Evaluation of pronasale, nasolabial and paranasal asymmetries in patients with unilateral cleft lip and palate using three-dimensional imaging

A BSTRACT O BJECTIVE: Facial symmetry is an important component of a successful treatment of patients with cleft lip and palate. The aim of this retrospective study was to examine the pronasale, nasolabial, and paranasal region asymmetries in patients with nonsyndromic unilateral cleft lip and pal ate (UCLP) using three-dimensional (3D) facial imaging. M ATERIALS AND M ETHOD: The study group consisted of 29 patients with complete UCLP aged 8–29 years. 3D ste reophotogrammetric soft tissue recordings of all patients were analyzed. Measurements were performed on the cleft and noncleft side and compared with each other by the paired t-test. R ESULTS: Statistically significant differences were ob served between the cleft and noncleft sides. Alar contour-Pronasale distance was longer on the cleft side than on the noncleft side, with the difference between them being statistically significant (p<0.05). The Subnasale-Pronasale / Alar contour-Pronasale ratio was also significantly lower on the cleft side than on the noncleft side (p<0.05). C ONCLUSION: Patients with UCLP did not present signifi cant asymmetries regarding Cheek and Buccal contours and Chelion-Subnasale and Christa Philtry-Subnasale heights. Asymmetrical appearance was prominent on alar base and pronasale regions. C ITATION: Alpağan


INTRODUCTION
A symmetrical face is considered one of the main features of attractiveness. 1 People are sensitive to different levels of facial asymmetry and perceive symmetrical faces as more attractive. 2 Mild facial asymmetries are common biological features that can even be considered aesthetically pleasing 3 ; however, because severe facial asymmetries have an adverse effect on external appearance, corrective treatments are important issues. A typical anomaly that produces mild or severe facial asymmetries is the cleft lip and palate (CLP). These facial asymmetries are common in patients with bilateral (BCLP) and unilateral cleft lip and palate (UCLP). 4 In patients with UCLP, significant asymmetries of the nose and upper lip may remain even after extensive treatment during infancy. 5,6 In previous studies on patients with UCLP, it was reported that the nose was generally asymmetrical, the tip of the nose was deformed, flattened and deviated to the unaffected side. 7,8 However, it has also been stated that the nasoalveolar molding treatment plays an important role in providing nasal symmetry in patients with UCLP. 9 It is widely accepted that there is a link between subjectively evaluated attractiveness and objective symmetry analyzes, 1,10,11 and there are several studies on the facial asymmetries of CLP patients in the literature. 7,[12][13][14] These studies were conducted using various methods, such as direct anthropometric measurements, 3 postero-posteroanterior cephalometric radiographs, 15 two-dimensional photographs, 16 cone-beam computed tomographies, 17 and three-dimensional (3D) stereophotogrammetry images. [18][19][20] Posteroanterior radiographic analysis, which is frequently used to evaluate facial asymmetries, is an effective method by which to demonstrate skeletal asymmetry; however, the soft tissues that cover skeletal structures can compensate for the underlying skeletal anomaly, to either reflect it as is or as more severe. 21,22 Facial asymmetries are also 3D anomalies with frontal, sagittal, and vertical components; therefore, the use of 3D imaging methods by which to simultaneously assess these three components to examine asymmetry is presumed to be more accurate. 14 After the development of high-resolution digital cameras, 3D stereophotogrammetry methods have become popular because they provide more detailed imaging of the facial soft tissues. 23 3D stereophotogrammety imaging can be used as a successful technique in orthodontic patients and those with craniofacial anomalies, such as CLP, and the facial asymmetries of these patients can be examined in detail. [24][25][26] The aim of this study was to evaluate paranasal and nasolabial asymmetry in patients with UCLP using by acquiring 3D data. The null hypothesis tested was that there were no significant differences in 3D landmark asymmetry between the cleft and noncleft sides of the patients with complete UCLP.

MATERIALS AND METHOD
This study was approved by the University Ethics Committee before commencement of the study. This singlecentered and retrospective investigation was conducted on 29 patients (13 females, 16 males) from 8 to 29 years old (mean age: 15.45 years) with nonsyndromic complete UCLP. The inclusion criteria were as follows: 1) absence of any systemic or metabolic disease and 2) absence of any congenital anomaly other than cleft lip and palate. Patients undergone growth modification therapy and orthognathic surgery before taking 3D images were excluded. All CLP patients who underwent orthodontic treatment (125 patients aged 8-32 years old) were evaluated first based on the inclusion criteria. Fifty-two of these patients were excluded from the study because 8 of them had isolated cleft palate, 42 had BCLP,and 2 had no stereophotogrammetry records. Of the remaining 73 patients, 44 were excluded from the study because they had previously undergone growth modification therapies or orthognathic surgery before the 3D images were taken.
Stereophotogrammetric images of all patients were assessed. All images were taken using the noninvasive 3dMDface System (3dMD LLC, Atlanta, GA, USA) with an image-capture time of 1.5 ms. All images were taken under standard office lighting conditions and a natural head position, which have high clinical reproducibility. The 3D images were reoriented and analyzed using 3dMD Vultus ® software ver. 2.3.0.2 (3dMD LLC, Atlanta, GA, USA). All 3dMD images were reoriented in all dimensions to standardize them and all sections that were not included in the analyses were removed.
The anthropometric landmarks used in this study are shown in Figure 1. The linear, angular, and proportional measurements are shown in Figures 2A-C. All measurements and landmark identifications were per-formed by a single operator. The coronal plane (CP) was determined as the line passing through the outer canthi of both eyes. Measurements performed in this study included Cheilion (Ch)-Alar curvature (Ac), Ac-Pronasale (Pr), Ac-Subnasale (Sn), Christa philtry (Cph)-Sn, Buccal contour-Soft tissue Nasion´-Sn, Sn-Pr/Ac-Pr, Cheek point (Ck)-CP, Ac-CP, and Buccal contour-CP. These measurements were taken symmetrically on the cleft and noncleft sides and compared each other.

Descriptions of the parameters
Ch-Ac (mm): distance between Cheilion (Ch) point and Ac point.  Cheek point Right CkR

10
Cheek point Left CkL

RESULTS
The linear, angular, and proportional measurements were compared and were shown in Table 1. The Ac-Prn was longer on the cleft side than on the noncleft side, and the difference was statistically significant (p<0.05). The Sn-Prn/Ac-Prn was significantly lower on the cleft side than on the noncleft side (p<0.05).

DISCUSSION
One of the main objectives in the treatment of patients with UCLP is to create a symmetrical appearance of the nasolabial region. Although some patients with UCLP have satisfactory functional results after primary repair of the cleft, others need more revisions because of their nasolabial asymmetry. 27 In previous studies conducted on patients with UCLP, it has been reported that the nose was generally asymmetric; because the alar base shape is even more flat because of insufficient bone support on the affected side, and the columella is wider and shorter on the cleft side. 28 It may be difficult to do objective evaluation of soft tissue symmetry

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Bc -Coronal Plane 14 -15 in patients with cleft due to its complexity; therefore, the use of 3D facial images has become more popular in recent years for evaluating facial asymmetries in patients with UCLP. 29,30 Although perfect symmetry is not expected in patients with cleft lip and palate, the nasolabial area where asymmetry is most prominent should be examined using these 3D methods. Previous studies that investigated the accuracy of anthropometric measurements using 3D stereophotogrammetry, it was concluded that the system was a reliable technique for facial soft tissue analysis. 23,[31][32][33][34][35][36][37] Therefore, in the present study, the measurements on the cleft and noncleft sides in patients with UCLP were compared using non-cal history, very few areas on those in our study group exhibited significant asymmetry. These findings might have resulted in midface deficiencies of both the cleft and noncleft sides instead of severe asymmetrical characteristics. In addition, this study group can be considered as substantially heterogeneous because the exact primary surgical procedures performed could not be identified as a result of the lack of documentation. Another limitation of the present study may be wide age range. In their study, Kyrkanides et al. 40 compared patients with UCLP and noncleft patients for symmetry analysis in different age groups. Because the faces of the noncleft controls presented less symmetrical characteristics, particularly in those within the postpubertal age group, the researchers reported that the difference in symmetry between the two groups decreased with growth and development. 40 Consequently, because of the many confounding effects in patients with clefts, such as primary surgical type, revisions, cleft severity, and growth period, etc. as seen in the previous studies, these can be considered the most common limitations.

CONCLUSION
Our analyses of symmetry using 3D stereophotogrammetric images showed that nasolabial asymmetry was more intense on the pronasale and alar base regions in patients with UCLP. Further studies are needed using larger sample size and groups that are more homogeneous. invasive 3D stereophotogrammetry system to quantitatively evaluate nasolabial symmetry.
The null hypothesis was rejected in the present study. It was found that there were significant differences between the cleft and noncleft side of the patients in two of the nine soft-tissue measurements that were assessed. Ac-Prn distance was longer on the cleft side than on the noncleft side, which was in agreement with results of previous studies. 20,28 Because of insufficient bone support within the cleft region, the nasal base was more flat and the pronasale point was deviated toward the noncleft side. Bagante et al. 28 compared the Al-Prn (mm) distance, which is similar to the Ac-Prn (mm) measurement on cleft and noncleft sides of patients with UCLP. They found that this distance was significantly shorter on the cleft side than the noncleft side. 28 The reason for the different results of similar measurements might be the characteristics of the patients who were in the study group, who had undergone a secondary rhinoplasty surgery that allowed repositioning of the nasal septum and pronasale. In accordance with this finding, Sn-Prn/Ac-Prn was lower on the cleft side because the Ac-Prn distance was longer on that side. This result suggested that the nostril shape on the cleft side was wider and appeared to be more asymmetrical than that on the noncleft side because of significant differences in the vertical dimensions. In previous studies, it has been reported that nasoalveolar molding (NAM) was beneficial for providing symmetry in the vertical direction. 38,39 Nevertheless, patients who were in the present study did not have NAM therapy.