig. 1. For the lateral cephalometric analysis, the error margin was determined by repeating the measurements of the variables on randomly selected 20 radiographic images at 2-week intervals with the same operator; the paired sample t test showed no significant mean differences in the two data sets. 2.1. Statistical analysis Statistical data analysis was performed using the SPSS (IBM SPSS Statistics 22.0) software. Spearman correlation was applied in order to evaluate the strength of the relationship between two quantitative variables that did not meet the conditions of normal distribution. The mean values of quantitative attributes meeting the conditions of normal distribution in two independent sample groups were com- pared by applying the parametric Student t criterion, while the comparison of the medians was performed by applying the http://creativecommons.org/licenses/by-nc-nd/4.0/ http://creativecommons.org/licenses/by-nc-nd/4.0/ Fig. 1 – Cephalometric landmarks and measurements. Landmarks: (A) the deepest point on the curve of the bone between the anterior nasal spine and dental alveolus; (B) the deepest midline point on the mandible between the infradentale and the pogonion; N (Nasion), the most anterior point of the frontonasal suture in the middle; S (Sella), the center of the sella turcica; U1, the most labial point on the crown of the maxillary central incisor; Cm (Columella), the most anterior point on the columella of the nose; Ns, soft tissue Nasion; Prn (Pronasale), the most protruded point of the nasal apex; Sn (Subnasale), midpoint of the columella base at the apex of the nasolabial angle; Ls (Labiale superius), midpoint of the upper vermilion line; Li (Labiale inferius), midpoint of the lower vermilion line; Pog', soft tissue Pogonion; Me', soft tissue Menton. Measurements: SNA, sagittal position of the maxilla; SNB, sagittal position of the mandible; ANB, sagittal jaw relationship; Cm-Prn-Ns, nose tip angle; Ns- Prn-Pog', facial convexity; Prn-Ns-Pog', nasomental angle; Pog'-Ns-Ls, upper lip-chin angle; Pog'-Ns-Li, lower lip-chin angle; Ls-E (a), distance from upper lip (Ls) to the E line (the line formed by connecting the Prn and Pog' points); Li-E (b), distance from the lower lip (Li) to the E line; A-Sn (c), upper lip thickness at point A; U1-Ls (d), upper lip thickness at the maxillary central incisor; TFH (e), facial height; LFH (f), lower facial height; UPW (g), width of the upper pharynx, measured as the distance from the point of the posterior outline of the soft palate to the closest point on the posterior pharyngeal wall; LPW (h), width of the lower pharynx, measured as the distance from the intersection of the posterior border of the tongue and the inferior border of the mandible to the closest point on the posterior pharyngeal wall. m e d i c i n a 5 2 ( 2 0 1 6 ) 3 0 7 – 3 1 4 309 nonparametric Mann–Whitney U test. Correlation analysis of SNA, SNB, and ANB angles as well as the parameters of soft tissues and the airways was performed. The most specific predictors of the decrease in the upper and lower pharyngeal width were assessed using the logistic regression analysis. Differences and interdependence between the attributes were considered to be statistically significant if P < 0.05. 3. Results A comparison of the cephalometric values of soft tissue and airway measurements between Class I and II subjects was performed. It showed that patients with Class II anomalies had a statistically significantly (P < 0.01) the upper and the lower lips closer to the E line and a smaller facial convexity angle (P < 0.001). They also demonstrated increased naso- mental (P < 0.001), upper lip-chin (P < 0.001), and lower lip- chin (P < 0.001) angles, compared to Class I subjects. The upper and lower pharyngeal airways were significantly wider (P < 0.05) in Class I than in Class II patients (Table 1). No difference in facial height or the thickness of the upper lip between Class I and II subjects was found. We evaluated the influence of sex on the soft tissues and the pharyngeal airways. In Class I subjects, differences of soft tissues between males and females were found: girls had a statistically significantly smaller upper lip-chin angle, lower lip-chin angle, the thickness of the upper lip, and lower facial height, compared to boys (Table 2). The comparison of boys to girls in the Class II group showed that in girls, the upper lip was statistically significantly more distal to the E line; they also had smaller facial convexity angles, smaller upper lip-chin angles, and smaller thickness of the upper lip, compared to boys (Table 3). The differences in the morphology of the soft tissues and the airways between boys and girls in Class I and II groups were evaluated. The comparison of mean values by applying the parametric Student t test showed that girls in the Class II group had statistically significantly smaller facial convexity angles (P < 0.001), smaller distances from the lower lip to the E line (P < 0.05), and increased nasomental (P < 0.001), upper lip- chin (P < 0.001), and lower lip-chin (P < 0.001) angles, com- pared to girls in the Class I group. The analysis applying the non-parametric Mann–Whitney U test showed that girls with Class II anomalies had smaller distances from the upper lip to the E line (P < 0.05), compared to girls in the Class I group. Upper pharyngeal width was significantly smaller in Class II girls than in the Class I group (P < 0.05). When analyzing boys, the Student t test showed that boys with Class II malocclusion had statistically significantly smaller distances from the lower lip to the E line (P < 0.05), smaller thickness of the upper lip (P < 0.05), and increased upper lip-chin angles (P < 0.05), compared to those in the Class I group. No statistically significant differences in other cephalometric measurements were detected between boys of Class I and II groups. We performed correlation analysis in order to evaluate the relationship of the sagittal position of the maxilla (SNA), the sagittal position of the mandible (SNB), and the sagittal jaw relationship (ANB) with the width of the airways. A statistically significant positive correlation was found between the width of the upper pharynx and the position of the jaws: with an increasing width of the upper pharynx, the SNA (rs = 0.238, P < 0.01) and SNB (rs = 0.301, P < 0.001) angles were increasing as well. It was found a negative correlation between the width of the upper pharynx and the ANB angle (rs = �0.186, P < 0.05): the ANB angle was decreasing with an increasing width of the upper pharynx (Fig. 2). A statistically significant negative correlation between the width of the lower pharynx and the Table 1 – Soft tissue and upper airway measurements in Class I and II subjects. Soft tissue and upper airway measurements Class I Class II P Upper lip to E line (Ls-E), mm �5.20 � 0.51 �3.54 � 0.50 0.002 Lower lip to E line (Li-E), mm �3.33 � 0.43 �1.43 � 0.43 0.003 Facial convexity (Ns-Prn-Pog'),8 127.41 � 0.49 124.30 � 0.42 0.001 Nose tip angle (Cm-Prn-Ns),8 108.55 � 0.66 107.38 � 0.68 NS Nasomental angle (Prn-Ns-Pog'),8 30.77 � 0.35 32.88 � 0.36 0.001 Upper lip-chin angle (Pog'-Ns-Ls),8 7.13 � 0.31 9.06 � 0.33 0.001 Lower lip-chin angle (Pog'-Ns-Li),8 3.49 � 0.23 4.71 � 0.26 0.001 Upper lip thickness at point A (A-Sn), mm 16.16 � 0.23 15.89 � 0.23 NS Upper lip thickness at upper incisor (U1-Ls), mm 12.01 � 0.23 11.58 � 0.23 NS Facial height (TFH), mm 113.15 � 0.96 113.09 � 0.82 NS Lower facial height (LFH), mm 65.59 � 0.72 66.45 � 0.94 NS Upper pharyngeal width, mm 13.02 � 0.48 11.68 � 0.53 0.03 Lower pharyngeal width, mm 10.53 � 0.34 9.37 � 0.38 0.01 NS, not significant. Table 3 – Soft tissue and upper airway measurements in Class II, according to gender. Soft tissue and upper airway measurements Gender P Male Female Upper lip to E line (Ls-E), mm �2.27 � 3.59 �4.16 � 4.27 0.05 Lower lip to E line (Li-E), mm �0.62 � 3.48 �1.80 � 2.86 NS Facial convexity (Ns-Prn-Pog'),8 124.79 � 2.97 123.04 � 3.03 0.03 Nose tip angle (Cm-Prn-Ns),8 107.77 � 4.54 106.90 � 5.69 NS Nasomental angle (Prn-Ns-Pog'),8 33.05 � 2.46 33.37 � 3.05 NS Upper lip-chin angle (Pog'-Ns-Ls),8 10.19 � 2.41 9.02 � 2.15 0.05 Lower lip-chin angle (Pog'-Ns-Li),8 5.37 � 2.09 4.71 � 1.74 NS Upper lip thickness at point A (A-Sn), mm 16.57 � 1.57 15.44 � 1.88 0.01 Upper lip thickness at upper incisor (U1-Ls), mm 11.62 � 1.78 11.74 � 1.81 NS Facial height (TFH), mm 115.16 � 6.57 112.92 � 6.34 NS Lower facial height (LFH), mm 67.78 � 5.67 65.13 � 4.84 NS Upper pharyngeal width, mm 11.45 � 4.42 12.14 � 4.06 NS Lower pharyngeal width, mm 9.09 � 2.80 10.08 � 3.25 NS NS, not significant. Table 2 – Soft tissue and upper airway measurements in Class I, according to gender. Soft tissue and upper airway measurements Gender P Male Female Upper lip to E line (Ls-E), mm �4.87 � 4.98 �5.13 � 2.87 NS Lower lip to E line (Li-E), mm �3.14 � 4.06 �3.04 � 2.83 NS Facial convexity (Ns-Prn-Pog'),8 126.68 � 4.88 127.33 � 2.65 NS Nose tip angle (Cm-Prn-Ns),8 107.85 � 5.65 108.65 � 4.79 NS Nasomental angle (Prn-Ns-Pog'),8 31.53 � 3.56 30.65 � 1.97 NS Upper lip-chin angle (Pog'-Ns-Ls),8 8.37 � 2.66 6.60 � 2.02 0.001 Lower lip-chin angle (Pog'-Ns-Li),8 4.23 � 1.84 3.17 � 1.58 0.005 Upper lip thickness at point A (A-Sn), mm 17.14 � 1.68 15.54 � 1.61 0.0001 Upper lip thickness at upper incisor (U1-Ls), mm 12.75 � 1.68 11.42 � 1.68 0.001 Facial height (TFH), mm 117.80 � 6.30 110.05 � 5.63 NS Lower facial height (LFH), mm 68.74 � 5.06 64.38 � 7.23 0.005 Upper pharyngeal width, mm 11.89 � 3.02 13.06 � 3.93 NS Lower pharyngeal width, mm 9.83 � 2.91 9.20 � 2.37 NS NS, not significant. m e d i c i n a 5 2 ( 2 0 1 6 ) 3 0 7 – 3 1 4310 distance from the upper (rs = �0.204; P < 0.05) and the lower (rs = �0.243, P < 0.005) lips to the E line (rs = �0.203, P < 0.05) (Fig. 3) was found. The distance from the upper and the lower lips to the E line was increasing with a decreasing width of the lower pharynx. Logistic regression analysis was performed to evaluate significant factors that could predict airway constriction. The most significant risk factors affecting the reduction in the width of the upper and the lower pharynx in all subjects and separately in males and females are presented in Table 4. The Fig. 2 – Linear relationship between the size of the ANB angle and the width of the upper pharynx (P < 0.05). m e d i c i n a 5 2 ( 2 0 1 6 ) 3 0 7 – 3 1 4 311 reduction in the width of the upper pharynx was influenced by the following risk factors: a decrease in the SNB angle, an increase in the nose tip (Cm-Prn-Ns) angle. A decrease of the SNB angle by 1 degree increased the risk of a 1-mm reduction in the width of the upper pharynx by 17%, an increase of the Cm-Prn-Ns angle by 1 degree increased this risk by 14%. The reduction in the width of the lower pharynx was influenced by an increase in the distance between the upper lip and the E line and increased upper lip thickness. An increased distance between the upper lip and the E line by 1 mm increased the risk of a 1-mm reduction in the width of the lower pharynx by 15%, and an increase in the thickness of the upper lip by 1 mm increased this risk by 26%. The upper pharynx in girls was influenced by the following risk factors: an increase in the ANB angle, an increase in the nose tip (Cm-Prn-Ns) angle. An increase of the ANB angle by 1 degree increased the risk of a 1-mm reduction in the width of Fig. 3 – Linear relationship between the distance from the upper the width of the lower pharynx. the upper pharynx by 86%, an increase of the Cm-Prn-Ns angle by 1 degree increased this risk by 19%. The upper pharynx in boys was influenced by a decrease in the SNB angle and an increase in the nose tip angle (Cm-Prn-Ns). A decrease of the SNB angle by 1 degree increased the risk of a 1-mm reduction in the width of the upper pharynx by 47%, and an increase of the Cm-Prn-Ns angle by 1 degree increased this risk by 23%. The lower pharynx in boys was influenced by an increase in the upper lip-chin angle. An increase of this angle by 1 degree increased the risk of a 1-mm reduction in the width of the lower pharynx by 54%. 4. Discussion There is widespread and growing interest in facial esthetics and its attractiveness, and it has become one of the goals of the contemporary orthodontic treatment. Scientific research on the quantitative measurable bases of facial esthetics is still in progress, and various analyses of the soft tissues are performed, evaluating facial morphology and helping to plan orthodontic treatment [16–19]. When analyzing human face, maxillofacial surgeons, plastic surgeons, and orthodontists always try to set certain principles that would help in maxillofacial reconstruction or the treatment of orthodontic malocclusion [17,19–21]. Most frequently, the analysis of the soft tissue profile and the evaluation of the relationships of the nose, lips, and chin are performed [22]. Literature data suggest that the features of the nose and other facial structures depend on a person's race and ethnic group, and a number of analyses have been proposed to evaluate them [16,20]. Various techniques are used for the analysis of the soft tissue profile, including lateral cephalometric radiographs [20], digital photography [22], 3D photography [23,24], and magnetic resonance imaging [25]. Most frequently, the analysis of the soft tissues is performed by evaluating facial profile images or cephalometric analysis. Zhang et al. compared the data of facial profile analysis obtained via cephalometric radiographs or digital photography, and did not find any significant (a, P < 0.05), and the lower (b, P < 0.01) lips to the E line and Table 4 – Factors affecting the risk of the reduction in the width of the upper and the lower pharynx, adjusted for age. Factor OR 95% CI P Reduction in the width of the upper pharynx Sagittal position of the mandible (SNB) 0.83 0.73–0.96 0.009 Nose tip angle (Cm-Prn-Ns) 1.14 1.04–1.26 0.005 Reduction in the width of the lower pharynx Distance between the upper lip and the E line 1.15 1.02–1.29 0.024 Upper lip thickness 1.26 1.00–1.59 0.052 Reduction in the width of the upper pharynx in females Sagittal jaw relationship (ANB) 1.86 1.16–2.98 0.010 Nose tip angle (Cm-Prn-Ns) 1.19 1.04–1.35 0.011 Reduction in the width of the lower pharynx in females Nose tip angle (Cm-Prn-Ns) 0.91 0.83–1.01 0.066 Upper lip thickness 1.38 1.01–1.88 0.042 Reduction in the width of the upper pharynx in males Sagittal position of the mandible (SNB) 0.68 0.52–0.90 0.006 Nose tip angle (Cm-Prn-Ns) 1.236 1.04–1.52 0.017 Reduction in the width of the lower pharynx in males Upper lip-chin angle (Pog'-Ns-Ls) 1.54 1.13–2.11 0.007 OR, odds ratio; CI, confidence interval. m e d i c i n a 5 2 ( 2 0 1 6 ) 3 0 7 – 3 1 4312 differences between these techniques [26]. The methods used for the evaluation of upper airway patency include fluoroscopy [8], nasal endoscopy [8,27], cephalometric radiographs [1,12– 14], 3D computed tomography [8,28], cone beam computed tomography [15], and magnetic resonance imaging [13]. The greatest accuracy may be achieved when analyzing 3D images [8], yet the disadvantages of this technique are high radiation exposure and high costs, and therefore cephalography is used as an alternative technique for the planning of orthodontic treatment [29]. Studies comparing cephalometry with mag- netic resonance imaging (MRI) suggest evaluating nasophar- ynx and laryngopharynx on cephalograms, refraining from evaluating the oropharynx due to overlapping structures [13]. Scientific literature indicates that cephalography allows for performing high-quality simultaneous evaluations of the airways and skeletal and soft tissues [11,30], and suggests using cephalography as a simple and sufficiently informative technique [10,31]. In our study, we chose cephalometric radiography images for the evaluation of soft and skeletal tissues and the airways. During this analysis, we evaluated the measurements of skeletal structures in the sagittal plane, the soft tissues of the lips, nose, and chin, and the structure of the airways in the upper and the lower parts of the pharynx. A patient's respiratory function is an important factor in diagnostics and orthodontic treatment planning, and it has a direct correlation with the size of the upper airways [32,33]. In our study, subjects with Angle Class II malocclusion had a significantly more convex facial profile, compared to Class I patients. The increased convexity of the facial profile was associated with the position of the upper and the lower lips closer to the E line, a decreased convexity angle, an increased nasomental angle, and increased upper lip-chin and lower lip- chin angles. Angle Class II patients were found to have significantly narrower upper airways. Researchers analyzing the soft tissue profile state that facial convexity is one of the parameters that have a statistically reliable relationship with pharyngeal airway pathology. Adequate treatment of orthodontic anomalies at a young age may prevent or alleviate pathological changes of the airways [5]. According to Basheer et al., individuals who breathe through the mouth have more convex faces and protruding incisors, compared to those who breathe through the nose [2]. Gulsen et al. stated that the convexity of facial soft tissues is related to the position of the jaws [20]. The findings of this study confirm the aforemen- tioned statements – a greater facial convexity and narrower pharyngeal airways were detected in Angle Class II subjects. The correlation analysis conducted in our study showed that an increasing width of the upper pharynx was associated with an increasing sagittal mandibular angle (SNB) and a decreasing sagittal maxillo-mandibular angle (ANB). This indicates that Angle class II subjects had narrower upper airways. The evaluation of the changes with respect to sex showed that girls with Angle Class II malocclusion had convex facial profiles: smaller facial convexity angles, smaller distances from the upper and the lower lips to the E line, and greater nasomental, upper lip-chin, and lower lip-chin angles, compared to girls in the Class I group. In boys with Class II malocclusion, increased facial convexity was related to a smaller distance from the lower lip to the E line, a decreased upper lip thickness, and an increased upper lip-chin angle. The evaluation of the influence of sex on the soft tissues showed that in girls with Class I malocclusion, upper lip-chin angles, lower lip-chin angles, the width of the upper and the lower parts of the upper lip, and lower facial height were smaller, compared to boys of the same group. Girls with Angle Class II malocclusion had greater distances between the upper lip and the E line, smaller facial convexity angles, smaller upper lip- chin angles, and smaller upper lip thickness, compared to boys of the same group. There was no difference in airway measurements between the sexes. The retrognathic position of the mandible may cause pharyngeal airway constriction in patients with a convex facial profile. Facial profile convexity may be one of the risk factors of sleep apnea. A study conducted by Ikävalko et al. showed that m e d i c i n a 5 2 ( 2 0 1 6 ) 3 0 7 – 3 1 4 313 of all healthcare specialists working with children, orthodon- tists can perform the most exact evaluations of facial convexity because other specialists lack knowledge about the importance of the facial profile in the diagnostics of airway pathology [5]. The results of studies conducted by Dimaggio et al. [22] and Souki et al. [4] suggest that the nasolabial angle in patients with Angle Class I is statistically significantly greater than in those with Angle Class II malocclusion. A small nasolabial angle may be detected in patients who breathe through the mouth [4]. The data of our study confirm these results as we found in Class II subjects more protruded upper lips, increased upper lip-chin angle, decreased distance to the E line, comparing to Class I. This is due to the protrusion of the upper incisors and the upper lip, which in turn is caused by imbalance of the linguolabial positioning. The growth and development of the maxillofacial system should be closely monitored during the critical pre-puberty period in order to prevent future nose breathing disorders – especially in patients with possible nasal breathing disorders. The condition of these patients should be followed by a team of specialists consisting of a dentist, an orthodontist, a pediatri- cian, an ENT specialist, and an allergist, who should ensure timely correction of nose breathing disorders during the period of the active growth and development of the maxillofacial system. The results of the present study show that upper airway obstruction and malocclusion are inter-related and cause changes in the facial profile. Since the cause-and-effect correlation between the size of the upper and the lower airways and the type of malocclusion has yet to be confirmed, sagittal and vertical skeletal discrepancies should be corrected interventionally during the period of growth and develop- ment, maximally approximating them to the normal status [33]. The function of the airway is of considerable importance in orthodontics and cannot be overlooked during treatment planning. 5. Conclusions During critical period of growth and development of the maxillofacial system, the patients with oral functional disturbances should be monitored and treated by a multidis- ciplinary team consisting of a dentist, an orthodontist, a pediatrician, an ENT specialist, and an allergologist. The aim of this team is timely diagnostics of disorders, adequate early treatment, and optimal recommendations for primary and secondary prevention, as well as patient monitoring through- out this growth period. Cephalometric radiographs producing 2D images are a sufficiently informative, simple, and inexpensive diagnostic modality, which could be recommended for use in daily clinical practice when diagnosing respiratory system disorders and the disorders of the morphology of skeletal and soft maxillofacial tissues. Cephalometric analysis applied in our study showed that Angle Class II patients with significantly decreased facial convexity angle, increased nasomental, upper lip-chin, and lower lip-chin angles, and upper and lower lips located more proximally to the E line more frequently had constricted airways. Conflict of interest The authors state that they have no conflicts of interest to declare. r e f e r e n c e s [1] Oz U, Orhan K, Rubenduz M. Two-dimensional lateral cephalometric evaluation of varying types of Class II subgroups on posterior airway space in postadolescent girls: a pilot study. J Orofac Orthop 2013;74(1):18–27. [2] Basheer B, Hegde KS, Bhat SS, Umar D, Baroudi K. Influence of mouth breathing on the dentofacial growth of children: a cephalometric study. J Int Oral Health 2014;6(6):50–5. [3] Šidlauskienė M, Smailienė D, Lopatienė K, Čekanauskas E, Pribuišienė R, Šidlauskas M. Relationships between malocclusion, body posture, and nasopharyngeal pathology in pre-orthodontic children. Med Sci Monit 2015;21:1765–73. [4] Souki BQ, Lopes PB, Veloso NC, Avelino RA, Pereira TB, Souza PE, et al. Facial soft tissues of mouth-breathing children: do expectations meet reality? Int J Pediatr Otorhinolaryngol 2014;78(7):1074–9. [5] Ikävalko T, Närhi M, Lakka T, Myllykangas R, Tuomilehto H, Vierola A, et al. Lateral facial profile may reveal the risk for sleep disordered breathing in children. Acta Odontol Scand 2015;73(7):550–5. [6] Indriksone I, Jakobsone G. The upper airway dimensions in different sagittal craniofacial patterns: a systematic review. Stomatologija 2014;16(3):109–17. [7] Muto T, Yamazaki A, Takeda S. A cephalometric evaluation of the pharyngeal airway space in patients with mandibular retrognathia and prognathia, and normal subjects. Int J Oral Maxillofac Surg 2008;37(3):228–31. [8] Kula K, Jeong AE, Halum S, Kendall D, Ghoneima A. Three dimensional evaluation of upper airway volume in children with different dental and skeletal malocclusions. J Biomed Graph Comput 2013;3(4):116–26. [9] Jakobsone G, Urtane I, Terauds I. Soft tissue profile of children with impaired nasal breathing. Stomatologija 2006;8(2):39–43. [10] Silva NN, Lacerda RH, Silva AW, Ramos TB. Assessment of upper airways measurements in patients with mandibular skeletal Class II malocclusion. Dental Press J Orthod 2015;20 (October (5)):86–93. [11] Sutherland K, Schwab RJ, Maislin G, Lee RW, Benedikstdsottir B, Pack AI, et al. Facial phenotyping by quantitative photography reflects craniofacial morphology measured on magnetic resonance imaging in Icelandic sleep apnea patients. Sleep 2014;37(5):959–68. [12] Ryu HH, Kim CH, Cheon SM, Bae WY, Kim SH, Koo SK, et al. The usefulness of cephalometric measurement as a diagnostic tool for obstructive sleep apnea syndrome: a retrospective study. Oral Surg Oral Med Oral Pathol Oral Radiol 2015;119(1):20–31. [13] Pirilä-Parkkinen K, Löppönen H, Nieminen P, Tolonen U, Pääkkö E, Pirttiniemi P. Validity of upper airway assessment in children: a clinical, cephalometric, and MRI study. Angle Orthod 2011;81(3):433–9. [14] Armalaitė J, Lopatienė K. Lateral teleradiography of the head as a diagnostic tool used to predict obstructive sleep apnea. Dentomaxillofac Radiol 2016;45(1):20150085. [15] Grauer D, Cevidanes LS, Styner MA, Ackerman JL, Proffit WR. Pharyngeal airway volume and shape from cone-beam http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0170 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0170 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0170 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0170 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0175 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0175 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0175 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0180 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0180 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0180 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0180 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0180 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0185 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0185 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0185 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0185 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0190 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0190 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0190 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0190 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0195 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0195 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0195 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0200 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0200 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0200 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0200 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0205 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0205 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0205 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0205 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0210 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0210 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0210 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0215 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0215 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0215 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0215 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0220 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0220 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0220 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0220 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0220 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0225 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0225 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0225 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0225 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0225 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0230 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0230 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0230 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0230 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0235 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0235 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0235 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0240 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0240 m e d i c i n a 5 2 ( 2 0 1 6 ) 3 0 7 – 3 1 4314 computed tomography: relationship to facial morphology. Am J Orthod Dentofacial Orthop 2009;136(6):805–14. [16] Joshi M, Wu LP, Maharjan S, Regmi MR. Sagittal lip positions in different skeletal malocclusions: a cephalometric analysis. Prog Orthod 2015;16:77. [17] Anic-Milosevic S, Mestrovic S, Prlić A, Slaj M. Proportions in the upper lip-lower lip-chin area of the lower face as determined by photogrammetric method. J Craniomaxillofac Surg 2010;38(2):90–5. [18] Anić-Milosević S, Lapter-Varga M, Slaj M. Analysis of the soft tissue facial profile by means of angular measurements. Eur J Orthod 2008;30(2):135–40. [19] Rose AD, Woods MG, Clement JG, Thomas CD. Lateral facial soft-tissue prediction model: analysis using Fourier shape descriptors and traditional cephalometric methods. Am J Phys Anthropol 2003;121(2):172–80. [20] Gulsen A, Okay C, Aslan BI, Uner O, Yavuzer R. The relationship between craniofacial structures and the nose in Anatolian Turkish adults: a cephalometric evaluation. Am J Orthod Dentofacial Orthop 2006;130(2):15–25. [21] Johal A, Patel SI, Battagel JM. The relationship between craniofacial anatomy and obstructive sleep apnoea: a case- controlled study. J Sleep Res 2007;16(3):319–26. [22] Dimaggio FR, Ciusa V, Sforza C, Ferrario VF. Photographic soft-tissue profile analysis in children at 6 years of age. Am J Orthod Dentofacial Orthop 2007;132(4):475–80. [23] Nanda V, Gutman B, Bar E, Alghamdi S, Tetradis S, Lusis AJ, et al. Quantitative analysis of 3-dimensional facial soft tissue photographic images: technical methods and clinical application. Prog Orthod 2015;16:21. [24] Choi JW, Lee JY, Oh TS, Kwon SM, Yang SJ, Koh KS. Frontal soft tissue analysis using a 3 dimensional camera following two-jaw rotational orthognathic surgery in skeletal class III patients. J Craniomaxillofac Surg 2014;42(3):220–6. [25] Lee RW, Sutherland K, Chan AS, Zeng B, Grunstein RR, Darendeliler MA, et al. Relationship between surface facial dimensions and upper airway structures in obstructive sleep apnea. Sleep 2010;33(9):1249–54. [26] Zhang X, Hans MG, Graham G, Kirchner HL, Redline S. Correlations between cephalometric and facial photographic measurements of craniofacial form. Am J Orthod Dentofacial Orthop 2007;131(1):67–71. [27] Passali FM, Bellussi L, Mazzone S, Passali D. Predictive role of nasal functionality tests in the evaluation of patients before nocturnal polysomnographic recording. Acta Otorhinolaryngol Ital 2011;31(2):103–8. [28] Mello Junior CF, Guimarães Filho HA, Gomes CA, Paiva CC. Radiological findings in patients with obstructive sleep apnea. J Bras Pneumol 2013;39(1):98–101. [29] Lee RW, Chan AS, Grunstein RR, Cistulli PA. Craniofacial phenotyping in obstructive sleep apnea – a novel quantitative photographic approach. Sleep 2009;32(1):37–45. [30] Sutherland K, Lee RW, Cistulli PA. Obesity and craniofacial structure as risk factors for obstructive sleep apnoea: impact of ethnicity. Respirology 2012;17(2):213–22. [31] Sato K, Shirakawa T, Sakata H, Asanuma S. Effectiveness of the analysis of craniofacial morphology and pharyngeal airway morphology in the treatment of children with obstructive sleep apnoea syndrome. Dentomaxillofac Radiol 2012;41(5):411–6. [32] Lopatiene K, Smailiene D, Sidlauskiene M, Cekanauskas E, Valaikaite R, Pribuisiene R. An interdisciplinary study of orthodontic, orthopedic, and otorhinolaryngological findings in 12–14-year-old preorthodontic children. Medicina (Kaunas) 2013;49(11):479–86. [33] Ucar FI, Uysal T. Comparision of orofacial airway dimensions in subject with different breathing pattern. Prog Orthod 2012;13(3):210–7. http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0240 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0240 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0245 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0245 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0245 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0250 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0250 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0250 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0250 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0255 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0255 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0255 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0260 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0260 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0260 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0260 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0265 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0265 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0265 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0265 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0270 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0270 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0270 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0275 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0275 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0275 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0280 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0280 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0280 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0280 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0285 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0285 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0285 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0285 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0290 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0290 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0290 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0290 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0295 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0295 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0295 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0295 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0300 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0300 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0300 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0300 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0305 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0305 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0305 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0310 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0310 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0310 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0315 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0315 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0315 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0320 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0320 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0320 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0320 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0320 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0325 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0325 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0325 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0325 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0325 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0330 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0330 http://refhub.elsevier.com/S1010-660X(16)30060-X/sbref0330 Relationship between malocclusion, soft tissue profile, and pharyngeal airways: A cephalometric study 1 Introduction 2 Materials and methods 2.1 Statistical analysis 3 Results 4 Discussion 5 Conclusions Conflict of interest References