- Email: [email protected]
Postoperative stability of conventional bimaxillary surgery compared with maxillary impaction surgery with mandibular autorotation for patients with skeletal class II retrognathia
YBJOM-5828; No. of Pages 5
ARTICLE IN PRESS Available online at www.sciencedirect.com
ScienceDirect British Journal of Oral and Maxillofacial Surgery xxx (2019) xxx–xxx
Postoperative stability of conventional bimaxillary surgery compared with maxillary impaction surgery with mandibular autorotation for patients with skeletal class II retrognathia S. Kita a,∗ , K. Fujita b , H. Imai b , M. Aoyagi a , K. Shimazaki a , I. Yonemitsu a , S. Omura b , T. Ono a a b
Department of Orthodontic Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan Department of Oral and Maxillofacial Surgery, Yokohama City University Medical Centre, Kanagawa, Japan
Accepted 16 October 2019
Abstract We aimed to compare the postoperative stability of conventional bimaxillary surgery (with bilateral sagittal split osteotomy) with that of maxillary impaction surgery (with mandibular autorotation without bilateral sagittal split osteotomy) in patients with skeletal class II retrognathia. Patients were assigned to have conventional bimaxillary surgery (conventional group, n = 6) or mandibular autorotation (experimental group, n = 7). Measurements were made using serial lateral cephalometric radiographs taken immediately preoperatively (T0), immediately postoperatively (T1), and one year later (T2) to assess the variation in operative change (T1-T0) and relapse (T2-T1). There was no significant difference in median (range) surgical change in the anterior movement at point B (conventional group, 4.5 (3.0–11.0) mm; experimental group 4.1 (2.1–6.4) mm). However, there was a significant difference in median (range) surgical posterior movement relapse at point B (conventional group −1.7 (−2.3 to −0.5) mm; experimental group −0.6 (−1.0 to 1.0) mm; p = 0.032). Mandibular advancement with mandibular autorotation is therefore a more stable procedure than mandibular advancement with bilateral sagittal split osteotomy in patients with skeletal class II retrognathia. © 2019 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
Keywords: mandibular retrognathism; mandibular autorotation; mandibular advancement; relapse; osteoarthritis; progressive condylar resorption
Introduction Bilateral sagittal split osteotomy (BSSO) is an orthognathic operation that is often used to correct mandibular hypoplasia, including skeletal class II deformity, anterior open bite, ∗ Corresponding author at: Department of Orthodontic Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan. Tel./Fax: +81 3 5803 5529. E-mail address: [email protected] (S. Kita).
and osteoarthritis. Postoperative alterations after mandibular advancement surgery with BSSO, such as increased loading of the temporomandibular joint (TMJ) or positional condylar changes, may occur.1,2 Postoperative skeletal relapse is affected by movements of bone at the osteotomy sites as well as changes in the position and morphology of the condyles.3 The extent to which these changes exceed the natural adaptive capacity of the TMJ is likely to give rise to a clinical complication known as progressive condylar resorption.1,3 This is reported as a late postoperative relapse (over six
https://doi.org/10.1016/j.bjoms.2019.10.309 0266-4356/© 2019 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
Please cite this article in press as: S. Kita, K. Fujita, H. Imai et al.. Postoperative stability of conventional bimaxillary surgery compared with maxillary impaction surgery with mandibular autorotation for patients with skeletal class II retrognathia. Br J Oral Maxillofac Surg (2019), https://doi.org/10.1016/j.bjoms.2019.10.309
YBJOM-5828; No. of Pages 5
2
ARTICLE IN PRESS
S. Kita, K. Fujita, H. Imai et al. / British Journal of Oral and Maxillofacial Surgery xxx (2019) xxx–xxx
months) after BSSO for mandibular advancement, and leads to reduced posterior facial height, clockwise mandibular rotation, mandibular retrognathism, and anterior open bite.3–6 Previous investigators assumed that atrophy resulted from resorption as a result of increased muscle tension of the geniohyoid and the anterior digastric muscles.4,7 However, condylar resorption associated with BSSO is affected by several factors, including female sex, young age (15–35 years), mandibular hypoplasia with a high angle of the mandibular plane, preoperative dysfunction of the TMJ, posterior inclination of the condylar neck, large mandibular advancement, counter-clockwise rotation of the proximal segments of the mandible, increased muscle tension of the geniohyoid and anterior digastric muscles, and type of fixation.2,4–6,8–12 Surgical factors associated with relapse (such as mandibular advancement, counter-clockwise rotation of the proximal segments of the mandible, increased tension in the geniohyoid and the anterior digastric muscles, and type of fixation) may be avoided if BSSO is not done. Sperry et al used maxillary superior repositioning (impaction) and mandibular autorotation for orthognathic surgery,13 as the mandible is assumed to rotate in a counter-clockwise direction when this technique is used. However, surgical precision and stable fixation were lacking. Few studies, therefore, have evaluated the postoperative stability of orthognathic surgery with mandibular autorotation. Recently, studies regarding the effects of surgery with maxillary impaction, mandibular autorotation, and a straight-locking miniplate (SLM) technique in patients with oseoarthritis and skeletal class II deformity were published (Fig. 1).14,15 The SLM technique is a simple method of accurate maxillary superior repositioning with no intraoperative measurement. Using it, surgical precision and stable fixation are possible. Our aim in this study therefore was to compare postoperative stability after conventional bimaxillary surgery with BSSO without the SLM technique (conventional group) with that after maxillary impaction surgery with mandibular autorotation and the SLM technique (experimental group).
Patients and methods Female patients with mandibular retrognathism who had orthognathic surgery from 2006 – 2015 were included in the study. To minimise surgeon-related bias, one surgeon operated on all patients in the both groups with titanium miniplates and screws. The inclusion criteria were skeletal class II dentofacial deformities with an angle between the lines connecting points A, N, and B (ANB) >4◦ , mandibular hypoplasia with a high angled mandibular plane (SN-MP) >40◦ (Fig. 2), and a complete series of identifiable lateral cephalometric radiographs.11,12 The exclusion criteria were a history of facial fracture, other syndromes, asymmetry, and unavailability or incompletely identifiable series of lateral cephalometric radiographs.
Fig. 1. Intraoperative view of SLM fixation to the zygomatic buttress above the Le Fort I osteotomy line and the mandible. The SLM maintain the vertical distance between the skull base and mandible and can reproduce the CR position of the condyle during the surgery.
Ultimately, 13 patients were included and divided into two groups according to the operation done: the conventional bimaxillary surgery with BSSO but without SLM (conventional group) and the maxillary impaction surgery with mandibular autorotation and SLM (experimental group). There were six patients in the conventional group and seven in the experimental group. The median (range) age at the time of operation was 34 (20–42) years in the conventional group and 28 (18–39) years in the experimental group. Patients in the conventional group had a Le Fort I osteotomy and BSSO, and patients in the experimental group a Le Fort I osteotomy with or without the “Wunderer” procedure, and mandibular autorotation without BSSO. All patients had orthodontic treatment before and after operation. Operative and postoperative skeletal changes were evaluated using lateral cephalometric radiographs taken immediately before (T0), immediately after (T1), and one year after operation (T2). The surgical changes were defined as T1 minus T0 and the postoperative changes (relapse) were defined as T2 minus T1. All reference planes were transferred from T0 to T2 according to the Sella-Nasion (SN) plane-registered superimposition.
Please cite this article in press as: S. Kita, K. Fujita, H. Imai et al.. Postoperative stability of conventional bimaxillary surgery compared with maxillary impaction surgery with mandibular autorotation for patients with skeletal class II retrognathia. Br J Oral Maxillofac Surg (2019), https://doi.org/10.1016/j.bjoms.2019.10.309
ARTICLE IN PRESS
YBJOM-5828; No. of Pages 5
S. Kita, K. Fujita, H. Imai et al. / British Journal of Oral and Maxillofacial Surgery xxx (2019) xxx–xxx
3
included horizontal distances from point A and point B to the y-axis and vertical distances from point A and point B to the x-axis. The five angular measurements included the angle between the lines connecting points S, N, and A (SNA); the angle between the lines connecting points S, N, and B (SNB); the angle between the lines connecting points A, N, and B (ANB); the angle between the SN lines and the mandibular plane (SN-MP); and the angle between the x-axis and the plane of the ramus (RI) (Fig. 2).
Statistical analysis We used the Mann-Whitney U test to compare the significance of differences between the groups, and probabilities of <0.05 were accepted as significant. All measurements were repeated by the same examiner after an interval of one month. The method error was calculated using the intraclass correlation coefficient (ICC), which was greater than 0.95 for all linear and angular cephalometric variables measured. Data are presented as median (range). Fig. 2. Skeletal landmarks, reference lines and angles used in the cephalometric analysis are shown. S, sella; N, nasion; A, A-point; B, B-point; Me, menton; Ar, articulare; x-axis, defined with the origin at N and forming a 7◦ angle upward from the SN plane; y-axis, defined as the line perpendicular to the x-axis and passing through S; A(x), horizontal position of point A; A(y), vertical position of point A; B(x), horizontal position of point A; B(y), vertical position of point B; SN-MP, the angle of the SN plane to the mandibular plane; ramus inclination (RI), the angle of the y-axis to the ramus plane.
For the cephalometric measurements, we constructed an x-y coordinate system.16 The x-axis originated at the N-point and formed an angle of 7◦ upwards from the SN plane. The y-axis was defined as the line perpendicular to the x-axis and passing through the S-point. The positions of the landmarks were recorded as the linear measurements in relation to the xand y-axes (Fig. 2). We identified four linear, and five angular, cephalometric measurements. The four linear measurements
Results The cephalometric measurements at each time point are summarised in Table 1. There was no significant between-group difference in personal or clinical characteristics immediately preoperatively.
Comparison of surgical change immediately before and after operation Horizontal and vertical measurements, and angle measurements are shown in Table 2.
Table 1 Median (range) of the variables according to conventional bimaxillary surgery group and mandibular autorotation surgery group at each time. Data are median (range). Group
A (x) (mm) A (y) (mm) B (x) (mm) B (y) (mm) SNA (◦ ) SNB (◦ ) ANB (◦ ) SN-MP (◦ ) RI (◦ )
CB
MA
T0
T1
T2
T0
T1
T2
71.0 (60.2–77.1) 63.0 (58.0–66.5) 52.1 (42.7–62.0) 111.5 (107.4–122.8) 82.3 (79.2–90.9) 72.9 (71.7–79.9) 10.1 (6.5–11.0) 47.0 (43.2–52.0) −0.5 (−6.6–4.6)
70.6 (59.9–73.0) 62.9 (54.0–64.6) 55.6 (48.9–67.7) 113.7 (111.1–123.6) 82.1 (79.1–87.0) 75.4 (73.8–82.1) 4.5 (1.7–9.3) 45.3 (43.0–54.1) 2.2 (−1.5–6.8)
70.6 (59.9–72.7) 63.0 (54.0–64.7) 54.2 (46.8–66.9) 111.4 (110.7–122.7) 82.0 (79.0–87.0) 74.4 (73.6–81.4) 5.4 (1.9–9.9) 46.3 (40.9–52.0) 2.6 (−5.8–5.9)
70.0 (62.9–77.6) 65.3 (61.8–67.2) 49.4 (33.8–67.9) 114.9 (109.3–123.6) 81.0 (79.5–84.3) 73.1 (66.9–78.8) 9.9 (5.5–14.1) 48.3 (35.2–50.4) −3.0 (−16.5–8.0)
70.3 (62.3–77.1) 59.7 (58.3–64.3) 54.7 (37.9–70.0) 111.5 (107.6–120.0) 80.1 (75.5–83.8) 74.8 (68.8–79.5) 8.0 (0.2–11.3) 44.3 (33.9–48.0) 1.0 (−12.7–10.6)
70.3 (62.6–76.9) 60.0 (58.3–64.6) 53.8 (38.7–69.9) 110.4 (106.0–119.0) 80.3 (76.0–83.8) 75.0 (69.1–79.4) 8.0 (1.0–11.2) 45.1 (33.2–48.5) 2.0 (−15.2–11.8)
CB = conventional bimaxillary surgery; MA = mandibular autorotation surgery; T0 = immediately preoperatively; T1= immediately postoperatively; T2= after one year.
Please cite this article in press as: S. Kita, K. Fujita, H. Imai et al.. Postoperative stability of conventional bimaxillary surgery compared with maxillary impaction surgery with mandibular autorotation for patients with skeletal class II retrognathia. Br J Oral Maxillofac Surg (2019), https://doi.org/10.1016/j.bjoms.2019.10.309
ARTICLE IN PRESS
YBJOM-5828; No. of Pages 5
4
S. Kita, K. Fujita, H. Imai et al. / British Journal of Oral and Maxillofacial Surgery xxx (2019) xxx–xxx
Table 2 Comparison of the surgical changes between the conventional bimaxillary surgery group and the mandibular autorotation surgery group. Data are median (range). P values were not significant. T1-T0
CB
MA
A (x) (mm) A (y) (mm) B (x) (mm) B (y) (mm) SNA (◦ ) SNB (◦ ) ANB (◦ ) SN-MP (◦ ) RI (◦ )
−0.1 (−5.4 to 0.6) −0.2 (−6.4 to 0.9) 4.5 (3.0 to 11.0) 3.4 (−4.7 to 4.8) −0.1 (−4.7 to 1.1) 2.5 (2.1 to 4.8) −4.0 (−7.2 to −1.3) −1.2 (−9 to 3.1) 3.0 (−0.6 to 6.5)
−0.6 (−6.0 to 0.3) −4.4 (−7.0 to −1.9) 4.1 (2.1 to 6.4) −1.7 (−4.0 to −0.5) −0.9 (−5.3 to 0.5) 2.1 (0.7 to 2.6) −2.8 (−7.4 to −0.9) −3.1 (−5.3 to 1.3) 2.8 (1.1 to 4.0)
CB = conventional bimaxillary surgery; MA = mandibular autorotation surgery; T0= immediately preoperatively; T1= immediately postoperatively; T2= after one year. Table 3 Comparison of the surgical relapse between the conventional bimaxillary surgery group and the mandibular autorotation surgery group. Data are median (range). T2-T1
CB
MA
p value
A(x) (mm) A(y) (mm) B(x) (mm) B(y) (mm) SNA (◦ ) SNB (◦ ) ANB (◦ ) SN-MP (◦ ) RI (◦ )
0.0 (−0.3 to 0.1) 0.1 (0.0 to 0.1) −1.7 (−2.3 to −0.5) −1.2 (−3.3 to 0.7) −0.1 (−0.1 to 0.4) −0.8 (−1.2 to −0.2) 0.9 (0.2 to 1.1) −0.1 (−2.1 to 3.1) −1.1 (−5.7 to 1.6)
0.0 (−0.6 to 0.6) 0.1 (0.0 to 1.3) −0.6 (−1.0 to 1.0) −1.0 (−1.7 to 1.3) 0.1 (−0.1 to 0.5) −0.3 (−0.4 to 1.0) 0.4 (−1.0 to 0.8) −0.2 (−1.5 to 2.1) 0.6 (−2.5 to 1.2)
0.77 0.36 0.032* 0.47 0.38 0.044* 0.053 0.94 0.15
∗
p < 0.05.
Comparison of surgical relapse immediately and one year after operation Horizontal measurements: there was no significant difference between the two groups (Table 3). However, there was a significant difference in the mean surgical relapse (T2-T1) in the posterior movement at point B (p = 0.032; Table 3). Vertical measurements: are also shown in Table 3. There were no significant differences between the two groups for vertical changes at points A and B. Angle measurements: are also shown in Table 3. The SNB of the conventional group showed a significantly greater decrease than that of the experimental group (p = 0.044). There were no significant differences between the two groups in the remaining angle measurements.
Discussion After orthognathic surgery that includes mandibular advancement, postoperative surgical relapse is common.17 There are two patterns of skeletal relapse: “early” and “late”.6 “Early” skeletal relapse is thought to be caused by the operative technique – that is – insufficient intraoperative positioning of the condyle resulting in subsequent displacement
of the mandibular proximal segment and slippage of the osteotomy.18–20 On the basis of the change in the angle between the x-axis and the plane of the ramus (%) in the conventional group, we suggest that the mandibular proximal segment was displaced when the maxilla and the mandible, respectively, were fixed. In contrast, patients in the experimental group had a Le Fort I osteotomy with or without the “Wunderer” procedure and mandibular autorotation with the SLM technique without BSSO. The SLM technique is a simple way of accurately repositioning the superior maxilla without the requirement for intraoperative measurement. The SLM maintains the proximal segment with the condyle in position.14 In the experimental group, therefore, the proximal segment of the mandible was not displaced when the maxilla was fixed. As a result of differences in techniques, point B in the conventional group had more posterior movement than the experimental group. In the conventional group, the SNB angle significantly decreased and the ANB angle significantly increased. The SNB angle in the conventional group decreased more than that in the experimental group, which suggests that operation in the experimental group with the SLM technique was a stable procedure for correction of mandibular hypoplasia, including skeletal class II deformity. In contrast, “late” skeletal relapse is thought to be caused by progressive condylar resorption.20–22 After orthognathic surgery this is multifactorial, and osteoarthritis is a serious risk factor.21,22 Mandibular advancement surgery should therefore be done only when the condyles are stable, and postoperative mechanical loading on the TMJ should be avoided in high-risk patients such as those with osteoarthritis.22 We have therefore avoided mandibular advancement surgery in such patients. We found no signs of obvious osteoarthritis in patients in the conventional group, but it was present in all patients in the experimental group. Patients in the experimental group who had risk factors for late relapse,11,12 such as mandibular hypoplasia with a high mandibular plane angle and osteoarthritis, had Le Fort I osteotomy with or without the “Wunderer” procedure, and mandibular autorotation without BSSO, to reduce muscular tension. In a previous study, bone loss was predominantly found at the anterior part of the condyle.23 With counter-clockwise rotation of the mandible, the anterior part of the condyle that is not loaded may be resorbed.24 Late surgical relapse can be seen six months postoperatively.6 We evaluated late surgical relapse with lateral cephalometric radiographs that were taken immediately and one year postoperatively, and no obvious relapse was seen in the experimental group. These results suggest that mandibular autorotation surgery may avoid late surgical relapse caused by progressive condylar resorption. However, we did not evaluate the shape of the condyle with computed tomography (CT). Several studies have suggested that this continues over five years, 6,25 so further long-term followup and morphological evaluation with CT are required. In addition, the technique is limited by several conditions: first, there should be no canting of the maxilla; secondly, there
Please cite this article in press as: S. Kita, K. Fujita, H. Imai et al.. Postoperative stability of conventional bimaxillary surgery compared with maxillary impaction surgery with mandibular autorotation for patients with skeletal class II retrognathia. Br J Oral Maxillofac Surg (2019), https://doi.org/10.1016/j.bjoms.2019.10.309
YBJOM-5828; No. of Pages 5
ARTICLE IN PRESS
S. Kita, K. Fujita, H. Imai et al. / British Journal of Oral and Maxillofacial Surgery xxx (2019) xxx–xxx
should be no facial asymmetry; and thirdly, the upper central incisor edge can be set to an aesthetically appropriate position on the counter-clockwise rotational orbit of the mandible. In addition, in some cases it is not possible to improve the facial profile by surgery with mandibular autorotation without BSSO alone. In such cases, genioplasty is necessary to improve the facial profile. In conclusion, our findings suggest that mandibular advancement with mandibular autorotation and the SLM technique for patients with skeletal class II deformity and osteoarthritis is a more stable operation than mandibular advancement with BSSO. Although studies that enrol more patients and have a longer-term follow-up are necessary, this operation seems to be superior in patients with risk factors for progressive condylar resorption.
Ethics statement/confirmation of patients’ permission This study was approved by the Tokyo Medical and Dental University institutional review board (receipt number 1118) and the Yokohama City University Medical Centre institutional review board (receipt number B110512003). Patients’ informed consent was obtained.
Conflict of interest We have no conflicts of interest.
References 1. Mousoulea S, Kloukos D, Sampaziotis D, et al. Condylar resorption in orthognathic patients after mandibular bilateral sagittal split osteotomy: A systematic review. Eur J Orthod 2017;39:294–309. 2. Dicker GJ, Tuijt M, Koolstra JH, et al. Static and dynamic loading of mandibular condyles and their positional changes after bilateral sagittal split advancement osteotomies. Int J Oral Maxillofac Surg 2012;41:1131–6. 3. Xi T, Schreurs R, Van Loon B, et al. 3D analysis of condylar remodelling and skeletal relapse following bilateral sagittal split advancement osteotomies. J Craniomaxillofacial Surg 2015;43:462–8. 4. de Moraes PH, Rizzati-Barbosa CM, Olate S, et al. Condylar resorption after orthognathic surgery: a systematic review. Int J Morphol 2012;30:1023–8. 5. Catherine Z, Breton P, Bouletreau P. Management of dentoskeletal deformity due to condylar resorption: literature review. Oral Surg Oral Med Oral Pathol Oral Radiol 2016;121:126–32. 6. Eggensperger N, Smolka K, Luder J, et al. Short- and long-term skeletal relapse after mandibular advancement surgery. Int J Oral Maxillofac Surg 2006;35:36–42. 7. Phillips RM, Bell WH. Atrophy of mandibular condyles after sagittal ramus split osteotomy: report of case. J Oral Surg 1978;36:45–9.
5
8. Ow A, Cheung LK. Skeletal stability and complications of bilateral sagittal split osteotomies and mandibular distraction osteogenesis: an evidence-based review. J Oral Maxillofac Surg 2009;67:2344–53. 9. Bermell-Baviera A, Bellot-Arcís C, Montiel-Company JM, et al. Effects of mandibular advancement surgery on the temporomandibular joint and muscular and articular adaptive changes—a systematic review. Int J Oral Maxillofac Surg 2016;45:545–52. 10. Dicker GJ, Castelijns JA, Tuinzing DB, et al. Do the changes in muscle mass, muscle direction, and rotations of the condyles that occur after sagittal split advancement osteotomies play a role in the aetiology of progressive condylar resorption? Int J Oral Maxillofac Surg 2015;44:627–31. 11. Hwang SJ, Haers PE, Seifert B, et al. Non-surgical risk factors for condylar resorption after orthognathic surgery. J Craniomaxillofacial Surg 2004;32:103–11. 12. Hwang SJ, Haers P.E., Zimmerman A, et al. Surgical risk factors for condylar resorption after orthognathic surgery. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2000;89:542–52. 13. Sperry TP, Steinberg MJ, Gans BJ. Mandibular movement during autorotation as a result of maxillary impaction surgery. Am J Orthod 1982;81:116–23. 14. Omura S, Kimizuka S, Iwai T, et al. An accurate maxillary superior repositioning technique without intraoperative measurement in bimaxillary orthognathic surgery. Int J Oral Maxillofac Surg 2012;41:949–51. 15. Iwai T, Omura S, Honda K, et al. An accurate bimaxillary repositioning technique using straight locking miniplates for the mandible-first approach in bimaxillary orthognathic surgery. Odontology 2017;105:122–6. 16. Choi SH, Yoo HJ, Lee JY, et al. Stability of pre-orthodontic orthognathic surgery depending on mandibular surgical techniques: SSRO vs IVRO. J Craniomaxillofacial Surg 2016;44:1209–15. 17. Sahoo NK, Jayan B, Thakral A, et al. Skeletal relapse following sagittal split ramus osteotomy advancement. J Maxillofac Oral Surg 2015;14:357–62. 18. Stroster TG, Pangrazio-Kulbersh V. Assessment of condylar position following bilateral sagittal split ramus osteotomy with wire fixation or rigid fixation. Int J Adult Orthodon Orthognath Surg 1994;9:55–63. 19. Van Sickels JE, Tiner BD, Keeling SD, et al. Condylar position with rigid fixation versus wire osteosynthesis of a sagittal split advancement. J Oral Maxillofac Surg 1999;57:31–5. 20. Watzke IM, Turvey TA, Phillips C, et al. Stability of mandibular advancement after sagittal osteotomy with screw or wire fixation: A comparative study. J Oral Maxillofac Surg 1990;48:108–23. 21. Wolford LM, Reiche-Fischel O, Mehra P. Changes in temporomandibular joint dysfunction after orthognathic surgery. J Oral Maxillofac Surg 2003;61:655–60. 22. Kobayashi T, Izumi N, Kojima T, et al. Progressive condylar resorption after mandibular advancement. Br J Oral Maxillofac Surg 2012;50:176–80. 23. Hoppenreijs TJ, Freihofer HP, Stoelinga PJ, et al. Condylar remodelling and resorption after Le Fort I and bimaxillary osteotomies in patients with anterior open bite: A clinical and radiological study. Int J Oral Maxillofac Surg 1998;27:81–91. 24. O’Ryan F, Epker BN. Temporomandibular joint function and morphology: Observations on the spectra of normalcy. Oral Surg Oral Med Oral Pathol 1984;58:272–9. 25. Simmons KE, Turvey TA, Phillips C, et al. Surgical-orthodontic correction of mandibular deficiency: five-year follow-up. Int J Adult Orthodon Orthognath Surg 1992;7:67–79.
Please cite this article in press as: S. Kita, K. Fujita, H. Imai et al.. Postoperative stability of conventional bimaxillary surgery compared with maxillary impaction surgery with mandibular autorotation for patients with skeletal class II retrognathia. Br J Oral Maxillofac Surg (2019), https://doi.org/10.1016/j.bjoms.2019.10.309
ARTICLE IN PRESS Available online at www.sciencedirect.com
ScienceDirect British Journal of Oral and Maxillofacial Surgery xxx (2019) xxx–xxx
Postoperative stability of conventional bimaxillary surgery compared with maxillary impaction surgery with mandibular autorotation for patients with skeletal class II retrognathia S. Kita a,∗ , K. Fujita b , H. Imai b , M. Aoyagi a , K. Shimazaki a , I. Yonemitsu a , S. Omura b , T. Ono a a b
Department of Orthodontic Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan Department of Oral and Maxillofacial Surgery, Yokohama City University Medical Centre, Kanagawa, Japan
Accepted 16 October 2019
Abstract We aimed to compare the postoperative stability of conventional bimaxillary surgery (with bilateral sagittal split osteotomy) with that of maxillary impaction surgery (with mandibular autorotation without bilateral sagittal split osteotomy) in patients with skeletal class II retrognathia. Patients were assigned to have conventional bimaxillary surgery (conventional group, n = 6) or mandibular autorotation (experimental group, n = 7). Measurements were made using serial lateral cephalometric radiographs taken immediately preoperatively (T0), immediately postoperatively (T1), and one year later (T2) to assess the variation in operative change (T1-T0) and relapse (T2-T1). There was no significant difference in median (range) surgical change in the anterior movement at point B (conventional group, 4.5 (3.0–11.0) mm; experimental group 4.1 (2.1–6.4) mm). However, there was a significant difference in median (range) surgical posterior movement relapse at point B (conventional group −1.7 (−2.3 to −0.5) mm; experimental group −0.6 (−1.0 to 1.0) mm; p = 0.032). Mandibular advancement with mandibular autorotation is therefore a more stable procedure than mandibular advancement with bilateral sagittal split osteotomy in patients with skeletal class II retrognathia. © 2019 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
Keywords: mandibular retrognathism; mandibular autorotation; mandibular advancement; relapse; osteoarthritis; progressive condylar resorption
Introduction Bilateral sagittal split osteotomy (BSSO) is an orthognathic operation that is often used to correct mandibular hypoplasia, including skeletal class II deformity, anterior open bite, ∗ Corresponding author at: Department of Orthodontic Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan. Tel./Fax: +81 3 5803 5529. E-mail address: [email protected] (S. Kita).
and osteoarthritis. Postoperative alterations after mandibular advancement surgery with BSSO, such as increased loading of the temporomandibular joint (TMJ) or positional condylar changes, may occur.1,2 Postoperative skeletal relapse is affected by movements of bone at the osteotomy sites as well as changes in the position and morphology of the condyles.3 The extent to which these changes exceed the natural adaptive capacity of the TMJ is likely to give rise to a clinical complication known as progressive condylar resorption.1,3 This is reported as a late postoperative relapse (over six
https://doi.org/10.1016/j.bjoms.2019.10.309 0266-4356/© 2019 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
Please cite this article in press as: S. Kita, K. Fujita, H. Imai et al.. Postoperative stability of conventional bimaxillary surgery compared with maxillary impaction surgery with mandibular autorotation for patients with skeletal class II retrognathia. Br J Oral Maxillofac Surg (2019), https://doi.org/10.1016/j.bjoms.2019.10.309
YBJOM-5828; No. of Pages 5
2
ARTICLE IN PRESS
S. Kita, K. Fujita, H. Imai et al. / British Journal of Oral and Maxillofacial Surgery xxx (2019) xxx–xxx
months) after BSSO for mandibular advancement, and leads to reduced posterior facial height, clockwise mandibular rotation, mandibular retrognathism, and anterior open bite.3–6 Previous investigators assumed that atrophy resulted from resorption as a result of increased muscle tension of the geniohyoid and the anterior digastric muscles.4,7 However, condylar resorption associated with BSSO is affected by several factors, including female sex, young age (15–35 years), mandibular hypoplasia with a high angle of the mandibular plane, preoperative dysfunction of the TMJ, posterior inclination of the condylar neck, large mandibular advancement, counter-clockwise rotation of the proximal segments of the mandible, increased muscle tension of the geniohyoid and anterior digastric muscles, and type of fixation.2,4–6,8–12 Surgical factors associated with relapse (such as mandibular advancement, counter-clockwise rotation of the proximal segments of the mandible, increased tension in the geniohyoid and the anterior digastric muscles, and type of fixation) may be avoided if BSSO is not done. Sperry et al used maxillary superior repositioning (impaction) and mandibular autorotation for orthognathic surgery,13 as the mandible is assumed to rotate in a counter-clockwise direction when this technique is used. However, surgical precision and stable fixation were lacking. Few studies, therefore, have evaluated the postoperative stability of orthognathic surgery with mandibular autorotation. Recently, studies regarding the effects of surgery with maxillary impaction, mandibular autorotation, and a straight-locking miniplate (SLM) technique in patients with oseoarthritis and skeletal class II deformity were published (Fig. 1).14,15 The SLM technique is a simple method of accurate maxillary superior repositioning with no intraoperative measurement. Using it, surgical precision and stable fixation are possible. Our aim in this study therefore was to compare postoperative stability after conventional bimaxillary surgery with BSSO without the SLM technique (conventional group) with that after maxillary impaction surgery with mandibular autorotation and the SLM technique (experimental group).
Patients and methods Female patients with mandibular retrognathism who had orthognathic surgery from 2006 – 2015 were included in the study. To minimise surgeon-related bias, one surgeon operated on all patients in the both groups with titanium miniplates and screws. The inclusion criteria were skeletal class II dentofacial deformities with an angle between the lines connecting points A, N, and B (ANB) >4◦ , mandibular hypoplasia with a high angled mandibular plane (SN-MP) >40◦ (Fig. 2), and a complete series of identifiable lateral cephalometric radiographs.11,12 The exclusion criteria were a history of facial fracture, other syndromes, asymmetry, and unavailability or incompletely identifiable series of lateral cephalometric radiographs.
Fig. 1. Intraoperative view of SLM fixation to the zygomatic buttress above the Le Fort I osteotomy line and the mandible. The SLM maintain the vertical distance between the skull base and mandible and can reproduce the CR position of the condyle during the surgery.
Ultimately, 13 patients were included and divided into two groups according to the operation done: the conventional bimaxillary surgery with BSSO but without SLM (conventional group) and the maxillary impaction surgery with mandibular autorotation and SLM (experimental group). There were six patients in the conventional group and seven in the experimental group. The median (range) age at the time of operation was 34 (20–42) years in the conventional group and 28 (18–39) years in the experimental group. Patients in the conventional group had a Le Fort I osteotomy and BSSO, and patients in the experimental group a Le Fort I osteotomy with or without the “Wunderer” procedure, and mandibular autorotation without BSSO. All patients had orthodontic treatment before and after operation. Operative and postoperative skeletal changes were evaluated using lateral cephalometric radiographs taken immediately before (T0), immediately after (T1), and one year after operation (T2). The surgical changes were defined as T1 minus T0 and the postoperative changes (relapse) were defined as T2 minus T1. All reference planes were transferred from T0 to T2 according to the Sella-Nasion (SN) plane-registered superimposition.
Please cite this article in press as: S. Kita, K. Fujita, H. Imai et al.. Postoperative stability of conventional bimaxillary surgery compared with maxillary impaction surgery with mandibular autorotation for patients with skeletal class II retrognathia. Br J Oral Maxillofac Surg (2019), https://doi.org/10.1016/j.bjoms.2019.10.309
ARTICLE IN PRESS
YBJOM-5828; No. of Pages 5
S. Kita, K. Fujita, H. Imai et al. / British Journal of Oral and Maxillofacial Surgery xxx (2019) xxx–xxx
3
included horizontal distances from point A and point B to the y-axis and vertical distances from point A and point B to the x-axis. The five angular measurements included the angle between the lines connecting points S, N, and A (SNA); the angle between the lines connecting points S, N, and B (SNB); the angle between the lines connecting points A, N, and B (ANB); the angle between the SN lines and the mandibular plane (SN-MP); and the angle between the x-axis and the plane of the ramus (RI) (Fig. 2).
Statistical analysis We used the Mann-Whitney U test to compare the significance of differences between the groups, and probabilities of <0.05 were accepted as significant. All measurements were repeated by the same examiner after an interval of one month. The method error was calculated using the intraclass correlation coefficient (ICC), which was greater than 0.95 for all linear and angular cephalometric variables measured. Data are presented as median (range). Fig. 2. Skeletal landmarks, reference lines and angles used in the cephalometric analysis are shown. S, sella; N, nasion; A, A-point; B, B-point; Me, menton; Ar, articulare; x-axis, defined with the origin at N and forming a 7◦ angle upward from the SN plane; y-axis, defined as the line perpendicular to the x-axis and passing through S; A(x), horizontal position of point A; A(y), vertical position of point A; B(x), horizontal position of point A; B(y), vertical position of point B; SN-MP, the angle of the SN plane to the mandibular plane; ramus inclination (RI), the angle of the y-axis to the ramus plane.
For the cephalometric measurements, we constructed an x-y coordinate system.16 The x-axis originated at the N-point and formed an angle of 7◦ upwards from the SN plane. The y-axis was defined as the line perpendicular to the x-axis and passing through the S-point. The positions of the landmarks were recorded as the linear measurements in relation to the xand y-axes (Fig. 2). We identified four linear, and five angular, cephalometric measurements. The four linear measurements
Results The cephalometric measurements at each time point are summarised in Table 1. There was no significant between-group difference in personal or clinical characteristics immediately preoperatively.
Comparison of surgical change immediately before and after operation Horizontal and vertical measurements, and angle measurements are shown in Table 2.
Table 1 Median (range) of the variables according to conventional bimaxillary surgery group and mandibular autorotation surgery group at each time. Data are median (range). Group
A (x) (mm) A (y) (mm) B (x) (mm) B (y) (mm) SNA (◦ ) SNB (◦ ) ANB (◦ ) SN-MP (◦ ) RI (◦ )
CB
MA
T0
T1
T2
T0
T1
T2
71.0 (60.2–77.1) 63.0 (58.0–66.5) 52.1 (42.7–62.0) 111.5 (107.4–122.8) 82.3 (79.2–90.9) 72.9 (71.7–79.9) 10.1 (6.5–11.0) 47.0 (43.2–52.0) −0.5 (−6.6–4.6)
70.6 (59.9–73.0) 62.9 (54.0–64.6) 55.6 (48.9–67.7) 113.7 (111.1–123.6) 82.1 (79.1–87.0) 75.4 (73.8–82.1) 4.5 (1.7–9.3) 45.3 (43.0–54.1) 2.2 (−1.5–6.8)
70.6 (59.9–72.7) 63.0 (54.0–64.7) 54.2 (46.8–66.9) 111.4 (110.7–122.7) 82.0 (79.0–87.0) 74.4 (73.6–81.4) 5.4 (1.9–9.9) 46.3 (40.9–52.0) 2.6 (−5.8–5.9)
70.0 (62.9–77.6) 65.3 (61.8–67.2) 49.4 (33.8–67.9) 114.9 (109.3–123.6) 81.0 (79.5–84.3) 73.1 (66.9–78.8) 9.9 (5.5–14.1) 48.3 (35.2–50.4) −3.0 (−16.5–8.0)
70.3 (62.3–77.1) 59.7 (58.3–64.3) 54.7 (37.9–70.0) 111.5 (107.6–120.0) 80.1 (75.5–83.8) 74.8 (68.8–79.5) 8.0 (0.2–11.3) 44.3 (33.9–48.0) 1.0 (−12.7–10.6)
70.3 (62.6–76.9) 60.0 (58.3–64.6) 53.8 (38.7–69.9) 110.4 (106.0–119.0) 80.3 (76.0–83.8) 75.0 (69.1–79.4) 8.0 (1.0–11.2) 45.1 (33.2–48.5) 2.0 (−15.2–11.8)
CB = conventional bimaxillary surgery; MA = mandibular autorotation surgery; T0 = immediately preoperatively; T1= immediately postoperatively; T2= after one year.
Please cite this article in press as: S. Kita, K. Fujita, H. Imai et al.. Postoperative stability of conventional bimaxillary surgery compared with maxillary impaction surgery with mandibular autorotation for patients with skeletal class II retrognathia. Br J Oral Maxillofac Surg (2019), https://doi.org/10.1016/j.bjoms.2019.10.309
ARTICLE IN PRESS
YBJOM-5828; No. of Pages 5
4
S. Kita, K. Fujita, H. Imai et al. / British Journal of Oral and Maxillofacial Surgery xxx (2019) xxx–xxx
Table 2 Comparison of the surgical changes between the conventional bimaxillary surgery group and the mandibular autorotation surgery group. Data are median (range). P values were not significant. T1-T0
CB
MA
A (x) (mm) A (y) (mm) B (x) (mm) B (y) (mm) SNA (◦ ) SNB (◦ ) ANB (◦ ) SN-MP (◦ ) RI (◦ )
−0.1 (−5.4 to 0.6) −0.2 (−6.4 to 0.9) 4.5 (3.0 to 11.0) 3.4 (−4.7 to 4.8) −0.1 (−4.7 to 1.1) 2.5 (2.1 to 4.8) −4.0 (−7.2 to −1.3) −1.2 (−9 to 3.1) 3.0 (−0.6 to 6.5)
−0.6 (−6.0 to 0.3) −4.4 (−7.0 to −1.9) 4.1 (2.1 to 6.4) −1.7 (−4.0 to −0.5) −0.9 (−5.3 to 0.5) 2.1 (0.7 to 2.6) −2.8 (−7.4 to −0.9) −3.1 (−5.3 to 1.3) 2.8 (1.1 to 4.0)
CB = conventional bimaxillary surgery; MA = mandibular autorotation surgery; T0= immediately preoperatively; T1= immediately postoperatively; T2= after one year. Table 3 Comparison of the surgical relapse between the conventional bimaxillary surgery group and the mandibular autorotation surgery group. Data are median (range). T2-T1
CB
MA
p value
A(x) (mm) A(y) (mm) B(x) (mm) B(y) (mm) SNA (◦ ) SNB (◦ ) ANB (◦ ) SN-MP (◦ ) RI (◦ )
0.0 (−0.3 to 0.1) 0.1 (0.0 to 0.1) −1.7 (−2.3 to −0.5) −1.2 (−3.3 to 0.7) −0.1 (−0.1 to 0.4) −0.8 (−1.2 to −0.2) 0.9 (0.2 to 1.1) −0.1 (−2.1 to 3.1) −1.1 (−5.7 to 1.6)
0.0 (−0.6 to 0.6) 0.1 (0.0 to 1.3) −0.6 (−1.0 to 1.0) −1.0 (−1.7 to 1.3) 0.1 (−0.1 to 0.5) −0.3 (−0.4 to 1.0) 0.4 (−1.0 to 0.8) −0.2 (−1.5 to 2.1) 0.6 (−2.5 to 1.2)
0.77 0.36 0.032* 0.47 0.38 0.044* 0.053 0.94 0.15
∗
p < 0.05.
Comparison of surgical relapse immediately and one year after operation Horizontal measurements: there was no significant difference between the two groups (Table 3). However, there was a significant difference in the mean surgical relapse (T2-T1) in the posterior movement at point B (p = 0.032; Table 3). Vertical measurements: are also shown in Table 3. There were no significant differences between the two groups for vertical changes at points A and B. Angle measurements: are also shown in Table 3. The SNB of the conventional group showed a significantly greater decrease than that of the experimental group (p = 0.044). There were no significant differences between the two groups in the remaining angle measurements.
Discussion After orthognathic surgery that includes mandibular advancement, postoperative surgical relapse is common.17 There are two patterns of skeletal relapse: “early” and “late”.6 “Early” skeletal relapse is thought to be caused by the operative technique – that is – insufficient intraoperative positioning of the condyle resulting in subsequent displacement
of the mandibular proximal segment and slippage of the osteotomy.18–20 On the basis of the change in the angle between the x-axis and the plane of the ramus (%) in the conventional group, we suggest that the mandibular proximal segment was displaced when the maxilla and the mandible, respectively, were fixed. In contrast, patients in the experimental group had a Le Fort I osteotomy with or without the “Wunderer” procedure and mandibular autorotation with the SLM technique without BSSO. The SLM technique is a simple way of accurately repositioning the superior maxilla without the requirement for intraoperative measurement. The SLM maintains the proximal segment with the condyle in position.14 In the experimental group, therefore, the proximal segment of the mandible was not displaced when the maxilla was fixed. As a result of differences in techniques, point B in the conventional group had more posterior movement than the experimental group. In the conventional group, the SNB angle significantly decreased and the ANB angle significantly increased. The SNB angle in the conventional group decreased more than that in the experimental group, which suggests that operation in the experimental group with the SLM technique was a stable procedure for correction of mandibular hypoplasia, including skeletal class II deformity. In contrast, “late” skeletal relapse is thought to be caused by progressive condylar resorption.20–22 After orthognathic surgery this is multifactorial, and osteoarthritis is a serious risk factor.21,22 Mandibular advancement surgery should therefore be done only when the condyles are stable, and postoperative mechanical loading on the TMJ should be avoided in high-risk patients such as those with osteoarthritis.22 We have therefore avoided mandibular advancement surgery in such patients. We found no signs of obvious osteoarthritis in patients in the conventional group, but it was present in all patients in the experimental group. Patients in the experimental group who had risk factors for late relapse,11,12 such as mandibular hypoplasia with a high mandibular plane angle and osteoarthritis, had Le Fort I osteotomy with or without the “Wunderer” procedure, and mandibular autorotation without BSSO, to reduce muscular tension. In a previous study, bone loss was predominantly found at the anterior part of the condyle.23 With counter-clockwise rotation of the mandible, the anterior part of the condyle that is not loaded may be resorbed.24 Late surgical relapse can be seen six months postoperatively.6 We evaluated late surgical relapse with lateral cephalometric radiographs that were taken immediately and one year postoperatively, and no obvious relapse was seen in the experimental group. These results suggest that mandibular autorotation surgery may avoid late surgical relapse caused by progressive condylar resorption. However, we did not evaluate the shape of the condyle with computed tomography (CT). Several studies have suggested that this continues over five years, 6,25 so further long-term followup and morphological evaluation with CT are required. In addition, the technique is limited by several conditions: first, there should be no canting of the maxilla; secondly, there
Please cite this article in press as: S. Kita, K. Fujita, H. Imai et al.. Postoperative stability of conventional bimaxillary surgery compared with maxillary impaction surgery with mandibular autorotation for patients with skeletal class II retrognathia. Br J Oral Maxillofac Surg (2019), https://doi.org/10.1016/j.bjoms.2019.10.309
YBJOM-5828; No. of Pages 5
ARTICLE IN PRESS
S. Kita, K. Fujita, H. Imai et al. / British Journal of Oral and Maxillofacial Surgery xxx (2019) xxx–xxx
should be no facial asymmetry; and thirdly, the upper central incisor edge can be set to an aesthetically appropriate position on the counter-clockwise rotational orbit of the mandible. In addition, in some cases it is not possible to improve the facial profile by surgery with mandibular autorotation without BSSO alone. In such cases, genioplasty is necessary to improve the facial profile. In conclusion, our findings suggest that mandibular advancement with mandibular autorotation and the SLM technique for patients with skeletal class II deformity and osteoarthritis is a more stable operation than mandibular advancement with BSSO. Although studies that enrol more patients and have a longer-term follow-up are necessary, this operation seems to be superior in patients with risk factors for progressive condylar resorption.
Ethics statement/confirmation of patients’ permission This study was approved by the Tokyo Medical and Dental University institutional review board (receipt number 1118) and the Yokohama City University Medical Centre institutional review board (receipt number B110512003). Patients’ informed consent was obtained.
Conflict of interest We have no conflicts of interest.
References 1. Mousoulea S, Kloukos D, Sampaziotis D, et al. Condylar resorption in orthognathic patients after mandibular bilateral sagittal split osteotomy: A systematic review. Eur J Orthod 2017;39:294–309. 2. Dicker GJ, Tuijt M, Koolstra JH, et al. Static and dynamic loading of mandibular condyles and their positional changes after bilateral sagittal split advancement osteotomies. Int J Oral Maxillofac Surg 2012;41:1131–6. 3. Xi T, Schreurs R, Van Loon B, et al. 3D analysis of condylar remodelling and skeletal relapse following bilateral sagittal split advancement osteotomies. J Craniomaxillofacial Surg 2015;43:462–8. 4. de Moraes PH, Rizzati-Barbosa CM, Olate S, et al. Condylar resorption after orthognathic surgery: a systematic review. Int J Morphol 2012;30:1023–8. 5. Catherine Z, Breton P, Bouletreau P. Management of dentoskeletal deformity due to condylar resorption: literature review. Oral Surg Oral Med Oral Pathol Oral Radiol 2016;121:126–32. 6. Eggensperger N, Smolka K, Luder J, et al. Short- and long-term skeletal relapse after mandibular advancement surgery. Int J Oral Maxillofac Surg 2006;35:36–42. 7. Phillips RM, Bell WH. Atrophy of mandibular condyles after sagittal ramus split osteotomy: report of case. J Oral Surg 1978;36:45–9.
5
8. Ow A, Cheung LK. Skeletal stability and complications of bilateral sagittal split osteotomies and mandibular distraction osteogenesis: an evidence-based review. J Oral Maxillofac Surg 2009;67:2344–53. 9. Bermell-Baviera A, Bellot-Arcís C, Montiel-Company JM, et al. Effects of mandibular advancement surgery on the temporomandibular joint and muscular and articular adaptive changes—a systematic review. Int J Oral Maxillofac Surg 2016;45:545–52. 10. Dicker GJ, Castelijns JA, Tuinzing DB, et al. Do the changes in muscle mass, muscle direction, and rotations of the condyles that occur after sagittal split advancement osteotomies play a role in the aetiology of progressive condylar resorption? Int J Oral Maxillofac Surg 2015;44:627–31. 11. Hwang SJ, Haers PE, Seifert B, et al. Non-surgical risk factors for condylar resorption after orthognathic surgery. J Craniomaxillofacial Surg 2004;32:103–11. 12. Hwang SJ, Haers P.E., Zimmerman A, et al. Surgical risk factors for condylar resorption after orthognathic surgery. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2000;89:542–52. 13. Sperry TP, Steinberg MJ, Gans BJ. Mandibular movement during autorotation as a result of maxillary impaction surgery. Am J Orthod 1982;81:116–23. 14. Omura S, Kimizuka S, Iwai T, et al. An accurate maxillary superior repositioning technique without intraoperative measurement in bimaxillary orthognathic surgery. Int J Oral Maxillofac Surg 2012;41:949–51. 15. Iwai T, Omura S, Honda K, et al. An accurate bimaxillary repositioning technique using straight locking miniplates for the mandible-first approach in bimaxillary orthognathic surgery. Odontology 2017;105:122–6. 16. Choi SH, Yoo HJ, Lee JY, et al. Stability of pre-orthodontic orthognathic surgery depending on mandibular surgical techniques: SSRO vs IVRO. J Craniomaxillofacial Surg 2016;44:1209–15. 17. Sahoo NK, Jayan B, Thakral A, et al. Skeletal relapse following sagittal split ramus osteotomy advancement. J Maxillofac Oral Surg 2015;14:357–62. 18. Stroster TG, Pangrazio-Kulbersh V. Assessment of condylar position following bilateral sagittal split ramus osteotomy with wire fixation or rigid fixation. Int J Adult Orthodon Orthognath Surg 1994;9:55–63. 19. Van Sickels JE, Tiner BD, Keeling SD, et al. Condylar position with rigid fixation versus wire osteosynthesis of a sagittal split advancement. J Oral Maxillofac Surg 1999;57:31–5. 20. Watzke IM, Turvey TA, Phillips C, et al. Stability of mandibular advancement after sagittal osteotomy with screw or wire fixation: A comparative study. J Oral Maxillofac Surg 1990;48:108–23. 21. Wolford LM, Reiche-Fischel O, Mehra P. Changes in temporomandibular joint dysfunction after orthognathic surgery. J Oral Maxillofac Surg 2003;61:655–60. 22. Kobayashi T, Izumi N, Kojima T, et al. Progressive condylar resorption after mandibular advancement. Br J Oral Maxillofac Surg 2012;50:176–80. 23. Hoppenreijs TJ, Freihofer HP, Stoelinga PJ, et al. Condylar remodelling and resorption after Le Fort I and bimaxillary osteotomies in patients with anterior open bite: A clinical and radiological study. Int J Oral Maxillofac Surg 1998;27:81–91. 24. O’Ryan F, Epker BN. Temporomandibular joint function and morphology: Observations on the spectra of normalcy. Oral Surg Oral Med Oral Pathol 1984;58:272–9. 25. Simmons KE, Turvey TA, Phillips C, et al. Surgical-orthodontic correction of mandibular deficiency: five-year follow-up. Int J Adult Orthodon Orthognath Surg 1992;7:67–79.
Please cite this article in press as: S. Kita, K. Fujita, H. Imai et al.. Postoperative stability of conventional bimaxillary surgery compared with maxillary impaction surgery with mandibular autorotation for patients with skeletal class II retrognathia. Br J Oral Maxillofac Surg (2019), https://doi.org/10.1016/j.bjoms.2019.10.309