Three-dimensional evaluation of skeletal and dental changes in patients with skeletal class III malocclusion and facial asymmetry after surgical-orthodontic treatment

Abstract

OBJECTIVE:

To evaluate skeletal and dental changes in patients with skeletal Class III malocclusion and facial asymmetry after surgical-orthodontic treatment using cone-beam computerized tomography (CBCT).

METHODS:

This study included forty adult patients diagnosed with skeletal Class III malocclusion and asymmetry who underwent either isolated mandibular surgery or bimaxillary surgery. CBCT scans were taken before treatment (T0), at the completion of presurgical orthodontic treatment (T1) and after treatment (T2). Mimics 17.0 and 3-Matics 7.0 were used to measure skeletal and dental parameters. Skeletal and dental changes within each group from pretreatment to posttreatment were assessed, and Pearson correlation analysis was used to analyze the correlations among skeletal changes.

RESULTS:

The three-dimensional changes in condylar position were insignificant after surgical-orthodontic treatment in either group (P > 0.05). However, in the one-jaw surgery group, there were significant backward rotations of the condyle and ramus on the nondeviated side (P < 0.05), and the condyle on the deviated side rotated inward and forward significantly in the two-jaw surgery group (P < 0.05) at T2. There were no significant differences in the changes in the total alveolar bone thickness of bilateral first molars during dental decompensation (P > 0.05). The ratio between the buccal and the total bone thickness around the maxillary first molar on the deviated side decreased significantly at T1, as did those around the mandibular first molar on the nondeviated side (P < 0.05).

CONCLUSIONS:

Condylar angulations were less stable after treatment (7 to 9 months after surgery) in both the one-jaw and the two-jaw surgery groups, while condylar displacements were insignificant. In addition, orthodontists should keep a watchful eye to the relative position of the root in the alveolar bone during tooth decompensation.

Keywords

Skeletal class III patients with facial asymmetry cone-beam computerized tomography (CBCT)surgical-orthodontic treatment

1 Introduction

Skeletal class III malocclusion with facial asymmetry is characterized by skeletal discrepancies in the sagittal, vertical and transverse directions, usually involving the mandible or/and maxilla [1]. Transverse disparity is one of the most prevalent complaints for patients with this maxillofacial deformity, which is accompanied by oral dysfunctions, temporomandibular joint disorder (TMD), psychosocial problems and so on [2]. To correct functional and aesthetical problems of patients, surgical-orthodontic treatment is considered the most effective therapy for moderate to severe craniofacial asymmetry [3].

Bilateral sagittal splint ramus osteotomy (BSSRO) [4] has become one of the most common surgical techniques for correcting mandibular protrusion with asymmetry via asymmetric mandibular setback. When skeletal asymmetry involves the maxillomandibular complex, especially with a severe occlusal plane cant, Le Fort I osteotomy should be considered as well. There is no consensus about changes [5, 6] in frontal ramal inclination, which may influence the asymmetry of bilateral angle prominence. Additionally, some studies have found that orthognathic surgery can lead to displacements of the condylar and disc. If the postoperative position of the temporomandibular joint (TMJ) is unstable, surgical stability cannot be maintained [7]. Recently, most studies [8, 9] have indicated that condylars in patients with facial asymmetry return to the pretreatment position six months after surgery, but postoperative condylar angulations are still being disputed. Most previous studies have investigated postoperative condylar changes using cone-beam computerized tomography (CBCT) in three-dimensional (3D) views [10]. Nonetheless, the results could be affected by factors such as the matrix size, window level and width, and slice thickness [11]. There are few studies conducting measurements in preoperative and postoperative reconstructed 3D models, which are more precise than previous methods.

Since jaws and arches are asymmetric in skeletal class III patients with facial asymmetry, transverse dental axes of the posterior teeth are different from those of patients without asymmetry [12]. Dental decompensation is necessary to make teeth upright in alveolar bone so that satisfactory treatment outcomes can be obtained for patients. Most previous researches [13 –15] assessed dental movements of anterior teeth of skeletal class III malocclusion after surgery, but reports about posterior teeth movements are rare. During surgical-orthodontic treatment, both the movements of the teeth and the relative position of the roots in the alveolar bone should be monitored. Once the scope of the alveolar bone is exceeded, periodontal health will be degraded [16]. Therefore, 3D evaluations of dental changes are helpful to move teeth safely and effectively.

The purpose of this retrospective study was to assess skeletal and dental changes after surgical-orthodontic treatment and analyze the relationships among skeletal changes in patients with skeletal class III malocclusion and facial asymmetry undergoing BSSRO with or without Le Fort I osteotomy by CBCT with 3D analysis programs.

2 Materials and Methods

2.1 Study subjects

This retrospective research was conducted with the approval of the ethical committee of the Affiliated Stomatology Hospital, Chongqing Medical University (CQHS-HRB-2019-3). Forty adult patients at the abovementioned hospital were selected who underwent BSSRO with or without Le Fort I osteotomy by a single surgeon from January 2011 to December 2018. The inclusion criteria were as follows: (1) skeletal class III malocclusion (ANB < 0°); (2) facial asymmetry (hard tissue chin point deviation > 4 mm); (3) inclusion of preoperative and postoperative orthodontic treatment; (4) rigid fixation methods of bone segments; (5) available CBCT scans of good quality, taken before treatment (T0), at the completion of presurgical orthodontic treatment (T1) and after treatment (more than six months after surgery) (T2). The exclusion criteria were (1) systematic diseases, congenital syndromes, or cleft lip or palate; (2) TMD or progressive TMJ lesions; (3) previous facial trauma or surgical-orthodontic treatment; (4) missing first molars or dental defects of the first molars; and (5) angle reduction. According to the type of orthognathic surgery, samples were divided into 2 groups: the one-jaw surgery group who underwent BSSRO and the two-jaw surgery group who underwent maxillary Le Fort I osteotomy and BSSRO.

2.2 Images acquisition and assessment

CBCT scans were acquired at a 0.4 mm×0.4 mm×0.4 mm voxel size level and the exposure conditions were set at a matrix of 400×400 pixels in each CT slice and a 0.25 mm slice thickness (KaVo Dental Gmb H, USA; 80 mA, 80 kVp, and 8.9-second scan time) at T0, T1 and T2. Every patient was positioned with a natural head posture and maximum intercuspation. The 3D images in the Digital Imaging and Communications (DICOM) in Medicine format were imported to Mimics 17.0 software (Materialise, Leuven, Belgium), and 3D craniomaxillofacial models were reconstructed. In addition, 3-Matics 9.0 software (Materialise) was used to measure linear and angular measurements.

2.3 Landmarks and measurements

CBCT data were exported in DICOM format to the Mimics 17.0 software for creating three-dimensional craniofacial models; and the multiplanar visualization was combined with the 3D image reconstructions to locate anatomic landmarks. These Mimics project files of 3D models and landmarks were loaded into the 3-matics 9.0 software. Then, measurements by 3-Matics 9.0 software were begun to do. Firstly, the Create datum plane tool was used to establish reference planes which were perpendicular to each other by six landmarks one the cranial base, including the horizontal plane, coronal plane and sagittal plane. In addition, lines and other planes were created by relevant creation tools. Finally, linear and angular measurements were taken using the Measure Length tool and the Measure Angle tool. Landmarks and reference planes are defined in Figs. 1 and 2 and Table 1. Skeletal (maxilla, mandible and condylar) and dental (first molars and alveolar bone around them) characteristics from pretreatment to posttreatment were measured within each group.

Fig.1

Reference planes and skeletal landmarks used in the study (as described in Table 1). A, frontal view of craniofacial bone. B, Lateral view of craniofacial bone. C, bottom view of the maxillary. D and E, frontal and lateral views of mandible. F, reference planes: a, horizontal plane; b, coronal plane; c, sagittal plane.

Fig.2

Landmarks of first molar used in the study (as showed in Table 1). A and B, buccal and mesial views of maxillary first molar. C and D, buccal and mesial views of mandilular first molar.

Table 1

Definitions of landmarks and reference planes

Landmark	Definition
Or (L/R)	The lowest point of the infraorbital margin (L/R)
Po R	The most superior point of right outer acoustic meatus
ZT (L/R)	The lowest point of the zygomaticotemporal suture (L/R)
Ba	Anterior-inferior margin of the foramen magnum
GPF (L/R)	The most posterosuperior point of grand palatal foramen (L/R)
Me	The most inferior midpoin on the symphysis
Cdt (L/R)	The most superior point of the condylar head (L/R)
Cdp (L/R)	The most posterior point of the condylar head (L/R)
CdD (L/R)	The most distal point of the condylar head (L/R)
CdM (L/R)	The most medial point of the condylar head (L/R)
CdC (L/R)	Geometric centers of the condyle head (L/R)
Si (L/R)	The most inferior point of sigmoid notch of the mandibular bone (L/R)
Gol (L/R)	The most lateral point of curvature along the angle of the mandible (L/R)
Gop (L/R)	The most posterior point of curvature along the angle of the mandible (L/R)
MtF (L/R)	The most anterior point of mental foramen (L/R)
U6MBC (L/R)	The highest point of the maxillary first molar medial buccal cusp (L/R)
L6DBC (L/R)	The highest point of the mandibular first molar distal buccal cusp (L/R)
6C (L/R)	The centre point of mesiodistal and buccolingual of the occlusal surface of the first molar (L/R)
6R (L/R)	The centre point of the root bifurcation of the first molar (L/R)
U6MA (L/R)	The inferior point of the mandibular first molar medial buccal root (L/R)
L6MA (L/R)	The inferior point of the mandibular first molar medial root (L/R)
6MRB (L/R)	The most buccal point of the first molar medial root cervix (L/R)
6MRL (L/R)	The most lingual point of the first molar medial root cervix (L/R)
HP (coronal plane)	The plane passing through the bilateral orbitale and the right porion points
CP (coronal plane)	The plane crossing the lowest point of the zygomaticotemporal suture of the two sides and perpendicular to horizontal plane
SP (sagital plane)	The plane crossing anteriorinferior margin of the foramen magnum and perpendicular to the horizontal plane and coronal plane

L/R, left/right; U6: maxillary first molar; L6: mandibular first molar.

For the maxilla, frontal maxillary inclination and axial maxillary inclination were measured. The mandible was evaluated from two aspects: the distal segment and the proximal segment. Measurements of the distal segment included menton deviation, the distance from the mental foramen to the midsagittal plane (MtF-S), mandibular body asymmetry, frontal mandibular inclination and axial mandibular inclination. Furthermore, the proximal segment included the condylar and ramus. Linear distances from the center of the condylar head to three reference planes (CdC-H, CdC-S and CdC-C) were measured to estimate the 3D position of the condylar, and axial condyle inclination, coronal ramus and condyle inclination, and lateral ramus and condyle inclination were also included. In addition, the maxillary and mandibular occlusal plane inclinations were assessed by the angles between the interbilateral first molar line and the horizontal plane (Fig. 3 and Table 2). The location of the menton deviation in relation to the sagittal plane was the deviated side, and the opposite side was defined as the nondeviated side.

Fig.3

Maxillary and mandibular measurements (Table 2). A, frontal view of craniofacial bone. c, sagittal plane; d, menton deviation; e, MtF-S; f, mandible body length. B, frontal view of maxilla. a, horizontal plane; g, frontal maxillary inclination. C, top view of craniofacial bone. h, axial maxillary inclination. D, frontal view of mandible. i, frontal mandilular inclination. E, top view of mandible. j, axial mandilular inclination. F, frontal view of mandible. k, CdC-H; l, CdC-S. G and H, top view of mandible. b, coronal plane; m, CdC-C; n, axial condyle inclination. I, frontal view of mandible. o, coronal condyle inclination; coronal ramus inclination. J, lateral view of mandible. q, lateral condyle inclination; r, lateral ramus inclination. K, frontal view of maxilla. s, maxillary occlusal plane inclination. L, frontal view of mandible. t, mandilular occlusal plane inclination. D: deviated side; ND: nondeviated side

Table 2

Description of the angular and linear measurements used in this study

Measurements	Description
Skeletal parameters
Frontal maxillary inclination (°)	Angle between HP and bi-GPF projected to CP
Axial maxillary inclination (°)	Angle between SP and bi-GPF projected to HP
Menton deviation (mm)	Distance from Me to SP
MtF-S (mm)	Distance from MtF to SP
Mandible body asymmetry (mm)	Difference between bilateral mandible body length (Distance from Gol to Me)
Frontal mandibular inclination (°)	Angle between HP and bi-MtF projected to CP
Axial mandibular inclination (°)	Angle between SP and bi-MtF projected to HP
CdC-H (mm)	Distances from CdC to HP
CdC-S (mm)	Distances from CdC to SP
CdC-C (mm)	Distances from CdC to CP
Axial condyle inclination (°)	Angle between SP and the line connecting CdM- CdD projected to HP
Coronal condyle inclination (°)	Angle between SP and the line connecting Cdt-Si projected to CP
Coronal ramus inclination (°)	Angle between SP and the line connecting CdD-Gol projected to CP
Lateral condyle inclination (°)	Angle between HP and the line connecting Cdt-Si projected to SP
Lateral ramus inclination (°)	Angle between HP and the line connecting Cdp-Gop projected to SP
Maxillary occlusal plane inclination (°)	Angle between HP and bi-U6MBC projected to CP
Mandibular occlusal plane inclination (°)	Angle between HP and bi-L6DBC projected to CP
Dental parameters
Faciolingual crown angulation of first molar (°)	Angle between SP and the long axis of first molar connecting 6C and 6R projected to CP
Mesiodistal crown angulation of first molar (°)	Angle between HP and the long axis of first molar connecting 6C and 6R projected to SP
Buccal alveolar bone thickness of U6 (mm)	Distance from U6MA to the tangent of the external contour of the buccal cortical plate
Lingual alveolar bone thickness of U6 (mm)	Distance from U6MA to the tangent of the external contour of the lingual cortical plate
Total alveolar bone thickness of U6 (mm)	Sum of buccal and lingual alveolar bone thickness of maxillary first molar
Buccal alveolar bone thickness of U6/ Total alveolar bone thickness of U6	The ratio between buccal and total alveolar bone thickness around maxillary first molar
Buccal cancellous bone thickness of L6 (mm)	Distance from L6MA to the tangent of the inner contour of the buccal cortical plate
Lingual cancellous bone thickness of L6 (mm)	Distance from L6MA to the tangent of the inner contour of the lingual cortical plate
Total cancellous bone thickness of L6 (mm)	Sum of buccal and lingual alveolar bone thickness of maxillary first molar
Buccal cancellous bone thickness of L6 / Total cancellous bone thickness of L6	The ratio between buccal and total cancellous bone thickness around mandibular first molar

Terms and definitions are listed in Table 1.

For the dental characteristics, first molars were selected for analysis. Crown angulations (faciolingual and mesiodistal) and their relative positions in the alveolar bone were included, and the latter were estimated by measuring the buccal alveolar/cancellous bone thickness, lingual alveolar/cancellous bone thickness and total alveolar/cancellous bone thickness around the mesio root of the first molar (Fig. 4 and Table 2).

Fig.4

Dental measurements (Table 2). A, frontal view of craniofacial bone. SP:sagittal plane; a and b, faciolingual crown angulation of maxillary and mandibular first molar. B, lateral view of craniofacial bone. c and d, mesiodistal crown angulation of maxillary and mandibular first molar. C: section view of maxillary first molar and maxilla, which were cut along the plane constructed by U6MRB, U6MRL and U6MA. e and f, buccal and lingual alveolar bone thickness. D: section view of maxillary first molar and maxilla, which were cut along the plane constructed by L6MRB, L6MRL and L6MA. g and h, buccal and lingual cancellous bone thickness.

2.4 Statistical analysis

To avoid investigator-related bias, all variables were evaluated twice manually at a two-week interval by the same operator (Ye Ming), and intra-class correlation coefficients (ICCs) were used to analyze intraobserver reliability. All variables were measured twice at a two-week interval by the same operator (Ye Ming) and the mean of the two measurements was used in the final statistical analysis. Statistical analyses were conducted using IBM SPSS Statistics version 20.0 software (IBM Co., Armonk, NY, USA). The paired-samples T test was used to compare the changes in skeletal measurements between T0 and T2 for both groups. The changes in the crown inclinations of the first molars from T0 to T2 and alveolar bone thickness around them between T0 and T1 were assessed by utilizing the paired-samples T test. Additionally, Pearson correlation analysis was used to analyze the correlations among the changes in skeletal variables. All hypothesis tests were set at a 5% level of significance (P < 0.05).

3 Result

Forty adults of skeletal class III malocclusion with facial asymmetry were included in this retrospective study. The general characteristics of the subjects are shown in Table 3. The average time of postsurgical orthodontic treatment was 7.56±2.14 months in the one-jaw surgery group and 9.60±3.16 months in the two-jaw surgery group. The ICC results (range, 0.892 to 0.911) indicated high intraobserver reliability in this study.

Table 3
General characteristics of samples

Goup One-jaw surgery group Two-jaw surgery group

Sample sizes (n) 20 20

Age in years (SD) 21.18(5.08) 24.33(4.13)

Male/female (n) 7/13 6/14

Postsurgical orthodontic treatment time (mean±SD) (ms) 7.56±2.14 9.60±3.16

Goup	One-jaw surgery group	Two-jaw surgery group
Sample sizes (n)	20	20
Age in years (SD)	21.18(5.08)	24.33(4.13)
Male/female (n)	7/13	6/14
Postsurgical orthodontic treatment time (mean±SD) (ms)	7.56±2.14	9.60±3.16

n, number; SD, standard deviation; ms, months.

3.1 Postoperative changes in the skeletal measurements (maxilla and mandibular body) after surgical-orthodontic treatment (T0-T2) within each group

In the two groups, menton deviation and asymmetry of the bilateral mandible body length were markedly improved (P < 0.01). MtF-S on the nondeviated side (P < 0.01) significantly increased, and that on the deviated side decreased (P < 0.01), indicating a horizontal shift of the distal segment towards the nondeviated side in SSRO. Either group exhibited a significant increase of axial mandibular inclination and decrease of frontal mandibular inclination (P < 0.05), indicating yaw and roll rotation of the distal segment after SSRO (Table 4). Additionally, in contrast to the yaw direction, only the frontal maxillary inclination decreased significantly after Le Fort I osteotomy in the two-jaw surgery group (P < 0.05). Compared to T0, there was a significant improvement only in the mandibular occlusal plane inclination in the one-jaw surgery group (P < 0.05), although the two-jaw surgery group showed significant corrections in the mandibular and maxillary occlusal plane inclinations at the T2 stage (P < 0.05) (Table 4).

Table 4
Postoperative changes in the skeletal measurements between T0 and T2 within each group

Measurements One-jaw surgery group Two-jaw surgery group

T0 T2 P value T0 T2 P value

Frontal maxillary inclination (°) 1.82±1.25 1.79±1.01 0.803 2.20±1.64 1.55±0.71 0.045*

Axial maxillary inclination (°) 89.87±1.26 89.53±2.81 0.900 88.68±2.78 88.96±3.95 0.855

Menton deviation (mm) 11.04±0.65 5.07±1.77 0.002 8.42±3.99 3.38±3.13 0.010

Mandible body asymmetry (mm) 14.45±7.73 6.56±8.33 0.000 12.45±4.03 4.56±2.57 0.003

Frontal mandibular inclination (°) 3.47±1.45 1.60±1.04 0.023* 4.60±3.07 1.68±2.90 0.007**

Axial mandibular inclination (°) 86.48±1.82 89.96±3.65 0.013* 85.93±4.36 88.78±4.36 0.025*

MtF-S (D) (mm) 31.47±3.56 28.02±2.31 0.003 29.94±3.07 26.42±1.82 0.007

MtF-S (ND) (mm) 15.83±3.23 19.39±2.59 0.002 15.00±3.30 18.55±3.23 0.009

Axial condyle inclination (D) (°) 74.53±13.23 72.37±13.14 0.267 67.47±7.65 65.07±8.06 0.043*

Axial condyle inclination (ND) (°) 66.03±9.40 66.90±9.42 0.598 74.22±13.12 72.98±11.25 0.090

Coronal condyle inclination (D) (°) 55.77±81.01 56.01±84.21 0.866 54.18±74.52 52.69±74.15 0.131

Coronal condyle inclination (ND) (°) 39.04±68.43 38.40±66.14 0.732 29.36±59.88 96.44±88.37 0.621

Coronal ramus inclination (D) (°) 7.82±2.60 7.97±3.58 0.850 9.80±4.47 9.52±4.73 0.758

Coronal ramus inclination (ND) (°) 16.54±3.74 15.56±4.23 0.116 16.53±2.14 14.43±3.10 0.045*

Lateral condyle inclination (D) (°) 47.68±5.53 46.87±6.88 0.566 46.47±6.85 44.86±6.66 0.005*

Lateral condyle inclination (ND) (°) 45.71±5.07 48.88±4.41 0.009** 45.72±8.60 47.16±7.98 0.121

Lateral ramus inclination (D) (°) 84.34±3.09 84.51±3.44 0.837 83.91±7.94 81.73±8.36 0.045*

Lateral ramus inclination (ND) (°) 78.30±1.13 81.33±2.75 0.017* 79.66±7.95 79.72±7.42 0.960

Maxillary occlusal plane inclination (°) 1.56±1.18 1.16±.99 0.188 1.78±1.79 –0.29±.99 0.007**

Mandibular occlusal plane inclination (°) 2.66±1.47 1.25±1.80 0.018* 3.02±1.86 .038±1.18 0.038*

Measurements	One-jaw surgery group	Two-jaw surgery group
Frontal maxillary inclination (°)	1.82±1.25	1.79±1.01	0.803	2.20±1.64	1.55±0.71	0.045*
Axial maxillary inclination (°)	89.87±1.26	89.53±2.81	0.900	88.68±2.78	88.96±3.95	0.855
Menton deviation (mm)	11.04±0.65	5.07±1.77	0.002**	8.42±3.99	3.38±3.13	0.010**
Mandible body asymmetry (mm)	14.45±7.73	6.56±8.33	0.000**	12.45±4.03	4.56±2.57	0.003**
Frontal mandibular inclination (°)	3.47±1.45	1.60±1.04	0.023*	4.60±3.07	1.68±2.90	0.007**
Axial mandibular inclination (°)	86.48±1.82	89.96±3.65	0.013*	85.93±4.36	88.78±4.36	0.025*
MtF-S (D) (mm)	31.47±3.56	28.02±2.31	0.003**	29.94±3.07	26.42±1.82	0.007**
MtF-S (ND) (mm)	15.83±3.23	19.39±2.59	0.002**	15.00±3.30	18.55±3.23	0.009**
Axial condyle inclination (D) (°)	74.53±13.23	72.37±13.14	0.267	67.47±7.65	65.07±8.06	0.043*
Axial condyle inclination (ND) (°)	66.03±9.40	66.90±9.42	0.598	74.22±13.12	72.98±11.25	0.090
Coronal condyle inclination (D) (°)	55.77±81.01	56.01±84.21	0.866	54.18±74.52	52.69±74.15	0.131
Coronal condyle inclination (ND) (°)	39.04±68.43	38.40±66.14	0.732	29.36±59.88	96.44±88.37	0.621
Coronal ramus inclination (D) (°)	7.82±2.60	7.97±3.58	0.850	9.80±4.47	9.52±4.73	0.758
Coronal ramus inclination (ND) (°)	16.54±3.74	15.56±4.23	0.116	16.53±2.14	14.43±3.10	0.045*
Lateral condyle inclination (D) (°)	47.68±5.53	46.87±6.88	0.566	46.47±6.85	44.86±6.66	0.005*
Lateral condyle inclination (ND) (°)	45.71±5.07	48.88±4.41	0.009**	45.72±8.60	47.16±7.98	0.121
Lateral ramus inclination (D) (°)	84.34±3.09	84.51±3.44	0.837	83.91±7.94	81.73±8.36	0.045*
Lateral ramus inclination (ND) (°)	78.30±1.13	81.33±2.75	0.017*	79.66±7.95	79.72±7.42	0.960
Maxillary occlusal plane inclination (°)	1.56±1.18	1.16±.99	0.188	1.78±1.79	–0.29±.99	0.007**
Mandibular occlusal plane inclination (°)	2.66±1.47	1.25±1.80	0.018*	3.02±1.86	.038±1.18	0.038*

Values are presented as mean±standard deviation. The paired-samples T test was used to compare the difference between T0 and T2. D: deviated side; ND: nondeviated side; *P < 0.05; **P < 0.01.

3.2 Sequential changes in condylar position and angulations after surgical-orthodontic treatment (T0-T2) within each group

There were no significant differences in the changes of 3D position of condylar process after surgical-orthodontic treatment in either group (P > 0.05) (data not shown in Table 4). In the one-jaw surgery group, the lateral ramus and condyle inclination on the nondeviated side significantly increased after treatment (P < 0.05), exhibiting a backward rotation of the ramus and condyle. However, there were in the changes of axial condylar inclination, coronal ramus and condyle inclination on both sides, and lateral ramus and condyle inclination on the no significant differences deviated side between T0 and T2 (P > 0.05) (Table 4).

In the two-jaw surgery group, the coronal ramus inclination on the nondeviated side significantly decreased (P < 0.05) and no statistically significant differences were observed on the opposite side (P > 0.05) at T2. The axial condyle inclination and lateral ramus and condyle inclination on the deviated side were significantly smaller at T2 than those at T1 (P < 0.05), which showed inward and forward rotations of the condylar. However, no significant differences about the changes of other variables were found at the completion of treatment, including axial condyle inclination, lateral ramus and condyle inclination on the nondeviated side and coronal ramus and condyle inclination on the deviated side (P > 0.05) (Table 4).

3.3 The changes in dental measurements from T0 to T2 within each group

The two groups exhibited upright tendencies about bilateral first molars after presurgical orthodontic treatment (T0-T1) (P > 0.05). In the one-jaw surgery group, there was no significant difference in the buccolingual dental axis of the maxillary first molar on either side between T1 and T2, and T0 and T2 (P > 0.05). At the stages of T1-T2 and T0-T2, the mandibular first molar on the nondeviated side was significantly inclined lingually (P < 0.05) and that on the deviated side was inclined buccally (P > 0.05), even though the latter effect was not statistically significant (Table 5).

Table 5
The changes in the faciolingual crown inclinations of the bilateral first molar from T0 and T2 in the one-jaw surgery group

Measurements T0 T1 T2 T0 vs. T1 T1 vs. T2 T0 vs. T2

Faciolingual crown angulation of U6 (D) (°) 164.54±4.61 168.12±6.02 168.84±4.00 0.274 0.382 0.258

Faciolingual crown angulation of U6 (ND) (°) 177.59±2.25 175.99±1.55 175.76±4.46 0.200 0.487 0.302

Faciolingual crown angulation of L6(D) (°) 27.51±8.19 125.21±10.66 21.22±6.87 0.423 0.599 0.662

Faciolingual crown angulation of L6(ND) (°) 13.15±2.14 11.30±4.94 16.33±6.38 0.103 0.025* 0.049*

Measurements	T0	T1	T2	T0 vs. T1	T1 vs. T2	T0 vs. T2
Faciolingual crown angulation of U6 (D) (°)	164.54±4.61	168.12±6.02	168.84±4.00	0.274	0.382	0.258
Faciolingual crown angulation of U6 (ND) (°)	177.59±2.25	175.99±1.55	175.76±4.46	0.200	0.487	0.302
Faciolingual crown angulation of L6(D) (°)	27.51±8.19	125.21±10.66	21.22±6.87	0.423	0.599	0.662
Faciolingual crown angulation of L6(ND) (°)	13.15±2.14	11.30±4.94	16.33±6.38	0.103	0.025*	0.049*

Values are presented as mean±standard deviation. The paired-samples T test was used to compare the difference between T0 and T1, T1 and T2, and T0 and T2. U6: maxillary first molar; L6: mandibular first molar; D: deviated side; ND: nondeviated side; *P < 0.05; **P < 0.01.

In the two-jaw surgery group, only the changes in the mandibular first molar buccolingual angulations on the deviated side were significant during the stage of T1-T2 (P < 0.05). Compared to T0, the mandibular first molar on the deviated side and maxillary first molar on the nondeviated side were significantly inclined buccally (P < 0.05), whereas the maxillary first molar on the deviated side (P < 0.01) and the mandibular first molar on the nondeviated side (P > 0.05) were inclined buccally at T2 (Table 6).

Table 6

The changes in the faciolingual crown inclinations of the bilateral first molar from T0 and T2 in the two-jaw surgery group

Measurements	T0	T1	T2	T0 vs. T1	T1 vs. T2	T0 vs. T2
Faciolingual crown angulation of U6(D) (°)	164.26±5.78	166.11±9.89	169.35±3.87	0.452	0.247	0.008**
Faciolingual crown angulation of U6(ND) (°)	178.52±4.93	176.18±7.99	175.12±5.98	0.261	0.165	0.036*
Faciolingual crown angulation of L6(D) (°)	25.39±6.86	22.93±8.21	19.26±7.91	0.164	10.008**	0.015*
Faciolingual crown angulation of L6(ND) (°)	12.85±6.94	14.09±7.08	15.78±3.90	0.536	0.629	0.332

In addition, the mesiodistal angulations of all first molars exhibited no significant changes from T0 to T2 in the two groups (P > 0.05) (data not shown in Tables 5 and 6). There were also no significant differences in the total alveolar bone thickness of the bilateral molars during dental decompensation between T0 and T1 (P > 0.05). The ratio between the buccal and total alveolar bone thickness around the maxillary first molar on the deviated side was significantly smaller at T1 than at T0 (P < 0.05), as was the ratio between buccal and total cancellous bone thickness around the mandibular first molar on the nondeviated side (P < 0.05). There were no significant differences in those around the maxillary first molar on the nondeviated side and mandibular first molar on the deviated side (P > 0.05) (Table 7).

Table 7

Positional changes in the alveolar bone around the mesio root of the first molar after presurgical-orthodontic treatment period (T0-T1)

Measurements	T0	T1	P value
Total alveolar bone thickness of U6 (D) (mm)	14.03±1.39	13.47±1.91	0.321
Total alveolar bone thickness of U6 (ND) (mm)	12.57±0.92	12.27±2.09	0.536
Buccal alveolar bone thickness of U6/ Total alveolar bone thickness of U6 (D)	27.66±10.09	23.23±11.28	0.031*
Buccal alveolar bone thickness of U6/ Total alveolar bone thickness of U6 (ND)	18.11±5.56	15.79±9.83	0.199
Total cancellous bone thickness of L6 (D) (mm)	6.84±1.08	6.62±1.51	0.527
Total cancellous bone thickness of L6 (ND) (mm)	7.01±1.45	7.02±1.22	0.939
Buccal cancellous bone thickness of L6 / Total cancellous bone thickness of L6 (D)	24.01±19.26	19.70±31.67	0.500
Buccal cancellous bone thickness of L6 / Total cancellous bone thickness of L6 (ND)	31.28±14.77	20.45±17.92	0.024*

Values are presented as mean±standard deviation. The paired-samples T test was used to compare the difference between T0 and T1. D: deviated side; ND: nondeviated side. *P < 0.05; **P < 0.01.

3.4 Pearson correlation coefficients for the changes in skeletal parameters after surgical-orthodontic treatment (T0-T2) in the two groups

The change in menton deviation was significantly positively correlated with that of the frontal mandibular inclination (P < 0.05) and MtF-S on the deviated side (P < 0.01) between T0 and T2 in the two groups. There was a significantly positively correlation between the changes in the mandibular occlusal plane inclination and frontal mandibular inclination (P < 0.01) in BSSRO. In the two-jaw surgery group, the change in the maxillary occlusal plane inclination was significantly positively correlated with that of frontal maxillary inclination (P < 0.01) and that of the mandibular occlusal plane inclination (P < 0.05) after treatment. No correlations were found among other skeletal changes (Tables 8 and 9).

Table 8
The analysis of correlations among the changes of skeletal measurements after surgical-orthodontic treatment in the one-jaw surgery group

Correlation coefficient Δ Frontal mandibular inclination Δ Axial mandibular inclination Δ MtF-S(D) Δ Lateral condyle inclination (ND) Δ Lateral ramus inclination (ND) Δ Mandibular occlusal plane inclination

Δ Menton deviation 0.459 (0.039*) 0.405 (0.498) 0.949 (0.003) 0.763 (0.134) –0.314 (0.607) –0.507 (0.383)

Δ Frontal mandibular inclination 0.725 (0.166) 0.803 (0.006) 0.080 (0.898) –0.237 (0.701) 0.889 (0.003**)

Δ Axial mandibular inclination 0.102 (0.870) –0.273 (0.656) 0.152 (0.807) –0.148 (0.812)

Δ MtF-S(D) –0.719 (0.171) 0.868 (0.056) 0.862 (0.029)

Δ Lateral condyle inclination (ND) 0.755 (0.009) –0.007 (0.991)

Δ Lateral ramus inclination (ND) –0.103 (0.869)

Correlation coefficient	Δ Frontal mandibular inclination	Δ Axial mandibular inclination	Δ MtF-S(D)	Δ Lateral condyle inclination (ND)	Δ Lateral ramus inclination (ND)	Δ Mandibular occlusal plane inclination
Δ Menton deviation	0.459 (0.039*)	0.405 (0.498)	0.949 (0.003**)	0.763 (0.134)	–0.314 (0.607)	–0.507 (0.383)
Δ Frontal mandibular inclination		0.725 (0.166)	0.803 (0.006**)	0.080 (0.898)	–0.237 (0.701)	0.889 (0.003**)
Δ Axial mandibular inclination			0.102 (0.870)	–0.273 (0.656)	0.152 (0.807)	–0.148 (0.812)
Δ MtF-S(D)				–0.719 (0.171)	0.868 (0.056)	0.862 (0.029*)
Δ Lateral condyle inclination (ND)					0.755 (0.009*)	–0.007 (0.991)
Δ Lateral ramus inclination (ND)						–0.103 (0.869)

Pearson correlation analysis was performed in this study. “ Δ” indicates the changes between pretreatment and posttreatment stages. D: deviated side; ND: nondeviated side. *P < 0.05; **P < 0.01. “+” represents a positive correlation; “–” represents a negative correlation.

Table 9

The analysis of correlations among the changes of skeletal measurements after surgical-orthodontic treatment in the two-jaw surgery group

Correlation coefficient (P value)	Δ Frontal maxillary inclination	Δ Frontal mandibular inclination	Δ Axial mandibular inclination	Δ MtF-S (D)	Δ Axial condyle inclination (D)	Δ Coronal ramus inclination (ND)	Δ Lateral ramus inclination (D)	Δ Lateral condyle inclination (D)	Δ Mandibular occlusal plane inclination	Δ Maxillary occlusal plane inclination
Δ Menton deviation	0.514 (0.238)	0.884 (0.047*)	0.409 (0.212)	0.932 (0.001**)	0.010 (0.978)	–0.138 (0.618)	0.332 (0.318)	0.262 (0.437)	0.101 (0.768)	–0.328 (0.324)
Δ Frontal maxillary inclination		0.204 (0.661)	0.557 (0.194)	0.270 (0.558)	0.583 (0.169)	0.098 (0.835)	–0.546 (0.205)	–0.184 (0.692)	0.625 (0.081)	0.983 (0.007**)
Δ Frontal mandibular inclination			0.409 (0.212)	0.976 (0.005**)	0.010 (0.978)	–0.138 (0.686)	0.332 (0.318)	0.231 (0.494)	0.962 (0.009**)	0.563 (0.071)
Δ Axial mandibular inclination				0.046 (0.894)	–0.389 (0.237)	–0.379 (0.250)	–0.625 (0.222)	0.253 (0.453)	–0.386 (0.242)	0.011 (0.974)
Δ MtF-S (D)					–0.466 (0.148)	0.637 (0.089)	–0.362 (0.273)	–0.219 (0.518)	0.945 (0.015*)	0.101 (0.768)
Δ Axial condyle inclination (D)						0.210 (0.536)	0.015 (0.965)	0.126 (0.711)	0.232 (0.493)	0.117 (0.733)
Δ Coronal ramus inclination (ND)							0.400 (0.326)	0.748 (0.133)	0.593 (0.841)	–0.219 (0.776)
Δ Lateral ramus inclination (D)								0.945 (0.004**)	–0.205 (0.545)	0.319 (0.428)
Δ Lateral condyle inclination (D)									–0.396 (0.228)	0.101 (0.768)
Δ Mandibular occlusal plane inclination										0.888 (0.018*)

4 Discussion

In this study, we used CBCT with 3D analysis devices to study the changes in the skeletal and dental tissues of skeletal class III malocclusion patients with facial asymmetry after surgical-orthodontic treatment. The utilization of CBCT overcomes limitations of two-dimensional traditional radiography, such as magnification errors, overlapping of anatomic structures, and may not be influenced by tilted head posture [17]. Compared to conventional multislice computed tomography, CBCT has the advantages of low amounts of radiation and operating costs [18]. Mimics software based on the CBCT images can provide us with accurate 3D reconstruction models [19], which can be rotated freely by the observer, to analyze the complex dentofacial structures, especially the TMJ. However, Neiva et al. [20] thought that reliable values of identifying landmarks were lower in 3D reconstruction models than in the multiplanar visualization. Actually, the latter could be influenced by the anatomic structure, skull position and so on [21]. Therefore, to reduce the errors, this study located anatomic landmarks tentatively on the 3D reconstruction models and then reconfirmed them via multiplanar views.

The present study found that, accompanied by horizontal displacements and roll and yaw rotation of the distal segment after SSRO, menton deviation and asymmetry of the bilateral mandible body length could be greatly reduced. There was a strong correlation between the correction of menton deviation and movements of the distal segment, including horizontal displacements and roll rotation towards the nondeviated side. Moreover, the mandibular occlusal plane cant was markedly corrected due to the roll rotation of the distal segment after BSSRO. Baek et al. [22] reported that the coronal ramus inclination on the deviated side was smaller than that on the nondeviated side in mandibular asymmetry patients. Our study found that the coronal ramus inclination on the nondeviated side significantly decreased and that on the opposite side was unchanged in the two-jaw surgery group. It could be suggested that the discrepancy in the coronal ramus inclinations on both sides was reduced, which improved the symmetricity of the frontal appearance to some extent after treatment in the two-jaw surgery group, whereas that effect was not significant in the one-jaw surgery group. On the other hand, the roll rotation of the maxilla decreased the maxillary inclination in the coronal view and the occlusal plane cant of the upper jaw was significantly improved after Le Fort I osteotomy. Several studies [23, 24] had shown the correction of maxillary cant was positively correlated with that of lip line cant. Accordingly, these findings suggested that bimaxillary surgery could promote more asymmetry than BSSRO alone for correcting skeletal class III malocclusion and facial asymmetry.

In this study, our results indicated that the condylar position was stable after surgical-orthodontic treatment (approximately 7 to 9 months after surgery), consistent with previous reports [8 –10]. Nonetheless, there are controversial issues about changes in condylar angles after orthognathic surgery due to different measurement methods and the timing of postoperative assessments. Similar to a previous report [25], the condylar angle in the axial view changed little in the one-jaw surgery group, but the condylar on the deviated side rotated mesially for patients who underwent bimaxillary surgery after treatment. Fernández et al. [26] demonstrated that the medial rotation of the condylar was one of the risk factors for TMJ with disk displacements and/or degenerative lesions. Additionally, while the condylar neck and ramus on the nondeviated side rotated backward after isolated mandibular setback, there were few negative effects resulting in mandibular forward relapse. On the other hand, the two-jaw surgery group showed forward rotation of the condylar on the deviated side, and this result was similar to that of Kim et al. [27]. They claimed that the change might be related to the maxillary surgical procedure and would become one of the causes of surgical relapse. Thus, it is crucial for clinicians not to overload the condylars in case of increasing its instability during postsurgical orthodontic treatment, and to pay close attention to the condition of the TMJ to avoid TMD and postoperative recurrence after surgery.

There is no consensus about the relationships between the movements of the distal segment and the changes of the proximal segment in skeletal class III asymmetry patients after mandibular surgery. Yamada and his team [28] claimed that the extent of mandibular setback, rather than asymmetrical setback of the distal segment, had a critical influence on the postoperative position of the condylar. In contrast, Kim [6] held the opposite viewpoint. However, our results did not find a significant correlation between the angulations of the condylar and the movements of the distal segment after SSRO with or without Le Fort I osteotomy. This result might be related to individual differences in studying samples. Other investigators hypothesized that the proximal segment position could be affected by factors like the anatomic shape of the mandibular body, the fixation method, and the surgeon’s experience [29].

This study chose the first molar, which was the key of occlusion, to investigate the changes in the dental axes and surrounding alveolar bone using 3D reconstruction programs. During presurgical orthodontic treatment, the first molars of the two groups all exhibited upright tendencies in the buccolingual view. These changes were called dental decompensation and important for the orthognathic surgeons to move bone segments successfully. After surgical-orthodontic treatment, the mandibular first molars on the nondeviated side were inclined lingually, while those on the deviated side were inclined buccally in either group. Song et al. [30] demonstrated that the changes in the faciolingual crown angles of the lower molars were usually attributed to surgical changes in SSRO since it was limited to correct transverse dental axes in presurgical or postsurgical orthodontic treatment, especially facial asymmetry patients. According to traditional biological principles [31], alveolar bone around the tooth would remodel to a similar degree following orthodontic tooth movement. However, most scholars [16 , 33] have declared that unlimited tooth movement is impractical. This can be explained by the fact that alveolar bone is made of active cancellous bone inside and inert cortical bone outside and the scope of tooth movement depends largely on the thickness of the cancellous bone. In this experiment, the total alveolar thickness of the bilateral molar remained constant at the stage of dental decompensation. The ratio between buccal and total bone thickness around the maxillary first molar on the deviated side decreased significantly, as did those around the mandibular first molar on the nondeviated side. It indicated that their root apexes were positioned closer to the buccal cortical plate than before treatment. Therefore, orthodontists should keep a watchful eye to the relative position between the root and the cortical plates around it while decompensating the tilted posterior tooth; otherwise, the tooth and its periodontal health will be damaged, such as root resorption, fenestrations or dehisences, and the treatment outcome will also be influenced.

The present study explored precisely skeletal and dental changes in skeletal class III malocclusion patients with facial asymmetry after surgical-orthodontic treatment by utilizing CBCT scans with 3D analysis programs. It can be suggested that orthodontists and surgeons should monitor TMJ after surgery and periodontal health during tooth decompensation. Recently, digital surgical-orthodontic treatment has been prevailing in this field, so accurate 3D measurements and analysis preoperatively and postoperatively are required to make prognosis judgment and the treatment plan, and to evaluate clinical efficacy and so on. The measurement method in our study could be a good alternative.

Nonetheless, larger-size and long-term studies would be helpful to better understand the efficacy and stability of orthognathic surgery in the future. Further research is needed to evaluate the changes in soft tissues and airway between single-jaw surgery and bimaxillary surgery.

5 Conclusion

This study concluded that surgical-orthodontic treatment obviously improved asymmetry in the maxillofacial hard tissues of skeletal class III patients with facial asymmetry. In addition, condylar angulations were less stable after treatment (at 7 to 9 months after surgery) in both the one-jaw and the two-jaw surgery groups, while condylar displacements were not significant. Furthermore, orthodontists should keep a watchful eye to the relative position of the root in the alveolar bone during tooth decompensation.

Conflict of interest

The authors declare that they have no conflict of interest.

Footnotes

Acknowledgments

This work was financially supported through grants from the National Natural Science Foundation of China (81470722), the Medical and the Natural Science Foundation of Chongqing (2018ZDXM020), the Natural Science Foundation of Chongqing (cstc2016jcyjA0238), Innovation Team Building at Institutions of Higher Education of Chongqing (CXTDG201602006).

References

Haraguchi

, Takada

and Yasuda

, Facial asymmetry in subjects with skeletal Class III deformity, Angle Orthodontist 72(1) (2002), 28–35.

Suzuki-Okamura

, Higashihori

, Kawamoto

, et al., Three-dimensional analysis of hard and soft tissue changes in patients with facial asymmetry undergoing 2-jaw surgery, Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology 120(3) (2015), 299–306.

Georgalis

and Woods

M.G.

, A study of Class III treatment: orthodontic camouflage vs orthognathic surgery, Australian Orthodontic Journal 31(2) (2015), 138–48.

Patel

P.K.

and Novia

M.V.

, The surgical tools: The LeFort I, bilateral sagittal split osteotomy of the mandible, and the osseous genioplasty, Clinics in Plastic Surgery 34(3) (2007), 447–475.

Zhao

, Gu

and Zhao

, Three dimensional evaluation of orthognathic operation on the maxillofacial hard tissue symmetry change, Stomatology 35(4) (2015), 262–265.

Kim

J.W.

, Son

W.S.

, Kim

S.S.

and Kim

Y.I.

, Proximal segment changes after bilateral sagittal split ramus osteotomy in facial asymmetry patients, Journal of Oral and Maxillofacial Surgery 73(8) (2015), 1592–1605.

Mucedero

, Coviello

, Baccetti

, et al., Stability factors after double-jaw surgery in Class III malocclusion. A systematic review, Angle Orthodontist 78(6) (2008), 1141–1152.

Baek

S.H.

, Kim

T.K.

and Kim

M.J.

, Is there any difference in the condylar position and angulation after asymmetric mandibular setback? Oral Surgery Oral Medicine Oral Pathology Oral Radiology & Endodontology 101(2) (2006), 155–163.

Choi

B.J.

, Kim

B.S.

, Lim

J.M.

, et al., Positional change in mandibular condyle in facial asymmetric patients after orthognathic surgery: cone-beam computed tomography study, Maxillofacial Plastic and Reconstructive Surgery 40(1) (2018), 13.

10.

Zhan

, Gao

, Fan

and Ma

, The effects of dentoalveolar distraction extraction on alveolar ridge preservation: Cone-beam computed tomography and X-ray analysis in canine model, Journal of X-ray Science and Technology 26(5) (2018), 834–851.

11.

Kawamata

, Fujishita

, Nagahara

, et al., Three-dimensional computed tomography evaluation of postsurgical condylar displacement after mandibular osteotomy, Oral Surgery Oral Medicine Oral Pathology Oral Radiology & Endodontics 85(4) (1998), 371.

12.

Zhang

, Liu

, Zhang

, et al., Relationship between dental arch anomalies and craniofacial characteristics in patients with deviated mandible, Chin J Orthod 17(4) (2010), 201–203.

13.

, Hu

, Huang

, et al., A three-dimensional analysis of skeletal and dental characteristics in skeletal class III patients with facial asymmetry, Journal of X-ray Science and Technology 26(3) (2018), 449–462.

14.

Cappellozza

J.A.Z.

, Guedes

F.P.

, Nary

, et al., Orthodontic decompensation in skeletal Class III malocclusion: redefining the amount of movement assessed by Cone-Beam Computed Tomography, Dental Press Journal of Orthodontics 20(5) (2015), 28–34.

15.

Park

H.M.

, Lee

Y.K.

, Choi

J.Y.

and Baek

S.H.

, Maxillary incisor inclination of skeletal Class III patients treated with extraction of the upper first premolars and two-jaw surgery: conventional orthognathic surgery vs surgery-first approach, Angle Orthodontist 84(4) (2014), 720.

16.

Handelman

C.S.

, The anterior alveolus: its importance in limiting orthodontic treatment and its influence on the occurrence of iatrogenic sequelae, Angle Orthodontist 66(2) (1996), 109–10.

17.

Xia

J.J.

, Jaime

and Teichgraeber

J.F.

, New clinical protocol to evaluate craniomaxillofacial deformity and plan surgical correction, Journal of Oral & Maxillofacial Surgery 67(10) (2009), 2093–2106.

18.

Kapila

S.D.

and Nervina

J.M.

, CBCT in orthodontics: assessment of treatment outcomes and indications for its use, Dento Maxillo Facial Radiology 44(1) (2015), 20140282.

19.

Solaro

, Pierangeli

, Pizzoni

, et al., From computerized tomography data processing to rapid manufacturing of custom-made prostheses for cranioplasty. Case report, Journal of Neurosurgical Sciences 52(4) (2008), 113–116.

20.

N.M.

, Soares

A.C.

, De

O.L.C.

, et al., Evaluation of cephalometric landmark identification on CBCT multiplanar and 3D reconstructions, Angle Orthodontist 85(1) (2015), 11–17.

21.

de Oliveira

A.E.

, Cevidanes

L.H.

, Phillips

, et al., Observer reliability of three-dimensional cephalometric landmark identification on cone-beam computerized tomography, Oral Surgery Oral Medicine Oral Pathology Oral Radiology and Endodontics 107(2) (2009), 256–265.

22.

Baek

, Paeng

J.Y.

, Lee

J.S.

and Hong

, Morphologic evaluation and classification of facial asymmetry using 3-dimensional computed tomography, J Oral Maxillofac Surg 70(5) (2012), 1161–1169.

23.

Lee

G.C.

, Yoo

J.K.

, Kim

S.H.

and Moon

C.H.

, Lip line changes in Class III facial asymmetry patients after orthodontic camouflage treatment, one-jaw surgery, and two-jaw surgery: A preliminary study, Angle Orthod 87(2) (2017), 239–245.

24.

Kim

Y.H.

, Jeon

, Rhee

J.T.

and Hong

, Change of lip cant after bimaxillary orthognathic surgery, Journal of Oral and Maxilofacial Surgery 68(5) (2010), 1106–1111.

25.

Tyan

, Kim

H.H.

, Park

K.H.

, et al., Sequential changes of postoperative condylar position in patients with facial asymmetry, Angle Orthodontist 87(2) (2016), 260–268.

26.

Fernández

S.J.

, Gómez González

J.M.

and del Hoyo

J.A.

, Relationship between condylar position, dentofacial deformity and temporomandibular joint dysfunction: an MRI and CT prospective study, Journal of Cranio-maxillo-facial Surgery 26(1) (1998), 35.

27.

Kim

Y.J.

, Lee

and Chun

Y.S.

, et al., Condylar positional changes up to 12 months after bimaxillary surgery for skeletal class III malocclusions, Journal of Oral and Maxillofacial Surgery 72(1) (2014), 145–156.

28.

Yamada

, Hanada

, Sultana

M.H.

, et al., The relationship between frontal facial morphology and occlusal force in orthodontic patients with temporomandibular disorder, Journal of Oral Rehabilitation 27(5) (2010), 412–421.

29.

Komori

, Aigase

, Sugisaki

and Tanabe

, Cause of early skeletal relapse after mandibular setback, American Journal of Orthodontics & Dentofacial Orthopedics 95(1) (1989), 29–36.

30.

Song

H.S.

, Choi

S.H.

, Cha

J.Y.

, et al., Comparison of changes in the transverse dental axis between patients with skeletal Class III malocclusion and facial asymmetry treated by orthognathic surgery with and without presurgical orthodontic treatment, Korean Journal of Orthodontics 47(4) (2017), 256–267.

31.

Sarikaya

, Haydar

, Ciğer

and Ariyürek

, Changes in alveolar bone thickness due to retraction of anterior teeth, American Journal of Orthodontics and Dentofacial Orthopedics 122(1) (2002), 15–26.

32.

, Liu

and J.

, Cephalometric study of alveolar remodeling during incisior retraction, Journal of Practical Stomatology 20(4) (2004), 431–433.

33.

Fang

, Xu

and Mao

, Dental alveolar effects of maxillary anterior teeth retraction with implant anchorage: A computed tomography evaluation, China Journal of Oral and Maxillofacial Surgery 6(1) (2008), 28–33.

Three-dimensional evaluation of skeletal and dental changes in patients with skeletal class III malocclusion and facial asymmetry after surgical-orthodontic treatment

Abstract

OBJECTIVE:

METHODS:

RESULTS:

CONCLUSIONS:

Keywords

1 Introduction

2 Materials and Methods

2.1 Study subjects

2.2 Images acquisition and assessment

2.3 Landmarks and measurements

3 Result

Table 3 General characteristics of samples Goup One-jaw surgery group Two-jaw surgery group Sample sizes (n) 20 20 Age in years (SD) 21.18(5.08) 24.33(4.13) Male/female (n) 7/13 6/14 Postsurgical orthodontic treatment time (mean±SD) (ms) 7.56±2.14 9.60±3.16

3.3 The changes in dental measurements from T0 to T2 within each group

5 Conclusion

Conflict of interest

Footnotes

Acknowledgments

References

Table 3
General characteristics of samples

Goup One-jaw surgery group Two-jaw surgery group

Sample sizes (n) 20 20

Age in years (SD) 21.18(5.08) 24.33(4.13)

Male/female (n) 7/13 6/14

Postsurgical orthodontic treatment time (mean±SD) (ms) 7.56±2.14 9.60±3.16