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Int. J. Oral Maxillofac. Surg. 2014; xxx: xxx–xxx http://dx.doi.org/10.1016/j.ijom.2014.03.001, available online at http://www.sciencedirect.com
Clinical Paper Orthognathic Surgery
Long-term evaluation of swallowing function before and after sagittal split ramus osteotomy
S. Namaki1, N. Maekawa1, J. Iwata1, K. Sawada2, M. Namaki3, T. Bjornland4, Y. Yonehara1 1
Department of Oral and Maxillofacial Surgery, Nihon University School of Dentistry, Tokyo, Japan; 2Department of Oral and Maxillofacial Radiology, Nihon University School of Dentistry, Tokyo, Japan; 3 Department of Oral and Maxillofacial Surgery, Juntendo University School of Medicine, Tokyo, Japan; 4Department of Oral Surgery and Oral Medicine, Faculty of Dentistry, University of Oslo, Oslo, Norway
S. Namaki, N. Maekawa, J. Iwata, K. Sawada, M. Namaki, T. Bjornland, Y. Yonehara: Long-term evaluation of swallowing function before and after sagittal split ramus osteotomy. Int. J. Oral Maxillofac. Surg. 2014; xxx: xxx–xxx. # 2014 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. Abstract. The aim of this study was to determine whether mandibular setback by sagittal split ramus osteotomy (SSRO) influences swallowing function. The subjects were 14 patients with skeletal class III malocclusions who underwent setback surgery by SSRO. Morphological changes were studied on cephalograms, and swallowing function was evaluated by videofluorography before the operation (T0) and at 7–10 days (T1), 3 months (T2), and 6 months (T3) after surgery. The angle between nasion, sella, and hyoid bone (HSN) and the sella–hyoid distance had increased significantly at T1. The hyoid bone returned to the preoperative position at T2. There were no significant changes in the oropharyngeal space at any time. On videofluorographic assessment, lingual movement, soft palate movement, and epiglottic movement had decreased at T1, but all patients recovered at T2. The oral transit time was significantly longer at T1 than at T0. Our results confirm that SSRO influences swallowing function. Swallowing function appears to stabilize by 3 months after surgery.
The sagittal split ramus osteotomy (SSRO) is a common treatment for mandibular prognathism and results in functional and aesthetic improvements. Mandibular setback influences the tongue and pharyngeal airway.1,2 Several studies have shown changes in craniofacial, tongue, hyoid, and pharyngeal morphology after mandibular setback surgery.3–11 Such changes include a reduction in pharyngeal airway volume and changes in the tongue and hyoid positions 0901-5027/000001+06 $36.00/0
on static imaging techniques, such as lateral and posterior–anterior cephalography, computed tomography (CT),8–10 and magnetic resonance imaging (MRI)11; however the functional consequences of these changes remain unclear. Previous studies have assessed the effects of mandibular setback surgery on masticatory function,12,13 stomatognathic function,14 sleep apnea,1,2 psychosocial status,15 and articulation.16 However, whether or not mandibular setback affects
Key words: swallowing function; orthognathic surgery; oropharyngeal airway; hyoid bone. Accepted for publication 3 March 2014
swallowing movements remains a matter of debate. Changes in tongue position may influence swallowing function during the oral preparatory phase and oral phase. Altered hyoid position and pharyngeal airway volume may affect swallowing function during the pharyngeal phase. Generally, the effects of various diseases on swallowing function are evaluated by videofluorography,17–19 which is used to assess the oral and pharyngeal transit times.20
# 2014 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
Please cite this article in press as: Namaki S, et al. Long-term evaluation of swallowing function before and after sagittal split ramus osteotomy, Int J Oral Maxillofac Surg (2014), http://dx.doi.org/10.1016/j.ijom.2014.03.001
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The aim of this study was to investigate the effects of SSRO and mandibular setback on craniofacial and pharyngeal morphology and on swallowing function. Craniofacial and pharyngeal morphology and swallowing function were evaluated by videofluorography before and after SSRO. Materials and methods Subjects
The subjects were 14 patients (two men and 12 women; average age 25.9 10.6 years) with dentofacial deformities, who had skeletal class III malocclusion with or
without open bite and asymmetry. The patients underwent SSRO in the department of oral and maxillofacial surgery of the study hospital. Patients who underwent Le Fort I osteotomy were excluded. All subjects received preoperative and postoperative orthodontic treatment. SSRO was performed according to the Obwegeser21 and Dal Pont22 method. The fragments were fixed with the use of titanium plates (Wu¨rzburg Titanium Plating System; Stryker Leibinger GmbH, Freiburg, Germany) and resorbable fixation devices (Super Fixsorb-MX; Takiron Co., Osaka, Japan). Each subject received a preoperative dose of dexamethasone (mean dose 4.5 mg) immediately prior to surgery,
followed by postoperative treatment with dexamethasone (mean dose 2.1 mg/day) for 2 days to control postoperative swelling. The average amount of mandibular setback was 7.65 3.23 mm. Intermaxillary fixation with the use of elastics or steel wires was maintained for 4–6 days postoperatively. Informed consent was obtained from all subjects after explaining the study procedures in detail. The protocol was approved by the institutional ethics committee. Cephalometric analysis
Morphological changes were evaluated on lateral cephalometric radiographs that
Fig. 1. Cephalometric linear and angular measurements. (1) sella–nasion–A point (SNA) angle. (2) sella–nasion–B point (SNB) angle. (3) A point–nasion–B point (ANB) angle. (4) HSN angle: angle between nasion, sella, and hyoid bone (lowest point of hyoid bone). (5) S–H: distance from sella to hyoid bone. (6) C3–H: distance from the most antero-inferior point of the third cervical vertebra to the hyoid bone. (7) D1: distance from posterior nasal spine (PNS) to the dorsum of the tongue on a line perpendicular to the S–N line. (8) PPS: distance from posterior pharyngeal wall to the PNS on a line parallel to the Frankfort horizontal (FH) plane. (9) SPPS: distance from the posterior pharyngeal wall to the middle of the line from PNS to PSP (tip of the soft palate) on a line parallel to the FH plane. (10) MPS: distance from the posterior pharyngeal wall to the dorsum of the tongue on a line parallel to the FH plane that runs through PSP. (11) IPS: distance from the posterior pharyngeal wall to the surface of the tongue on a line parallel to the FH plane that runs through C2 (the most antero-inferior point of the second cervical vertebra). (12) EPS: distance from the posterior pharyngeal wall to the tip of the epiglottis on a line parallel to the FH plane.
Please cite this article in press as: Namaki S, et al. Long-term evaluation of swallowing function before and after sagittal split ramus osteotomy, Int J Oral Maxillofac Surg (2014), http://dx.doi.org/10.1016/j.ijom.2014.03.001
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Swallowing function before and after SSRO were taken with the Frankfort horizontal plane (FH plane) parallel to the floor and with the patient in centric occlusion. Evaluations were performed before surgery (T0) and at 7–10 days (T1), 3 months (T2), and 6 months (T3) after surgery. All cephalograms were traced and analyzed by the same examiner. Fig. 1 shows the landmarks and contours that are commonly used for orthodontic analysis, as well as additional variables that were used to evaluate the pharyngeal airway. Four angles and three linear distances were measured to assess dentoskeletal morphological changes. Five linear distances were calculated to evaluate the pharyngeal airways. Videofluorography
Table 1. Cephalometric angular and linear measurements.* (1) (2) (3) (4) (5) (6) (7) * y
T1
T2
T3
81.2 3.7 80.0 4.2y 1.2 2.3y 92.9 4.5y 129.3 8.8y 43.7 6.0 14.1 4.2
81.4 3.8 80.6 4.3 0.8 2.1 91.4 4.9 119.7 7.9 40.5 5.6 13.8 4.2
81.2 3.6 80.1 3.7 1.1 2.0 91.7 4.2 119.7 7.9 40.2 3.4 12.1 3.6
For measurements see Fig. 1. P < 0.05.
(8) PPS, mm (9) SPPS, mm (10) MPS, mm (11) IPS, mm (12) EPS, mm
T0
T1
T2
T3
26.8 5.2 15.9 4.0 20.8 6.1 16.8 5.0 16.2 4.1
25.9 5.0 14.4 3.7 17.9 5.3 15.4 4.8 16.5 3.6
27.0 4.5 15.2 3.6 19.0 5.7 15.4 5.8 15.7 5.6
27.6 4.2 14.8 4.0 18.8 5.5 15.8 4.7 16.2 3.7
For measurements see Fig. 1.
and after SSRO were adjusted with the use of the Bonferroni correction. A significance level of 5% was used throughout the study. The statistical analysis was performed using SPSS statistical software (Dr. SPSS II for Windows; SPSS Japan Inc., Tokyo, Japan).
changes in the oropharyngeal spaces at any time point. However, the MPS distance (distance from the posterior pharyngeal wall to the dorsum of the tongue on a line parallel to the FH plane that runs through the tip of the soft palate) after surgery (T1, T2, T3) was slightly shorter than that before surgery.
Results Cephalometric analysis
Videofluorography
Tables 1 and 2 show the cephalometric angular and linear measurements and the width of the oropharynx. The angle between nasion, sella, and hyoid bone (HSN) and the distance from sella to hyoid bone (S–H) increased significantly at T1, but there was no change at T2 or T3. The hyoid bone returned to the preoperative position at T2. There were no significant
Table 3 shows the results of videofluorographic qualitative evaluations before and after SSRO. Lingual movement, soft palate movement, epiglottic movement, and oral cavity stasis decreased at T1, but recovered in all patients at T2. Lingual movement and soft palate movement were poor in 10 or more patients, and stasis in the epiglottic valleculae and in the oral
Table 3. Variables qualitatively evaluated by videofluorography before and after SSRO in 14 patients. T0
T1
T2
T3
Lingual movement
Move: 13 Poor: 1
Move: 3 Poor: 11
Move: 13 Poor: 1
Move: 12 Poor: 2
Barium inflow into pharynx before swallowing
Yes: 0 No: 14
Yes: 2 No: 12
Yes: 0 No: 14
Yes: 0 No: 14
Soft palate movement
Move: 14 Poor: 0
Move: 4 Poor: 10
Move: 14 Poor: 0
Move: 12 Poor: 2
Epiglottic movement
Move: 13 Poor: 1
Move:4 Poor: 10
Move: 14 Poor: 0
Move: 13 Poor: 1
Stasis in epiglottic valleculae
Yes: 5 No: 9
Yes: 9 No: 5
Yes: 3 No: 11
Yes: 2 No: 12
Stasis in oral cavity after swallowing
Yes: 0 Little: 8 No: 6
Yes: 4 Little: 10 No: 0
Yes: 1 Little: 11 No: 2
Yes: 0 Little: 8 No: 6
Data analysis
Data were analyzed by conventional statistical methods. The mean, range, and standard deviation were calculated for each variable. Values obtained before
T0 81.1 3.8 84.1 4.6 3.0 2.9 90.0 5.0 118.3 9.1 40.6 5.7 14.7 4.3
Table 2. Width of the oropharynx.*
*
Swallowing was assessed by videofluorography in all patients. Videofluorography was performed before SSRO, at 4–6 days after the release of intermaxillary fixation, and at 3 and 6 months after surgery to qualitatively and quantitatively analyze deglutition. The contrast material used was 10 ml of liquid barium. Images were recorded, converted digitally, and analyzed with InterVideo WinDVD Creator software (InterVideo, Inc., Fremont, CA, USA). Qualitative assessments included lingual movement, barium inflow into the pharynx before swallowing, soft palate movement, epiglottic movement, stasis in the epiglottic valleculae, and stasis in the oral cavity after swallowing. Swallowing was also assessed quantitatively. The oral transit time, pharyngeal transit time, and total transit time were measured before and after SSRO, and the values were compared. The oral transit time was defined as the time required for the barium to move through the oral cavity, measured from the first backward movement of the barium until the head of the barium passed the lowest point of the mandibular ramus. The pharyngeal transit time was defined as the time required for the barium to move through the pharynx, measured from the time that the head of the barium passed the lowest point of the mandibular ramus until the tail of the barium left the cricopharyngeal region. The oral transit time and pharyngeal transit time were summed to derive the total transit time.
SNA,8 SNB,8 ANB,8 HSN,8 S–H, mm C3–H, mm D1, mm
SSRO, sagittal split ramus osteotomy.
Please cite this article in press as: Namaki S, et al. Long-term evaluation of swallowing function before and after sagittal split ramus osteotomy, Int J Oral Maxillofac Surg (2014), http://dx.doi.org/10.1016/j.ijom.2014.03.001
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Fig. 2. Videofluorometric quantitative evaluation (time, s). The oral transit time was significantly longer at T1 than T0. The pharyngeal transit time was significantly decreased at T1 compared to T0. There were no significant differences in the total transit time at any time point.
cavity after swallowing was observed in most patients at T1. Fig. 2 shows the oral transit time, pharyngeal transit time, and total transit time. The mean oral transit time increased significantly from 0.41 0.19 s before the operation to 0.58 0.25 s at T1. However, oral transit times at T3 and T4 were significantly shorter than the oral transit time at T1. The mean pharyngeal transit time decreased significantly from 0.30 0.08 s before the operation to 0.25 0.10 s at T1. The pharyngeal transit time at T4 was significantly longer than that at T1. There were no significant differences in the total transit time at any time point. Swallowing function had improved on quantitative assessment at 3 months (T2) after orthognathic surgery. This did not change even after 6 months (T3).
Discussion
Normal occlusion can be obtained after mandibular setback surgery in patients with skeletal class III jaw deformities. Mandibular setback causes changes in the pharyngeal airway space,4,5,8–11 as well as the positions of the hyoid bone3,5,6 and tongue.7 It is important to assess the pharyngeal airway and hyoid bone position. These previous studies demonstrated changes in the pharyngeal airway and surrounding hard and soft tissues on Xray examination and MRI, but no functional assessments were done. Other studies have performed functional assessments to assess masticatory function,12–14 stomatognathic function,15 articulation,16
and oxygen saturation,1 but not swallowing function. Swallowing is one of the most important functions of the oral cavity and pharynx. The oral preparatory phase, oral phase, and pharyngeal phase of swallowing are negatively affected by orthognathic surgery. This phenomenon is apparently caused by changes in the position of the mandible, hyoid bone, tongue, and suprahyoid muscles. Generally, the administration of steroids is routine to reduce the swelling after orthognathic surgery. Swelling after orthognathic surgery is expected to affect swallowing function. Some studies have evaluated the use of steroids for reducing postoperative oedema after orthognathic surgery.23,24 The authors administered steroids to all patients who underwent orthognathic surgery in order to reduce the postoperative oedema. The influence of postoperative oedema on swallowing function was thus prevented by the administration of steroids. Videofluorography has been used to examine the anatomy of the oral cavity and pharynx and to examine the pharynx and larynx before and after swallowing.25 The effects of orthognathic surgery and associated morphological changes were evaluated by performing videofluorography before and after surgery in the same patient. It is important to follow-up the same patient over the course of time. In the present study, lateral cephalograms were use to assess craniofacial and pharyngeal morphology. This technique has the advantage of low cost, convenience, high reproducibility, and minimal exposure to radiation. Techni-
ques such as three-dimensional CT and MRI are associated with high costs and high radiation. Our results showed that the position of the hyoid bone was significantly displaced downward and backward early after surgery and gradually returned to its original position by 3 months after surgery. The gradual return of the hyoid bone to its original position has been reported previously in patients who have undergone mandibular setback surgery.1,5 The oropharyngeal space did not change significantly, but narrowed slightly immediately after setback surgery. Jakobsone et al. found no change in cephalometric measurements of the oropharyngeal space after orthognathic surgery, as well as no change in cross-sectional areas calculated from CT scans.9 However, there was a significant increase in the oropharyngeal volume after surgery. That study was unable to confirm a correlation between the measurements on CT scans and corresponding measurements on lateral cephalograms of the oropharyngeal airway. Therefore, evaluation of the oropharynx on the basis of only still images appears to have its limitations. The authors performed videofluorographic examinations to assess qualitative and quantitative dynamics. Videofluorography may be a useful method for evaluating the function of the oral cavity and pharyngeal airway. The characteristics of swallowing can vary considerably and depend on the individual subject. Therefore, it is important to perform follow-up observations in the same patient. On qualitative videofluorographic assessment, lingual movement, soft palate
Please cite this article in press as: Namaki S, et al. Long-term evaluation of swallowing function before and after sagittal split ramus osteotomy, Int J Oral Maxillofac Surg (2014), http://dx.doi.org/10.1016/j.ijom.2014.03.001
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Swallowing function before and after SSRO movement, epiglottic movement, and oral cavity stasis decreased at T1, but recovered in all patients by T2. Stasis in the epiglottic valleculae and the oral cavity after swallowing was observed in most patients early after surgery. Barium was also found to remain in the oral cavity after deglutition. On qualitative evaluation, the oral transit time early after surgery was significantly prolonged as compared with the value before surgery. Cephalometric analysis showed that the hyoid bone position moved downward and backward at T1 as compared with that before the operation. The position of the hyoid bone and contraction of the suprahyoid muscles during swallowing were thus altered after orthognathic surgery. The positions of the tongue and suprahyoid muscles changed, and these muscles could not move in synchrony. These findings indicate that the oral transit time is prolonged in the early postoperative period. The pharyngeal transit time was significantly shorter early after surgery than before surgery. On qualitative assessment, stasis in the epiglottic valleculae and the oral cavity after swallowing were observed in most patients in the early postoperative period. Cephalometric analysis showed that the width of the oropharynx decreased slightly early after surgery. Shortening of the pharyngeal transit time was associated with a decreased volume of barium in the oral cavity. In conclusion, the oral transit time was significantly shorter at T2 and T3 than at T1, and the pharyngeal transit time was significantly longer at T3 than at T1. There were no differences in total transit time at any time point. On qualitative assessment, all elements tended to improve during the 3 months after surgery. On cephalometric analysis, the position of the hyoid bone and width of the oropharynx at T2 had returned to their preoperative status. Therefore, swallowing function appears to stabilize by 3 months after surgery. Funding
This study was supported by a Grant from Sato Fund, Nihon University School of Dentistry, and a Grant-in-Aid for Scientific Research (C) from the Japanese Society for the Promotion of Science (24593063). Competing interests
There is no conflict of interest related to the individual authors’ commitments and any project support.
Ethical approval
The protocol was approved by the Ethics Committee of Nihon University School of Dentistry (2012-8). Patient consent
Informed consent was obtained from all subjects after explaining the study procedures in detail. References 1. Kitagawa K, Kobayashi T, Goto H, Yokobayashi T, Kitamura N, Saito C. Effects of mandibular setback surgery on oropharyngeal airway and arterial oxygen saturation. Int J Oral Maxillofac Surg 2008;37:328–33. 2. Foltan R, Hoffmannova J, Donev F, Vik M, Sedy J, Kufa R, et al. The impact of Le Fort I advancement and bilateral sagittal split osteotomy setback on ventilation during sleep. Int J Oral Maxillofac Surg 2009;38:1036–40. 3. Kitahara T, Hoshino Y, Maruyama K, In E, Takahashi I. Changes in the pharyngeal airway space and hyoid bone position after mandibular setback surgery for skeletal Class III jaw deformity in Japanese woman. Am J Orthod Dentofacial Orthop 2010;138: 708e1–1. 4. Chen F, Terada K, Hua Y, Saito I. Effects of bimaxillary surgery and mandibular setback surgery on pharyngeal airway measurements in patients with Class III skeletal deformities. Am J Orthod Dentofacial Orthop 2007;131:372–7. 5. Eggensperger N, Smolka W, Iizuka T. Longterm changes of hyoid bone position and pharyngeal airway size following mandibular setback by sagittal split ramus osteotomy. J Craniomaxillofac Surg 2005;33:111–7. 6. Athanasiou AE, Toutountzakis N, Mavreas D, Ritzau M, Wenzel A. Alteration of hyoid bone position and pharyngeal depth and their relationship after surgical correction of mandibular prognathism. Am J Orthod Dentofacial Orthop 1991;100:259–65. 7. Hwang S, Chung CJ, Choi YJ, Huh JK, Kim KH. Changes of hyoid, tongue and pharyngeal airway after mandibular setback surgery by intraoral vertical ramus osteotomy. Angle Orthod 2010;80:302–8. 8. Degerliyurt K, Ueki K, Hashiba Y, Marukawa K, Simsek B, Okabe K, et al. The effect of mandibular setback or two-jaws surgery on pharyngeal airway among different genders. Int J Oral Maxillofac Surg 2009;38: 647–52. 9. Jakobsone G, Neimane L, Krumina G, Latvai R. Two- and three-dimensional evaluation of the upper airway after bimaxillary correction of Class III malocclusion. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2010;110:234–42.
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10. Degerliyurt K, Ueki K, Hshiba Y, Marukawa K, Nakagawa K, Yamamoto E. A comparative CT evaluation of pharyngeal airway changes in class III patients receiving bimaxillary surgery or mandibular setback surgery. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2008;105:495–501. 11. Meisami T, Musa M, Keller A, Cooper R, Clokie CM, Sandor GK. Magnetic resonance imaging assessment of airway status after orthognathic surgery. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2007;103: 458–63. 12. Kobayashi T, Honma K, Shingaki S, Nakajima T. Changes in masticatory function after orthognathic treatment in patients with mandibular prognathism. Br J Oral Maxillofac Surg 2001;39:260–5. 13. Braber W, Glas H, Bilt A, Bosman F. Masticatory function in retrognathic patients, before and after mandibular advancement surgery. J Oral Maxillofac Surg 2004;62: 549–54. 14. Nakata Y, Ueda HM, Kato M, Tabe H, Shikata-Wakisaka N, Matsumoto E, et al. Changes in stomatognathic function induced by orthognathic surgery in patients with mandibular prognathism. J Oral Maxillofac Surg 2007;65:444–51. 15. Kim SJ, Kim MR, Shin SW, Chun YS, Kim EJ. Evaluation on the psychosocial status of orthognathic surgery patients. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009;108:828–32. 16. Lierde KM, Schepers S, Timmermans L, Verhoye I, Cauwenberg PV. The impact of mandibular advancement on articulation, resonance and voice characteristics in Flemish speaking adults: a pilot study. Int J Oral Maxillofac Surg 2006;35:137–44. 17. Pauloski BR, Rademaker AW, Logemann JA, McConnel FM, Heiser MA, Cardinale S, et al. Surgical variables affecting swallowing in patients treated for oral/oropharyngeal cancer. Head Neck 2004;26:625– 36. 18. Pauloski BR, Rademaker AW, Logemann JA, Lazarus CL, Newman L, Hamner A, et al. Swallow function and perception of dysphagia in patients with head and neck cancer. Head Neck 2002;24:555–65. 19. Borggreven PA, Verdonck-de Leeuw I, Rinkel RN, Langendijk JA, Roos JC, David EF, et al. Swallowing after major surgery of the oral cavity or oropharynx: a prospective and longitudinal assessment of patients treated by microvascular soft tissue reconstruction. Head Neck 2007;29:638–47. 20. Namaki S, Tanaka T, Hara Y, Ohki H, Shinohara M, Yonehara Y. Videofluorographic evaluation of dysphagia before and after surgical flap and scar modification in patients with oral cancer—surgical procedure for dysphagia improvement. J Plast Surg Hand Surg 2011;45:136–42. 21. Obwegeser HL. The surgical correction of mandibular prognathism and retrognathia
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with consideration of genioplasty. Oral Surg Oral Med Oral Pathol 1957;10:677–89. 22. Dal Pont G. Retromolar osteotomy for the correction of prognathism. J Oral Surg 1961;19:42–7. 23. Soudeh C, Daljit KD. Review of evidence for the use of steroids in orthognathic surgery. Br J Oral Maxillofac Surg 2012; 50:97–101. 24. Dan AE, Thygesen TH, Pinholt EM. Corticosteroid administration in oral and orthog-
nathic surgery: a systematic review of the literature and meta-analysis. J Oral Maxillofac Surg 2010;68:2207–20. 25. Logemann JA. Evaluation and treatment of swallowing disorders. 2nd ed. Austin, Texas; 1998: 23–35.
Address: Shunsuke Namaki Department of Oral and Maxillofacial Surgery
Nihon University School of Dentistry 1-8-13 Kanda-Surugadai Chiyoda-ku Tokyo 101-8310 Japan Tel: +81 3 3219 8102 Fax: +81 3 3219 8355 E-mail: [email protected]
Please cite this article in press as: Namaki S, et al. Long-term evaluation of swallowing function before and after sagittal split ramus osteotomy, Int J Oral Maxillofac Surg (2014), http://dx.doi.org/10.1016/j.ijom.2014.03.001
Int. J. Oral Maxillofac. Surg. 2014; xxx: xxx–xxx http://dx.doi.org/10.1016/j.ijom.2014.03.001, available online at http://www.sciencedirect.com
Clinical Paper Orthognathic Surgery
Long-term evaluation of swallowing function before and after sagittal split ramus osteotomy
S. Namaki1, N. Maekawa1, J. Iwata1, K. Sawada2, M. Namaki3, T. Bjornland4, Y. Yonehara1 1
Department of Oral and Maxillofacial Surgery, Nihon University School of Dentistry, Tokyo, Japan; 2Department of Oral and Maxillofacial Radiology, Nihon University School of Dentistry, Tokyo, Japan; 3 Department of Oral and Maxillofacial Surgery, Juntendo University School of Medicine, Tokyo, Japan; 4Department of Oral Surgery and Oral Medicine, Faculty of Dentistry, University of Oslo, Oslo, Norway
S. Namaki, N. Maekawa, J. Iwata, K. Sawada, M. Namaki, T. Bjornland, Y. Yonehara: Long-term evaluation of swallowing function before and after sagittal split ramus osteotomy. Int. J. Oral Maxillofac. Surg. 2014; xxx: xxx–xxx. # 2014 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. Abstract. The aim of this study was to determine whether mandibular setback by sagittal split ramus osteotomy (SSRO) influences swallowing function. The subjects were 14 patients with skeletal class III malocclusions who underwent setback surgery by SSRO. Morphological changes were studied on cephalograms, and swallowing function was evaluated by videofluorography before the operation (T0) and at 7–10 days (T1), 3 months (T2), and 6 months (T3) after surgery. The angle between nasion, sella, and hyoid bone (HSN) and the sella–hyoid distance had increased significantly at T1. The hyoid bone returned to the preoperative position at T2. There were no significant changes in the oropharyngeal space at any time. On videofluorographic assessment, lingual movement, soft palate movement, and epiglottic movement had decreased at T1, but all patients recovered at T2. The oral transit time was significantly longer at T1 than at T0. Our results confirm that SSRO influences swallowing function. Swallowing function appears to stabilize by 3 months after surgery.
The sagittal split ramus osteotomy (SSRO) is a common treatment for mandibular prognathism and results in functional and aesthetic improvements. Mandibular setback influences the tongue and pharyngeal airway.1,2 Several studies have shown changes in craniofacial, tongue, hyoid, and pharyngeal morphology after mandibular setback surgery.3–11 Such changes include a reduction in pharyngeal airway volume and changes in the tongue and hyoid positions 0901-5027/000001+06 $36.00/0
on static imaging techniques, such as lateral and posterior–anterior cephalography, computed tomography (CT),8–10 and magnetic resonance imaging (MRI)11; however the functional consequences of these changes remain unclear. Previous studies have assessed the effects of mandibular setback surgery on masticatory function,12,13 stomatognathic function,14 sleep apnea,1,2 psychosocial status,15 and articulation.16 However, whether or not mandibular setback affects
Key words: swallowing function; orthognathic surgery; oropharyngeal airway; hyoid bone. Accepted for publication 3 March 2014
swallowing movements remains a matter of debate. Changes in tongue position may influence swallowing function during the oral preparatory phase and oral phase. Altered hyoid position and pharyngeal airway volume may affect swallowing function during the pharyngeal phase. Generally, the effects of various diseases on swallowing function are evaluated by videofluorography,17–19 which is used to assess the oral and pharyngeal transit times.20
# 2014 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
Please cite this article in press as: Namaki S, et al. Long-term evaluation of swallowing function before and after sagittal split ramus osteotomy, Int J Oral Maxillofac Surg (2014), http://dx.doi.org/10.1016/j.ijom.2014.03.001
YIJOM-2870; No of Pages 6
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Namaki et al.
The aim of this study was to investigate the effects of SSRO and mandibular setback on craniofacial and pharyngeal morphology and on swallowing function. Craniofacial and pharyngeal morphology and swallowing function were evaluated by videofluorography before and after SSRO. Materials and methods Subjects
The subjects were 14 patients (two men and 12 women; average age 25.9 10.6 years) with dentofacial deformities, who had skeletal class III malocclusion with or
without open bite and asymmetry. The patients underwent SSRO in the department of oral and maxillofacial surgery of the study hospital. Patients who underwent Le Fort I osteotomy were excluded. All subjects received preoperative and postoperative orthodontic treatment. SSRO was performed according to the Obwegeser21 and Dal Pont22 method. The fragments were fixed with the use of titanium plates (Wu¨rzburg Titanium Plating System; Stryker Leibinger GmbH, Freiburg, Germany) and resorbable fixation devices (Super Fixsorb-MX; Takiron Co., Osaka, Japan). Each subject received a preoperative dose of dexamethasone (mean dose 4.5 mg) immediately prior to surgery,
followed by postoperative treatment with dexamethasone (mean dose 2.1 mg/day) for 2 days to control postoperative swelling. The average amount of mandibular setback was 7.65 3.23 mm. Intermaxillary fixation with the use of elastics or steel wires was maintained for 4–6 days postoperatively. Informed consent was obtained from all subjects after explaining the study procedures in detail. The protocol was approved by the institutional ethics committee. Cephalometric analysis
Morphological changes were evaluated on lateral cephalometric radiographs that
Fig. 1. Cephalometric linear and angular measurements. (1) sella–nasion–A point (SNA) angle. (2) sella–nasion–B point (SNB) angle. (3) A point–nasion–B point (ANB) angle. (4) HSN angle: angle between nasion, sella, and hyoid bone (lowest point of hyoid bone). (5) S–H: distance from sella to hyoid bone. (6) C3–H: distance from the most antero-inferior point of the third cervical vertebra to the hyoid bone. (7) D1: distance from posterior nasal spine (PNS) to the dorsum of the tongue on a line perpendicular to the S–N line. (8) PPS: distance from posterior pharyngeal wall to the PNS on a line parallel to the Frankfort horizontal (FH) plane. (9) SPPS: distance from the posterior pharyngeal wall to the middle of the line from PNS to PSP (tip of the soft palate) on a line parallel to the FH plane. (10) MPS: distance from the posterior pharyngeal wall to the dorsum of the tongue on a line parallel to the FH plane that runs through PSP. (11) IPS: distance from the posterior pharyngeal wall to the surface of the tongue on a line parallel to the FH plane that runs through C2 (the most antero-inferior point of the second cervical vertebra). (12) EPS: distance from the posterior pharyngeal wall to the tip of the epiglottis on a line parallel to the FH plane.
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Swallowing function before and after SSRO were taken with the Frankfort horizontal plane (FH plane) parallel to the floor and with the patient in centric occlusion. Evaluations were performed before surgery (T0) and at 7–10 days (T1), 3 months (T2), and 6 months (T3) after surgery. All cephalograms were traced and analyzed by the same examiner. Fig. 1 shows the landmarks and contours that are commonly used for orthodontic analysis, as well as additional variables that were used to evaluate the pharyngeal airway. Four angles and three linear distances were measured to assess dentoskeletal morphological changes. Five linear distances were calculated to evaluate the pharyngeal airways. Videofluorography
Table 1. Cephalometric angular and linear measurements.* (1) (2) (3) (4) (5) (6) (7) * y
T1
T2
T3
81.2 3.7 80.0 4.2y 1.2 2.3y 92.9 4.5y 129.3 8.8y 43.7 6.0 14.1 4.2
81.4 3.8 80.6 4.3 0.8 2.1 91.4 4.9 119.7 7.9 40.5 5.6 13.8 4.2
81.2 3.6 80.1 3.7 1.1 2.0 91.7 4.2 119.7 7.9 40.2 3.4 12.1 3.6
For measurements see Fig. 1. P < 0.05.
(8) PPS, mm (9) SPPS, mm (10) MPS, mm (11) IPS, mm (12) EPS, mm
T0
T1
T2
T3
26.8 5.2 15.9 4.0 20.8 6.1 16.8 5.0 16.2 4.1
25.9 5.0 14.4 3.7 17.9 5.3 15.4 4.8 16.5 3.6
27.0 4.5 15.2 3.6 19.0 5.7 15.4 5.8 15.7 5.6
27.6 4.2 14.8 4.0 18.8 5.5 15.8 4.7 16.2 3.7
For measurements see Fig. 1.
and after SSRO were adjusted with the use of the Bonferroni correction. A significance level of 5% was used throughout the study. The statistical analysis was performed using SPSS statistical software (Dr. SPSS II for Windows; SPSS Japan Inc., Tokyo, Japan).
changes in the oropharyngeal spaces at any time point. However, the MPS distance (distance from the posterior pharyngeal wall to the dorsum of the tongue on a line parallel to the FH plane that runs through the tip of the soft palate) after surgery (T1, T2, T3) was slightly shorter than that before surgery.
Results Cephalometric analysis
Videofluorography
Tables 1 and 2 show the cephalometric angular and linear measurements and the width of the oropharynx. The angle between nasion, sella, and hyoid bone (HSN) and the distance from sella to hyoid bone (S–H) increased significantly at T1, but there was no change at T2 or T3. The hyoid bone returned to the preoperative position at T2. There were no significant
Table 3 shows the results of videofluorographic qualitative evaluations before and after SSRO. Lingual movement, soft palate movement, epiglottic movement, and oral cavity stasis decreased at T1, but recovered in all patients at T2. Lingual movement and soft palate movement were poor in 10 or more patients, and stasis in the epiglottic valleculae and in the oral
Table 3. Variables qualitatively evaluated by videofluorography before and after SSRO in 14 patients. T0
T1
T2
T3
Lingual movement
Move: 13 Poor: 1
Move: 3 Poor: 11
Move: 13 Poor: 1
Move: 12 Poor: 2
Barium inflow into pharynx before swallowing
Yes: 0 No: 14
Yes: 2 No: 12
Yes: 0 No: 14
Yes: 0 No: 14
Soft palate movement
Move: 14 Poor: 0
Move: 4 Poor: 10
Move: 14 Poor: 0
Move: 12 Poor: 2
Epiglottic movement
Move: 13 Poor: 1
Move:4 Poor: 10
Move: 14 Poor: 0
Move: 13 Poor: 1
Stasis in epiglottic valleculae
Yes: 5 No: 9
Yes: 9 No: 5
Yes: 3 No: 11
Yes: 2 No: 12
Stasis in oral cavity after swallowing
Yes: 0 Little: 8 No: 6
Yes: 4 Little: 10 No: 0
Yes: 1 Little: 11 No: 2
Yes: 0 Little: 8 No: 6
Data analysis
Data were analyzed by conventional statistical methods. The mean, range, and standard deviation were calculated for each variable. Values obtained before
T0 81.1 3.8 84.1 4.6 3.0 2.9 90.0 5.0 118.3 9.1 40.6 5.7 14.7 4.3
Table 2. Width of the oropharynx.*
*
Swallowing was assessed by videofluorography in all patients. Videofluorography was performed before SSRO, at 4–6 days after the release of intermaxillary fixation, and at 3 and 6 months after surgery to qualitatively and quantitatively analyze deglutition. The contrast material used was 10 ml of liquid barium. Images were recorded, converted digitally, and analyzed with InterVideo WinDVD Creator software (InterVideo, Inc., Fremont, CA, USA). Qualitative assessments included lingual movement, barium inflow into the pharynx before swallowing, soft palate movement, epiglottic movement, stasis in the epiglottic valleculae, and stasis in the oral cavity after swallowing. Swallowing was also assessed quantitatively. The oral transit time, pharyngeal transit time, and total transit time were measured before and after SSRO, and the values were compared. The oral transit time was defined as the time required for the barium to move through the oral cavity, measured from the first backward movement of the barium until the head of the barium passed the lowest point of the mandibular ramus. The pharyngeal transit time was defined as the time required for the barium to move through the pharynx, measured from the time that the head of the barium passed the lowest point of the mandibular ramus until the tail of the barium left the cricopharyngeal region. The oral transit time and pharyngeal transit time were summed to derive the total transit time.
SNA,8 SNB,8 ANB,8 HSN,8 S–H, mm C3–H, mm D1, mm
SSRO, sagittal split ramus osteotomy.
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Fig. 2. Videofluorometric quantitative evaluation (time, s). The oral transit time was significantly longer at T1 than T0. The pharyngeal transit time was significantly decreased at T1 compared to T0. There were no significant differences in the total transit time at any time point.
cavity after swallowing was observed in most patients at T1. Fig. 2 shows the oral transit time, pharyngeal transit time, and total transit time. The mean oral transit time increased significantly from 0.41 0.19 s before the operation to 0.58 0.25 s at T1. However, oral transit times at T3 and T4 were significantly shorter than the oral transit time at T1. The mean pharyngeal transit time decreased significantly from 0.30 0.08 s before the operation to 0.25 0.10 s at T1. The pharyngeal transit time at T4 was significantly longer than that at T1. There were no significant differences in the total transit time at any time point. Swallowing function had improved on quantitative assessment at 3 months (T2) after orthognathic surgery. This did not change even after 6 months (T3).
Discussion
Normal occlusion can be obtained after mandibular setback surgery in patients with skeletal class III jaw deformities. Mandibular setback causes changes in the pharyngeal airway space,4,5,8–11 as well as the positions of the hyoid bone3,5,6 and tongue.7 It is important to assess the pharyngeal airway and hyoid bone position. These previous studies demonstrated changes in the pharyngeal airway and surrounding hard and soft tissues on Xray examination and MRI, but no functional assessments were done. Other studies have performed functional assessments to assess masticatory function,12–14 stomatognathic function,15 articulation,16
and oxygen saturation,1 but not swallowing function. Swallowing is one of the most important functions of the oral cavity and pharynx. The oral preparatory phase, oral phase, and pharyngeal phase of swallowing are negatively affected by orthognathic surgery. This phenomenon is apparently caused by changes in the position of the mandible, hyoid bone, tongue, and suprahyoid muscles. Generally, the administration of steroids is routine to reduce the swelling after orthognathic surgery. Swelling after orthognathic surgery is expected to affect swallowing function. Some studies have evaluated the use of steroids for reducing postoperative oedema after orthognathic surgery.23,24 The authors administered steroids to all patients who underwent orthognathic surgery in order to reduce the postoperative oedema. The influence of postoperative oedema on swallowing function was thus prevented by the administration of steroids. Videofluorography has been used to examine the anatomy of the oral cavity and pharynx and to examine the pharynx and larynx before and after swallowing.25 The effects of orthognathic surgery and associated morphological changes were evaluated by performing videofluorography before and after surgery in the same patient. It is important to follow-up the same patient over the course of time. In the present study, lateral cephalograms were use to assess craniofacial and pharyngeal morphology. This technique has the advantage of low cost, convenience, high reproducibility, and minimal exposure to radiation. Techni-
ques such as three-dimensional CT and MRI are associated with high costs and high radiation. Our results showed that the position of the hyoid bone was significantly displaced downward and backward early after surgery and gradually returned to its original position by 3 months after surgery. The gradual return of the hyoid bone to its original position has been reported previously in patients who have undergone mandibular setback surgery.1,5 The oropharyngeal space did not change significantly, but narrowed slightly immediately after setback surgery. Jakobsone et al. found no change in cephalometric measurements of the oropharyngeal space after orthognathic surgery, as well as no change in cross-sectional areas calculated from CT scans.9 However, there was a significant increase in the oropharyngeal volume after surgery. That study was unable to confirm a correlation between the measurements on CT scans and corresponding measurements on lateral cephalograms of the oropharyngeal airway. Therefore, evaluation of the oropharynx on the basis of only still images appears to have its limitations. The authors performed videofluorographic examinations to assess qualitative and quantitative dynamics. Videofluorography may be a useful method for evaluating the function of the oral cavity and pharyngeal airway. The characteristics of swallowing can vary considerably and depend on the individual subject. Therefore, it is important to perform follow-up observations in the same patient. On qualitative videofluorographic assessment, lingual movement, soft palate
Please cite this article in press as: Namaki S, et al. Long-term evaluation of swallowing function before and after sagittal split ramus osteotomy, Int J Oral Maxillofac Surg (2014), http://dx.doi.org/10.1016/j.ijom.2014.03.001
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Swallowing function before and after SSRO movement, epiglottic movement, and oral cavity stasis decreased at T1, but recovered in all patients by T2. Stasis in the epiglottic valleculae and the oral cavity after swallowing was observed in most patients early after surgery. Barium was also found to remain in the oral cavity after deglutition. On qualitative evaluation, the oral transit time early after surgery was significantly prolonged as compared with the value before surgery. Cephalometric analysis showed that the hyoid bone position moved downward and backward at T1 as compared with that before the operation. The position of the hyoid bone and contraction of the suprahyoid muscles during swallowing were thus altered after orthognathic surgery. The positions of the tongue and suprahyoid muscles changed, and these muscles could not move in synchrony. These findings indicate that the oral transit time is prolonged in the early postoperative period. The pharyngeal transit time was significantly shorter early after surgery than before surgery. On qualitative assessment, stasis in the epiglottic valleculae and the oral cavity after swallowing were observed in most patients in the early postoperative period. Cephalometric analysis showed that the width of the oropharynx decreased slightly early after surgery. Shortening of the pharyngeal transit time was associated with a decreased volume of barium in the oral cavity. In conclusion, the oral transit time was significantly shorter at T2 and T3 than at T1, and the pharyngeal transit time was significantly longer at T3 than at T1. There were no differences in total transit time at any time point. On qualitative assessment, all elements tended to improve during the 3 months after surgery. On cephalometric analysis, the position of the hyoid bone and width of the oropharynx at T2 had returned to their preoperative status. Therefore, swallowing function appears to stabilize by 3 months after surgery. Funding
This study was supported by a Grant from Sato Fund, Nihon University School of Dentistry, and a Grant-in-Aid for Scientific Research (C) from the Japanese Society for the Promotion of Science (24593063). Competing interests
There is no conflict of interest related to the individual authors’ commitments and any project support.
Ethical approval
The protocol was approved by the Ethics Committee of Nihon University School of Dentistry (2012-8). Patient consent
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Address: Shunsuke Namaki Department of Oral and Maxillofacial Surgery
Nihon University School of Dentistry 1-8-13 Kanda-Surugadai Chiyoda-ku Tokyo 101-8310 Japan Tel: +81 3 3219 8102 Fax: +81 3 3219 8355 E-mail: [email protected]
Please cite this article in press as: Namaki S, et al. Long-term evaluation of swallowing function before and after sagittal split ramus osteotomy, Int J Oral Maxillofac Surg (2014), http://dx.doi.org/10.1016/j.ijom.2014.03.001
