Abstract
Background
This study aimed to investigate the facial soft tissue characteristics of patients with different types of malocclusion.
Methods
The 3dMD scanning data of patients with malocclusion admitted to our hospital from January 2018 to April 2022 were analyzed retrospectively. Forty-seven patients with Class I malocclusion, 43 patients with Class II malocclusion and 44 patients with Class III malocclusion were selected. All patients underwent 3dMD scans prior to orthodontic treatment. Then the differences in the 3D morphological parameters of the facial soft tissues were compared between different sexes and different types of malocclusion. Spearman’s correlation was further used to analyze the correlation between each parameter and the classification of malocclusion.
Results
In the Class I group and Class II group, there were no significant differences in the 3D morphometric parameters of malocclusion patients of different sexes (P > 0.05). There were significant differences between Al (R)-AL (L), Ac (R)-Ac (L), Prn-Ac (L), n-Prn-Sn, and Al (R)-Al (L)/Ac (L)-Ah (L) values among the three groups of patients. Spearman correlation analysis showed that Ac (R)-Ac (L) and Al (R)-Al (L)/Ac (R)-Ac (L) were correlated with the type of malocclusion.
Conclusion
Differences in facial soft tissues exist in patients with Class I, II, and III malocclusion. 3dMD technique may be helpful in developing an effective treatment plan prior to orthodontic treatment.
Keywords: Malocclusion, Facial soft tissue, 3dMD face system
Background
Malocclusion is the misalignment of teeth, dental arches, jaws and craniofacial structure. A cross-sectional study found that the prevalence of malocclusion reached 83.9% in Chinese preschool children [1]. Malocclusion seriously affects the occlusal function and periodontal health of patients and may lead to masticatory problems, temporomandibular joint disorders, and dental caries [2, 3]. In addition, malocclusion also influences patients’ appearance and thus has a serious negative impact on their physical and mental development [4, 5]. Currently, surgical correction of malocclusion is often used clinically to achieve a good bite and a satisfactory facial appearance [6, 7]. However, some patients can not get a satisfactory appearance after orthodontic treatment, possibly attributed to the complex facial tissue structure [8, 9]. Therefore, it is essential to study the characteristics of facial soft tissue structures of patients with different classifications of malocclusion in order to develop targeted orthodontic treatment plans and improve treatment outcomes.
According to Angle’s classification, the malocclusion can be classified as Class I, Class II, and Class III [10–12]. Class I malocclusion (neutroclusion) presents with a correct occlusal relationship between upper and lower first molars (mesiobuccal cusp of the maxillary first molar occludes in line with the buccal groove of the mandibular first molar), but with anomalies in the rest of the teeth, such as overcrowded teeth and sparse teeth. Class II malocclusion (distoclusion) is characterized by the mesiobuccal cusp of the maxillary first molar occluding anterior to the buccal groove of the mandibular first molar, and is often accompanied by malposed teeth. The main symptoms of Class II malocclusion are deep overjet, maxillary prognathism, and mandibular retrognathism. Class III malocclusion (mesioclusion) has the mesiobuccal cusp of the maxillary first molar occluding posterior to the buccal groove of the mandibular first molar, manifesting as underbite [6, 10].
The malocclusion is associated with features of face soft tissues [7, 13, 14]. For example, protruding upper anterior teeth of patients with Class II malocclusion result in upper lip protrusion and convex facial profile, and may cause a relatively short anterior face [13, 14]. Also, there are sex differences in the facial soft tissue characteristics of patients with malocclusion [15]. Male patients with malocclusion have thicker facial soft tissues than female patients [15]. However, some studies have also reported no significant differences in sagittal skeletal types between the sexes [16]. Collectively, there are specific effects of different types of malocclusion on facial appearance.
Although current orthodontic treatment methods can improve the facial appearance of patients to a certain extent, the complexity of facial tissue structure means that some patients still do not achieve the desired facial improvement after treatment. Moreover, existing research on the facial soft tissue characteristics of patients with different types of malocclusion is still insufficient. Therefore, this study aims to fill this gap by conducting an in-depth analysis of the facial soft tissue characteristics of patients with malocclusions, exploring their correlation with the types of malocclusion. 3dMD can image human subjects from multiple angles and, subsequently, 3D images can be acquired through the software. The advantages of this method are the absence of motion artifacts, short imaging time, high color resolution, and the ability to perform repeat analysis without invasive harm [17, 18]. This study innovatively employs 3dMD technology to elucidate the distinct facial soft tissue characteristics in patients with Class I, II, and III malocclusions, providing a comprehensive three-dimensional analysis that enhances the precision of orthodontic planning. The incorporation of gender-specific analysis in our research offers a novel perspective on the influence of malocclusion types on facial soft tissue, potentially leading to more tailored and effective orthodontic interventions.
Subjects and methods
Study subjects
Forty-seven patients with Class I malocclusion admitted to our hospital from January 2018 to April 2022 were selected as the Class I group (22 males and 25 females), aged from 8 to 16 years. Forty-three patients with Class II malocclusion admitted at the same time were included in the Class II group (15 males and 28 females) and 44 patients with Class III malocclusion in the Class III group (21 males and 23 females), aged from 9 to 15 years. Inclusion criteria included: (1) conformed to the diagnosis of Angle’s Class I, II, and III malocclusion, respectively; (2) complete dentition (excluding third molars); (3) aligned teeth or moderate or severe crowding. Exclusion criteria included: (1) previous history of orthodontic treatment and cosmetic surgery; (2) combined maxillofacial tumors and trauma; (3) congenital cleft lip and palate.
Sample size calculation
The sample size calculation was conducted using G*Power (version 3.1.9.2). For repeated measures ANOVA, parameters were set as follows: within-subjects design, effect size f = 0.25, α = 0.05, power (1-β) = 0.95, number of groups = 3, number of measurements = 3, and a correlation among repeated measures of 0.5. This calculation yielded a total sample size of 134 individuals.
Study methods
Both three groups were divided into two subgroups according to sex and then scanned with the 3dMD face system (3dMD LLC, Atlanta, GA, USA) before treatment. The scanning procedures were as follows. Patients were scanned in a sitting position with steady breathing, teeth occluded, tongue relaxed, and head kept symmetrical on both sides. The scanner was calibrated by the photographer according to the operating instructions before imaging. The instrument was automatically focused to capture a 180-degree image of the face between the ears at a speed of 1.5 ms. The obtained data were imported into 3dMD® vultus software for further analysis.
Observation parameters
A series of data were collected from patients before orthodontic treatment, including linear measurement of the nose, upper lip, philtrum, oral fissure, and angular measurement of the nose itself and multiple angles between the nose and upper lip. Dolphin software was used to calculate patients’ 3D morphological parameters separately. The abbreviations and definitions of the parameters are shown in Table 1. All of the above measurements were taken three times by the same researcher, and the mean values were taken.
Table 1.
Definition of three-dimensional morphological parameters
| Three-dimensional morphological parameters | Abbreviations | Definition | |
|---|---|---|---|
| 1 | Nasal length (mm) | N-Prn | Distance from nation to pronasale |
| 2 | Nasal height (mm) | N-Sn | Distance from nation to subnasale |
| 3 | Nasal breadth (mm) | Al (R)-Al (L) | Distance between the right alare and left alare |
| 4 | Nasal depth (mm) | Prn-Sn | Distance from subnasale to pronasale |
| 5 | Columellar length (mm) | Sn-C | Distance between subnasale and columella peak |
| 6 | Columellar width (mm) | Sn’ (R)-Sn’ (L) | Distance from right midpoint of columella to left midpoint of columella |
| 7 | Alar base width (mm) | Ac (R)-Ac (L) | Distance from right ala curvature point to left ala curvature point |
| 8 | Alar length (mm) | Prn-Ac (L) | Distance from pronasale to ala curvature point |
| 9 | Alar height (mm) | Ac (L)-Ah (L) | Distance from ala curvature point to high point of left nasal ala |
| 10 | Unilateral nostril floor width (mm) | Sn-Sbal (L) | Distance from subnasale to subalare |
| 11 | Nostril floor width (mm) | Sbal (R) - Sbal (L) | Distance from right subalare to left subalare |
| 12 | Philtrum length (mm) | Sn-Ls | Distance between subnasale and labrale superius |
| 13 | Philtrum width (mm) | Cph (R) - Cph (L) | Distance from right column philtrum to left column philtrum |
| 14 | Mouth width (mm) | Ch (R)-Ch (L) | Distance between right cheilion and left cheilion |
| 15 | Upper lip length (mm) | Sn-Sto | Distance from subnasale to stomion |
| 16 | Innercanthal distance (mm) | En (R) - En (L) | Distance between right entocanthion and left entocanthion |
| 17 | Nasal tip angle (deg) | n-Prn-Sn | Angle formed by the line connecting nasion and pronasale and the line connecting pronasale and subnasale. |
| 18 | Nasolabial angle (deg) | C-Sn-Ls | Angle formed by the line connecting columella peak and subnasale and the line connecting subnasale and labrale superiu |
| 19 | Alar angle (deg) | Ac (R)-Prn-Ac (L) | Angle formed by the line connecting right alar curvature point and pronasale and the line connecting pronasale and left alar curvature point |
| 20 | Right nostril angle (deg) | C’ (R)-Sbal (R)-Sbal (L) | Angle formed by the highest point of the right nostril with right subalare and left subalare |
| 21 | Left nostril angle (deg) | C’ (L)-Sbal (L)-Sbal (R) | Angle formed by the highest point of the left nostril with left subalare and right subalare |
| 22 | Nasal breadth -nasal height index | Al (R)-Al (L)/N-Sn | Nasal breadth/nasal height |
| 23 | Nasal depth-nasal height index | Prn-Sn/N-Sn | Nasal depth/nasal height |
| 24 | Nasal depth-nasal width index | Prn-Sn/Al(R)-Al(L) | Nasal depth/nasal width |
| 25 | Nose width-nose length index | Al(R)-Al(L)/N-Prn | Nasal width/nasal length |
| 26 | Alar length-nasal floor width index | Prn-Ac (L)/Al (R)-Al (L) | Alar length/nasal floor width |
| 27 | Columellar length-nasal depth index | Sn-C/Prn-Sn | Columellar length/nasal depth |
| 28 | Alar height-nasal height index | Ac (L)-Ah (L)/N-Sn | Alar height/nasal height |
| 29 | Nasal breadth-nasal base width index | Al (R)-Al (L)/Ac (L)-Ah (L) | Nasal breadth/nasal base width |
| 30 | Philtrum width-philtrum length index | Cph (R)-Cph (L)/Sn-Ls | Philtrum width/philtrum length |
| 31 | Mouth width-innercanthal distance index | Ch (R)-Ch (L)/En (R)-En (L) | Mouth width/innercanthal distance |
Statistical analysis
All data were statistically analyzed using SPSS26.0 statistical software. The measurement data that conformed to a normal distribution were expressed as mean ± standard deviation (SD). The differences in measurement outcomes between male and female patients were analyzed using an independent t-test to explore the effect of sex on the outcomes. One-way analysis of variance was performed to analyze the differences among the three groups, and the Tukey test was a post-hoc test. Spearman correlation analysis was conducted to analyze the correlation between each parameter and the classification of malocclusion. P < 0.05 was considered a statistically significant difference.
Results
Comparison of 3D morphological parameters between different sexes
We analyzed the baseline characteristics of the three groups. There was no statistical difference in sex and age among the three groups of patients (P > 0.05), so the three groups were comparable. We analyzed the differences in the 3D morphometric parameters of the face between males and females with malocclusion, aiming to explore the effect of sex on the parameters. The results showed no significant differences in the 3D morphometric parameters of malocclusion patients of different sexes in the Class I group and Class II group (P > 0.05). However, in the Class III group, Prn-Ac (L) value was significantly higher in males compared to females (P = 0.037), while the remaining parameters were not significantly different (Table 2).
Table 2.
Comparison of 3D morphological parameters between different sexes in the three groups
| Three-dimensional morphological parameters | Class I group | Class II group | Class III group | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Male (n = 22) | Female (n = 25) | t-value | P-value | Male (n = 15) |
Female (n = 28) | t-value | P-value | Male (n = 21) | Female (n = 23) | t-value | P-value | ||
| N-Prn | 42.2 ± 3.2 | 41.9 ± 3.4 | 0.332 | 0.741 | 41.0 ± 4.9 | 41.1 ± 4.3 | -0.068 | 0.946 | 42.7 ± 3.4 | 41.9 ± 3.3 | 0.833 | 0.41 | |
| N-Sn | 48.2 ± 2.6 | 47.9 ± 2.9 | 0.412 | 0.682 | 47.5 ± 4.4 | 47.4 ± 3.9 | 0.077 | 0.939 | 48.4 ± 2.8 | 48.2 ± 3.9 | 0.222 | 0.826 | |
| Al (R)-AL (L) | 38.3 ± 3.0 | 38.1 ± 2.3 | 0.273 | 0.786 | 38.1 ± 2.3 | 36.7 ± 2.9 | 1.663 | 0.104 | 39.3 ± 2.9 | 37.9 ± 2.4 | 1.776 | 0.083 | |
| Prn-Sn | 16.1 ± 2.1 | 15.8 ± 1.9 | 0.556 | 0.581 | 15.5 ± 1.8 | 15.5 ± 1.7 | 0.134 | 0.894 | 16.0 ± 1.7 | 16.6 ± 2.6 | -0.814 | 0.42 | |
| Sn-C | 11.6 ± 1.7 | 11.3 ± 1.8 | 0.541 | 0.591 | 11.2 ± 2.2 | 11.0 ± 1.6 | 0.334 | 0.74 | 11.5 ± 1.3 | 11.2 ± 1.5 | 0.701 | 0.487 | |
| Sn’ (R)-Sn’ (L) | 7.8 ± 1.5 | 7.9 ± 0.8 | -0.292 | 0.772 | 7.5 ± 1.0 | 7.5 ± 1.0 | 0.06 | 0.953 | 7.9 ± 0.9 | 7.9 ± 1.1 | -0.154 | 0.878 | |
| Ac (R)-Ac (L) | 34.3 ± 3.4 | 34.9 ± 2.6 | -0.601 | 0.551 | 32.7 ± 4.1 | 32.2 ± 4.1 | 0.399 | 0.692 | 33.7 ± 3.3 | 33.0 ± 2.9 | 0.765 | 0.449 | |
| Prn-Ac (L) | 28.1 ± 2.4 | 28.1 ± 2.2 | 0.070 | 0.944 | 27.4 ± 3.4 | 26.5 ± 1.9 | 0.919 | 0.37 | 29.0 ± 2.6 | 27.5 ± 1.9 | 2.159 | 0.037 | |
| Ac (L)-Ah (L) | 11.9 ± 1.7 | 11.8 ± 1.9 | 0.119 | 0.906 | 11.6 ± 3 | 11.0 ± 1.4 | 0.932 | 0.357 | 11.8 ± 1.2 | 11.2 ± 1.2 | 1.621 | 0.113 | |
| Sn-Sbal (L) | 11.0 ± 1.2 | 10.9 ± 1.4 | 0.293 | 0.771 | 11.4 ± 1.2 | 10.8 ± 1.3 | 1.522 | 0.136 | 11.3 ± 1.1 | 11.0 ± 1.3 | 0.845 | 0.403 | |
| Sbal (R)-Sbal (L) | 21.4 ± 2.2 | 21.5 ± 2.7 | -0.086 | 0.932 | 22.3 ± 2.5 | 20.9 ± 3.3 | 1.446 | 0.156 | 22.7 ± 2.2 | 21.4 ± 3.4 | 1.491 | 0.143 | |
| Sn-Ls | 14.4 ± 2.3 | 13.7 ± 1.8 | 1.132 | 0.264 | 13.7 ± 1.8 | 13.6 ± 1.6 | 0.137 | 0.891 | 14.6 ± 1.8 | 13.9 ± 2.3 | 1.249 | 0.219 | |
| Cph (R)-Cph (L) | 10.4 ± 1.1 | 10.3 ± 1.4 | 0.404 | 0.688 | 10.0 ± 1.9 | 9.9 ± 1.4 | 0.247 | 0.807 | 10.4 ± 1.5 | 10.2 ± 1.5 | 0.641 | 0.525 | |
| Ch (R)-Ch (L) | 43.8 ± 3.9 | 43.3 ± 4.2 | 0.372 | 0.712 | 40.9 ± 7.8 | 42.0 ± 3.3 | -0.662 | 0.512 | 43.5 ± 5.9 | 44.2 ± 4.3 | -0.404 | 0.688 | |
| Sn-Sto | 22.2 ± 2.3 | 21.4 ± 2.0 | 1.268 | 0.211 | 23.5 ± 5.6 | 22.2 ± 2 | 1.071 | 0.291 | 23.9 ± 5.4 | 21.7 ± 2.6 | 1.746 | 0.088 | |
| En (R)-En (L) | 40.2 ± 3.3 | 40.2 ± 3.3 | 0.089 | 0.930 | 39.3 ± 2.6 | 39.6 ± 2.6 | -0.356 | 0.724 | 41.2 ± 2.5 | 39.6 ± 3.6 | 1.661 | 0.105 | |
| n-Prn-Sn | 85.8 ± 7.0 | 85.4 ± 7.7 | 0.183 | 0.865 | 89.2 ± 8.8 | 89.1 ± 6.5 | 0.019 | 0.985 | 83.8 ± 5.4 | 84.1 ± 5.8 | -0.174 | 0.863 | |
| C-Sn-Ls | 100.1 ± 11.8 | 94.8 ± 9.9 | 1.673 | 0.101 | 99.2 ± 9.8 | 100.1 ± 12.2 | -0.236 | 0.814 | 95.4 ± 11.4 | 97.1 ± 8.3 | -0.6 | 0.551 | |
| Ac (R)-Prn-Ac (L) | 76 ± 6.2 | 77.4 ± 5.8 | -0.767 | 0.447 | 78.5 ± 5.3 | 78.3 ± 4.2 | 0.169 | 0.867 | 77.4 ± 7.9 | 78.3 ± 6.2 | -0.411 | 0.683 | |
| C’ (R)-Sbal (R)-Sbal (L) | 89.1 ± 6.8 | 90.2 ± 7.8 | -0.519 | 0.606 | 92.8 ± 5.4 | 92.2 ± 6.0 | 0.329 | 0.744 | 90.7 ± 8.3 | 90.1 ± 8.5 | 0.248 | 0.805 | |
| C’ (L)-Sbal (L)-Sbal (R) | 89.6 ± 7.3 | 90.5 ± 7.4 | -0.405 | 0.687 | 92.8 ± 5.6 | 92.6 ± 6.2 | 0.134 | 0.894 | 90.3 ± 7.4 | 90.3 ± 8.2 | -0.016 | 0.987 | |
| Al (R)-Al (L)/N-Sn | 0.7965 ± 0.07 | 0.7982 ± 0.06 | -0.096 | 0.924 | 0.8063 ± 0.05 | 0.7762 ± 0.06 | 1.622 | 0.112 | 0.8145 ± 0.06 | 0.7907 ± 0.07 | 1.188 | 0.242 | |
| Prn-Sn/N-Sn | 0.3357 ± 0.05 | 0.3299 ± 0.04 | 0.458 | 0.649 | 0.3278 ± 0.03 | 0.3277 ± 0.04 | 0.008 | 0.993 | 0.3321 ± 0.04 | 0.3457 ± 0.06 | -0.954 | 0.346 | |
| Prn-Sn/Al (R)-Al (L) | 0.4221 ± 0.06 | 0.4151 ± 0.05 | 0.449 | 0.655 | 0.4078 ± 0.04 | 0.4224 ± 0.04 | -1.182 | 0.244 | 0.4092 ± 0.05 | 0.4391 ± 0.07 | -1.598 | 0.117 | |
| Al (R)-Al (L)/N-Prn | 0.9133 ± 0.10 | 0.9155 ± 0.09 | -0.081 | 0.936 | 0.9377 ± 0.09 | 0.8975 ± 0.08 | 1.479 | 0.147 | 0.925 ± 0.08 | 0.9095 ± 0.08 | 0.647 | 0.521 | |
| Prn-Ac (L)/Al (R)-Al (L) | 0.824 ± 0.08 | 0.809 ± 0.08 | 0.646 | 0.522 | 0.8504 ± 0.16 | 0.8334 ± 0.09 | 0.369 | 0.716 | 0.8673 ± 0.11 | 0.8395 ± 0.08 | 0.996 | 0.325 | |
| Sn-C/Prn-Sn | 0.7178 ± 0.07 | 0.7124 ± 0.06 | 0.298 | 0.767 | 0.7180 ± 0.07 | 0.7129 ± 0.06 | 0.245 | 0.808 | 0.719 ± 0.06 | 0.6833 ± 0.08 | 1.667 | 0.103 | |
| Ac (L)-Ah (L)/N-Sn | 0.2465 ± 0.04 | 0.2459 ± 0.03 | 0.055 | 0.957 | 0.2459 ± 0.06 | 0.2331 ± 0.03 | 0.787 | 0.442 | 0.2434 ± 0.03 | 0.2324 ± 0.03 | 1.37 | 0.178 | |
| Al (R)-Al (L)/Ac(L)-Ah (L) | 1.1221 ± 0.08 | 1.0961 ± 0.05 | 1.31 | 0.197 | 1.1785 ± 0.13 | 1.1487 ± 0.10 | 0.854 | 0.398 | 1.1727 ± 0.08 | 1.1561 ± 0.09 | 0.64 | 0.526 | |
| Cph (R)-Cph (L)/Sn-Ls | 0.7368 ± 0.12 | 0.7601 ± 0.15 | -0.572 | 0.570 | 0.7434 ± 0.17 | 0.7349 ± 0.14 | 0.183 | 0.856 | 0.7189 ± 0.10 | 0.738 ± 0.08 | -0.687 | 0.496 | |
| Ch (R)-Ch (L)/En (R)-En (L) | 1.0934 ± 0.12 | 1.0866 ± 0.14 | 0.179 | 0.859 | 1.0472 ± 0.23 | 1.0654 ± 0.11 | -0.357 | 0.723 | 1.0569 ± 0.14 | 1.1206 ± 0.13 | -1.587 | 0.125 | |
Comparison of 3D morphological parameters between different malocclusion types
We compared the differences in the three-dimensional morphometric parameters of the facial soft tissues in the three groups. There were significant differences between Al (R)-AL (L), Ac (R)-Ac (L), Prn-Ac (L), n-Prn-Sn and Al (R)-Al (L)/Ac (L)-Ah (L) among the three groups of patients (P < 0.05) (Table 3).
Table 3.
Comparison of 3D morphological parameters between different malocclusion types (Mean ± SD)
| Three-dimensional morphological parameters | Class I group (n = 47) | Class II group (n = 43) | Class III group (n = 44) | F-value | P-value |
|---|---|---|---|---|---|
| N-Prn | 42.0 ± 3.3 | 41.1 ± 4.4 | 42.3 ± 3.3 | 1.276 | 0.283 |
| N-Sn | 48.1 ± 2.7 | 47.4 ± 4.0 | 48.3 ± 3.4 | 0.735 | 0.481 |
| Al (R)-AL(L) | 38.2 ± 2.6 | 37.2 ± 2.8b | 38.6 ± 2.7 | 3.245 | 0.042 |
| Prn-Sn | 16.0 ± 2.0 | 15.5 ± 1.7 | 16.3 ± 2.2 | 1.893 | 0.155 |
| Sn-C | 11.4 ± 1.7 | 11.1 ± 1.8 | 11.4 ± 1.4 | 0.402 | 0.670 |
| Sn’ (R)-Sn’ (L) | 7.8 ± 1.2 | 7.5 ± 1.0 | 7.9 ± 1.0 | 1.583 | 0.209 |
| Ac (R)-Ac (L) | 34.6 ± 3.0a | 32.4 ± 4.1 | 33.3 ± 3.1 | 4.913 | 0.009 |
| Prn-Ac (L) | 28.1 ± 2.3a | 26.8 ± 2.5b | 28.2 ± 2.4 | 4.679 | 0.011 |
| Ac (L)-Ah (L) | 11.8 ± 1.8 | 11.2 ± 2.1 | 11.4 ± 1.2 | 1.297 | 0.277 |
| Sn-Sbal (L) | 10.9 ± 1.3 | 11.0 ± 1.3 | 11.2 ± 1.2 | 0.465 | 0.629 |
| Sbal (R) - Sbal (L) | 21.4 ± 2.5 | 21.4 ± 3.1 | 22.1 ± 2.9 | 0.748 | 0.475 |
| Sn-Ls | 14.1 ± 2.0 | 13.7 ± 1.7 | 14.2 ± 2.1 | 1.005 | 0.369 |
| Cph (R) - Cph (L) | 10.3 ± 1.3 | 9.9 ± 1.6 | 10.3 ± 1.5 | 0.929 | 0.398 |
| Ch (R)-Ch (L) | 43.6 ± 4.0 | 41.6 ± 5.2 | 43.9 ± 5.1 | 2.776 | 0.066 |
| Sn-Sto | 21.8 ± 2.1 | 22.6 ± 3.7 | 22.7 ± 4.3 | 0.997 | 0.372 |
| En (R) - En (L) | 40.2 ± 3.3 | 39.5 ± 2.6 | 40.4 ± 3.2 | 1.049 | 0.353 |
| n-Prn-Sn | 85.6 ± 7.3a | 89.1 ± 7.3b | 84.0 ± 5.6 | 6.548 | 0.002 |
| C-Sn-Ls | 97.3 ± 11.0 | 99.7 ± 11.3 | 96.3 ± 9.8 | 1.191 | 0.307 |
| Ac (R)-Prn-Ac (L) | 76.8 ± 6.0 | 78.3 ± 4.6 | 77.9 ± 7.0 | 0.842 | 0.433 |
| C’ (R)-Sbal (R)-Sbal (L) | 89.7 ± 7.3 | 92.4 ± 5.7 | 90.4 ± 8.3 | 1.745 | 0.179 |
| C’ (L)-Sbal (L)-Sbal (R) | 90.1 ± 7.3 | 92.7 ± 6.0 | 90.3 ± 7.7 | 1.794 | 0.170 |
| Al (R)-Al (L)/N-Sn | 0.7955 ± 0.06 | 0.7839 ± 0.06 | 0.7995 ± 0.07 | 0.681 | 0.508 |
| Prn-Sn/N-Sn | 0.3321 ± 0.04 | 0.3269 ± 0.03 | 0.3383 ± 0.05 | 0.833 | 0.437 |
| Prn-Sn/Al (R)-Al (L) | 0.4175 ± 0.05 | 0.4170 ± 0.04 | 0.4232 ± 0.06 | 0.259 | 0.772 |
| Al (R)-Al (L)/N-Prn | 0.9094 ± 0.09 | 0.9050 ± 0.09 | 0.9130 ± 0.08 | 0.043 | 0.958 |
| Prn-Ac (L)/Al (R)-Al (L) | 0.8121 ± 0.08 | 0.8287 ± 0.12 | 0.8472 ± 0.09 | 1.618 | 0.202 |
| Sn-C/Prn-Sn | 0.7149 ± 0.06 | 0.7170 ± 0.06 | 0.6953 ± 0.07 | 0.703 | 0.497 |
| Ac (L)-Ah (L)/N-Sn | 0.2459 ± 0.03 | 0.2370 ± 0.04 | 0.2370 ± 0.03 | 0.914 | 0.403 |
| Al (R)-Al (L)/Ac (L)-Ah (L) | 1.1046 ± 0.07a, b | 1.1486 ± 0.11 | 1.1587 ± 0.09 | 5.585 | 0.005 |
| Cph (R)-Cph (L)/Sn-Ls | 0.7354 ± 0.14 | 0.7284 ± 0.14 | 0.7231 ± 0.09 | 0.293 | 0.746 |
| Ch (R)-Ch (L)/En (R)-En (L) | 1.0834 ± 0.13 | 1.0542 ± 0.16 | 1.0860 ± 0.14 | 0.709 | 0.494 |
NoteaP < 0.05 vs. Class II group; bP < 0.05 vs. Class III group
Correlation analysis of 3D morphological parameters and malocclusion types
We used Spearman correlation analysis to investigate the correlation of each measure with the classification of malocclusion. The results showed that Ac (R)-Ac (L) (P = 0.0499) and Al (R)-Al (L)/Ac (R)-Ac (L) (P = 0.0007) were correlated with malocclusion types (Table 4).
Table 4.
Correlation analysis of 3D morphological parameters and types of malocclusion
| N-Prn | N-Sn | Al (R)-Al (L) | Prn-Sn | Sn-C | Sn’ (R)-Sn’ (L) | Ac (R)-Ac (L) | Prn-Ac (L) | Ac (L)-Ah (L) | Sn-Sbal (L) | Sbal (R)-Sbal (L) | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| r | 0.013 | 0.001 | 0.023 | 0.008 | -0.039 | 0.027 | -0.170 | -0.016 | -0.078 | 0.109 | 0.129 |
| p | 0.880 | 0.989 | 0.793 | 0.928 | 0.654 | 0.759 | 0.050* | 0.856 | 0.416 | 0.210 | 0.138 |
| Sn-Ls | Cph (R)-Cph (L) | Ch (R)-Ch (L) | Sn-Sto | En (R)-En (L) | n-Prn-Sn | C-Sn-Ls | Ac (R)-Prn-Ac (L) | C’ (R)-Sbal (R)-Sbal (L) | C’ (L)-Sbal (L)-Sbal (R) | ||
| r | 0.015 | -0.027 | 0.077 | 0.114 | -0.006 | -0.09 | -0.024 | 0.090 | 0.050 | 0.030 | |
| p | 0.863 | 0.756 | 0.374 | 0.189 | 0.949 | 0.301 | 0.780 | 0.299 | 0.570 | 0.729 | |
| Al (R)-Al (L)/N-Sn | Prn-Sn/N-Sn | Prn-Sn/Al (R)-Al (L) | Al (R)-Al (L)/N-Prn | Prn-Ac (L)/Ac (R)-Ac (L) | Sn-C/Prn-Sn | Ac (L)-Ah (L)/N-Sn | Al (R)-Al (L)/Ac (R)-Ac (L) | Cph (R)-Cph (L)/Sn-Ls | Ch (R)-Ch (L)/En (R)-En (L) | ||
| r | 0.010 | 0.025 | -0.012 | 0.016 | 0.147 | -0.061 | -0.101 | 0.290 | -0.008 | 0.040 | |
| p | 0.911 | 0.776 | 0.895 | 0.856 | 0.091 | 0.487 | 0.244 | 0.001* | 0.923 | 0.648 | |
Discussion
The main factors causing malocclusion include genetic and environmental factors [19]. Malocclusion not only affects the normal work and life of patients, but also easily leads to inferiority complex [2–5]. Orthodontic treatment can restore the normal occlusal function, and effectively improve the facial appearance of patients with malocclusion. However, because of the complex facial tissue structure, some patients fail to get a satisfactory appearance after orthodontic treatment [8, 9]. This study sets itself apart by conducting a detailed three-dimensional analysis of facial soft tissue characteristics across diverse types of malocclusion, using the advanced 3dMD scanning technology. Our approach surpasses traditional two-dimensional methods by providing a more nuanced and comprehensive evaluation that considers both classification and gender-specific variations. Furthermore, the study enhances clinical orthodontic strategies by identifying and correlating critical three-dimensional morphological parameters with specific malocclusion types, thereby contributing to the development of more customized treatment plans.
In the present study, there were no significant differences in the facial 3D morphometric parameters by gender in patients with Class I and Class II malocclusion. It is suggested that the effect of malocclusion on the morphological structure of the facial soft tissues was not significantly related to the sex of the patients. In patients with Class III malocclusion, Prn-Ac (L) value was higher in males than in females, with no significant differences in the remaining parameters. Al Zain et al. also reported that adult Emirati males and females with Class I malocclusion exhibited similar cephalometric features [20]. In contrast, Gayun et al. demonstrated that, in adolescent patients with skeletal malocclusion, females were 1.942 times more likely to have anterior displacement of the condyle process than males (95% CI: 1.166–3.236) [21]. These different conclusions may be caused by the different populations and sample sizes included.
The present study found marked differences in Al (R)-AL (L), Ac (R)-Ac (L), Prn-Ac (L), n-Prn-Sn and Al (R)-Al (L)/Ac (L)-Ah (L) values among patients with Class I, II and III malocclusion. The results suggest that there may be differences in the facial morphological characteristics of patients with different classifications of malocclusion. Further analysis revealed a correlation between malocclusion types and the parameters Ac (R)-Ac (L) and Al (R)-Al (L)/Ac (R)-Ac (L). When developing an orthodontic treatment plan, it is necessary to consider the patients’ malocclusion type and the corresponding facial features to ensure orthodontic outcomes. Both Ac (R)-Ac (L) and Al (R)-Al (L)/Ac (R)-Ac (L) reflect the soft tissue characteristics of the patient’s nose. Controlling the soft tissue changes of the nose is also a factor to be considered in orthodontic surgery [22]. Song W J et al. identified that patients with Class II malocclusion were more likely to have severe root resorption after orthodontic treatment compared to patients with Class I malocclusion [23]. A Meta-analysis showed that the maxillary arch width was smaller in Class II division 1 malocclusion compared to Class I malocclusion, but there was no difference in the mandibular arch width between the two classifications [24]. It is indicated that patients with Class II division 1 malocclusion should be considered for maxillary arch expansion treatment during orthodontic treatment and clinician should pay attention to the matching of the maxillary and mandibular arch shapes [24]. The above findings are consistent with the present study. However, Chen G H et al. reported the opposite results that compared with Class II malocclusion patients, Class III malocclusion patients present with smaller width of the maxillary canine and maxillary basal bone arch and larger width of the mandibular basal arch [25]. The different conclusions may be related to the different sample sizes included.
Evaluation of facial asymmetry based on clinical photographs sometimes differs from evaluation using cephalometric X-ray frontal view [26]. Kwon et al. proved that compared with two-dimensional measurement of facial soft tissue parameters, three-dimensional techniques are more useful for visualizing the degree of malocclusion, and provide a valid assessment criterion for the evaluation of pre- and post-surgical outcomes [27]. In this study, the 3dMD technique was used to analyze the facial soft tissue characteristics before orthodontic treatment in patients with different classifications of malocclusion, which may help in the subsequent orthodontic treatment. Collectively, we found that there are differences in the facial soft tissues of patients with Class I, II, and III malocclusion. Obtaining their facial 3D morphological parameters by 3dMD may help to develop an effective orthodontic treatment plan. There are still some limitations to this study. Firstly, it is in the form of retrospective research. In addition, the sample size we used for analysis is relatively small. Subsequent large-scale sample collection is needed to verify our conclusions.
Conclusion
There are differences in the facial soft tissues of patients with Class I, II, and III malocclusion, and Ac (R)-Ac (L) and Al (R)-Al (L)/Ac (R)-Ac (L) are correlated with malocclusion type. The 3dMD technique may contribute to developing an effective treatment plan prior to orthodontic treatment.
Acknowledgements
Not applicable.
Author contributions
Jin-xing Guo and Xinze Xu designed the study methodology. Liwen Fan Yong-chu Pan interpreted the results and edited the final manuscript. All authors read and have approved the manuscript for submission.
Funding
This study was approved by Jiangsu Province Capability Improvement Project through Science, Technology and Education-Jiangsu Provincial Research Hospital Cultivation Unit [grant number YJXYYJSDW4]; and Jiangsu Provincial Medical Innovation Center [grant number CXZX202227].
Data availability
The datasets used and/or analyzed during the current study are available from corresponding author on reasonable request.
Declarations
Ethics approval and consent to participate
This study was approved by the ethic committee of The Affiliated Stomatological Hospital of Nanjing Medical University. The written informed consent was obtained from patient or their patients.
Consent for publication
Not applicable.
Competing interests
The authors declare no competing interests.
Footnotes
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
The datasets used and/or analyzed during the current study are available from corresponding author on reasonable request.