Accepted Manuscript Maxillary Posterior Segmentation Using an Oscillating Saw in Le Fort I Posterior or Superior Movement without Pterygomaxillary Separation Nara Kang, DDS, PhD Kyung-Gyun Hwang, DDS, PhD Chang-Joo Park, DDS, PhD PII:
S0278-2391(14)00420-0
DOI:
10.1016/j.joms.2014.04.007
Reference:
YJOMS 56289
To appear in:
Journal of Oral and Maxillofacial Surgery
Received Date: 23 May 2013 Revised Date:
10 April 2014
Accepted Date: 10 April 2014
Please cite this article as: Kang N, Hwang K-G, Park C-J, Maxillary Posterior Segmentation Using an Oscillating Saw in Le Fort I Posterior or Superior Movement without Pterygomaxillary Separation, Journal of Oral and Maxillofacial Surgery (2014), doi: 10.1016/j.joms.2014.04.007. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT
Maxillary Posterior Segmentation Using an Oscillating Saw in Le Fort I
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Posterior or Superior Movement without Pterygomaxillary Separation
Nara Kang, DDS, PhD,* Kyung-Gyun Hwang, DDS, PhD,† and Chang-Joo Park, DDS, PhD‡
*
Professor, Division of Oral and Maxillofacial Surgery, Department of Dentistry, College of
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†
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Private Practice, Apgujeong New Face Surgery, Seoul, South Korea
Medicine, Hanyang University, Seoul, South Korea ‡
Assistant Professor, Division of Oral and Maxillofacial Surgery, Department of Dentistry,
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College of Medicine, Hanyang University, Seoul, South Korea
Address correspondence and reprint requested to Prof. Chang-Joo Park:
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Room 540, College of Medicine, Hanyang University,
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Haengdang-dong 17, Seongdong-gu, 133-791, Seoul, South Korea
Tel.: +82-2-2290-8646 Fax: +82-2-2290-8673
e-mail: [email protected]
ACCEPTED MANUSCRIPT Purpose: Any remaining tuberosity or pterygoid plate frequently interferes with posterior or superior movement of the maxilla, if no pterygomaxillary separation is performed in lowlevel Le Fort I osteotomy. The objective in this study was to describe a technique for
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maxillary posterior segmentation using an oscillating saw in Le Fort I posterior or superior movement without pterygomaxillary separation and to present our preliminary multicenter experience with this technique.
SC
Materials and Methods: We retrospectively evaluated patients who underwent double jaw surgery at three orthognathic surgery centers from May 2010 to December 2012. In all cases,
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the segmentation procedure was performed using an oscillating saw on a posterior or tuberosity area of the maxilla following downfracture obtained by leverage alone without pterygomaxillary separation, below or near the lower part of the pterygoid plate. Results: A total of 1,231 patients (411 males and 820 females; mean age, 24.9 years) were
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enrolled. Mean surgical time for the maxillary procedure was 55.9 minutes. None of the patients received a blood transfusion, and no significant soft or hard tissue complications clinically compromised the healing of the repositioned maxilla. The mean amounts of
EP
maxillary posterior and superior movement were 3.4 mm (range, 2.1 to 5.6 mm) and 4.0 mm
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(range, 1.3 to 5.6 mm), respectively. Conclusions: Our preliminary results indicate that our maxillary posterior segmentation procedure using an oscillating saw in low-level stepped Le Fort I osteotomy could be completed safely and effectively for posterior or superior repositioning of the maxilla with no need to disturb the integrity of the pterygoid plate.
1
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Introduction
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The Le Fort I osteotomy is a safe, reliable, and predictable procedure to correct dentofacial deformities.1 While a number of techniques and instruments are available to achieve safe pterygomaxillary separation during a conventional Le Fort I osteotomy, concerns about the
SC
risk of complications resulting from pterygomaxillary separation have led to the development of the leverage-alone technique, which avoids the use of osteotomes for pterygomaxillary
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dysjunction, and low-level osteotomy techniques anterior to the pterygomaxillary junction.2 However, these techniques have not been widely adopted even though they can facilitate successful repositioning of the maxilla.3
The Le Fort I osteotomy with a total maxillary setback or posterior impaction is frequently
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indicated in patients with bimaxillary protrusion, which is a common dentofacial pattern in Asians.4 In addition, since introduction of the concept of minimal orthodontic preparation prior to orthognathic surgery, or “surgery first,”5,6 the demand for maxillary surgery has been
EP
increasing. In cases of posterior or superior movement of the maxilla, in particular,
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reduction of the maxillary posterior area (tuberosity) or the pterygoid plate, which can limit the precise repositioning of the downfractured maxilla, is essential. In this study, we describe a simple technique for maxillary posterior segmentation using an oscillating saw after accomplishing maxillary downfracture using leverage alone without pterygomaxillary separation in low-level stepped Le Fort I osteotomy. This technique reduces interference with the pterygoid plate in posterior or superior movements of the maxilla. We 2
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also report our preliminary retrospective results using this technique in a multicenter setting.
3
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Materials and Methods
Between May 2010 and December 2012, we retrospectively evaluated patients who underwent surgery from three orthognathic surgery centers (two were private clinics and one
SC
was university hospital). At all three centers, the attending surgeon used this technique for the
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maxillary osteotomy. Patients were required to be 1) non-syndromic, 2) diagnosed with maxillary excess or protrusion, 3) treated by this technique in combination with mandibular surgery, either sagittal split ramus osteotomy (SSRO) or intraoral vertico-sagittal ramus osteotomy (IVSRO),6 and 4) followed clinically and radiologically for up to one year after surgery. The amounts of Le Fort I maxillary posterior and superior movement were
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determined on lateral cephalographs, which were serially taken, traced and overlapped. Guidelines of the Helsinki Declaration were followed at all treatment phases. As a
AC C
board (IRB).
EP
retrospective analysis, this study was granted an exemption from the institutional review
4
ACCEPTED MANUSCRIPT
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Surgical Technique
An overall schematic drawing of our technique is presented in Fig. 1. The anterior cut is initiated at the piriform aperture and courses laterally. The term of “low-level” Le Fort I is
SC
selected in contradistinction to “high” Le Fort I, which is relatively more familiar to surgeons.2,7 The posterior horizontal cut, which is performed 5 mm above the root apices of
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the maxillary molars, is located inferiorly to the anterior cut. These two parallel cuts are connected with a vertical cut at the level of the maxillary first molar.8 After routine osteotomies in the lateral wall and septum of the nose, the straight lateral nasal wall osteotomes are inserted in cuts in the medial antral walls to the point of change in timbre,
TE D
and maxillary downfracture is accomplished by bilateral application and leverage using superior ramus separators. Because the posterior horizontal cut is positioned below or near the lower part of the pterygomaxillary junction (Fig. 2), no pterygomaxillary separation is
EP
indicated. The pterygoid plate usually remains intact after maxillary downfracture.
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A grooving osteotomy surrounding the pyramidal osseous portion, including the descending palatine artery, is carried out using a round bur.9 This pyramidal portion is gently twisted and removed using rongeurs, which are positioned on the groove. The artery is then easily exposed and saved. The oscillating saw is placed in the posterior area or tuberosity of the maxilla, behind the exposed artery (Fig. 3). Compared to osteotomes, the oscillating saw produces thin and delicate cuts, causing minimal damage to or perforation of the thick and 5
ACCEPTED MANUSCRIPT mobile mucosa of the soft palate, even though sawing is performed in a full-depth manner (Fig. 4). Complete mobilization of the posterior segment is confirmed by inserting the curved periosteal elevator in the osteotomy line. This posterior segment is generally overlapping and
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does not interfere in repositioning of the maxilla; however, removal of the posterior segment is required for maxillary setback.
If the posterior area is occupied by the maxillary third molars, extraction is performed
SC
before the vestibular incision for maxillary procedure. However, deeply impacted third molars are removed by sinus floor approach after maxillary downfracture. Moreover,
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simultaneous removal of the third molars facilitates posterior segmentation, because the extraction socket decreases the amount of bone removal. More precise bony adjustments are conducted as planned, and rigid fixation of the repositioned maxilla is achieved in a standard
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EP
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manner.
6
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Results
Of 1,231 patients, 411 were male and 820 were female (mean age, 24.9 years; age range, 18.1 to 43.4 years). Mean surgery time of the maxillary procedure was 55.9 minutes (range, 35 to
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91 minutes). Mandibular surgery types were SSRO (499 patients) and IVSRO (732 patients). The mean amounts of maxillary posterior and vertical movement were 3.4 mm (range, 2.1 to
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5.6 mm) and 4.0 mm (range, 1.3 to 5.6 mm), respectively. Patients were discharged from the hospital after an average of 2 days (range, 2 to 5 days). Significant neurovascular complications requiring blood transfusion were not noted in any patient. In addition, no significant soft or hard tissue complications clinically compromised the healing of the
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EP
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repositioned maxilla in any patient.
7
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Discussion
In addition to the rare incidences of serious vascular, neurological, or ophthalmic complications following Le Fort I osteotomy,10-13 there is the possibility of direct or indirect
SC
injury to structures in the pterygoid plate and the adjacent skull base region during pterygomaxillary separation with osteotomes. Patterns of fracture of the pterygoid plates are
M AN U
difficult to predict, regardless of the use/non-use14 of osteotomes or the type of osteotomes,1,15 and despite the various techniques and instruments that were specifically designed for pterygomaxillary dysjunction in conventional Le Fort I osteotomy. Attempts to reduce these complications have resulted in the development of techniques for low-level Le
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Fort I osteotomy that do not require pterygomaxillary separation, such as the leverage-alone technique16 or tuberosity osteotomy.2,7,17,18
Low-level maxillary osteotomies, including Le Fort I and posterior maxillary segment
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osteotomies, were first described by Wassmund and Schuchardt,17,18 and a modified
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procedure was suggested by West and Epker.19 In both these procedures, the highest-risk site of separation is at the junction of the osseous tuberosity and the anterior aspect of the pterygoid plate.7 This region is traditionally difficult to visualize and should be approached with caution due to the proximity of the internal maxillary artery and the pterygoid venous plexus,7 mainly because posterior segment osteotomy is carried out before maxillary downfracture. In our technique, because the maxillary downfracture is already achieved by leverage without pterygomaxillary dysjunction, posterior segmentation of the tuberosity area 8
ACCEPTED MANUSCRIPT of the maxilla can be easily and safely performed with an oscillating saw with full visualization. Unfavorable fractures of the pterygoid plate are also less likely, and in particular, there is no need to disturb the integrity of the high risk zone,2 including the
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pterygoid plate, even in cases of posterior or superior movement of the maxilla. Because our technique involves the use of an oscillating saw, some surgeons might be concerned about the possibility of soft tissue damage to the tuberosity sites or the palatal
SC
mucosa. Soft tissue damage may be even more of a concern in cases where simultaneous removal of the maxillary third molars is required. However, if the buccal posterior pedicle
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and the descending palatine artery are properly protected and secured during sawing,20 healing of the repositioned maxilla is not compromised, despite small perforations or cuts in the palatal mucosa. Usually, partially or fully impacted maxillary third molars do not result in complications when using this technique. However, in cases of erupted maxillary third molars
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that are removed before maxillary downfracture, buccal soft tissue pedicles of the extraction sites should be carefully protected by tunneling and retraction to prevent the damage by oscillating saw. As shown in our recent report using 3 dimensional cone-beam computed
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tomography,21 this technique has the additional advantage of minimizing volumetric changes in the upper airway following bimaxillary surgery for skeletal Class III malocclusions.
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Minimization of the pushing effect of the posterior segment of the maxilla, which is overlapped or removed by this technique, on the upper airway could explain these controversial findings.
In conclusion, maxillary downfracture is achieved without pterygomaxillary separation in low-level Le Fort I osteotomy, as stepped osteotomies are located below or near the lower part of the pterygomaxillary junction. Our preliminary results from 1,231 patients show that 9
ACCEPTED MANUSCRIPT segmentation of the maxillary posterior or tuberosity area by an oscillating saw could be safely and effectively performed for posterior or superior repositioning of the maxilla while ensuring the integrity of structures in the high risk zone, including the pterygoid plate.
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However, further comparative study to contrast between this technique and the conventional
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pterygomaxillary separation using an osteotome in Le Fort I osteotomy will be needed.
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Acknowledgements
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This work was supported by the research fund of Hanyang University (HY-2012-MC).
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References
1. Hernández-Alfaro F, Guijarro-Martínez R: "Twist technique" for pterygomaxillary dysjunction in minimally invasive Le Fort I osteotomy. J Oral Maxillofac Surg
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71:389, 2013
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2. O'Regan B, Bharadwaj G: Prospective study of the incidence of serious posterior maxillary haemorrhage during a tuberosity osteotomy in low level Le Fort I operations. Br J Oral Maxillofac Surg 45:538, 2007
3. O'Regan B, Bharadwaj G: Pterygomaxillary separation in Le Fort I osteotomy UK
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OMFS consultant questionnaire survey. Br J Oral Maxillofac Surg 44:20, 2006 4. Choi BK, Yang EJ, Oh KS, et al: Assessment of blood loss and need for transfusion
71:358, 2013
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during bimaxillary surgery with or without maxillary setback. J Oral Maxillofac Surg
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5. Lee NK, Kim YK, Yun PY, et al: Evaluation of post-surgical relapse after mandibular setback surgery with minimal orthodontic preparation. J Craniomaxillofac Surg 41:47, 2013
6. Choung PH: A new osteotomy for the correction of mandibular prognathism: techniques and rationale of the intraoral vertico-sagittal ramus osteotomy. J Craniomaxillofac Surg 20:153, 1992 12
ACCEPTED MANUSCRIPT 7. Trimble LD, Tideman H, Stoelinga PJ: A modification of the pterygoid plate separation in low-level maxillary osteotomies. J Oral Maxillofac Surg 41:544, 1983 8. Kaminish RM, Davis WH, Hochwald DA, et al: Improved Maxillary stability with
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modified Le Fort I technique. J Oral Maxillofac Surg 41:203-205, 1983 9. Johnson LM, Arnett GW: Pyramidal osseous release around the descending palatine
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artery: a surgical technique. J Oral Maxillofac Surg 49:1356, 1991
10. Lanigan DT, Tubman DE: Carotid-cavernous sinus fistula following Le Fort I
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osteotomy. J Oral Maxillofac Surg 45:969, 1987
11. Newlands C, Dixon A, Altman K: Ocular palsy following Le Fort 1 osteotomy: a case report. Int J Oral Maxillofac Surg 33:101, 2004
12. Procopio O, Fusetti S, Liessi G, et al: False aneurysm of the sphenopalatine artery
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after a Le Fort I osteotomy: report of 2 cases. J Oral Maxillofac Surg 61:520, 2003 13. Hanu-Cernat LM, Hall T: Late onset of abducens palsy after Le Fort I maxillary
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osteotomy. Br J Oral Maxillofac Surg 47:414, 2009
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14. Precious DS, Goodday RH, Bourget L, et al: Pterygoid plate fracture in Le Fort I osteotomy with and without pterygoid chisel: A computed tomography scan evaluation of 58 patients. J Oral Maxillofac Surg 51:151, 1993 15. Stajcić Z: Altering the angulation of a curved osteotome - does it have effects on the type of pterygomaxillary disjunction in Le Fort I osteotomy? An experimental study. Int J Oral Maxillofac Surg 20:301, 1991
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ACCEPTED MANUSCRIPT 16. Precious DS, Morrison A, Ricard D: Pterygomaxillary separation without the use of an osteotome. J Oral Maxillofac Surg 49:98, 1991 17. Wassmund M: Lehrbuch der praktischen Chirurgie des Mundes und der Kiefer Bd 1.
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Leipzig, Johann Ambrosius Barth, 1939 18. Schuchardt K: Experiences with the surgical treatment of deformities of the jaws: prognathic, micrognathic and open bite, in: Wallace AB (ed.), Second Congress of
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International Society of Plastic Surgeons, London, Livingstone, 1959
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19. West RA, Epker BN: Posterior maxillary sinus: its place in the treatment of dentofacial deformities. J Oral Surg 30:562, 1972
20. Siebert JW, Angrigiani C, McCarthy JG, et al: Blood supply of the Le Fort I maxillary segment: an anatomic study. Plast Reconstr Surg 100:843, 1997
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21. Lee Y, Chun YS, Kang N, et al: Volumetric changes in the upper airway after bimaxillary surgery for skeletal class III malocclusions: A case series study using 3-
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2012
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dimensional cone-beam computed tomography. J Oral Maxillofac Surg 70:2867,
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Figure Legends
FIGURE 1. Schematic drawing of maxillary posterior segmentation using an oscillating saw
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in low-level stepped Le Fort I osteotomy without pterygomaxillary separation.
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FIGURE 2. Skull rapid prototyping model. Note that the posterior horizontal cut is positioned below or near the lower part of the pterygomaxillary junction.
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FIGURE 3. The oscillating saw is placed on the posterior or tuberosity area of the
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downfractured maxilla behind the exposed descending palatine artery (arrow).
FIGURE 4. Cuts produced by the oscillating saw are thin and delicate compared to those
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created by osteotomes.
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S0278-2391(14)00420-0
DOI:
10.1016/j.joms.2014.04.007
Reference:
YJOMS 56289
To appear in:
Journal of Oral and Maxillofacial Surgery
Received Date: 23 May 2013 Revised Date:
10 April 2014
Accepted Date: 10 April 2014
Please cite this article as: Kang N, Hwang K-G, Park C-J, Maxillary Posterior Segmentation Using an Oscillating Saw in Le Fort I Posterior or Superior Movement without Pterygomaxillary Separation, Journal of Oral and Maxillofacial Surgery (2014), doi: 10.1016/j.joms.2014.04.007. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT
Maxillary Posterior Segmentation Using an Oscillating Saw in Le Fort I
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Posterior or Superior Movement without Pterygomaxillary Separation
Nara Kang, DDS, PhD,* Kyung-Gyun Hwang, DDS, PhD,† and Chang-Joo Park, DDS, PhD‡
*
Professor, Division of Oral and Maxillofacial Surgery, Department of Dentistry, College of
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†
SC
Private Practice, Apgujeong New Face Surgery, Seoul, South Korea
Medicine, Hanyang University, Seoul, South Korea ‡
Assistant Professor, Division of Oral and Maxillofacial Surgery, Department of Dentistry,
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College of Medicine, Hanyang University, Seoul, South Korea
Address correspondence and reprint requested to Prof. Chang-Joo Park:
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Room 540, College of Medicine, Hanyang University,
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Haengdang-dong 17, Seongdong-gu, 133-791, Seoul, South Korea
Tel.: +82-2-2290-8646 Fax: +82-2-2290-8673
e-mail: [email protected]
ACCEPTED MANUSCRIPT Purpose: Any remaining tuberosity or pterygoid plate frequently interferes with posterior or superior movement of the maxilla, if no pterygomaxillary separation is performed in lowlevel Le Fort I osteotomy. The objective in this study was to describe a technique for
RI PT
maxillary posterior segmentation using an oscillating saw in Le Fort I posterior or superior movement without pterygomaxillary separation and to present our preliminary multicenter experience with this technique.
SC
Materials and Methods: We retrospectively evaluated patients who underwent double jaw surgery at three orthognathic surgery centers from May 2010 to December 2012. In all cases,
M AN U
the segmentation procedure was performed using an oscillating saw on a posterior or tuberosity area of the maxilla following downfracture obtained by leverage alone without pterygomaxillary separation, below or near the lower part of the pterygoid plate. Results: A total of 1,231 patients (411 males and 820 females; mean age, 24.9 years) were
TE D
enrolled. Mean surgical time for the maxillary procedure was 55.9 minutes. None of the patients received a blood transfusion, and no significant soft or hard tissue complications clinically compromised the healing of the repositioned maxilla. The mean amounts of
EP
maxillary posterior and superior movement were 3.4 mm (range, 2.1 to 5.6 mm) and 4.0 mm
AC C
(range, 1.3 to 5.6 mm), respectively. Conclusions: Our preliminary results indicate that our maxillary posterior segmentation procedure using an oscillating saw in low-level stepped Le Fort I osteotomy could be completed safely and effectively for posterior or superior repositioning of the maxilla with no need to disturb the integrity of the pterygoid plate.
1
ACCEPTED MANUSCRIPT
Introduction
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The Le Fort I osteotomy is a safe, reliable, and predictable procedure to correct dentofacial deformities.1 While a number of techniques and instruments are available to achieve safe pterygomaxillary separation during a conventional Le Fort I osteotomy, concerns about the
SC
risk of complications resulting from pterygomaxillary separation have led to the development of the leverage-alone technique, which avoids the use of osteotomes for pterygomaxillary
M AN U
dysjunction, and low-level osteotomy techniques anterior to the pterygomaxillary junction.2 However, these techniques have not been widely adopted even though they can facilitate successful repositioning of the maxilla.3
The Le Fort I osteotomy with a total maxillary setback or posterior impaction is frequently
TE D
indicated in patients with bimaxillary protrusion, which is a common dentofacial pattern in Asians.4 In addition, since introduction of the concept of minimal orthodontic preparation prior to orthognathic surgery, or “surgery first,”5,6 the demand for maxillary surgery has been
EP
increasing. In cases of posterior or superior movement of the maxilla, in particular,
AC C
reduction of the maxillary posterior area (tuberosity) or the pterygoid plate, which can limit the precise repositioning of the downfractured maxilla, is essential. In this study, we describe a simple technique for maxillary posterior segmentation using an oscillating saw after accomplishing maxillary downfracture using leverage alone without pterygomaxillary separation in low-level stepped Le Fort I osteotomy. This technique reduces interference with the pterygoid plate in posterior or superior movements of the maxilla. We 2
ACCEPTED MANUSCRIPT
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EP
TE D
M AN U
SC
RI PT
also report our preliminary retrospective results using this technique in a multicenter setting.
3
ACCEPTED MANUSCRIPT
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Materials and Methods
Between May 2010 and December 2012, we retrospectively evaluated patients who underwent surgery from three orthognathic surgery centers (two were private clinics and one
SC
was university hospital). At all three centers, the attending surgeon used this technique for the
M AN U
maxillary osteotomy. Patients were required to be 1) non-syndromic, 2) diagnosed with maxillary excess or protrusion, 3) treated by this technique in combination with mandibular surgery, either sagittal split ramus osteotomy (SSRO) or intraoral vertico-sagittal ramus osteotomy (IVSRO),6 and 4) followed clinically and radiologically for up to one year after surgery. The amounts of Le Fort I maxillary posterior and superior movement were
TE D
determined on lateral cephalographs, which were serially taken, traced and overlapped. Guidelines of the Helsinki Declaration were followed at all treatment phases. As a
AC C
board (IRB).
EP
retrospective analysis, this study was granted an exemption from the institutional review
4
ACCEPTED MANUSCRIPT
RI PT
Surgical Technique
An overall schematic drawing of our technique is presented in Fig. 1. The anterior cut is initiated at the piriform aperture and courses laterally. The term of “low-level” Le Fort I is
SC
selected in contradistinction to “high” Le Fort I, which is relatively more familiar to surgeons.2,7 The posterior horizontal cut, which is performed 5 mm above the root apices of
M AN U
the maxillary molars, is located inferiorly to the anterior cut. These two parallel cuts are connected with a vertical cut at the level of the maxillary first molar.8 After routine osteotomies in the lateral wall and septum of the nose, the straight lateral nasal wall osteotomes are inserted in cuts in the medial antral walls to the point of change in timbre,
TE D
and maxillary downfracture is accomplished by bilateral application and leverage using superior ramus separators. Because the posterior horizontal cut is positioned below or near the lower part of the pterygomaxillary junction (Fig. 2), no pterygomaxillary separation is
EP
indicated. The pterygoid plate usually remains intact after maxillary downfracture.
AC C
A grooving osteotomy surrounding the pyramidal osseous portion, including the descending palatine artery, is carried out using a round bur.9 This pyramidal portion is gently twisted and removed using rongeurs, which are positioned on the groove. The artery is then easily exposed and saved. The oscillating saw is placed in the posterior area or tuberosity of the maxilla, behind the exposed artery (Fig. 3). Compared to osteotomes, the oscillating saw produces thin and delicate cuts, causing minimal damage to or perforation of the thick and 5
ACCEPTED MANUSCRIPT mobile mucosa of the soft palate, even though sawing is performed in a full-depth manner (Fig. 4). Complete mobilization of the posterior segment is confirmed by inserting the curved periosteal elevator in the osteotomy line. This posterior segment is generally overlapping and
RI PT
does not interfere in repositioning of the maxilla; however, removal of the posterior segment is required for maxillary setback.
If the posterior area is occupied by the maxillary third molars, extraction is performed
SC
before the vestibular incision for maxillary procedure. However, deeply impacted third molars are removed by sinus floor approach after maxillary downfracture. Moreover,
M AN U
simultaneous removal of the third molars facilitates posterior segmentation, because the extraction socket decreases the amount of bone removal. More precise bony adjustments are conducted as planned, and rigid fixation of the repositioned maxilla is achieved in a standard
AC C
EP
TE D
manner.
6
ACCEPTED MANUSCRIPT
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Results
Of 1,231 patients, 411 were male and 820 were female (mean age, 24.9 years; age range, 18.1 to 43.4 years). Mean surgery time of the maxillary procedure was 55.9 minutes (range, 35 to
SC
91 minutes). Mandibular surgery types were SSRO (499 patients) and IVSRO (732 patients). The mean amounts of maxillary posterior and vertical movement were 3.4 mm (range, 2.1 to
M AN U
5.6 mm) and 4.0 mm (range, 1.3 to 5.6 mm), respectively. Patients were discharged from the hospital after an average of 2 days (range, 2 to 5 days). Significant neurovascular complications requiring blood transfusion were not noted in any patient. In addition, no significant soft or hard tissue complications clinically compromised the healing of the
AC C
EP
TE D
repositioned maxilla in any patient.
7
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Discussion
In addition to the rare incidences of serious vascular, neurological, or ophthalmic complications following Le Fort I osteotomy,10-13 there is the possibility of direct or indirect
SC
injury to structures in the pterygoid plate and the adjacent skull base region during pterygomaxillary separation with osteotomes. Patterns of fracture of the pterygoid plates are
M AN U
difficult to predict, regardless of the use/non-use14 of osteotomes or the type of osteotomes,1,15 and despite the various techniques and instruments that were specifically designed for pterygomaxillary dysjunction in conventional Le Fort I osteotomy. Attempts to reduce these complications have resulted in the development of techniques for low-level Le
TE D
Fort I osteotomy that do not require pterygomaxillary separation, such as the leverage-alone technique16 or tuberosity osteotomy.2,7,17,18
Low-level maxillary osteotomies, including Le Fort I and posterior maxillary segment
EP
osteotomies, were first described by Wassmund and Schuchardt,17,18 and a modified
AC C
procedure was suggested by West and Epker.19 In both these procedures, the highest-risk site of separation is at the junction of the osseous tuberosity and the anterior aspect of the pterygoid plate.7 This region is traditionally difficult to visualize and should be approached with caution due to the proximity of the internal maxillary artery and the pterygoid venous plexus,7 mainly because posterior segment osteotomy is carried out before maxillary downfracture. In our technique, because the maxillary downfracture is already achieved by leverage without pterygomaxillary dysjunction, posterior segmentation of the tuberosity area 8
ACCEPTED MANUSCRIPT of the maxilla can be easily and safely performed with an oscillating saw with full visualization. Unfavorable fractures of the pterygoid plate are also less likely, and in particular, there is no need to disturb the integrity of the high risk zone,2 including the
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pterygoid plate, even in cases of posterior or superior movement of the maxilla. Because our technique involves the use of an oscillating saw, some surgeons might be concerned about the possibility of soft tissue damage to the tuberosity sites or the palatal
SC
mucosa. Soft tissue damage may be even more of a concern in cases where simultaneous removal of the maxillary third molars is required. However, if the buccal posterior pedicle
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and the descending palatine artery are properly protected and secured during sawing,20 healing of the repositioned maxilla is not compromised, despite small perforations or cuts in the palatal mucosa. Usually, partially or fully impacted maxillary third molars do not result in complications when using this technique. However, in cases of erupted maxillary third molars
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that are removed before maxillary downfracture, buccal soft tissue pedicles of the extraction sites should be carefully protected by tunneling and retraction to prevent the damage by oscillating saw. As shown in our recent report using 3 dimensional cone-beam computed
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tomography,21 this technique has the additional advantage of minimizing volumetric changes in the upper airway following bimaxillary surgery for skeletal Class III malocclusions.
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Minimization of the pushing effect of the posterior segment of the maxilla, which is overlapped or removed by this technique, on the upper airway could explain these controversial findings.
In conclusion, maxillary downfracture is achieved without pterygomaxillary separation in low-level Le Fort I osteotomy, as stepped osteotomies are located below or near the lower part of the pterygomaxillary junction. Our preliminary results from 1,231 patients show that 9
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However, further comparative study to contrast between this technique and the conventional
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pterygomaxillary separation using an osteotome in Le Fort I osteotomy will be needed.
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Acknowledgements
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This work was supported by the research fund of Hanyang University (HY-2012-MC).
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References
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6. Choung PH: A new osteotomy for the correction of mandibular prognathism: techniques and rationale of the intraoral vertico-sagittal ramus osteotomy. J Craniomaxillofac Surg 20:153, 1992 12
ACCEPTED MANUSCRIPT 7. Trimble LD, Tideman H, Stoelinga PJ: A modification of the pterygoid plate separation in low-level maxillary osteotomies. J Oral Maxillofac Surg 41:544, 1983 8. Kaminish RM, Davis WH, Hochwald DA, et al: Improved Maxillary stability with
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14. Precious DS, Goodday RH, Bourget L, et al: Pterygoid plate fracture in Le Fort I osteotomy with and without pterygoid chisel: A computed tomography scan evaluation of 58 patients. J Oral Maxillofac Surg 51:151, 1993 15. Stajcić Z: Altering the angulation of a curved osteotome - does it have effects on the type of pterygomaxillary disjunction in Le Fort I osteotomy? An experimental study. Int J Oral Maxillofac Surg 20:301, 1991
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ACCEPTED MANUSCRIPT 16. Precious DS, Morrison A, Ricard D: Pterygomaxillary separation without the use of an osteotome. J Oral Maxillofac Surg 49:98, 1991 17. Wassmund M: Lehrbuch der praktischen Chirurgie des Mundes und der Kiefer Bd 1.
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Leipzig, Johann Ambrosius Barth, 1939 18. Schuchardt K: Experiences with the surgical treatment of deformities of the jaws: prognathic, micrognathic and open bite, in: Wallace AB (ed.), Second Congress of
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19. West RA, Epker BN: Posterior maxillary sinus: its place in the treatment of dentofacial deformities. J Oral Surg 30:562, 1972
20. Siebert JW, Angrigiani C, McCarthy JG, et al: Blood supply of the Le Fort I maxillary segment: an anatomic study. Plast Reconstr Surg 100:843, 1997
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21. Lee Y, Chun YS, Kang N, et al: Volumetric changes in the upper airway after bimaxillary surgery for skeletal class III malocclusions: A case series study using 3-
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2012
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Figure Legends
FIGURE 1. Schematic drawing of maxillary posterior segmentation using an oscillating saw
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in low-level stepped Le Fort I osteotomy without pterygomaxillary separation.
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FIGURE 2. Skull rapid prototyping model. Note that the posterior horizontal cut is positioned below or near the lower part of the pterygomaxillary junction.
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FIGURE 3. The oscillating saw is placed on the posterior or tuberosity area of the
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downfractured maxilla behind the exposed descending palatine artery (arrow).
FIGURE 4. Cuts produced by the oscillating saw are thin and delicate compared to those
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created by osteotomes.
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