Changes in condylar position after BSSRO with and without Le Fort I osteotomy via surgery-first approach in mandibular prognathism with facial asymmetry

Accepted Manuscript Changes in condylar position after BSSRO with and without Le Fort I osteotomy via surgery-first approach in mandibular prognathism with facial asymmetry Jiyin Li, DDS, MSD, Sun-Youl Ryu, DDS, PhD, Hong-Ju Park, DDS, PhD, Min-Suk Kook, DDS, PhD, Seunggon Jung, DDS, PhD, Jeong Joon Han, DDS, MSD, HeeKyun Oh, DDS, PhD PII:

S2212-4403(17)30035-4

DOI:

10.1016/j.oooo.2017.01.009

Reference:

OOOO 1697

To appear in:

Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology

Received Date: 25 August 2016 Revised Date:

13 November 2016

Accepted Date: 26 January 2017

Please cite this article as: Li J, Ryu S-Y, Park H-J, Kook M-S, Jung S, Han JJ, Oh H-K, Changes in condylar position after BSSRO with and without Le Fort I osteotomy via surgery-first approach in mandibular prognathism with facial asymmetry, Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology (2017), doi: 10.1016/j.oooo.2017.01.009. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

ACCEPTED MANUSCRIPT Changes in condylar position after BSSRO with and without Le Fort I osteotomy via surgeryfirst approach in mandibular prognathism with facial asymmetry

Jiyin Li, DDS, MSD, 2Sun-Youl Ryu, DDS, PhD, 2Hong-Ju Park, DDS, PhD, 2Min-Suk Kook, DDS,

RI PT

1

PhD, 2Seunggon Jung, DDS, PhD, 3,4,*Jeong Joon Han, DDS, MSD, 2Hee-Kyun Oh, DDS, PhD

Graduate Dental School, Chonnam National University, Gwangju, 500-757, Republic of Korea

2

Department of Oral and Maxillofacial Surgery, School of Dentistry, Dental Science Research

M AN U

SC

1

Institute, Chonnam National University, Gwangju, 500-757, Republic of Korea 3

Department of Oral and Maxillofacial Surgery, Chonnam National University Hospital, Gwangju,

501-757, Republic of Korea

Department of Oral and Maxillofacial Surgery, School of Dentistry, Dental Research Institute, Seoul

TE D

4

National University, Seoul, 110-768, Republic of Korea

EP

*Corresponding author

AC C

Jeong Joon Han, DDS, MSD.

Clinical Professor, Department of Oral and Maxillofacial Surgery, Chonnam National University Hospital 42, Jebong-ro, Dong-Gu,

Gwangju 501-757 Korea. Tel: +82-62-220-5436; Fax: +82-62-220-5437 E-mail: [email protected]

ACCEPTED MANUSCRIPT This manuscript, or any part of it, has not been submitted or published and will not be submitted elsewhere for publication while being considered by the journal “Oral Surgery, Oral Medicine, Oral

Word count for the abstract: 200 words

RI PT

Pathology and Oral Radiology”.

references and 170 words of figure legends)

M AN U

Number of references: 39 references

SC

A complete manuscript word count: 4931 words (including 3653 words of body text, 1108 words for

Number of tables: 2 tables

AC C

EP

TE D

Number of figures: 5 figures

ACCEPTED MANUSCRIPT CONFLICT OF INTEREST

AC C

EP

TE D

M AN U

SC

RI PT

The authors have no financial interest to declare in relation to the content of this article

ACCEPTED MANUSCRIPT Abstract Objectives: This study aimed to evaluate changes in condylar position after bilateral sagittal split ramus osteotomy (BSSRO) with and without Le Fort I osteotomy via surgery-first approach in

RI PT

patients with facial asymmetry. Study Design: Eighteen patients (36 condyles) who received surgical-orthodontic treatment using a SFA were included and divided into two groups depending on the extent of surgery: BSSRO-only

SC

group (n=12) and BSSRO with Le Fort I osteotomy group (n=6). Using computed tomography images taken preoperatively, immediately postoperatively, and 6 months postoperatively, surgical and

M AN U

postoperative changes of the condylar position were analyzed three-dimensionally. Results: Both groups showed mainly lateral and inferior displacement with inward rotation immediately after surgery, and medial and superior returning movement with outward rotation 6 months after surgery. There was no statistical difference in time-course changes of the condylar position between two groups. In comparing the deviated and nondeviated sides, deviated side showed

side in both groups.

TE D

significantly greater amount of bodily shift and rotational movement after surgery than nondeviated

EP

Conclusion: These results suggest that BSSRO in SFA, either with or without Le Fort I osteotomy, may cause condylar displacement after surgery and displaced condyles return to their original position

AC C

in both deviated- and nondeviated sides.

Keywords: condylar displacement; orthognathic surgery; surgery-fist approach; facial asymmetry

ACCEPTED MANUSCRIPT INTRODUCTION Since Nagasaka et al.1 proposed the surgery-first approach (SFA) in surgical-orthodontic treatment to correct skeletal class III correction, the use of this alternative methodology is on the increase. In SFA,

RI PT

orthognathic surgery is performed without preoperative orthodontic preparation and is followed by regular postoperative dental alignments. Although minimal orthodontics are occasionally performed preoperatively, the concept implies that most of the orthodontic treatment is carried out

postoperatively.2 Compared with the conventional orthodontics-first approach (OFA), SFA protocols

SC

can lead to a significant decrease in total treatment time, and that may bring about a positive influence

M AN U

on patients’ satisfaction with treatment.3-6

Asymmetry of the face is one of the most common complaints among patients with dentofacial deformities, and it is more common in the mandible than in the maxilla.7, 8 It can be caused by several conditions including unilateral condylar hyperplasia or hypoplasia, hemifacial microsomia, or temporomandibular joint disorder (TMD). To correct facial asymmetry, bilateral sagittal split ramus

TE D

osteotomy (BSSRO) with or without Le Fort I osteotomy has been widely used and is regarded as a standard surgical procedure. Usually, in patients with facial asymmetry, three-dimensional positional changes of the bony segments are necessary to achieve successful surgical outcome in aspects of

EP

function and esthetics, thus a greater amount of interference between the bony segments may occur.9 When there remains bony interference between the segments, the condyle will exhibit a great

AC C

displacement including bodily shifts and rotational changes. Condylar displacement is one of the contributing factors to postoperative stability, which is the success criterion of orthognathic surgery. Many previous studies reported that condylar displacement during orthognathic surgery has a significant influence on early postoperative relapse and temporomandibular joint (TMJ) dysfunctions, such as TMJ pain, clicking sounds, disc displacement, and condylar resorption.9-16 The influencing factors for condylar displacement include the relationship with surrounding muscle tissue, joint edema and hemarthrosis, soft tissue and muscular tension, the method of condyle repositioning, misalignment of the bony fragment, fixation technique, and

ACCEPTED MANUSCRIPT rotational movement of the mandibular distal segment.9, 17-21 Through the literature review, many previous studies investigated condylar displacement after orthognathic surgery via OFA.9, 11, 12, 15, 18, 2022

However, to our knowledge, there are only a few reports that have studied postoperative condylar

displacement in patients who received orthognathic surgery to correct mandibular prognathism with

RI PT

facial asymmetry, especially via SFA.

The aim of this study was to evaluate changes in condylar position after BSSRO with and without Le

M AN U

SC

Fort I osteotomy via surgery-first surgical-orthodontic treatment in patients with facial asymmetry.

PATIENTS AND METHODS Patients

Of the patients who underwent orthognathic surgery in the Department of Oral and Maxillofacial

TE D

Surgery, Chonnam National University Hospital from 2010 to 2015, 18 patients (male:female = 12:6; mean age, 21.0 years; age range, 18–25 years) satisfying the inclusion criteria were included in this study. The inclusion criteria of patients were as follows:

EP

1) Mandibular prognathism

AC C

2) Facial asymmetry: facial asymmetry is defined as a mandibular dental midline deviation to the facial midline (glabella to anterior nasal spine) more than 4.0 mm23 3) Type of surgical-orthodontic treatment: SFA 4) Fixation method: semi-rigid fixation with one titanium miniplate and four monocortical screws on each side To evaluate the effect of the extent of the surgery on the condylar displacement, patients were divided into two groups: BSSRO-only group included 12 patients (male:female = 9:3; age, 21.3 years; age range, 18–25 years) and BSSRO with Le Fort I osteotomy group included 6 patients (male:female =

ACCEPTED MANUSCRIPT 3:3; age, 21.0 years; age range, 18–24 years). Preoperative and postoperative TMJ symptoms including clicking, crepitation, pain, and mouth opening limitation were analyzed retrospectively.

RI PT

Surgical procedures For maxillary surgery, conventional Le Fort I osteotomy was performed. After down-fracture of the maxilla, bony interferences between the mobilized maxillary segment and posterior region were

SC

removed. After intermaxillary fixation with intermediate occlusal splint, the maxillomandibular complex was repositioned to its planned position and fixed with two L-shaped miniplates at the

M AN U

piriform aperture and zygomatic buttress on each side. For mandibular surgery, modified BSSRO was performed. After splitting of the mandible, the bony interferences between the proximal and distal segments were removed. Fixation of the mandible was performed by semi-rigid fixation using one miniplate and four monocortical screws on each side. After surgery, intermaxillary fixation was maintained with a surgical splint for 3 weeks postoperatively. Postoperative orthodontic treatment was

TE D

begun after a 3-week postoperative healing period.

EP

Analysis of condylar displacement

To assess the surgical and postoperative changes of the condylar position, computed tomography (CT)

AC C

images were obtained before surgery (T0), 3 days postoperatively (T1), and 6 months postoperatively (T2). CT images were imported to the three-dimensional analysis program (OnDemand3D, Cybermed, Seoul, Korea) and superimposed to fit the cranial base and skull structures. The Frankfort Horizontal plane (FH plane) was used as the horizontal reference plane, passing through the right and left orbitale and right porion.14, 18 We set the x-axis as the vector from the right orbitale to the left orbitale and midsagittal plane as the plane that was perpendicular to the x-axis and passed through a nasion, which is defined as the middle point of the frontonasal suture. The plane that passed through the line passing both orbitale and perpendicular FH plane was set as the coronal plane. To quantify 3D changes in the

ACCEPTED MANUSCRIPT condylar position, a 3D coordinate system (x, y, z) was used: x-axis, medial (–) and lateral (+); y-axis, anterior (–) and posterior (+); z-axis, superior (+) and inferior (–) direction. To measure surgically induced perioperative changes and postoperative changes of the condylar position three dimensionally, 3D coordinates of the lateral pole of the condylar head (LP) and medial pole of the condylar head (MP)

RI PT

were obtained. The center of the condylar head (CC) was defined as the midpoint between the LP and MP, and its coordinate was calculated.

We divided the changes of the condylar position into bodily shifts and rotational changes.9, 18 After

SC

calculation of the coordinate changes in CC between each time point, the amount of bodily shift of CC in 3D was calculated using Euclidean distance. Rotational changes on the axial and coronal planes

connecting the LP and MP.9, 18

TE D

Statistical analysis

M AN U

were assessed by the calculation of the angle between pre- and postoperative condylar axes

Statistical analysis was performed using SPSS for Windows version 21.0 (SPSS Inc., Chicago, IL, USA). Time-dependent changes of the condylar position were examined by repeated-measures

EP

analysis of variance (ANOVA). Post hoc testing was done with Bonferroni technique. Statistical differences at each time point between the two groups and between the deviated and nondeviated

AC C

sides were calculated using Wilcoxon signed rank test and Mann-Whitney U test. The level of significance was set at p <0.05.

RESULTS Evaluation of condylar displacement The mean amount of mandibular setback movement was 7.7 ± 4.5 mm. According to the extent of the

ACCEPTED MANUSCRIPT surgery, the mean amount of mandibular setback movement was 8.7 ± 4.2 mm in BSSRO-only group and 5.8 ± 4.5 mm in BSSRO with Le Fort I osteotomy group. Although both groups showed significant time-course changes of the condylar position within each group (p < 0.01), there was no statistical difference in time-course changes of the condylar position between the two groups (Table 1).

RI PT

Immediately after surgery, both BSSRO-only group and BSSRO with Le Fort I osteotomy group showed lateral displacement of the condyle by 0.5 ± 0.9 mm (-1.27 mm to 2.56 mm) and 1.5 ± 1.6 mm (–0.27 mm to 5.18 mm), respectively. In the superior-inferior direction, both groups exhibited

SC

inferior displacement by 1.0 mm ± 1.1 mm (–1.45 mm to 3.01 mm) in BSSRO-only group and 1.2 ± 1.0 mm (0.03 mm to 3.34 mm) in BSSRO with Le Fort I osteotomy group. In anterior-posterior

M AN U

direction, both groups showed anterior displacement less than 0.2 mm (Figure 2). During the postoperative period, the condyle moved medially by 0.6 mm ± 0.8 mm (–1.15 mm to 1.85 mm) in BSSRO-only group and 1.2 ± 1.2 mm (–0.06 mm to 4.37 mm) in BSSRO with Le Fort I osteotomy group, and superiorly by 1.0 ± 1.0 mm (–0.85 mm to 2.93 mm) in BSSRO-only group and

TE D

1.5 ± 1.1 mm (–0.18 mm to 3.18 mm) in BSSRO with Le Fort I osteotomy group. A comparison of the condylar position at 6 months after surgery with that before surgery showed that the difference of the condylar position was less than 0.4 mm on x-, y-, and z-axes.

EP

In the analysis of the amount of bodily shift in 3D, BSSRO with Le Fort I osteotomy group showed greater surgical changes (T1-T0), postoperative changes (T2-T1), and total changes (T2-T0) on

AC C

average than BSSRO only group, though there was no statistically significant difference in surgical changes (T1-T0) and postoperative changes (T2-T1) between two groups (Table 2). For total changes (T2-T0), BSSRO with Le Fort I group showed significantly greater amount of bodily shift in 3D than BSSRO only group (p < 0.05), however, the difference between two groups was 0.52 mm. In terms of the rotational changes of the condyle on the axial plane, both groups showed inward rotation by 3.9 ± 3.9° (–4.46° to 10.25°) in BSSRO-only group and 3.1 ± 3.4° (–3.67° to 9.59°) in BSSRO with Le Fort I osteotomy group (Table 3). During the postoperative period, the condyle rotated outward by 0.3 ± 2.7° (–4.29° to 5.14°) in BSSRO-only group and 1.4 ± 2.7° (–4.93° to 6.12°)

ACCEPTED MANUSCRIPT in BSSRO with Le Fort I osteotomy group. Compared with preoperative condylar long axis, the condyle rotated inward 3.7 ± 3.5° in BSSRO-only group and 1.7 ± 1.4° in BSSRO with Le Fort I osteotomy group, and BSSRO-only group showed significantly greater inward rotation than BSSRO with Le Fort I osteotomy group (p < 0.05). On coronal plane, both groups showed surgically induced

RI PT

inferior rotation by 0.1 ± 2.4° (–3.20° to 5.05°) in BSSRO-only group and 0.4 ± 3.1° (–5.17° to 5.25°) in BSSRO with Le Fort I osteotomy group. During the postoperative period, the condyle rotated

inferiorly by 1.1 ± 2.9° (–6.32° to 6.96°) in BSSRO-only group and superiorly by 0.8 ± 2.4° (–4.17°

SC

to 6.26°) in BSSRO with Le Fort I osteotomy group. Compared with preoperative condylar long axis, the condyle rotated inferiorly by 1.2 ± 3.4 ° in BSSRO-only group, and superiorly by 0.4 ± 2.8° in

M AN U

BSSRO with Le Fort I osteotomy group.

The comparison of bodily shift and rotational movement between deviated and nondeviated sides in each group is presented in Tables 4 and 5. Both deviated and nondeviated sides in BSSRO-only and BSSRO with Le Fort I osteotomy groups exhibited mainly lateral and inferior displacement and

TE D

inward rotation immediately after surgery. The amount of bodily shift in 3D was significantly greater for the deviated side (2.03 ± 0.95 mm in BSSRO-only group and 2.86 ± 1.89 mm in BSSRO with Le Fort I osteotomy group) than for nondeviated side (1.33 ± 0.78 mm in BSSRO-only group and 1.62 ±

EP

1.06 mm in BSSRO with Le Fort I osteotomy group) (p < 0.01 for BSSRO-only group and p < 0.05 for BSSRO with Le Fort I osteotomy group). During the postoperative periods, both deviated and

AC C

nondeviated sides showed medial and superior movement and outward rotation to their original position. Compared to its original position (T2-T0), there was no statistically significant difference in the amount of bodily shift between the deviated and nondeviated sides.

TMJ symptoms Of the six condyles (five condyles in BSSRO-only group and one condyle in BSSRO with Le Fort I osteotomy group) that exhibited TMJ symptoms preoperatively, five condyles (four condyles in BSSRO-only group and one condyle in BSSRO with Le Fort I osteotomy group) did not have TMJ

ACCEPTED MANUSCRIPT symptoms postoperatively and one condyle in BSSRO-only group still showed TMJ symptom. Of the condyles that did not have preoperative TMJ symptoms, one condyle in BSSRO with Le Fort I

RI PT

osteotomy group showed TMJ symptom (clicking sound) postoperatively.

DISCUSSION

SC

In our study, we found that condyles in both BSSRO-only and BSSRO with Le Fort I osteotomy group displaced similarly after surgical-orthodontic treatment via SFA. Although the amount of

M AN U

displacement and rotation was different between the deviated and nondeviated sides, both sides exhibited lateral and inferior displacement and inward rotation.

Orthognathic surgery including intraoral vertical ramus osteotomy (IVRO) and BSSRO may cause changes of the condylar position, and Epker and Wylie24 asserted that maintenance of the normal

TE D

preoperative position of the mandibular condyles and contiguous proximal mandibular ramus after BSSRO was important to ensure the stability of the surgical result, to reduce adverse effects on the TMJ, and to improve masticatory function. To maintain preoperative condylar position, many

EP

investigators have developed the condylar positioning device (CPD) to maintain preoperative condylar position.25-29 Although several studies have reported successful surgical outcome after

AC C

orthognathic surgery with CPD, the postoperative condylar position may be different from the preoperative position, and the determination of the postoperative condylar position is still controversial.30, 31

Although numerous two-dimensional studies about condylar displacement after SSRO were reported, three-dimensional analysis of the positional changes of the condyle has been reported after CT was used for the diagnosis and treatment in orthognathic surgery.7, 11, 15, 18, 22 In the study by Lee and Park,22 condyles moved inferiorly 1 month after surgery in patients who received mandibular setback using BSSRO; however, anteroposterior and mediolateral displacement was not significant. Baek et al.11

ACCEPTED MANUSCRIPT reported that anteroposterior, mediolateral, and superior-inferior movement of the condyles were not significant 6 months after BSSRO. Ueki et al.15 also evaluated the horizontal changes of the condylar head with bent plate fixation, and they concluded that there were no significant differences between preoperative and 3-month postoperative CT in the anteroposterior and mediolateral displacement of

RI PT

the condyle. Kim et al.32 found that anterior-posterior condylar position in the glenoid fossa moved from an anterior position preoperatively to a concentric position after surgery and then tended to return to the preoperative position during post-retention period. Han and Hwang18 studied the

SC

condylar displacement depending on the fixation methods using 3D analysis, and they found that the difference in the condylar position between preoperatively and 3- to 6-month postoperative CT was

M AN U

clinically insignificant, and the mean amount was less than 0.4 mm in the anterior-posterior, mediallateral, and superior-inferior directions. They also reported that miniplate group (semi-rigid internal fixation) showed postoperative return of movement of the condyle by 102.2% of intraoperative lateral displacement. In our study, fixation of the mandibular segment was achieved by semi-rigid internal fixation. The 3D coordinates of CC in T0 and T2 showed the difference less than 0.4 mm for x, y, z

TE D

directions in BSSRO-only and BSSRO with Le Fort I osteotomy group, and this result is consistent with previous studies.11, 15, 18 Condyles displaced laterally by 0.82 mm on average regardless of the

EP

extent of the surgery, and returned medially by 95.1% of its perioperative displacement. Various contributing factors to condylar displacement—including the fixation methods, amount and

AC C

direction of the distal segment movement, bony interference and gap between bony segments, skill of manual condylar guidance, and osteotomy method—were suggested.9, 11, 13, 14, 18, 20, 33 Facial asymmetry also has been suggested as the contributing factor for condylar displacement.7, 9, 11, 15, 21 In the procedures for correction of facial asymmetry, the bony interferences or intersegmental gap between the proximal and distal segment is inevitable, which can lead to positional changes of the condyle. Previous studies have reported that the amount of mandibular movement did not correlate with condylar displacement in both mandibular setback and advancement.13, 22, 34 However, for the mandibular asymmetric setback, mandible may translate and rotate three-dimensionally, thus the

ACCEPTED MANUSCRIPT deviated and nondeviated sides may exhibit different bony interference and bony gap between the proximal and distal segments, and show different postoperative changes in the condylar position and angulation.11 In the study by Yang and Hwang,9 the amount of bodily shift in patients who received SSRO was evaluated depending on the methods for removal of bony interferences. In their study, the

RI PT

mean amount of bodily shift in the deviated side (1.99 mm in posterior bending osteotomy group and 1.92 mm in grinding group) was greater than that in nondeviated side (1.47 mm in posterior bending osteotomy group and 1.75 mm in grinding group). Baek et al.11 reported that there was outward tilting

SC

of the condylar neck in greater setback side and inward tilting in lesser setback side. Our results are consistent with these previous studies. In our study, the deviated and nondeviated sides in both groups

M AN U

showed inferior rotation and superior rotation, respectively, although there was no statistical difference. With respect to the amount of bodily shift in 3D depending on the deviated and nondeviated sides, condyles in the deviated side displaced 2.03 mm in BSSRO-only group and 2.86 mm in BSSRO with Le Fort I group on average; however, the nondeviated side showed the amount of

TE D

bodily shift only 66% (1.33 mm) and 56% (1.62 mm) of that in the deviated side. Regarding the extent of the surgery, Cevidanes et al.35 concluded that condylar displacement with two-jaw surgery was not significant when compared with maxillary only surgery. Kim et al.36

EP

evaluated condylar changes after isolated mandibular surgery and combined maxillary and mandibular surgery in mandibular prognathism using 3D images. They suggested that condylar displacements in

AC C

both BSSRO-only (0.28 mm) and BSSRO with Le Fort I osteotomy (0.31 mm) groups were clinically insignificant. In our study, surgical changes in BSSRO with Le Fort I osteotomy group had a greater amount of lateral displacement, although there was no significant difference between the two groups 6 months postoperatively. The BSSRO-only group exhibited the medial returning movement by 116.7% of the intraoperative lateral displacement, and its final position showed the difference less than 0.1 mm compared with preoperative position. In BSSRO with Le Fort I osteotomy group, the condyle returned medially to its original position by 80.7%. In the superior-inferior direction, both groups showed inferior displacement after surgery. During the postoperative periods, both groups showed superior returning movement.

ACCEPTED MANUSCRIPT Regarding the rotational changes, our study showed that condyles rotated inward on the horizontal plane in both BSSRO-only and BSSRO with Le Fort I osteotomy groups, and there were no statistically significant differences. A total of 19 of 24 condyles in BSSRO-only group and 8 of 12 condyles in BSSRO with Le Fort I osteotomy group rotated inward after surgery. 5 of 24 condyles in

RI PT

BSSRO-only group and 4 of 12 condyles in BSSRO with Le Fort I osteotomy group rotated outward after surgery. During the postoperative periods, 14 of 24 condyles in BSSRO-only group and 10 of 12 condyles in BSSRO with Le Fort I osteotomy group rotated in the opposite direction when compared

SC

with surgical changes, and returned to its original long-axis. Our results are consistent with the

previous studies that studied the postoperative rotational changes of the condyle after OFA.37, 38 Ghang

M AN U

et al.37 evaluated the postoperative 3D changes in the mandible after BSSRO with semi-rigid sliding plates. In their study, the condyle rotated inward by 1.78º on the axial view at 4–6 weeks after surgery and it rotated outward by 0.40º 6 months to 1 year postoperatively. Ueki et al.38 reported that BSSROonly and BSSRO with Le Fort I osteotomy group showed inward and inferior rotation of the condyle

TE D

2 weeks after surgery and condyle returned to its original position 6 months postoperatively. According to the previous studies, positional changes of the condyle after surgery may influence TMJ symptoms. Several studies have indicated that orthognathic surgery for dentofacial deformities can improve TMJ symptom.18, 38, 39 Hu et al.39 reported that only 30% of the patients with preoperative

EP

TMJ symptoms showed improvement in TMJ symptoms after SSRO. In the study by Ueki et al.,38

AC C

preoperative TMJ symptoms were improved after surgery in 80% (12 of 15) of the joints that received SSRO only and in 75% (6 of 8) of the joints that received SSRO with Le Fort I osteotomy. Han and Hwang18 reported that 50% of condyles with preoperative TMJ symptoms had no TMJ symptoms after surgery, and only one condyle of 42 preoperatively asymptomatic patients developed TMJ symptoms 3 months postoperatively. In our study, 5 of 6 symptomatic (4 of 5 in BSSRO only group and 1 of 1 in BSSRO with Le Fort I osteotomy group) joints showed improvement of symptoms after surgery, and one asymptomatic joint in BSSRO with Le Fort I osteotomy group developed TMJ symptoms postoperatively.

ACCEPTED MANUSCRIPT REFERENCES 1. Nagasaka H, Sugawara J, Kawamura H, et al. "Surgery first" skeletal Class III correction using the Skeletal Anchorage System. J Clin Orthod. 2009;43:97-105. 2. Lee NK, Kim YK, Yun PY, et al. Evaluation of post-surgical relapse after mandibular setback

RI PT

surgery with minimal orthodontic preparation. J Craniomaxillofac Surg. 2013;41:47-51.

3. Hernandez-Alfaro F, Guijarro-Martinez R, Peiro-Guijarro MA. Surgery first in orthognathic surgery: what have we learned? A comprehensive workflow based on 45 consecutive cases. J Oral Maxillofac

SC

Surg. 2014;72:376-390.

4. Liou EJ, Chen PH, Wang YC, et al. Surgery-first accelerated orthognathic surgery: orthodontic

M AN U

guidelines and setup for model surgery. J Oral Maxillofac Surg. 2011;69:771-780. 5. Min BK, Choi JY, Baek SH. Comparison of treatment duration between conventional three-stage method and surgery-first approach in patients with skeletal Class III malocclusion. J Craniofac Surg. 2014;25:1752-1756.

6. Yu HB, Mao LX, Wang XD, et al. The surgery-first approach in orthognathic surgery: a

TE D

retrospective study of 50 cases. Int J Oral Maxillofac Surg. 2015;44:1463-1467. 7. Cheong YW, Lo LJ. Facial asymmetry: etiology, evaluation, and management. Chang Gung Med J. 2011;34:341-351.

EP

8. Haraguchi S, Takada K, Yasuda Y. Facial asymmetry in subjects with skeletal Class III deformity. Angle Orthod. 2002;72:28-35.

AC C

9. Yang HJ, Hwang SJ. Change in condylar position in posterior bending osteotomy minimizing condylar torque in BSSRO for facial asymmetry. J Craniomaxillofac Surg. 2014;42:325-332. 10. Angle AD, Rebellato J, Sheats RD. Transverse displacement of the proximal segment after bilateral sagittal split osteotomy advancement and its effect on relapse. J Oral Maxillofac Surg. 2007;65:50-59. 11. Baek SH, Kim TK, Kim MJ. Is there any difference in the condylar position and angulation after asymmetric mandibular setback? Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2006;101:155163.

ACCEPTED MANUSCRIPT 12. Hackney FL, Van Sickels JE, Nummikoski PV. Condylar displacement and temporomandibular joint dysfunction following bilateral sagittal split osteotomy and rigid fixation. J Oral Maxillofac Surg. 1989;47:223-227. 13. Harris MD, Van Sickels JE, Alder M. Factors influencing condylar position after the bilateral

RI PT

sagittal split osteotomy fixed with bicortical screws. J Oral Maxillofac Surg. 1999;57:650-654; discussion 654-655.

14. Kang MG, Yun KI, Kim CH, et al. Postoperative condylar position by sagittal split ramus

SC

osteotomy with and without bone graft. J Oral Maxillofac Surg. 2010;68:2058-2064.

15. Ueki K, Degerliyurt K, Hashiba Y, et al. Horizontal changes in the condylar head after sagittal

M AN U

split ramus osteotomy with bent plate fixation. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2008;106:656-661.

16. Yoshida K, Rivera RS, Kaneko M, et al. Minimizing displacement of the proximal segment after bilateral sagittal split ramus osteotomy in asymmetric cases. J Oral Maxillofac Surg. 2001;59:15-18. 17. Bamber MA, Abang Z, Ng WF, et al. The effect of posture and anesthesia on the occlusal

TE D

relationship in orthognathic surgery. J Oral Maxillofac Surg. 1999;57:1164-1172; discussion 11721164.

18. Han JJ, Hwang SJ. Three-dimensional analysis of postoperative returning movement of

EP

perioperative condylar displacement after bilateral sagittal split ramus osteotomy for mandibular setback with different fixation methods. J Craniomaxillofac Surg. 2015;43:1918-1925.

AC C

19. Toro C, Robiony M, Costa F, et al. Conscious analgesia and sedation during orthognathic surgery: preliminary results of a method of preventing condylar displacement. Br J Oral Maxillofac Surg. 2007;45:378-381.

20. Ueki K, Marukawa K, Shimada M, et al. Change in condylar long axis and skeletal stability following sagittal split ramus osteotomy and intraoral vertical ramus osteotomy for mandibular prognathia. J Oral Maxillofac Surg. 2005;63:1494-1499. 21. Ueki K, Moroi A, Sotobori M, et al. Changes in temporomandibular joint and ramus after sagittal split ramus osteotomy in mandibular prognathism patients with and without asymmetry. J

ACCEPTED MANUSCRIPT Craniomaxillofac Surg. 2012;40:821-827. 22. Lee W, Park JU. Three-dimensional evaluation of positional change of the condyle after mandibular setback by means of bilateral sagittal split ramus osteotomy. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2002;94:305-309.

RI PT

23. Kim EJ, Palomo JM, Kim SS, et al. Maxillofacial characteristics affecting chin deviation between mandibular retrusion and prognathism patients. Angle Orthod. 2011;81:988-993.

24. Epker BN, Wylie GA. Control of the condylar-proximal mandibular segments after sagittal split

SC

osteotomies to advance the mandible. Oral Surg Oral Med Oral Pathol. 1986;62:613-617.

25. Gerressen M, Zadeh MD, Stockbrink G, et al. The functional long-term results after bilateral

Maxillofacial Surgery. 2006;64:1624-1630.

M AN U

sagittal split osteotomy (BSSO) with and without a condylar positioning device. Journal of Oral and

26. Helm G, Stepke MT. Maintenance of the preoperative condyle position in orthognathic surgery. Journal of Cranio-Maxillofacial Surgery. 1997;25:34-38.

27. Luhr HG. The significance of condylar position using rigid fixation in orthognathic surgery. Clin

TE D

Plast Surg. 1989;16:147-156.

28. Renzi G, Becelli R, Di Paolo C, et al. Indications to the use of condylar repositioning devices in the surgical treatment of dental-skeletal class III. J Oral Maxillofac Surg. 2003;61:304-309.

EP

29. Rotskoff KS, Herbosa EG, Villa P. Maintenance of condyle-proximal segment position in orthognathic surgery. J Oral Maxillofac Surg. 1991;49:2-7; discussion 7-8.

AC C

30. Costa F, Robiony M, Toro C, et al. Condylar positioning devices for orthognathic surgery: a literature review. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2008;106:179-190. 31. Ueki K, Moroi A, Sotobori M, et al. A hypothesis on the desired postoperative position of the condyle in orthognathic surgery: a review. Oral Surg Oral Med Oral Pathol Oral Radiol. 2012;114:567-576. 32. Kim YI, Jung YH, Cho BH, et al. The assessment of the short- and long-term changes in the condylar position following sagittal split ramus osteotomy (SSRO) with rigid fixation. J Oral Rehabil. 2010;37:262-270.

ACCEPTED MANUSCRIPT 33. Ueki K, Marukawa K, Shimada M, et al. Condylar and disc positions after intraoral vertical ramus osteotomy with and without a Le Fort I osteotomy. Int J Oral Maxillofac Surg. 2007;36:207-213. 34. Magalhaes AE, Stella JP, Tahasuri TH. Changes in condylar position following bilateral sagittal split ramus osteotomy with setback. Int J Adult Orthodon Orthognath Surg. 1995;10:137-145.

RI PT

35. Cevidanes LH, Bailey LJ, Tucker SF, et al. Three-dimensional cone-beam computed tomography for assessment of mandibular changes after orthognathic surgery. Am J Orthod Dentofacial Orthop. 2007;131:44-50.

SC

36. Kim YJ, Oh KM, Hong JS, et al. Do patients treated with bimaxillary surgery have more stable condylar positions than those who have undergone single-jaw surgery? J Oral Maxillofac Surg.

M AN U

2012;70:2143-2152.

37. Ghang MH, Kim HM, You JY, et al. Three-dimensional mandibular change after sagittal split ramus osteotomy with a semirigid sliding plate system for fixation of a mandibular setback surgery. Oral Surg Oral Med Oral Pathol Oral Radiol. 2013;115:157-166.

38. Ueki K, Marukawa K, Shimada M, et al. Condylar and disc positions after sagittal split ramus

2007;103:342-348.

TE D

osteotomy with and without Le Fort I osteotomy. Oral Surg Oral Med Oral Pathol Oral Radiol Endod.

39. Hu J, Wang D, Zou S. Effects of mandibular setback on the temporomandibular joint: a

AC C

discussion 380-371.

EP

comparison of oblique and sagittal split ramus osteotomy. J Oral Maxillofac Surg. 2000;58:375-380;

ACCEPTED MANUSCRIPT FIGURE LEGENDS Figure 1. A 3D coordinate system (x, y, z) for measurements. We set the x-axis as the vector from the right orbitale to the left orbitale and midsagittal plane as the plane that was perpendicular to the x-axis

RI PT

and passed through a nasion. The plane that passed through the line passing both orbitale and perpendicular to FH plane was set as the coronal plane. N, nasion; R_Or, right orbitale; L_Or, left orbitale; x-axis, medial (–) and lateral (+); y-axis, anterior (–) and posterior (+); z-axis, superior (+)

SC

and inferior (–) direction.

M AN U

Figure 2. Time-course changes (T0, T1 and T2) of the condylar position in BSSRO-only group (left) and BSSRO with Le Fort I osteotomy group (right). Both groups showed mainly lateral and inferior displacement with inward rotation immediately after surgery, and medial and superior returning movement with outward rotation 6 months after surgery. Red color, preoperative condylar position (T0); gray color, immediate postoperative condylar position (T1); blue color, condylar position in

AC C

EP

TE D

postoperative retention period (T2).

ACCEPTED MANUSCRIPT Table 1. Three-dimensional (3D) coordinates changes and the amount of bodily shift in CC with BSSRO-only versus BSSRO with Le Fort I osteotomy (LF1) with regard to surgical changes (T1-T0), postoperative changes (T2-T1), and total change (T2-T0). Surgical changes

Postoperative changes

Total change

(T1-T0)

(T2-T1)

(T2-T0)

z

BSSRO +

BSSRO-

BSSRO +

BSSRO-

BSSRO +

only

LF1

only

LF1

only

LF1

0.48 ±

1.50 ±

–0.56 ±

–1.21 ±

–0.08 ±

0.86†

1.63†

0.76‡

1.18†

0.58

–0.12 ±

–0.05 ±

–0.21 ±

–0.18 ±

–0.33 ±

0.74

0.51

0.57

1.08

–1.03 ±

–1.22 ±

0.95 ±

1.45 ±

1.07‡

1.03‡

1.00‡

1.08‡

0.29 ± 1.14

–0.23 ±

SC

y

BSSRO-

0.65

1.03

–0.08 ±

0.24 ±

0.74

0.63

M AN U

x

p value*

RI PT

Axis

NS

NS

NS

Note: There were no statistically significant differences between two groups in time-course changes of the x-, y-, and z-coordinates.

Data presented as mean ± standard deviation in millimeters. x values represent the lateral (+) and medial (–) displacements, y values represent the posterior (+) and anterior (–) displacements, and z

TE D

values represent the superior (+) and inferior (–) displacements.

Abbreviations: CC, center of condylar head; BSSRO, bilateral sagittal split ramus osteotomy; LF1, Le Fort I osteotomy; T0, preoperatively; T1, 3 days postoperatively; T2, at 6-month follow-up; NS, not significant.

By repeated measures analysis of variance with Bonferroni correction.

†

and ‡ Statistically significant at p <0.05 and p <0.01, respectively, by repeated measures analysis of

EP

*

group.

AC C

variance with Bonferroni correction for comparison of position of CC between each time point in each

ACCEPTED MANUSCRIPT Table 2. The amount of bodily shift of the condyle in three dimensions Surgical changes

Postoperative changes

Total changes

(T1-T0)

(T2-T1)

(T2-T0)

p

BSSRO +

only

LF1

Bodily

1.68

2.24

shift

± 0.92

± 1.59

BSSRO*

value

NS

BSSRO +

only

LF1

1.55

2.34

± 0.85

± 1.29

Data presented as mean ± standard deviation in millimeters.

p *

value

NS

BSSRO

BSSRO +

p

-only

LF1

value*

1.02

1.54

< 0.05

RI PT

BSSRO-

± 0.59

± 0.63

Abbreviations: BSSRO, bilateral sagittal split ramus osteotomy; LF1, Le Fort I osteotomy; T0,

EP

TE D

M AN U

By Mann-Whitney U test.

AC C

*

SC

preoperatively; T1, 3 days postoperatively; T2, at 6-month follow-up; NS, not significant.

ACCEPTED MANUSCRIPT Table 3. Amount of rotational movement of the condylar head with BSSRO-only versus BSSRO with Le Fort I osteotomy (LF1) in terms of surgical changes (T1-T0), postoperative changes (T2-T1), and total change (T2-T0). Surgical changes

Postoperative changes

Total change

(T1-T0)

(T2-T1)

(T2-T0)

∆ω

p

BSSRO*

only

LF1

value

3.93 ±

3.06 ±

3.92

3.37

0.10 ±

0.40 ±

2.40

3.13

NS

NS

BSSRO +

p

*

only

LF1

value

–0.25 ±

–1.39 ±

2.67

2.67

1.11 ±

–0.84 ±

2.86

2.42

NS

BSSRO-

BSSRO +

p

only

LF1

value*

3.68 ±

1.68 ±

3.52

1.36

1.22 ±

–0.44 ±

3.37

2.80

RI PT

∆θ

BSSRO +

< 0.05

SC

BSSRO-

< 0.01

NS

Note: ∆θ and ∆ω are the rotation angles of the condylar head on axial and coronal plane, respectively.

M AN U

Data presented as mean ± standard deviation in degrees. ∆θ values represent the inward (+) and outward (–) rotations and ∆ω values represent inferior (+) and superior (–) rotation. Abbreviations: BSSRO, bilateral sagittal split ramus osteotomy; LF1, Le Fort I osteotomy; T0, preoperatively; T1, 3 days postoperatively; T2, at 6-month follow-up; NS, not significant.

EP

TE D

By Mann-Whitney U test.

AC C

*

ACCEPTED MANUSCRIPT Table 4. Comparison of bodily shift and rotational movement of the condyle between deviated and nondeviated side in BSSRO-only group with regard to surgical changes (T1-T0), postoperative changes (T2-T1), and total change (T2-T0)

Postoperative changes

Total changes

(T1-T0)

(T2-T1)

(T2-T0)

Axis Dev

Non-dev

0.76

0.20

± 0.84

± 0.82

0.01

-0.25

± 0.87

± 0.60

-1.22

-0.83

± 1.29

± 0.81

2.03

1.33

± 0.95

± 0.78

p value*

Dev

Non-dev

p value*

Bodily shift

z

Total

NS

NS

<0.01

Rotational movement 2.69

± 2.29

± 4.85

0.62

-0.42

± 2.82

± 1.86

NS

± 0.59

± 0.88

-0.35

-0.07

± 0.64

± 0.47

0.99

0.90

± 1.09

± 0.95

1.72

1.37

± 0.73

± 0.95

-0.46

-0.03

± 2.16

± 3.19

NS

NS

NS

1.13

1.10

± 3.20

± 2.62

NS

<0.05

NS

NS

Non-dev

0.02

-0.18

± 0.64

± 0.53

-0.35

-0.32

± 0.82

± 0.45

-0.23

0.07

± 0.87

± 0.56

1.14

0.89

± 0.78

± 0.30

4.71

2.66

± 1.59

± 4.60

1.76

0.68

± 3.96

± 2.73

p

value*

NS

NS

NS

NS

NS

NS

EP

∆ω

5.17

-0.38

TE D

∆θ

-0.74

Dev

SC

y

NS

M AN U

x

RI PT

Surgical changes

Note: ∆θ and ∆ω are the rotation angles of the condylar head on axial and coronal plane, respectively.

AC C

Bodily shift and rotational movement are presented as mean ± standard deviation in millimeters and degrees, respectively. x values represent the lateral (+) and medial (–) displacements, y values represent the posterior (+) and anterior (–) displacements, and z values represent the superior (+) and inferior (–) displacements. Total is the amount of bodily shift of CC in three dimensions which is calculated using Euclidean distance. ∆θ values represent the inward (+) and outward (–) rotations and ∆ω values represent inferior (+) and superior (–) rotation. Abbreviations: BSSRO, bilateral sagittal split ramus osteotomy; LF1, Le Fort I osteotomy; T0, preoperatively; T1, 3 days postoperatively; T2, at 6-month follow-up; CC, center of condylar head; NS, not significant. *

By Wilcoxon signed rank test.

ACCEPTED MANUSCRIPT Table 5. Comparison of bodily shift and rotational movement of the condyle between deviated and nondeviated side in BSSRO with Le Fort I osteotomy group with regard to surgical changes (T1-T0), postoperative changes (T2-T1), and total change (T2-T0).

Postoperative changes

Total changes

(T1-T0)

(T2-T1)

(T2-T0)

Axis Dev

Non-dev

1.69

1.30

± 2.10

± 1.15

–0.03

–0.07

± 0.48

± 0.58

–1.81

–0.63

± 1.17

± 0.34

2.86

1.62

± 1.89

± 1.06

p value

*

Dev

Non-dev

p value

Bodily shift

z

Total

NS

NS

<0.05

Rotational movement 2.21

± 3.81

± 2.96

1.55

–0.74

± 3.43

± 2.58

NS

± 1.71

± 0.39

0.03

–0.39

± 1.04

± 1.17

1.72

1.18

± 1.25

± 0.90

2.50

2.18

± 1.84

± 0.49

–2.19

–0.58

± 2.43

± 2.86

NS

NS

NS

–0.97

–0.71

± 3.41

± 1.11

NS

NS

NS

NS

Non-dev

0.47

0.10

± 1.20

± 1.16

0.00

–0.45

± 1.06

± 1.05

–0.08

0.56

± 0.43

± 0.67

1.49

1.59

± 0.61

± 0.71

1.73

1.63

± 1.62

± 1.20

0.58

–1.45

± 3.33

± 1.91

p

value*

NS

NS

<0.05

NS

NS

NS

EP

∆ω

3.92

–1.20

TE D

∆θ

–1.22

Dev

SC

y

NS

M AN U

x

*

RI PT

Surgical changes

Note: ∆θ and ∆ω are the rotation angles of the condylar head on axial and coronal plane, respectively.

AC C

Bodily shift and rotational movement are presented as mean ± standard deviation in millimeters and degrees, respectively. x values represent the lateral (+) and medial (–) displacements, y values represent the posterior (+) and anterior (–) displacements, and z values represent the superior (+) and inferior (–) displacements. Total is the amount of bodily shift of CC in three dimensions which is calculated using Euclidean distance. ∆θ values represent the inward (+) and outward (–) rotations and ∆ω values represent inferior (+) and superior (–) rotation. Abbreviations: BSSRO, bilateral sagittal split ramus osteotomy; LF1, Le Fort I osteotomy; T0, preoperatively; T1, 3 days postoperatively; T2, at 6-month follow-up; CC, center of condylar head; NS, not significant. *

By Wilcoxon signed rank test.

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT Statement of Clinical Relevance BSSRO in SFA, either with or without Le Fort I osteotomy, may cause condylar displacement immediately after surgery and displaced condyles return to their original position in both deviated-

AC C

EP

TE D

M AN U

SC

RI PT

and nondeviated sides during the postoperative period, as in OFA.