Photographic analysis of orofacial soft tissue alterations related to rapid maxillary expansion in pediatric patients

Hande Uzunçıbuk; Maria Maddalena Marrapodi; Aida Meto; Gabriele Cervino; Marco Cicciù; Giuseppe Minervini

doi:10.22514/jocpd.2024.031

Journal of Clinical Pediatric Dentistry. 2024; 48(2): 26-39. doi: 10.22514/jocpd.2024.031

Original Research

Photographic analysis of orofacial soft tissue alterations related to rapid maxillary expansion in pediatric patients

Hande Uzunçıbuk¹, Maria Maddalena Marrapodi², Aida Meto³^,^*^,, Gabriele Cervino⁴^,^*^,, Marco Cicciù⁵, Giuseppe Minervini⁶^,⁷

¹Department of Orthodontics, Dentistry Faculty, Trakya University, 22030 Edirne, Turkey

²Department of Woman, Child, and General and Specialist Surgery, University of Campania “Luigi Vanvitelli”, 80138 Naples, Italy

³Department of Dentistry, Faculty of Dental Sciences, University of Aldent, 1007 Tirana, Albania

⁴Department of Biomedical and Dental Sciences, Morphological and Functional images, University of Messina “G. Martino” Polyclinic, 98125 Messina, Italy

⁵Department of General Surgery and Medical-Surgical Specialties, School of Dentistry, University of Catania, 95123 Catania, Italy

⁶Saveetha Dental College and Hospitals, Saveetha Institute of Medical and Technical Sciences (SIMATS), Saveetha University, 600077 Chennai, India

⁷Multidisciplinary Department of Medical-Surgical and Dental Specialties, University of Campania Luigi Vanvitelli, 80138 Naples, Italy

^*Corresponding Author(s):gcervino@unime.it (Gabriele Cervino); aida.meto@ual.edu.al (Aida Meto)

History

Submitted: 04 March 2023 | Accepted: 12 May 2023 | Published: 03 March 2024

Copyright:	©2024 The Author(s). Published by MRE Press.
	This is an open access article under the CC BY 4.0 license (https://creativecommons.org/licenses/by/4.0/).

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Abstract

Maxillary transverse deficiency is widely recognized as one of the most common skeletal issues in orthodontics, and rapid maxillary expansion (RME) is commonly employed as a treatment method. This study aimed to investigate the impact of RME on the soft tissues of the orofacial region in pediatric patients. The study included two groups: an experimental group comprising 30 patients (16 females and 14 males) with maxillary skeletal transverse deficiency who required rapid maxillary expansion (RME), and a control group consisting of patients (10 females and 10 males) who did not require RME or orthodontic treatment. Frontal and profile photographs were taken before and after RME for both groups. Frontal photographs were used to obtain 12 linear measurements, while profile photographs were used to perform 2 linear and 2 angular measurements using the “protractor” and “pixel ruler” software. Burstone-Legan, Steiner and Rickett’s analyses were performed to determine the locations of the upper and lower lips. Student t-test, paired samples t-test and Mann-Whitney U test were used to evaluate the data. In the experimental group, there was a statistically significant increase in nose width and intercommissural distance at the end of the treatment (p < 0.05). Similarly, both the experimental and control groups showed a statistically significant increase in the dorsum of nose length at T2 compared to the initial measurement (p < 0.05). Furthermore, the male participants in the experimental group exhibited a statistically significantly higher increase in nose length and dorsum of the nose during the T1 and T2 periods compared to the female participants in the experimental group (p < 0.05). RME may lead to changes in soft tissues in pediatric patients and was observed to be gender-specific. However, these changes were not clinically noticeable, and long-term follow-up studies are needed to determine the long-term effects of these changes.

Keywords:OrthodonticsMaxillary expansionPediatricsSoft tissue

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Cite this article

Hande Uzunçıbuk, Maria Maddalena Marrapodi, Aida Meto, Gabriele Cervino, Marco Cicciù, Giuseppe Minervini. Photographic analysis of orofacial soft tissue alterations related to rapid maxillary expansion in pediatric patients. Journal of Clinical Pediatric Dentistry. 2024; 48(2): 26-39. doi: 10.22514/jocpd.2024.031

1. Introduction

The maxilla is connected to several bones, including the frontal, lacrimal, nasal, ethmoid, palatine, vomer, zygoma, inferior nasal concha and sphenoid bones, through sutures to form the pterygopalatine, zygomaticomaxillary, frontomaxillary and palatomaxillary sutures with the facial bones [1, 2]. Maxillary deficiency refers to a narrowing of the maxillary arch, often resulting in a unilateral or bilateral posterior crossbite, which can be attributed to genetic and/or environmental factors [3]. Rapid maxillary expansion (RME) is a commonly used orthodontic treatment for pediatric patients [4, 5, 6] involving orthopedically separating the mid-palatal suture [7, 8, 9]. During RME, the maxillofacial sutures become tense, the pterygoid processes of the sphenoid bone expand outward, the palatine bones split, and the maxillary base moves forward [10, 11].

RME is often used to correct maxillary transversal skeletal deficiency, especially in young adolescent patients with posterior crossbite, moderate/severe crowding and obstructive sleep apnea. It is also performed on patients experiencing maxillary deficiency in the anterior region during the peak stage, where the growth of the mandible is hindered by the maxillary teeth [10, 12, 13, 14].

In addition to its orthopedic effects, the use of RME appliances can lead to orthodontic changes, including buccal tipping and extrusion movements of premolars and molars, as well as lateral rotations of posterior alveolar segments [15, 16]. These movements can cause the mandible to rotate backward and downward, resulting in an increase in facial height. It has been reported that RME can also cause changes in soft tissues due to the movements in the maxillary segments and maxillofacial sutures [16, 17, 18, 19]. Furthermore, studies utilizing posteroanterior radiographs have reported increases in nasal, maxillary and zygomatic width following RME, reflecting changes in hard tissues [18, 20, 21]. However, the impact of these alterations in hard tissues on the soft tissues has not been thoroughly investigated [18, 22, 23, 24]. Recent orthodontic treatment plans have placed a greater emphasis on enhancing soft tissues rather than solely focusing on tooth alignment, with the primary goal of improving facial esthetics [25, 26, 27, 28].

Numerous studies have utilized cone beam computed tomography (CBCT) images and 3D facial scans to assess changes in soft tissue following RME [29, 30, 31, 32, 33, 34, 35]. However, the use of 3D imaging systems in pediatric patients is limited, typically reserved for cases involving serious craniofacial anomalies or syndromes due to the high radiation dose associated with these scans [36, 37, 38]. Additionally, the cost of 3D imaging devices makes them inaccessible in many orthodontic clinics. Alternatively, orthodontic clinics routinely obtain photographs and radiographs from patients at the beginning, mid-stage and completion of treatment, allowing for clear observation of not only the changes in dentition and skeletal structure but also alterations in soft tissues resulting from orthodontic interventions [23, 24].

This study aimed to investigate the impact of RME on the soft tissues of young adolescents and its potential effects on facial aesthetics. Anthropometric measurements were performed on frontal and profile photographs to assess changes resulting from this commonly applied treatment for pediatric patients with maxillary skeletal deficiency and to explore potential gender differences associated with these changes.

2. Materials and methods

2.1 Subjects

A total of 30 patients with maxillary skeletal transverse deficiency, consisting of 16 females and 14 males, were included in this study. The inclusion criteria for this study were as follows: no history of previous orthodontic treatment, presence of unilateral or bilateral posterior crossbite, the inclusion of maxillary expansion in the treatment plans, and no history of craniofacial or systemic disease. In addition to the experimental group, a control group of 20 individuals (10 females and 10 males) who did not require RME or orthodontic treatment was also included. The mean chronological age for females was 11.23 ± 1.45, while for males, it was 12.13 ± 2.10. The skeletal maturity of both the experimental and control groups was determined using the S, H2 and MP3 cap stages at T1, based on the Greulich-Pyle Atlas, which was used to assess skeletal age. All study participants were from the same geographic region and belonged to the same racial group.

2.2 Sample size

An initial statistical evaluation was conducted to determine the sample size, considering a power of 90%, a two-tailed analysis, and a significance level of 5% (to correct for multiple comparisons), based on the mean of the nose width measurements at post-expansion (T2) (14.9 ± 1.02) and the mean of the measurements at pre-expansion (T1) (13.8 ± 1.12) obtained from a population of 12 patients (our preliminary results). The results indicated a minimum sample size of 22 individuals to obtain reliable comparative analytic results.

2.3 Treatment procedure

The RME devices utilized in this study consisted of an acrylic-cap splint covering only the posterior teeth and a Hyrax expansion screw (Leone Orthodontics, Firenze, Italy) (Fig. 1). The acrylic-cap splint was bonded to the upper teeth using a glass ionomer luting cement called Meron (VOCO, Cuxhaven, Germany). All the RME devices were manufactured by the same qualified technician to ensure consistency. Patients in the experimental group included individuals with mixed or permanent dentition, and no complications related to the stabilization of the RME appliances were reported. The Hyrax screws were activated twice daily (0.25 mm per turn). The activation of the Hyrax screw was performed for 2–3 weeks, aiming for a total expansion of 9–10 mm in accordance with the patient’s needs, with a 20% overcorrection. To evaluate the effectiveness of RME, occlusal radiographs were taken both before and after the treatment, allowing for the measurement of the separation of the mid-palatal suture (Fig. 2). Patients with poor oral hygiene and gingival inflammation received oral hygiene training as part of their treatment.

Fig. 1.RME device. The occlusal-coverage bonded type RME device with Hyrax screw used in the study is presented.

Fig. 2.Occlusal radiographs. Occlusal radiographs were taken before and after RME, and the separation of the midpalatal suture is presented.

2.4 Photographic assessment

To ensure standardization, all photographs were captured from the same distance of 110 cm using a Nikon d7200 camera equipped with a Sigma 105 macro lens. Frontal and profile photographs, which are commonly taken in orthodontic clinics by professional photograph technicians, were obtained with the patients maintaining their natural head position. Prior to the photographic examination, all accessories were removed to allow for a clear examination of the subjects. For the experimental group, initial photographs (T1) were taken prior to the application of RME. Intermediate phase photographs (T2) were captured immediately after the removal of the RME device. In contrast, the control group consisted of patients who presented to the clinic without prior orthodontic treatment, for whom photographs were taken at the beginning and six months later. The retention phase involved the expansion device being retained for approximately six months. The time interval between T1 and T2, representing the initial and intermediate phases, respectively, was approximately 6.3 months [3, 16, 39].

2.5 Measurements

To ensure the standardization of patient photographs at times T1 and T2, a 30 cm ruler was used for calibration purposes. The ruler was projected and photographed, and the resulting image was adjusted to achieve a 1-to-1 ratio with the actual size of the ruler. For the frontal view measurements, the patient’s interpupillary distance was superimposed in both T1 and T2 photographs (Fig. 3). In the profile measurements, the patient’s tragus overlaps and lip positions were used as reference points (Figs. 4,5). All measurements were recorded in millimeters (mm).

Fig. 3.Frontal measurements. A schematic diagram of 12 linear measurements made on frontal photographs is presented.

Fig. 4.Profile measurements. A schematic diagram of 2 linear and 2 angular measurements made on profile photographs is presented.

Fig. 5.Lip position measurements. Lip positions relative to different reference planes are presented.

2.6 Error of the study

The examiner (H.U.) repeated all measurements on 30 frontal and profile photographs of 15 randomly selected patients: five in the female experimental group, five in the male experimental group, and five in the control group to determine method error. The intraclass correlation coefficient (ICC) for all measurements was found to be nearly 1.00, indicating that the measurements could be repeated with negligible error that would not impact the results.

2.7 Statistical analysis

Statistical analysis was performed using SPSS software version 22.0 (SPSS, Chicago, IL, USA). The normal distribution of parameters was assessed using the Kolmogorov-Smirnov and Shapiro-Wilk tests. Student’s t-test was employed for comparing normally distributed parameters between two groups. Within-group comparisons of normally distributed parameters were conducted using paired samples t-test, the Mann-Whitney U test was used for comparing non-normally distributed parameters, and continuity (Yates) correction was applied for comparing qualitative data. Statistical significance level was set at p < 0.05.

3. Results

Table 1 presents the definition of measurements made on the frontal and profile photographs.

Table 1.The definition of measurements made on the frontal and profile photographs.

Planes	Landmark Definitions
Frontal Measurements
	1. Eye Width	Distance between the far right and left point of the eye
	2. Nasal Width of the Middle Third	Distance between the right and left of the middle third of the nose
	3. Nose Width	Distance between the right and left alare
	4. Upper Face Width	Distance between the right and left cheekbones
	5. Lower Face Width	Distance between the right and left gonion
	6. Intercanthal Distance	Distance between the right and left endocanthion
	7. Nose Length	Distance between the soft tissue nasion and subnasal point
	8. Upper Lip Length	Distance from subnasale to stomion
	9. Lower Lip/Chin Length	Distance from stomion to menton
	10. Intercommissural Distance	Distance between the right and left commissure
	11. Upper Lip Vermillion	Distance from labrale superior to stomion
	12. Lower Lip Vermillion	Distance from stomion to labrale inferior
Profile Measurements
	13. Dorsum of the Nose	The length of the nose’s external ridge
	14. Alar Base	The length of the alar base
	15. Soft Tissue Facial Angle	The angle formed by the glabella, subnasale and pogonion soft tissues
	16. Nasolabial Angle	The angle formed by columella, subnasale and labrale superior
Lip Positions
	17. B-Line	Shows the Burstone-Legan Analysis
	18. S-Line	Shows the Steiner Analysis
	19. E-Line	Shows the Rickett’s Analysis

The analysis revealed no statistically significant difference between the groups regarding gender (p > 0.05), indicating that gender distribution was similar in both the experimental and control groups (Table 2).

Table 2.Evaluation of groups in terms of gender.

	Experimental n (%)	Control n (%)	p
Female	16 (53.3%)	10 (50%)	1
Male	14 (46.7%)	10 (50%)
Continuity (yates) correction.

Table 3 displays the changes in frontal measurements obtained from the photographs. The results showed that within the experimental group, a statistically significant increase in nose width and intercommissural distance was observed at the end of the treatment (p < 0.05).

Table 3.Intergroup and intragroup evaluation of frontal measurements.

		Experimental (n = 30) Mean ± SD (median)	Control (n = 20) Mean ± SD (median)	¹p
Eye Width
	T1	12.54 ± 1.39	12.04 ± 1.23	0.199
	T2	12.57 ± 1.36	12.04 ± 1.23	0.169
	²p	0.379	0.330
Nasal Width of The Middle Third
	T1	7.49 ± 1.22	6.72 ± 0.67	0.013*
	T2	7.50 ± 1.20	6.73 ± 0.65	0.012*
	²p	0.482	0.166
Nose Width
	T1	14.00 ± 1.89	13.43 ± 1.28	0.211
	T2	14.91 ± 1.80	13.44 ± 1.27	0.001*
	²p	0.001*	0.106
Upper Face Width
	T1	55.87 ± 5.55	58.04 ± 3.41	0.095
	T2	55.90 ± 5.52	58.12 ± 3.45	0.086
	²p	0.813	0.163
Lower Face Width
	T1	48.30 ± 5.43	54.38 ± 3.96	0.001*
	T2	48.47 ± 5.39	54.46 ± 4.01	0.001*
	²p	0.198	0.185
Intercanthal Distance
	T1	12.67 ± 1.64	13.67 ± 1.65	0.041*
	T2	12.70 ± 1.67	13.67 ± 1.65	0.049*
	²p	0.161	1.000
Nose Length
	T1	18.69 ± 1.72	18.80 ± 0.89	0.757
	T2	18.86 ± 1.71	18.88 ± 0.93	0.960
	²p	0.097	0.024*
Upper Lip Length
	T1	8.78 ± 1.67	9.47 ± 0.72	0.054
	T2	8.77 ± 1.68	9.48 ± 0.69	0.044*
	²p	0.883	0.278
Lower Lip-Chin Length
	T1	17.39 ± 3.27	18.29 ± 1.44	0.192
	T2	17.58 ± 3.36	18.30 ± 1.43	0.301
	²p	0.093	0.010*
Intercommissural Distance
	T1	19.04 ± 2.03	18.40 ± 1.16	0.167
	T2	19.73 ± 2.02	18.43 ± 1.17	0.006*
	²p	0.001*	0.231
Upper Lip Vermillion
	T1	3.37 ± 0.78	3.69 ± 0.69	0.140
	T2	3.36 ± 0.71	3.70 ± 0.69	0.098
	²p	0.879	0.287
Lower Lip Vermillion
	T1	4.30 ± 0.76	5.03 ± 0.74	0.001*
	T2	4.35 ± 0.78	5.03 ± 0.73	0.004*
	²p	0.168	0.525
¹Student t test. ²Paired Samples t test. p < 0.05. SD: Standard Deviation.*

The nasal width of the middle third in the experimental group at both T1 and T2 was significantly higher than that of the control group (p < 0.05). Conversely, the lower face width, intercanthal distance and lower lip vermillion measurements in the experimental group at T1 and T2 were significantly lower than in the control group (p < 0.05).

Table 4 presents the changes in profile measurements obtained from the photographs. The dorsum of the nose and soft tissue facial angle in the experimental group at T1 and T2 were significantly higher than those in the control group (p < 0.05), while the alar base in the experimental group at T1 and T2 was significantly lower than the control group (p < 0.05). Within both groups, there was a significant increase in the dorsum of nose length at T2 (p < 0.05). However, there was no significant change in the upper and lower lip positions relative to different reference planes during the T1–T2 period (p > 0.05) (Table 5).

Table 4.Intergroup and intragroup evaluation of profile measurements.

		Experimental (n = 30) Mean ± SD (median)	Control (n = 20) Mean ± SD (median)	¹p
Dorsum of the Nose
	T1	14.82 ± 1.57	13.13 ± 1.12	0.001*
	T2	15.07 ± 1.50	13.92 ± 1.19	0.006*
	²p	0.001*	0.001*
Alar Base
	T1	5.37 ± 0.93	6.63 ± 0.69	0.001*
	T2	5.37 ± 0.93	6.63 ± 0.75	0.001*
	²p	0.932	0.935
Soft Tissue Facial Angle
	T1	162.94 ± 5.06	158.67 ± 3.06	0.001*
	T2	162.38 ± 4.37	158.63 ± 3.04	0.002*
	²p	0.317	0.242
Nasolabial Angle
	T1	114.93 ± 9.68	118.00 ± 10.94	0.301
	T2	115.70 ± 9.33	117.93 ± 10.96	0.443
	²p	0.184	0.482
¹Student t test. ²Paired Samples t test. p < 0.05. SD: Standard Deviation.*

Table 5.Intergroup and intragroup evaluation of upper and lower lip measurements.

		Experimental (n = 30) Mean ± SD (median)	Control (n = 20) Mean ± SD (median)	¹p
B-Line—Upper Lip
	T1	1.03 ± 0.82	1.18 ± 0.44	0.402
	T2	1.20 ± 0.73	1.19 ± 0.44	0.930
	²p	0.056	0.093
B-Line—Lower Lip
	T1	0.99 ± 1.02	1.46 ± 0.61	0.069
	T2	0.98 ± 0.90	1.46 ± 0.61	0.061
	²p	0.895	0.202
S-Line—Upper Lip
	T1	−0.12 ± 0.80	0.00 ± 0.54	0.563
	T2	0.01 ± 0.80	0.03 ± 0.57	0.931
	²p	0.148	0.235
S-Line—Lower Lip
	T1	−0.02 ± 1.02	−0.13 ± 0.67	0.653
	T2	−0.03 ± 0.94	−0.12 ± 0.65	0.715
	²p	0.897	0.268
E-Line—Upper Lip
	T1	−1.05 ± 1.28	−1.35 ± 0.41	0.242
	T2	−0.85 ± 1.42	−1.35 ± 0.40	0.077
	²p	0.346	0.836
E-Line—Lower Lip
	T1	−0.74 ± 1.04	−0.47 ± 0.98	0.345
	T2	−0.89 ± 0.92	−0.44 ± 0.96	0.101
	²p	0.060	0.077
¹Student t test. ²Paired Samples t test. p < 0.05. SD: Standard Deviation.*

Next, we assessed the relationship between the T1–T2 change amounts of the experimental and control groups (Table 6). The results showed that the increase in nose width, intercommissural distance and nasolabial angle measurements in the experimental group during the T1 and T2 period were significantly higher than in the control group, while the increase in the dorsum of nose measurement in the experimental group during the T1 and T2 period was significantly lower than in the control group (p < 0.05).

Table 6.Evaluation of the experimental and control groups in terms of T1–T2 change amounts.

		Experimental (n = 30)	Control (n = 20)
T1–T2 Difference	Mean ± SD (median)	Mean ± SD (median)	p
Frontal Measurements
	Eye Width	0.03 ± 0.18 (0)	0 ± 0 (0)	0.501
	Nasal Width of The Middle Third	0.01 ± 0.08 (0)	0.01 ± 0.03 (0)	0.335
	Nose Width	0.91 ± 0.47 (1)	0.01 ± 0.03 (0.01)	0.001*
	Upper Face Width	0.02 ± 0.54 (0)	0.09 ± 0.27 (0)	0.381
	Lower Face Width	0.17 ± 0.71 (0)	0.08 ± 0.26 (0.01)	0.967
	Intercanthal Distance	0.03 ± 0.10 (0)	0 ± 0 (0)	0.243
	Nose Length	0.18 ± 0.56 (0)	0.08 ± 0.14 (0.03)	0.444
	Upper Lip Length	−0.01 ± 0.40 (0)	0.02 ± 0.07 (0.01)	0.642
	Lower Lip-Chin Length	0.19 ± 0.59 (0)	0.01 ± 0.02 (0.01)	0.917
	Intercommissural Distance	0.69 ± 0.93 (0.18)	0.02 ± 0.08 (0)	0.006*
	Upper Lip Vermillion	−0.01 ± 0.21 (0)	0.01 ± 0.05 (0)	0.681
	Lower Lip Vermillion	0.06 ± 0.22 (0)	0 ± 0.03 (0)	0.898
Profile Measurements
	Dorsum of Nose	0.24 ± 0.37 (0)	0.79 ± 0.45 (1.02)	0.001*
	Alar Base	0 ± 0.04 (0)	0 ± 0.16 (0)	0.960
	Soft Tissue Facial Angle	−0.56 ± 3.01 (0)	−0.04 ± 0.16 (0)	0.429
	Nasolabial Angle	0.77 ± 3.10 (0.08)	−0.07 ± 0.45 (0)	0.003*
Upper and lower lip
	B-Line—Upper Lip	0.18 ± 0.49 (0)	0.01 ± 0.03 (0)	0.546
	B-Line—Lower Lip	−0.04 ± 0.52 (0)	0 ± 0.01 (0)	0.865
	E-Line—Upper Lip	0.20 ± 1.14 (0)	0 ± 0.06 (0)	0.695
	E-Line—Lower Lip	−0.14 ± 0.40 (−0.01)	0.03 ± 0.06 (0)	0.038*
	S-Line—Upper Lip	0.12 ± 0.45 (0.01)	0.02 ± 0.08 (0)	0.357
	S-Line—Lower Lip	−0.01 ± 0.57 (0)	0.01 ± 0.06 (0)	0.300
Mann Whitney U test. p < 0.05. SD: Standard Deviation.*

Table 7 presents the relationship between the T1–T2 change amounts of the experimental and control groups in females. The increase in nose width in the experimental group during the T1 and T2 period was significantly higher than in the control group, while the increase in the dorsum of nose measurement in the experimental group during the T1 and T2 period was significantly lower than in the control group in females (p < 0.05). In addition, while a decrease in upper lip length was observed in the T1 and T2 period in the experimental group, an increase was observed in the control group in females, and this difference was statistically significant (p < 0.05).

Table 7.Evaluation of the experimental and control groups in terms of T1–T2 change amounts in females.

		Experimental (n = 16)	Control (n = 10)
T1–T2 Difference (Female)	Mean ± SD (median)	Mean ± SD (median)	p
Frontal Measurements
	Eye Width	−0.01 ± 0.03 (0)	0 ± 0 (0)	0.429
	Nasal Width of The Middle Third	−0.01 ± 0.05 (0)	0 ± 0.01 (0)	0.058
	Nose Width	0.82 ± 0.41 (0.94)	0.02 ± 0.03 (0)	0.001*
	Upper Face Width	−0.19 ± 0.56 (0)	0.11 ± 0.34 (0)	0.029*
	Lower Face Width	0.04 ± 0.76 (0)	0.01 ± 0.02 (0.01)	0.583
	Intercanthal Distance	0.03 ± 0.10 (0)	0 ± 0 (0)	0.429
	Nose Length	0.06 ± 0.40 (0)	0.05 ± 0.10 (0.02)	0.661
	Upper Lip Length	−0.09 ± 0.50 (0)	0.04 ± 0.07 (0.01)	0.032*
	Lower Lip-Chin Length	0.19 ± 0.67 (0)	0.02 ± 0.03 (0.02)	0.578
	Intercommissural Distance	0.63 ± 0.93 (0.1)	0.04 ± 0.11 (0)	0.062
	Upper Lip Vermillion	−0.04 ± 0.29 (0)	0.01 ± 0.03 (0)	0.458
	Lower Lip Vermillion	0.10 ± 0.29 (0)	−0.01 ± 0.04 (0)	0.974
Profile Measurements
	Dorsum of Nose	0.16 ± 0.38 (0)	0.80 ± 0.48 (0.96)	0.004*
	Alar Base	−0.01 ± 0.05 (0)	0 ± 0.08 (0)	0.253
	Soft Tissue Facial Angle	−1.12 ± 3.96 (−0.63)	−0.05 ± 0.18 (0)	0.081
	Nasolabial Angle	0.55 ± 3.87 (0)	−0.21 ± 0.50 (0)	0.053
Upper and lower lip
	B-Line—Upper Lip	0.19 ± 0.57 (0)	0.02 ± 0.04 (0)	0.535
	B-Line—Lower Lip	0 ± 0.67 (0)	0.01 ± 0.01 (0)	0.284
	E-Line—Upper Lip	0.38 ± 1.55 (0)	−0.02 ± 0.08 (0)	0.863
	E-Line—Lower Lip	−0.14 ± 0.51 (0)	0.04 ± 0.08 (0.03)	0.261
	S-Line—Upper Lip	0.12 ± 0.57 (0)	0.02 ± 0.06 (0)	0.803
	S-Line—Lower Lip	−0.08 ± 0.74 (0)	0.02 ± 0.06 (0)	0.227
Mann Whitney U test. p < 0.05. SD: Standard Deviation.*

Table 8 presents the relationship between the T1–T2 change amounts of the experimental and control groups in males. The increase in nose width, intercommissural distance, dorsum of the nose, and nasolabial angle in the experimental group during the T1 and T2 period were significantly higher than the control group in males (p < 0.05).

Table 8.Evaluation of the experimental and control groups in terms of T1–T2 change amounts in males.

		Experimental (n = 14)	Control (n = 10)
T1–T2 Difference (Male)	Mean ± SD (median)	Mean ± SD (median)	p
Frontal Measurements
	Eye Width	0.07 ± 0.27 (0)	0 ± 0 (0)	0.160
	Nasal Width of The Middle Third	0.04 ± 0.11 (0)	0.02 ± 0.05 (0)	0.942
	Nose Width	1.02 ± 0.53 (1.03)	0 ± 0.02 (0.01)	0.001*
	Upper Face Width	0.27 ± 0.42 (0.08)	0.06 ± 0.18 (0.01)	0.311
	Lower Face Width	0.32 ± 0.64 (0.06)	0.14 ± 0.36 (0.01)	0.570
	Intercanthal Distance	0.03 ± 0.11 (0)	0 ± 0 (0)	0.398
	Nose Length	0.30 ± 0.69 (0.34)	0.11 ± 0.18 (0.03)	0.088
	Upper Lip Length	0.08 ± 0.23 (0.03)	−0.01 ± 0.06 (0.01)	0.105
	Lower Lip-Chin Length	0.19 ± 0.52 (0.01)	0.01 ± 0.01 (0.01)	0.438
	Intercommissural Distance	0.76 ± 0.97 (0.5)	0.01 ± 0.01 (0)	0.039*
	Upper Lip Vermillion	0.03 ± 0.06 (0)	0.01 ± 0.07 (0)	0.252
	Lower Lip Vermillion	0.01 ± 0.01 (0)	0 ± 0 (0)	0.804
Profile Measurements
	Dorsum of Nose	0.34 ± 0.35 (0.28)	0.78 ± 0.44 (1.03)	0.012*
	Alar Base	0.01 ± 0.03 (0)	0 ± 0.22 (0)	0.279
	Soft Tissue Facial Angle	0.08 ± 1.17 (0.02)	−0.03 ± 0.14 (0.01)	0.548
	Nasolabial Angle	1.03 ± 2.00 (0.33)	0.07 ± 0.35 (0)	0.022*
Upper and lower lip
	B-Line—Upper Lip	0.17 ± 0.40 (0)	0 ± 0 (0)	0.794
	B-Line—Lower Lip	−0.08 ± 0.28 (0.01)	0 ± 0.01 (0)	0.330
	E-Line—Upper Lip	−0.01 ± 0.22 (0)	0.01 ± 0.03 (0.01)	0.441
	E-Line—Lower Lip	−0.15 ± 0.25 (−0.06)	0.01 ± 0.03 (0)	0.080
	S-Line—Upper Lip	0.13 ± 0.28 (0.1)	0.02 ± 0.09 (0.01)	0.290
	S-Line—Lower Lip	0.06 ± 0.30 (0)	0.01 ± 0.05 (0)	0.944
Mann Whitney U test. p < 0.05. SD: Standard Deviation.*

Lastly, we assessed the relationship between the T1–T2 change amounts of females and males in the experimental groups (Table 9). The results indicated that an increase in nose length and dorsum of the nose in males during the T1 and T2 period was statistically significantly higher than in females (p < 0.05). Additionally, there was a significant decrease in upper lip length and upper face width in the T1 and T2 period in females, whereas an increase was observed in males, and the difference was statistically significant (p < 0.05).

Conversely, there was no statistically significant change in the relationship between the T1–T2 change amounts in the female and male control groups (p > 0.05).

Table 9.Evaluation of the female and male experimental groups in terms of T1–T2 change amounts.

		Female (n = 16)	Male (n = 14)
T1–T2 Difference (Experimental)	Mean ± SD (median)	Mean ± SD (median)	p
Frontal Measurements
	Eye Width	−0.01 ± 0.03 (0)	0.07 ± 0.27 (0)	0.163
	Nasal Width of The Middle Third	−0.01 ± 0.05 (0)	0.04 ± 0.11 (0)	0.079
	Nose Width	0.82 ± 0.41 (0.94)	1.02 ± 0.53 (1.03)	0.212
	Upper Face Width	−0.19 ± 0.56 (0)	0.27 ± 0.42 (0.08)	0.010*
	Lower Face Width	0.04 ± 0.76 (0)	0.32 ± 0.64 (0.06)	0.257
	Intercanthal Distance	0.03 ± 0.10 (0)	0.03 ± 0.11 (0)	0.923
	Nose Length	0.06 ± 0.40 (0)	0.30 ± 0.69 (0.34)	0.020*
	Upper Lip Length	−0.09 ± 0.50 (0)	0.08 ± 0.23 (0.03)	0.025*
	Lower Lip-Chin Length	0.19 ± 0.67 (0)	0.19 ± 0.52 (0.01)	0.685
	Intercommissural Distance	0.63 ± 0.93 (0.1)	0.76 ± 0.97 (0.5)	0.558
	Upper Lip Vermillion	−0.04 ± 0.29 (0)	0.03 ± 0.06 (0)	0.178
	Lower Lip Vermillion	0.10 ± 0.29 (0)	0.01 ± 0.01 (0)	0.612
Profile Measurements
	Dorsum of Nose	0.16 ± 0.38 (0)	0.34 ± 0.35 (0.28)	0.021*
	Alar Base	−0.01 ± 0.05 (0)	0.01 ± 0.03 (0)	0.070
	Soft Tissue Facial Angle	−1.12 ± 3.96 (−0.63)	0.08 ± 1.17 (0.02)	0.055
	Nasolabial Angle	0.55 ± 3.87 (0)	1.03 ± 2.00 (0.33)	0.227
Upper and lower lip
	B-Line—Upper Lip	0.19 ± 0.57 (0)	0.17 ± 0.40 (0)	0.543
	B-Line—Lower Lip	0 ± 0.67 (0)	−0.08 ± 0.28 (0.01)	0.439
	E-Line—Upper Lip	0.38 ± 1.55 (0)	−0.01 ± 0.22 (0)	0.874
	E-Line—Lower Lip	−0.14 ± 0.51 (0)	−0.15 ± 0.25 (−0.06)	0.817
	S-Line—Upper Lip	0.12 ± 0.57 (0)	0.13 ± 0.28 (0.1)	0.687
	S-Line—Lower Lip	−0.08 ± 0.74 (0)	0.06 ± 0.30 (0)	0.232
Mann Whitney U test. p < 0.05. SD: Standard Deviation.*

4. Discussion

Numerous studies have established that RME not only affects the hard tissues but also induces changes in the soft tissues of the orofacial region [14, 16, 29, 39, 40]. To evaluate these soft tissue changes resulting from RME, researchers have utilized various methods, including cephalometric radiographs, photographs, and 3D images/facial scans [7, 16, 19, 20, 29, 30, 39]. While CBCT images and 3D face scans offer more precise results and facilitate measurements, their routine use in orthodontic clinics is limited due to the high radiation dose associated with CBCT images and the cost of 3D face scans. In this present study, we opted to perform anthropometric measurements on routinely captured photographs to assess corresponding soft tissue changes.

In a study by Berger et al. [39], measurements were taken using only frontal photographs of patients who underwent SARME and orthopedic expansion. During the treatment, they observed changes in upper lip length, chin length, upper and lower face width, and upper and lower lip vermilion measurements. However, there was no statistically significant change between T1 and T2 by the end of the 1-year retention period [39]. Similarly, Truong et al. [19] reported that RME initially led to a significant increase in nasal width, but this measurement gradually returned to average levels with growth and development. However, this study was conducted within a time interval of six months. Although an increase in the nose width and intercommissural distance at the end of the treatment was found in the experimental group, a long-term follow-up is needed to determine whether these soft tissue changes are temporary or long-term.

According to literature, the retention period after expansion has been performed in different periods, such as 3 months, 6 months, and 1 year [16, 19, 30, 39, 41]. In this present study, retention was performed for 6 months to decrease the possibility of relapses [3, 16]. It has been determined that long-term retentions are usually made in cases with surgically-assisted expansion [21, 39]. Berger et al. [39] performed mid-term measurements without removing the bonded-type device, which may cause differences in values. In our study, all the measurements were performed before RME and after removing the RME device, but still, changes were determined in the experimental group measurements, which indicates a change in soft tissues immediately after RME in pediatric patients.

Berger et al. [39] reported a 2 mm increase in nose width following RME. In contrast, Gül et al. [29] found that although nose width increased, no significant changes were observed in bizygomatic width, philtrum width and upper vermillion height after RME. Torun examined soft tissue alterations in pre-adolescent and post-adolescent patients before and after RME and reported the highest increase in cheek projection in the prepubertal group. In addition, they observed statistically significant alterations in columella height, nasal vestibulum, philtrum diameter, upper lip length and columella diameter, while no significant changes were observed in nostril height, alar base, nasolabial angle or nostril width [16]. Comparatively, in this current study, we found that nose width and intercommissural distance increased at T2 only in the experimental group, while the dorsum of the nose length increased at T2 in both the experimental and control groups, indicating that nose length increases with growth and development, whereas nose width and intercommissural distance may expand due to RME. Although the nasal width of the middle third, lower face width, intercanthal distance and lower lip vermillion of the experimental group differed significantly from those of the control group, there were no changes within the groups at T1 and T2. We hypothesized that these results might be attributed to anatomical variations among the investigated patients.

Dos Santos et al. [11] used cephalometric radiographs to evaluate changes in soft tissue profiles after RME. By conducting various analyses such as Ricketts, Steiner, Legan-Burstone, Holdaway and McNamara analyses, the researchers found that although there was an initial forward movement of the upper lip immediately after expansion, it returned to its original position at the end of the 6-month retention period. Similarly, while the lower lip showed forward movement immediately after expansion, no statistically significant difference was observed at the end of the retention period. Comparatively, in this current study, the positions of the upper and lower lips at T1 and T2 were assessed using B, S and E lines. It was expected that the position of the lips would change due to the forward movement of the A point and the downward and backward rotation of the mandible following RME [4, 9, 17, 42]. However, no statistically significant change in the lip position was observed, which might be attributed to the study’s inability to employ 3D scans. As in growing patients, soft tissue changes can also occur during prosthetic procedures [43, 44, 45, 46, 47].

It is well recognized that females and males can exhibit variations in growth and developmental patterns, as well as differences in anatomical and bone structures, despite having the same chronological age [12, 31]. The results of this study indicate that there were no statistically significant changes in the relationship between the T1–T2 change amounts of the female and male control groups. However, it was observed that the increase in nose length, dorsum of the nose, upper face width and upper lip length in males from the experimental group during the T1 and T2 periods was significantly higher than that of females from the experimental group, suggesting that RME may have a more pronounced effect on soft tissue alterations in males than in females.

Kokich et al. [48] examined the perceptions of orthodontists, general dentists, and laypeople regarding minor variations in the size and alignment of anterior teeth and their relationship to the surrounding soft tissues. They reported that general dentists and laypeople were unable to detect a 4 mm midline deviation, and laypeople were unable to detect an incisal plane asymmetry until it was 3 mm [48]. Silva et al. [49] determined laypersons’ perceptions of dental and facial asymmetries and found that chin deviations of 6 mm or less were not noticed and did not have a statistically significant impact on the perception of facial attractiveness. Naini et al. [50] evaluated the differences in the aesthetic perception of soft tissue profile and concluded that a 4 mm protrusion or retrusion was frequently unnoticed regardless of the observer’s profession. According to the findings of this present study, although changes occurred in soft tissues after RME, these changes were observed to be less than 2 mm. Based on the existing literature, such small changes may not be clinically significant and might be undetectable by both professionals and laypeople.

5. Conclusions

In conclusion, the study revealed that RME treatment significantly increased nose width and intercommissural distance. Additionally, gender differences were observed, with males exhibiting a higher increase in nose length and dorsum of the nose compared to females. However, it is important to note that these changes were not clinically noticeable. Further long-term follow-up studies are necessary to assess the persistence and clinical significance of these soft tissue changes over time.

Availability of data and materials

The data presented in this study are available on reasonable request from the corresponding author.

Author contributions

AM and HU—designed the research study. HU—performed the research. GC—analyzed the data. MC, MMM and GM—wrote the manuscript. All authors contributed to the editorial changes in the manuscript. All authors read and approved the final manuscript.

Ethics approval and consent to participate

This study was carried out in accordance with the Helsinki Declaration, and the protocol was approved by the Ethics Committee of the University of Aldent, Tirana, Albania (Protocol number: 843/2022, Date: 7/11/2022). All patients and their parents gave written informed consent for participation.

Acknowledgment

The authors would like to acknowledge Süleyman Evren Öztaş for his support in design the research study.

Funding

This research received no external funding.

Conflict of interest

The authors declare no conflict of interest. Giuseppe Minervini is serving as one of the Editorial Board members of this journal. We declare that Giuseppe Minervini had no involvement in the peer review of this article and has no access to information regarding its peer review. Full responsibility for the editorial process for this article was delegated to MAM.

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