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Surgically Assisted Maxillary Expansion
Surgically Assisted Maxillary Expansion Norman J. Betts, DDS, MS a,b,c,* KEYWORDS Transverse maxillomandibular discrepancy Stability Surgically assisted maxillary expansion SAME KEY POINTS The transverse dimension of the maxillomandibular complex must be evaluated, diagnosed, and addressed to achieve stability after orthognathic correction. Orthopedic maxillary expansion (nonsurgical) is effective and stable in the young population before sutural closure and is not effective or stable in patients after sutural closure in the maxillofacial complex. Treatment with orthopedic expansion in this group leads to uncontrolled relapse and periodontal and occlusal complications of the teeth after the removal of orthodontic appliances. To achieve the desired expansion and stability, transverse maxillary expansion should be accomplished by sutural adjustments in the craniofacial complex, not by alveolar bending and dental tipping. The SAME (surgically assisted maxillary expansion) procedure is a combination of distraction osteogenesis and controlled soft tissue expansion. After the surgical procedure, the maxilla should remain stationary for at least 5 days before initiation of expansion at a rate of 0.5 mm/d. Surgical transverse changes are unstable for a longer period than are most other surgical or orthodontic movements. It takes approximately 6 months to achieve bony continuity in the midpalatal osteotomy site. Therefore, some form of skeletal retention is recommended for at least 6 to 12 months after expansion.
Introduction: nature of the problem Complete and accurate evaluation of a patient with a dentofacial deformity must include assessment of the transverse dimension. Few practitioners adequately evaluate the transverse dimension, often resulting in undiagnosed transverse maxillomandibular discrepancy. When a transverse maxillomandibular discrepancy exists, adult patients have traditionally been treated with orthodontic expansion or a segmental maxillary osteotomy, frequently leading to transverse maxillary instability and relapse after orthodontic appliance removal. Orthopedic or rapid maxillary expansion (ORME) is also a technique used to treat transverse maxillomandibular discrepancy. If used in the correct patient population, this technique is predicable and stable for the correction of transverse maxillomandibular discrepancy. It is of limited benefit in mature teenage and adult patients, because the maxillary articulations become increasingly resistant to expansion with aging. Techniques of surgically assisted maxillary expansion (SAME) have been developed to overcome this
a Private Practice, Chelsea Oral and Facial Surgery, 1303 South Main Street, Suite B, Chelsea, MI 48118, USA b Private Practice, Ann Arbor Oral and Facial Surgery, 3055 Plymouth Road, Suite 202, Ann Arbor, MI 48105, USA c Department of Oral and Maxillofacial Surgery, University of Michigan School of Dentistry, 3055 Plymouth Road, Suite 202, Ann Arbor, MI 48105, USA * Chelsea Oral and Facial Surgery, 1303 South Main Street, Suite B, Chelsea, MI 48118. E-mail address: [email protected]
Atlas Oral Maxillofacial Surg Clin N Am - (2015) -e1061-3315/15/$ - see front matter ª 2015 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.cxom.2015.10.003
age limitation. The SAME procedure is a combination of distraction osteogenesis and controlled soft tissue expansion. Discussion of SAME is often confusing because various combinations of maxillary, pterygopalatine lateral nasal, septal, and palatine osteotomies have been used, based on the surgeon’s theory of where resistance to expansion is located. The purpose of this article is to describe the clinical and radiographic evaluation of the transverse dimension in patients with dentofacial deformity and to present the indications for SAME and an anatomically based SAME technique.
Surgical technique Preoperative planning Accurate diagnosis and treatment of transverse maxillary deficiency are essential to the long-term stability after correction of any dentofacial deformity that includes a transverse discrepancy. However, diagnosis of transverse maxillary deficiency may be difficult, because minimal facial soft tissue changes are associated with isolated transverse maxillary hypoplasia. In contrast, isolated anteroposterior or vertical skeletal deformities are easier to diagnose, because they often have obvious associated facial soft tissue findings. Consequently, the transverse deformity is often not diagnosed when sagittal and vertical deformities exist concomitantly. Therefore, it is not surprising that clinical inspection for transverse maxillary deficiency has been shown to be of poor diagnostic value. Complete diagnosis of this deformity must include both clinical and radiographic evaluation.
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Clinical evaluation The existence and extent of a transverse discrepancy must be determined and the skeletal and dental components of the deformity must be differentiated before contemplating surgery (Box 1, Fig. 1).
Radiographic evaluation A standard posteroanterior (PA) cephalogram is the radiograph of choice for identification and evaluation of a transverse discrepancy. Ricketts developed the Rocky Mountain analysis and established relative norms using specific radiographic landmarks and measurements to analyze transverse discrepancies between the maxilla and mandible (Box 2, Fig. 2). Using these landmarks, it is possible to determine the effective maxillary width, effective mandibular width, and frontolateral facial lines. The effective maxillary width is the width of the maxilla between the points JL (jugale left) and JR (jugale right). The effective mandibular width is the width of the mandible between AG and GA. The frontolateral facial lines are the lateral lines constructed from OR (orbitale right) and OL (orbitale left) to the points AG and GA, respectively. Using these cephalometric landmarks, it is possible to determine the maxillomandibular width differential and the maxillomandibular transverse differential index for quantification of the transverse maxillary discrepancy (Fig. 3). The maxillomandibular width differential is the distance (in millimeters) measured from the frontolateral facial line to JL and JR, respectively, along a line from the frontolateral facial lines through JR and JL. This measurement is calculated independently for each side and compared with a normal value of 10 1.5 mm. If this value is greater than 10 mm, a transverse discrepancy between the maxilla and mandible exists. The values greater than 10 mm on each side are summed to quantify the total transverse deficiency. This technique is
Box 1. Clinical indicators of transverse maxillary deficiency 1. Facial soft tissue changes including paranasal hollowing, a narrowed alar base, and deepening of the nasolabial folds 2. Negative space (distance between the corner of the mouth and the buccal surfaces of the posterior maxillary teeth during full smile) 3. Unilateral or bilateral posterior crossbite (a distinction must be made between dental and skeletal crossbite) 4. Crowded, rotated, and palatally or buccally displaced teeth 5. Narrow and tapering maxillary arch form, described as hourglass shaped 6. High, narrow palatal arch 7. Associated skeletal deformities include maxillary vertical and anteroposterior hypoplasia and zygomatic hypoplasia (as a result of growth issues) 8. Other associated dentofacial deformities include vertical maxillary excess, mandibular prognathism or mandibular sagittal deficiency, apertognathia, and repaired cleft palate
useful in determining the total discrepancy and showing whether there is a greater deficiency or excess on 1 side or the other. However, this differential does not elucidate in which jaw the discrepancy exists and may be misinterpreted when mandibular asymmetry is present. The maxillomandibular transverse differential index is the age-specific expected maxillomandibular difference minus the actual measured maxillomandibular difference. The expected maxillomandibular difference is the age-appropriate expected AG-GA distance minus the age-appropriate expected JR-JL distance. The actual maxillomandibular difference is the actual AG-GA measurement minus the actual JR-JL measurement. In an adult patient, a maxillomandibular transverse differential index greater than 5 mm suggests a need for surgical expansion. As well as quantifying the total discrepancy, this method allows for the identification of which jaw is deficient or excessive, because actual values can be compared with normal values. Normal values have been suggested only for Caucasian, and these values should not be considered normal values for other races.
Treatment of transverse maxillomandibular discrepancy SAME combines an orthopedic appliance and osteotomies to achieve maxillary skeletal expansion in 1 to 2 weeks (Box 3). The technique chosen to correct the transverse discrepancy is dependent on many factors, but most important is the skeletal maturity of the patient (Box 4). Additional factors include the magnitude of the transverse discrepancy and whether gingival dehiscence or bony fenestration is already present on the maxillary canine and bicuspid teeth. Generally, patients in the primary dentition and the mixed dentition stage are treated by ORME. Transverse maxillary growth ceases and the maxillofacial sutures close at skeletal age 14 to 15 years in females and 15 to 16 years in males. Adults are best treated by SAME or segmental Le Fort osteotomy. After sutural closure, ORME is unsuccessful, because the expansion is composed primarily of alveolar or dental tipping, with little or no skeletal expansion. This situation can lead to many problems in adults, including an inability to activate the appliance, pain on activation, pressure necrosis of the palatal tissue under the appliance, tipping and extrusion of the maxillary teeth, bending of the alveolar bone, uncontrolled relapse after orthodontic appliance removal, and periodontal complications. These periodontal complications result from the tipping of the maxillary teeth out through the buccal cortical bone, resulting in cortical thinning, dehiscence, or fenestration of the maxillary teeth. If gingival inflammation is present, the patient is predisposed to gingival recession and dental instability (Fig. 4). In contrast, if the transverse maxillary deficiency is less than 5 mm of the total maxillomandibular discrepancy, sufficient buccal bone is generally present to allow for some dental tipping. In this case, ORME may be considered if there are no periodontal defects or gingival recession already present in the posterior maxillary quadrants.
Preparation and patient positioning Before the procedure, an expansion device must be placed. The best results are achieved when one of the several variations of the jackscrew appliance is used. To achieve expansion, a palatally positioned jackscrew is placed within a framework
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Fig. 1 (A) Intraoral view of severe transverse maxillary hypoplasia. There is a bilateral palatal crossbite and rotated, crowded, and displaced teeth. (B) Palatal view of a patient with transverse maxillary hypoplasia. Note the narrow, tapering, hourglass-shaped arch form in addition to the narrow and high palatal vault. (From Betts NJ, Vanarsdall RL, Barber HD, et al. Diagnosis and treatment of transverse maxillary deficiency. Int J Adult Orthodon Orthognath Surg 1995;10:77, 91; with permission.)
attached to the first molars and other teeth as available (usually the first bicuspid teeth). The most common jackscrew appliances used today are the Haas and Hyrax. The Haas appliance (Fig. 5) has acrylic palatal flanges incorporated into the appliance, which have been shown to decrease buccal tipping of the dentition and produce greater skeletal expansion. However, because of the acrylic palatal pads, there is a slightly increased risk of palatal tissue impingement, and food can become entrapped beneath the flanges. The Hyrax appliance (Fig. 6) is similar in design to the Haas appliance, with the exception that it does not have the acrylic palatal pads. Its use theoretically results in more dental tipping and less skeletal expansion. The occlusal coverage Haas appliance (Fig. 7) is a hybrid of the Haas appliance with a flat plane occlusal coverage splint. This appliance must be physically bonded to the maxillary teeth. Its use is recommended in patients with periodontally compromised dentition, because the appliance incorporates more of the teeth in the device (not just the first bicuspid and first molar teeth). Therefore, the transverse forces are distributed among more teeth. It may also be useful in patients with temporomandibular joint (TMJ) symptoms, because the appliance can be equilibrated like an occlusal coverage splint during expansion to minimize the premature dental interferences common during the transverse expansion. Like the Haas appliance, it use may result in less dental tipping and more skeletal expansion. However, because of problems with oral hygiene, it must be removed 3 to 4 months after placement and an immediate palatal coverage retainer placed to minimize transverse relapse (Box 4). The 3 principal areas of vertical and horizontal maxillary support are the nasomaxillary, zygomaticomaxillary, and pterygomaxillary buttresses (Fig. 8). The many maxillary
osteotomies that have been empirically proposed to facilitate lateral maxillary expansion reflect the controversy regarding the primary area of resistance to expansion in the craniofacial skeleton. Most recently, investigators have recommended sectioning of virtually all the maxillary bony articulations, that is, zygomaticomaxillary buttresses, midpalatal suture, and pterygomaxillary junction. An investigation by Shetty and coworkers attempted to give a biomechanical rational for the choice of osteotomies by analyzing the internal stress response after SAME in a photoelastic model fabricated from a human skull. A Hyrax appliance was placed and activated, and sequential cuts were performed on the model. The alterations in the internal stresses of the skull were recorded after each cut. All the bony buttresses of the maxilla contributed resistance to expansion, but the midpalatal suture followed by the pterygomaxillary articulations were the primary areas of resistance. These investigators also reported that forces caused by appliance activation have deep anatomic effects, with stresses present at sites distant from the force application. Even although this study has significant validity and reliability problems, it provides important information concerning
Box 2. Skeletal landmarks used in the evaluation of maxillomandibular transverse discrepancy 1. JR (jugale right) and JL (jugale left) (the intersection of the maxillary tuberosity and the zygomatic buttress) 2. AG (antegonion right) and GA (antegonion left) (the inferior margin of the antegonial protuberance, below the antegonial trihedral area) 3. OR (orbitale right) and OL (orbitale left) (representing the intersection of the orbits with the middle cranial fossa)
Fig. 2 The elements of the PA cephalometric analysis. These landmarks can be used to calculate the effective maxillary width and effective mandibular width, and the frontolateral lines can be constructed. (From Betts NJ, Vanarsdall RL, Barber HD, et al. Diagnosis and treatment of transverse maxillary deficiency. Int J Adult Orthodon Orthognath Surg 1995;10:78; with permission.)
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Betts practice should be limited to younger patients, because they require less extensive surgery to accomplish adequate maxillary expansion. Patient positioning in the operating room should be similar to that described for the Le Fort I osteotomy. Nasal intubation is preferred. However, because maxillomandibular fixation is not necessary for this surgical procedure, oral intubation can be used.
Surgical approach Based on the knowledge that the areas of resistance to transverse expansion include all the bony buttresses of the maxilla, the technique advocated is a subtotal Le Fort I maxillary osteotomy (Box 5, Fig. 9). The mandibular dentition should be decompensated before surgery to allow assessment of the amount of transverse expansion necessary and to assist in preventing postexpansion relapse with dental interdigitation. In addition, the maxillary expansion appliance must be placed preoperatively and the appliance key must be present in the operating suite to allow intraoperative activation.
Surgical caveats
Fig. 3 Worksheet used to determine the radiographic magnitude and location of the maxillomandibular transverse discrepancy. (From Betts NJ, Vanarsdall RL, Barber HD, et al. Diagnosis and treatment of transverse maxillary deficiency. Int J Adult Orthodon Orthognath Surg 1995;10:79; with permission.)
the areas of resistance to transverse expansion in the adult human skull. Typically, this procedure is performed in a hospital setting as an outpatient or 24-hour stay procedure. Although SAME has been successfully performed in the outpatient setting, this
During this procedure, the appliance is widened 3 to 4 mm and then turned back to a final opening of 1 to 1.5 mm. The perpendicular plate of the palatine bone is thick and offers significant resistance posteriorly. During maximal expansion, the surgeon should check that both maxillae are adequately mobile. If they are not, the osteotomies should be checked or more surgery performed. Sectioning of the posterior portions of the thin lateral nasal wall is unnecessary because it offers little resistance to transverse expansion. Release of the pterygoid plates is necessary because they are part of the sphenoid, which is a single bone without a midline suture. Therefore, orthopedic forces cannot widen the pterygoid plates, and they should be separated from the maxillae. SAME can also be used in cases of unilateral or asymmetric maxillary deformities. In this situation, the osteotomies outlined earlier are created on only 1 side, thus allowing a differential anchorage situation with more expansion on one side. As would be expected, on the nonoperated side, buccal bone bending and dental tipping occur. After appliance removal, almost complete relapse occurs on the nonoperated side.
Postoperative care, rehabilitation, and recovery
Box 3. Benefits of the SAME procedure 1. Improved dental and skeletal stability 2. Nonextraction orthodontic alignment of the dentition 3. Improved aesthetics by the elimination of negative space (distance between the corner of the mouth and the buccal surfaces of the posterior maxillary teeth during full smile) and a decrease in the buccal hollowing of the lateral maxilla 4. Improved long-term periodontal health 5. Improved nasal respiration as a result of widening of the nasal cavity and internal nasal valve (this widening results from the lateral repositioning of the lateral nasal walls during maxillary expansion)
Routine follow-up care should be similar to that of the Le Fort I osteotomy, with the exception that liquid diet is followed for only the first week and the diet is advanced from that time forward. After the surgical procedure, the maxilla should remain stationary for at least 5 days before initiation of expansion at a rate of 0.5 mm/d (2 activations of the jack screw appliance a day). This strategy is based on Ilizarov’s work in the extremities, which showed that a healing period of 5 days allows for capillary healing across the bony gap. Reestablishment of this blood supply leads to faster and more complete ossification of the expanded defect. Ilizarov showed that an expansion rate of 0.5 to 1 mm/d does not outstrip this critical blood supply. However, in the maxilla, a rate of 0.5 mm/d is recommended. Expansion rates greater than this may cause gingival recession
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Fig. 4 Palatal (A) and lateral (B, C) views of an adult patient who had previously undergone unsuccessful orthopedic rapid maxillary expansion. The expansion has relapsed and has also resulted in significant buccal gingival recession bilaterally in the canine and premolar regions. (From Betts NJ, Vanarsdall RL, Barber HD, et al. Diagnosis and treatment of transverse maxillary deficiency. Int J Adult Orthodon Orthognath Surg 1995;10:84; with permission.)
on the mesial side of the central incisors, especially if bone and attachment loss is already present. During expansion, the patient should feel little discomfort. If pain is experienced, there is bony interference or inadequate mobilization or the appliance is not functioning properly. However, symptoms of tightness and minor discomfort in the nasal root/glabellar area and posterior orbit can and do occur, with anatomic basis. Pain in the nasal root area can be attributed to an outward rotation of the maxillary halves around an axis of rotation located near the frontonasal suture (because the lateral nasal walls are not osteotomized completely during the surgical procedure) (Fig. 10). The pressure felt in the posterior orbit is caused by the small articulation of the palatine bone, which is not sectioned during the surgical procedure. Palatal expansion must occur within 4 weeks of surgery or the osteotomies may heal before the required transverse dimension has been achieved. During the period of expansion, immature attached gingival tissue should be seen medial to each central incisor tooth. This immature attached gingival tissue arises when skeletal or dental expansion exceeds the ability of the attached gingiva to remodel. It is a sign of successful expansion and should appear bilaterally and be
Fig. 5 Clinical example of a Haas palatal expansion device. (From Betts NJ, Vanarsdall RL, Barber HD, et al. Diagnosis and treatment of transverse maxillary deficiency. Int J Adult Orthodon Orthognath Surg 1995;10:83; with permission.)
symmetric. If gingival recession or gapping occurs between the gingiva and the root surface, the expansion rate should be decreased. In contrast to ORME, overcorrection is not recommended for SAME. Surgical transverse changes are unstable for a longer period than are most other surgical or orthodontic movements. It takes approximately 6 months to achieve bony continuity in the midpalatal osteotomy site. Therefore, some form of skeletal retention is recommended for at least 6 to 12 months after expansion. The expansion device can be retained for this purpose or a palatal coverage retainer can be placed (Fig. 11).
Potential complications Intraoperative complications of SAME are similar to those that occur with Le Fort I maxillary osteotomy. Intraoperative hemorrhage can be limited by respecting the relevant anatomy, carefully elevating nasal mucosa, limiting the lateral nasal wall osteotomies to the first 1.5 mm, and appropriately placing and orienting the pterygoid osteotome. By maintaining the horizontal osteotomy 5 mm above the dental apices, risk of devitalizing the teeth is diminished. The vertical osteotomy
Fig. 6 Hyrax expansion device. (From Betts NJ, Vanarsdall RL, Barber HD, et al. Diagnosis and treatment of transverse maxillary deficiency. Int J Adult Orthodon Orthognath Surg 1995;10:83; with permission.)
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Fig. 7 Occlusal coverage Haas-type appliance. (From Betts NJ, Vanarsdall RL, Barber HD, et al. Diagnosis and treatment of transverse maxillary deficiency. Int J Adult Orthodon Orthognath Surg 1995;10:83; with permission.)
between the central incisors should be performed with a spatula osteotome to preserve bony coverage of the medial surface of the central incisor roots. Preoperative orthodontics may be useful in splaying the roots in preparation for surgery. Postoperative complications can be divided into those caused by inadequate release of the maxillae (Box 6) and those caused by problems with the expansion device (Box 7, Figs. 12 and 13).
Other caveats (modification of the surgically assisted maxillary expansion procedure) There is increased resistance to expansion with increasing skeletal maturity and age. To achieve stable and adequate
Fig. 8 The maxillary buttresses: nasomaxillary, zygomaticomaxillary, and pterygomaxillary. Resistance to palatal expansion also arises from the midpalatal suture. (From Betts NJ, Vanarsdall RL, Barber HD, et al. Diagnosis and treatment of transverse maxillary deficiency. Int J Adult Orthodon Orthognath Surg 1995;10:85; with permission.)
expansion, the surgeon must perform more extensive surgery in older patients. Older patients often require rechecking of the osteotomies and scoring of the posterior wall of the sinus to achieve adequate mobilization. Palatal tori can be a significant barrier to palatal expansion, because they are composed of dense cortical bone. The presence of a palatal torus in this situation can be approached in 2 different ways. The ideal treatment is to surgically remove the torus 4 to 6 months before the SAME procedure. However, concomitant removal of the torus can be performed if the surgeon is willing to place the expansion appliance intraoperatively. The appliance must be fabricated on a model from
Box 5. Summary of the surgical procedure (see Fig. 9) Box 4. Indications for SAME 1. Skeletal maxillomandibular transverse discrepancy greater than 5 mm (Caucasian patients) 2. Significant transverse maxillary deficiency associated with a narrow maxilla and wide mandible 3. Failed orthodontic or orthopedic expansion 4. Necessity for a large amount (>7 mm) of expansion, or preference to avoid the potential increased risk of segmental osteotomies 5. Extremely thin, delicate gingival tissue or presence of significant buccal gingival recession in the caninebicuspid region of the maxilla 6. Significant nasal stenosis 7. Need for widening of the maxillary arch when no other skeletal deformity is present 8. Widening of the arch to provide space for dental alignment without requiring maxillary extractions to create space 9. Widening of the arch after collapse associated with the cleft palate deformity
1. Vestibular incision 5 mm above the mucogingival junction bilaterally from the first molar area to the midline 2. Bilateral maxillary osteotomy from the pyriform rim to the pterygomaxillary fissure; this osteotomy is created parallel to the maxillary occlusal plane with a step at the buttress and ostectomy performed the buttress to allow expansion 3. Release of the nasal septum (to prevent septal deviation during expansion) 4. Midline palatal osteotomy extended interdentally between the maxillary incisors and from the anterior nasal spine through the posterior nasal spine 5. Osteotomy of the anterior 1.5 mm of the lateral nasal wall 6. Bilateral release of the pterygoid plates 7. Activation of the appliance with a total widening of 1 to 1.5 mm, with evaluation for symmetric expansion 8. Soft tissue closure, including alar base cinch with nonresorbable suture and V-Y closure to control the soft tissues of the nasal base and upper lip
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Fig. 9 Individual steps in the technique of SAME (A) Preoperative state. (B) The Haas palatal expansion device in place before surgery. The appliance has not been activated. (C) Clinical photograph of the surgical incision identical to the one used for the LeFort I osteotomy, above the mucogingival junction. (D) The maxillary osteotomy extending from the pyriform rim to the pterygomaxillary fissure. This osteotomy is parallel to the occlusal plane, with a step and bone removed at the buttress to allow for expansion. (E) Clinical photograph showing the maxillary osteotomies. (F) Release of the nasal septum from anterior nasal spine to the posterior nasal spine. (G) The nasal septal release. (H) The midline palatal osteotomy. The osteotome is first directed inferiorly to split the alveolar bone between the maxillary central incisors and then posteriorly to split the hard palate. (I) Osteotome placement being used to split the alveolar bone between the maxillary central incisors. (J) Separation of the hard palate, with the osteotome directed posteriorly along the palate. (K) The lateral nasal wall osteotomy, which is carried posteriorly for 1.5 mm. (L) Release of the pterygoid plates from the tuberosity of the posterior maxilla. Note that a curved osteotome of less than 10 mm is being positioned in an inferior, anterior, and medial direction. (M) Clinical view of the placement of the curved osteotome to separate the pterygoid plates. (N) Expansion device key used for appliance activation. The key should be attached to floss or string to prevent accidental swallowing or aspiration. (O) Clinical view showing activation of the appliance with the key. (P) Frontal diagram of the completed SAME.
which the torus has been removed. Because a midpalatal incision is necessary to remove the torus, thus compromising palatal blood supply, the lateral, nasal, horizontal maxillary, pterygomaxillary, and anterior midpalatal osteotomies should be performed through vertical incisions in the buccal mucosa combined with subperiosteal tunneling. The torus is then removed by the conventional technique, and parasagittal palatal osteotomies are completed directly through this incision. The expansion appliance is then tested to ensure that it has no direct contact with the palatal tissues. When performing SAME on patients with a skeletal open bite or open-bite tendency, care must be taken to prevent worsening of the open bite with this procedure. If a ramped or angled cut is made from the pyriform rims to the maxillary buttress, the
maxilla preferentially moves inferiorly at the first molar during expansion (Fig. 14A). This movement can cause worsening of an open bite or conversion of an open-bite tendency to a skeletal open bite, therefore mandating a secondary maxillary osteotomy. Prevention of this problem requires modification of the SAME technique to ensure that all osteotomies of the anterior and lateral maxillary walls are parallel to the maxillary occlusal plane. A vertical step is created at the maxillary buttress so that transverse expansion can occur without bony interference in the buttress region. Bone removal of just less than half the desired amount of transverse expansion is completed at each buttress (see Fig. 14B). If a secondary Le Fort I maxillary osteotomy is planned because of the existence of other dentofacial deformities, the osteotomies for SAME should be placed in the
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Fig. 9 (continued) (Q) Palatal view of a Haas expansion device in place, with the vectors of expansion shown (R) An alar cinch suture and V-Y closure are used to close the incision to control the soft tissues of the upper lip and nasal base. Clinical photograph of a Boley gauge checking the width of the alar base of the nose after an alar cinch suture has been placed to reposition the tissues to the preoperative value. (S) Clinical photograph showing the use of a Boley gauge set at 10 mm to correctly close the vertical leg of the V-Y closure. (T) Completed V-Y closure. (U) Palatal view of the maxilla with the Haas appliance in place after 2 weeks of expansion. (V) Maxillary occlusal film showing the palatal expansion after 2 weeks. (W) Clinical palatal view of same patient 3 months after expansion with Haas appliance used as a retention device. (X) Haas appliance removed. (Y) Occlusal coverage transpalatal retainer which will be used for the next 3 months to prevent transverse relapse. This patient had preexisting TMJ problems, hence the occlusal coverage. (From Betts NJ, Vanarsdall RL, Barber HD, et al. Diagnosis and treatment of transverse maxillary deficiency. Int J Adult Orthodon Orthognath Surg 1995;10:86e9; with permission.)
location of the planned osteotomy cut of the future Le Fort procedure. This strategy is because the osteotomies in the anterior and lateral maxillary walls seldom completely heal after SAME, and this may compromise future osteotomies or the ability to apply rigid fixation.
Surgically assisted maxillary expansion versus segmental maxillary osteotomy and clinical results in the literature When a patient requires surgical correction of a transverse discrepancy, a decision must be made regarding which surgical technique (SAME or segmental maxillary osteotomy) will be used. Certainly, for a patient who requires a maxillary osteotomy to correct vertical or anteroposterior deformities, consideration should be given to the segmental maxillary osteotomy. There are some difference (other than SAME requiring a second surgical procedure) that merit discussion. The first is postoperative stability. Pogrel and associates studied 12 patients
1 year after SAME (still in orthodontic appliances) and found an 11.8% relapse at the maxillary first molar. Bays and Greco studied 19 patients who had undergone SAME who had completed orthodontic therapy more than 6 months previously and found an 8.8% relapse at the canines, 1% at the first bicuspid, and 7.7% at the first maxillary molar. The reported relapse in the transverse component of segmental maxillary osteotomies has been considerably higher. Stephens found a 30% and 23% relapse at the canine and molar regions, respectively, in 15 patients who had undergone segmental maxillary osteotomies with an average follow-up of 47.5 months after debanding. Phillips and colleagues compared the transverse stability in 39 patients who underwent either a 2-piece Le Fort osteotomy (n Z 26) or a 3piece Le Fort osteotomy (n Z 13). The postorthodontic followup was 14 to 47 months (mean Z 24.4 months). Significant transverse relapse in both groups was observed, ranging from 11% at the canines to 47% at the second molar in the 2-piece group and from 30% at the first premolar to 51% at the first molar in the 3-piece group.
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Fig. 10 The outward rotation of the maxillary halves around the axis of rotation located near the frontonasal suture. This situation results from incomplete lateral nasal wall osteotomies, which are not sectioned during surgery and articulate with the skull high in the nasal cavity. (From Betts NJ, Vanarsdall RL, Barber HD, et al. Diagnosis and treatment of transverse maxillary deficiency. Int J Adult Orthodon Orthognath Surg 1995;10:90; with permission.)
The pattern of transverse expansion is different for SAME than for maxillary segmental osteotomies. More expansion occurs at the canines and less at the molars after SAME. In contrast, during segmental Le Fort maxillary osteotomy, more expansion is achieved at the maxillary molars than at the canines. In the SAME procedure, all the maxillary articulations are not osteotomized superiorly and posteriorly (lateral nasal wall and palatine bone); therefore, the greater resistance to expansion in the posterior maxilla accounts for less posterior expansion. The inelasticity of the palatal mucosa is a major limiting factor for segmental Le Fort osteotomy. Widening of more than 6 mm is not stable or feasible. Therefore, transverse expansion greater than 7 mm would be an indication for SAME. SAME is generally performed early in the treatment sequence. Early expansion of the maxilla allows orthodontic alignment in the severely crowded maxillary arch without the need to extract teeth. Treatment plans that include a
9 segmental maxillary osteotomy often include extraction of teeth with partial orthodontic space closure to allow for safe performance of interdental osteotomies. In nonextraction segmental osteotomies, the dentition requires buccal expansion before surgery, which is unstable and prone to postoperative relapse. The major disadvantage of a treatment plan that includes SAME followed by a 1-piece Le Fort maxillary osteotomy is that 2 surgical procedures are required. If a patient who has had a SAME procedure requires a Le Fort osteotomy for correction of concomitant dentofacial deformity, a second procedure must occur after orthodontic decompensation of the maxillary and mandibular dentition. In contrast, a segmental maxillary osteotomy attempts to correct the deformities in all planes of space during 1 surgical procedure. The segmental maxillary osteotomy is a more difficult, more technically sensitive, and potentially more morbid procedure than a 1-piece maxillary osteotomy. Complications such as tooth root injuries, periodontal defects, and vascular compromise are more common in segmental than in 1-piece maxillary osteotomies. The total cumulative time under general anesthesia is approximately the same for SAME followed by a 1-piece Le Fort I as for a segmental Le Fort osteotomy. The potential postoperative morbidity is reduced when SAME followed by a 1-piece Le Fort maxillary osteotomy is performed. Surgical and operating costs are less for the segmental maxillary osteotomy when performed in the hospital, but costs could be less if the SAME were performed in an ambulatory or office setting.
Summary and suggestions regarding the correction of transverse discrepancies in adult patients For patients who require less than 5 mm of transverse expansion with adequate buccal bone present and no gingival recession on the posterior maxillary dentition, orthodontic/orthopedic expansion should be attempted. If the transverse discrepancy is greater than 5 mm, SAME should be performed early in the treatment sequence, after dental decompensation of the mandibular dentition. In a patient requiring a maxillary osteotomy for correction of concomitant dentofacial deformities with a transverse
Fig. 11 (A) Haas expansion device maintained as a retention device after expansion. Note the immature red granulation tissue present bilaterally on the medial surfaces of the maxillary central incisors. (B) Palatal coverage retainer used as a retention device. The acrylic base plate should not touch the anterior teeth and allows for orthodontic movement and closure of the midline diastema. (From Betts NJ, Vanarsdall RL, Barber HD, et al. Diagnosis and treatment of transverse maxillary deficiency. Int J Adult Orthodon Orthognath Surg 1995;10:91; with permission.)
Box 6. Complications associated with inadequate surgery (activation of an appliance against mature, intact sutures) 1. Pain and pressure 2. Dental tipping 3. Periodontal breakdown (as teeth are pushed through the buccal plate) 4. Palatal tissue impingement by the expansion device (possibly with tissue necrosis) 5. Postorthodontic relapse
Box 7. Complication caused by the expansion device 1. Lack of appliance expansion 2. Deformation of the appliance caused by processing errors (see Fig. 12) 3. Stripping or loosening of the midpalatal screw (see Fig. 13)
Fig. 12 (A) Example of an appliance that was overheated during fabrication, leading to deformation of the metal frame rather than expansion. The patient experienced pain from the palate with each activation of the expansion key. Note the absence of a midline diastema, indicating lack of maxillary expansion. (B) Palatal view after removal of the expansion appliance, showing a large ulcer on the plate extending to the alveolar ridge. (From Betts NJ, Vanarsdall RL, Barber HD, et al. Diagnosis and treatment of transverse maxillary deficiency. Int J Adult Orthodon Orthognath Surg 1995;10:91; with permission.)
Fig. 13 Occlusal view showing unequal expansion of a Haas appliance that had a malfunctioning jackscrew, although adequate expansion was achieved. (From Betts NJ, Vanarsdall RL, Barber HD, et al. Diagnosis and treatment of transverse maxillary deficiency. Int J Adult Orthodon Orthognath Surg 1995;10:92; with permission.)
Fig. 14 (A) The result of performing SAME using a ramped cut. As the expansion is performed, the maxilla moves inferiorly at the first molar, worsening an open bite or converting an open-bite tendency into a true open bite. (B) This problem of inferior movement of the maxilla during expansion can be overcome by performing the osteotomies parallel to the maxillary plane and creating a vertical cut at the buttress, with excision of bone in the amount of the planned movement. This allows the maxillary expansion to occur without any bony interference. (From Betts NJ, Vanarsdall RL, Barber HD, et al. Diagnosis and treatment of transverse maxillary deficiency. Int J Adult Orthodon Orthognath Surg 1995;10:92; with permission.)
Surgically Assisted Maxillary Expansion discrepancy of less than 7 mm, consideration should be given to segmental maxillary osteotomy. When a segmental maxillary osteotomy is used in a patient with a transverse discrepancy of greater than 6 mm, complete expansion at the molars is difficult to achieve at the time of surgery, because of palatal tissue inelasticity, and is difficult to retain in the posttreatment period. Therefore, SAME should be performed early in the treatment sequence, followed by a 1-piece Le Fort osteotomy. If 2 separate maxillary surgical procedures are planned, the SAME osteotomies should be performed where the 1piece maxillary osteotomies are projected to be. The diagnosis of maxillomandibular transverse discrepancy may be difficult in adult patients when sagittal and vertical deformities mask the transverse maxillary discrepancy. When appropriate clinical and radiographic assessments are performed, the correct diagnosis and treatment sequences can be applied, resulting in an acceptable and stable outcome.
Further readings Angell EH. Treatment of irregularities of the permanent or adult teeth. Dental Cosmos 1860;1:540e4. 599-601. Bailey L, White RP, Proffitt WR, Turvey TA. Segmental LeFort I osteotomy for management of transverse maxillary deficiency. J Oral Maxillofac Surg 1997;55:728e31. Banning LM, Gerard N, Steinberg BJ, Bogdanoff E. Treatment of transverse maxillary deficiency with emphasis on surgically assisted rapid maxillary expansion. Compend Cont Educ Dent 1996;17: 170e8. Basdra EK, Zoller JE, Komposch G. Surgically assisted rapid palatal expansion. J Clin Orthod 1995;29:762e6. Bays RA, Greco JM. Surgically assisted rapid palatal expansion: an outpatient technique with long-term stability. J Oral Maxillofac Surg 1992;50:110e3. Bays RA, Greco JM, Hale RG. Stability of surgically assisted rapid palatal expansion. A long term study. J Dent Res 1990;69:296. Bell WH, Epker BN. Surgical-orthodontic expansion of the maxilla. Am J Orthod 1976;70:517e28. Bell WH, Jacobs JD. Surgical-orthodontic correction of horizontal maxillary deficiency. J Oral Surg 1979;37:897e902. Bell RA. A review of maxillary expansion in relation to rate of expansion and patient’s age. Am J Orthod 1982;81:32e7. Betts NJ, Lisenby CW. Normal adult transverse jaw values obtained using standardized posteroanterior cephalometrics. J Dent Res 1994;73:298. Betts NJ, Rosenberg M. Two different alar cinch suturing techniques following surgical maxillary expansion. J Dent Res 1995;74:96. Betts NJ, Scully JR. Transverse maxillary distraction osteogenesis. In: Fonseca RJ, Marciani R, Turvey TA, editors. Oral and maxillofacial surgery. 2nd editionvol. III. St Louis (MO): Saunders; 2009. p. 219e37. Betts NJ, Fonseca RJ, Vig P, et al. Changes in the nasal and labial soft tissues after surgical repositioning of the maxilla. Int J Adult Orthodon Orthognath Surg 1993;8:7e23. Betts NJ, Vanarsdall RI, Barber HD, et al. Diagnosis and treatment of transverse maxillary deficiency. Int J Adult Orthodon Orthognath Surg 1995;10:75e96.
11 Betts NJ, Thanasas AG, Lisenby CW, Mosier KM. Evaluation of racial (African-American, Caucasian) and gender differences in skeletal transverse dimension. J Oral Maxillofac Surg 1997;55(Suppl 3):86e7. Buamrind S, Korn EL. Transverse development of human jaws between the ages of 8.5 and 15.5 years, studied longitudinally with the use of implants. J Dent Res 1990;69:1298e306. Crosby DR, Jacobs JD, Bell WH. Special adjunctive considerations: transverse (horizontal) maxillary deficiency. In: Bell WH, editor. Modern practice in orthognathic and reconstructive surgery, vol. 3. Philadelphia: WB Saunders; 1992. p. 2403e30. da Silva Filho OG, Boas MC, Capelozza Gilho L. Rapid maxillary expansion in the primary and mixed dentitions: a cephalometric evaluation. Am J Orthod 1991;100:171e81. Enlow DH. The facial growth process: part 1. In: Enlow DH, editor. Facial growth. 3rd edition. Philadelphia: WB Saunders; 1990. p. 58e76. Haas AJ. Rapid expansion of the maxillary dental arch and nasal cavity by opening the midpalatal suture. Angle Orthod 1961;31:73e90. Haas AJ. The treatment of maxillary deficiency by opening the midpalatal suture. Angle Orthod 1965;35:200e17. Ilizarov GA. Clinical applications of tension-stress effects for limb lengthening. Clin Orthop Relat Res 1990;(250):8e26. Kraut RA. Surgically assisted rapid maxillary expansion by opening the midpalatal suture. J Oral Surg 1984;42:651e5. Krebs A. Midpalatal suture expansion studied by the implant method over a seven year period. Trans Eur Orthod Soc 1964;40:131e42. Lanigan DT, Hey JH, West RA. Aseptic necrosis following maxillary osteotomies: report of 36 cases. J Oral Maxillofac Surg 1990;48: 142e56. Melson B. A histological study of the influence of sutural morphology and skeletal maturation on rapid palatal expansion in children. Trans Eur Orthod Soc 1972;48:499e507. Mossaz CF, Byloff FK, Richter M. Unilateral and bilateral corticotomies for correction of maxillary transverse discrepancies. Eur J Orthod 1992;14:110e6. Persson M, Thilander B. Palatal suture closure in man from 15-35 years of age. Am J Orthod 1977;72:42e52. Phillips C, Medland WH, Fields HW Jr, et al. Stability of surgical maxillary expansion. Int J Adult Orthodon Orthognath Surg 1992;7: 139e46. Pogrel MA, Kaban LB, Vargervik K, Baumrind S. Surgically assisted rapid maxillary expansion in adults. Int J Adult Orthodon Orthognath Surg 1992;7:37e41. Ricketts RM, Roth RH, Chaconas SJ, et al. Orthodontic diagnosis and planning.their roles in preventative and rehabilitative dentistry. Denver (CO): Rocky Mountain Data Systems; 1982. p. 20e5. 42, 50e59, 138, 233e235. Ricketts RM. Perspectives in the clinical application of cephalometrics, the first fifty years. Angle Orthod 1981;51:115e50. Shetty V, Cardid JM, Caputo AA, et al. Biomechanical rationale for surgical-orthodontic expansion of the adult maxilla. J Oral Maxillofac Surg 1994;52:742e9. Silverstein K, Quinn PD. Surgically-assisted rapid palatal expansion for management of transverse maxillary deficiency. J Oral Maxillofac Surg 1997;55:725e7. Stephens CR. An examination of the long-term stability of surgical-orthodontic maxillary expansion [Master’s thesis]. Columbus (OH): Ohio State University; 1986. Turvey TA. Maxillary expansion: a surgical technique based on surgicalorthodontic treatment objectives and anatomic considerations. J Maxillofac Surg 1985;13:51e8.
Introduction: nature of the problem Complete and accurate evaluation of a patient with a dentofacial deformity must include assessment of the transverse dimension. Few practitioners adequately evaluate the transverse dimension, often resulting in undiagnosed transverse maxillomandibular discrepancy. When a transverse maxillomandibular discrepancy exists, adult patients have traditionally been treated with orthodontic expansion or a segmental maxillary osteotomy, frequently leading to transverse maxillary instability and relapse after orthodontic appliance removal. Orthopedic or rapid maxillary expansion (ORME) is also a technique used to treat transverse maxillomandibular discrepancy. If used in the correct patient population, this technique is predicable and stable for the correction of transverse maxillomandibular discrepancy. It is of limited benefit in mature teenage and adult patients, because the maxillary articulations become increasingly resistant to expansion with aging. Techniques of surgically assisted maxillary expansion (SAME) have been developed to overcome this
a Private Practice, Chelsea Oral and Facial Surgery, 1303 South Main Street, Suite B, Chelsea, MI 48118, USA b Private Practice, Ann Arbor Oral and Facial Surgery, 3055 Plymouth Road, Suite 202, Ann Arbor, MI 48105, USA c Department of Oral and Maxillofacial Surgery, University of Michigan School of Dentistry, 3055 Plymouth Road, Suite 202, Ann Arbor, MI 48105, USA * Chelsea Oral and Facial Surgery, 1303 South Main Street, Suite B, Chelsea, MI 48118. E-mail address: [email protected]
Atlas Oral Maxillofacial Surg Clin N Am - (2015) -e1061-3315/15/$ - see front matter ª 2015 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.cxom.2015.10.003
age limitation. The SAME procedure is a combination of distraction osteogenesis and controlled soft tissue expansion. Discussion of SAME is often confusing because various combinations of maxillary, pterygopalatine lateral nasal, septal, and palatine osteotomies have been used, based on the surgeon’s theory of where resistance to expansion is located. The purpose of this article is to describe the clinical and radiographic evaluation of the transverse dimension in patients with dentofacial deformity and to present the indications for SAME and an anatomically based SAME technique.
Surgical technique Preoperative planning Accurate diagnosis and treatment of transverse maxillary deficiency are essential to the long-term stability after correction of any dentofacial deformity that includes a transverse discrepancy. However, diagnosis of transverse maxillary deficiency may be difficult, because minimal facial soft tissue changes are associated with isolated transverse maxillary hypoplasia. In contrast, isolated anteroposterior or vertical skeletal deformities are easier to diagnose, because they often have obvious associated facial soft tissue findings. Consequently, the transverse deformity is often not diagnosed when sagittal and vertical deformities exist concomitantly. Therefore, it is not surprising that clinical inspection for transverse maxillary deficiency has been shown to be of poor diagnostic value. Complete diagnosis of this deformity must include both clinical and radiographic evaluation.
oralmaxsurgeryatlas.theclinics.com
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Clinical evaluation The existence and extent of a transverse discrepancy must be determined and the skeletal and dental components of the deformity must be differentiated before contemplating surgery (Box 1, Fig. 1).
Radiographic evaluation A standard posteroanterior (PA) cephalogram is the radiograph of choice for identification and evaluation of a transverse discrepancy. Ricketts developed the Rocky Mountain analysis and established relative norms using specific radiographic landmarks and measurements to analyze transverse discrepancies between the maxilla and mandible (Box 2, Fig. 2). Using these landmarks, it is possible to determine the effective maxillary width, effective mandibular width, and frontolateral facial lines. The effective maxillary width is the width of the maxilla between the points JL (jugale left) and JR (jugale right). The effective mandibular width is the width of the mandible between AG and GA. The frontolateral facial lines are the lateral lines constructed from OR (orbitale right) and OL (orbitale left) to the points AG and GA, respectively. Using these cephalometric landmarks, it is possible to determine the maxillomandibular width differential and the maxillomandibular transverse differential index for quantification of the transverse maxillary discrepancy (Fig. 3). The maxillomandibular width differential is the distance (in millimeters) measured from the frontolateral facial line to JL and JR, respectively, along a line from the frontolateral facial lines through JR and JL. This measurement is calculated independently for each side and compared with a normal value of 10 1.5 mm. If this value is greater than 10 mm, a transverse discrepancy between the maxilla and mandible exists. The values greater than 10 mm on each side are summed to quantify the total transverse deficiency. This technique is
Box 1. Clinical indicators of transverse maxillary deficiency 1. Facial soft tissue changes including paranasal hollowing, a narrowed alar base, and deepening of the nasolabial folds 2. Negative space (distance between the corner of the mouth and the buccal surfaces of the posterior maxillary teeth during full smile) 3. Unilateral or bilateral posterior crossbite (a distinction must be made between dental and skeletal crossbite) 4. Crowded, rotated, and palatally or buccally displaced teeth 5. Narrow and tapering maxillary arch form, described as hourglass shaped 6. High, narrow palatal arch 7. Associated skeletal deformities include maxillary vertical and anteroposterior hypoplasia and zygomatic hypoplasia (as a result of growth issues) 8. Other associated dentofacial deformities include vertical maxillary excess, mandibular prognathism or mandibular sagittal deficiency, apertognathia, and repaired cleft palate
useful in determining the total discrepancy and showing whether there is a greater deficiency or excess on 1 side or the other. However, this differential does not elucidate in which jaw the discrepancy exists and may be misinterpreted when mandibular asymmetry is present. The maxillomandibular transverse differential index is the age-specific expected maxillomandibular difference minus the actual measured maxillomandibular difference. The expected maxillomandibular difference is the age-appropriate expected AG-GA distance minus the age-appropriate expected JR-JL distance. The actual maxillomandibular difference is the actual AG-GA measurement minus the actual JR-JL measurement. In an adult patient, a maxillomandibular transverse differential index greater than 5 mm suggests a need for surgical expansion. As well as quantifying the total discrepancy, this method allows for the identification of which jaw is deficient or excessive, because actual values can be compared with normal values. Normal values have been suggested only for Caucasian, and these values should not be considered normal values for other races.
Treatment of transverse maxillomandibular discrepancy SAME combines an orthopedic appliance and osteotomies to achieve maxillary skeletal expansion in 1 to 2 weeks (Box 3). The technique chosen to correct the transverse discrepancy is dependent on many factors, but most important is the skeletal maturity of the patient (Box 4). Additional factors include the magnitude of the transverse discrepancy and whether gingival dehiscence or bony fenestration is already present on the maxillary canine and bicuspid teeth. Generally, patients in the primary dentition and the mixed dentition stage are treated by ORME. Transverse maxillary growth ceases and the maxillofacial sutures close at skeletal age 14 to 15 years in females and 15 to 16 years in males. Adults are best treated by SAME or segmental Le Fort osteotomy. After sutural closure, ORME is unsuccessful, because the expansion is composed primarily of alveolar or dental tipping, with little or no skeletal expansion. This situation can lead to many problems in adults, including an inability to activate the appliance, pain on activation, pressure necrosis of the palatal tissue under the appliance, tipping and extrusion of the maxillary teeth, bending of the alveolar bone, uncontrolled relapse after orthodontic appliance removal, and periodontal complications. These periodontal complications result from the tipping of the maxillary teeth out through the buccal cortical bone, resulting in cortical thinning, dehiscence, or fenestration of the maxillary teeth. If gingival inflammation is present, the patient is predisposed to gingival recession and dental instability (Fig. 4). In contrast, if the transverse maxillary deficiency is less than 5 mm of the total maxillomandibular discrepancy, sufficient buccal bone is generally present to allow for some dental tipping. In this case, ORME may be considered if there are no periodontal defects or gingival recession already present in the posterior maxillary quadrants.
Preparation and patient positioning Before the procedure, an expansion device must be placed. The best results are achieved when one of the several variations of the jackscrew appliance is used. To achieve expansion, a palatally positioned jackscrew is placed within a framework
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Fig. 1 (A) Intraoral view of severe transverse maxillary hypoplasia. There is a bilateral palatal crossbite and rotated, crowded, and displaced teeth. (B) Palatal view of a patient with transverse maxillary hypoplasia. Note the narrow, tapering, hourglass-shaped arch form in addition to the narrow and high palatal vault. (From Betts NJ, Vanarsdall RL, Barber HD, et al. Diagnosis and treatment of transverse maxillary deficiency. Int J Adult Orthodon Orthognath Surg 1995;10:77, 91; with permission.)
attached to the first molars and other teeth as available (usually the first bicuspid teeth). The most common jackscrew appliances used today are the Haas and Hyrax. The Haas appliance (Fig. 5) has acrylic palatal flanges incorporated into the appliance, which have been shown to decrease buccal tipping of the dentition and produce greater skeletal expansion. However, because of the acrylic palatal pads, there is a slightly increased risk of palatal tissue impingement, and food can become entrapped beneath the flanges. The Hyrax appliance (Fig. 6) is similar in design to the Haas appliance, with the exception that it does not have the acrylic palatal pads. Its use theoretically results in more dental tipping and less skeletal expansion. The occlusal coverage Haas appliance (Fig. 7) is a hybrid of the Haas appliance with a flat plane occlusal coverage splint. This appliance must be physically bonded to the maxillary teeth. Its use is recommended in patients with periodontally compromised dentition, because the appliance incorporates more of the teeth in the device (not just the first bicuspid and first molar teeth). Therefore, the transverse forces are distributed among more teeth. It may also be useful in patients with temporomandibular joint (TMJ) symptoms, because the appliance can be equilibrated like an occlusal coverage splint during expansion to minimize the premature dental interferences common during the transverse expansion. Like the Haas appliance, it use may result in less dental tipping and more skeletal expansion. However, because of problems with oral hygiene, it must be removed 3 to 4 months after placement and an immediate palatal coverage retainer placed to minimize transverse relapse (Box 4). The 3 principal areas of vertical and horizontal maxillary support are the nasomaxillary, zygomaticomaxillary, and pterygomaxillary buttresses (Fig. 8). The many maxillary
osteotomies that have been empirically proposed to facilitate lateral maxillary expansion reflect the controversy regarding the primary area of resistance to expansion in the craniofacial skeleton. Most recently, investigators have recommended sectioning of virtually all the maxillary bony articulations, that is, zygomaticomaxillary buttresses, midpalatal suture, and pterygomaxillary junction. An investigation by Shetty and coworkers attempted to give a biomechanical rational for the choice of osteotomies by analyzing the internal stress response after SAME in a photoelastic model fabricated from a human skull. A Hyrax appliance was placed and activated, and sequential cuts were performed on the model. The alterations in the internal stresses of the skull were recorded after each cut. All the bony buttresses of the maxilla contributed resistance to expansion, but the midpalatal suture followed by the pterygomaxillary articulations were the primary areas of resistance. These investigators also reported that forces caused by appliance activation have deep anatomic effects, with stresses present at sites distant from the force application. Even although this study has significant validity and reliability problems, it provides important information concerning
Box 2. Skeletal landmarks used in the evaluation of maxillomandibular transverse discrepancy 1. JR (jugale right) and JL (jugale left) (the intersection of the maxillary tuberosity and the zygomatic buttress) 2. AG (antegonion right) and GA (antegonion left) (the inferior margin of the antegonial protuberance, below the antegonial trihedral area) 3. OR (orbitale right) and OL (orbitale left) (representing the intersection of the orbits with the middle cranial fossa)
Fig. 2 The elements of the PA cephalometric analysis. These landmarks can be used to calculate the effective maxillary width and effective mandibular width, and the frontolateral lines can be constructed. (From Betts NJ, Vanarsdall RL, Barber HD, et al. Diagnosis and treatment of transverse maxillary deficiency. Int J Adult Orthodon Orthognath Surg 1995;10:78; with permission.)
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Betts practice should be limited to younger patients, because they require less extensive surgery to accomplish adequate maxillary expansion. Patient positioning in the operating room should be similar to that described for the Le Fort I osteotomy. Nasal intubation is preferred. However, because maxillomandibular fixation is not necessary for this surgical procedure, oral intubation can be used.
Surgical approach Based on the knowledge that the areas of resistance to transverse expansion include all the bony buttresses of the maxilla, the technique advocated is a subtotal Le Fort I maxillary osteotomy (Box 5, Fig. 9). The mandibular dentition should be decompensated before surgery to allow assessment of the amount of transverse expansion necessary and to assist in preventing postexpansion relapse with dental interdigitation. In addition, the maxillary expansion appliance must be placed preoperatively and the appliance key must be present in the operating suite to allow intraoperative activation.
Surgical caveats
Fig. 3 Worksheet used to determine the radiographic magnitude and location of the maxillomandibular transverse discrepancy. (From Betts NJ, Vanarsdall RL, Barber HD, et al. Diagnosis and treatment of transverse maxillary deficiency. Int J Adult Orthodon Orthognath Surg 1995;10:79; with permission.)
the areas of resistance to transverse expansion in the adult human skull. Typically, this procedure is performed in a hospital setting as an outpatient or 24-hour stay procedure. Although SAME has been successfully performed in the outpatient setting, this
During this procedure, the appliance is widened 3 to 4 mm and then turned back to a final opening of 1 to 1.5 mm. The perpendicular plate of the palatine bone is thick and offers significant resistance posteriorly. During maximal expansion, the surgeon should check that both maxillae are adequately mobile. If they are not, the osteotomies should be checked or more surgery performed. Sectioning of the posterior portions of the thin lateral nasal wall is unnecessary because it offers little resistance to transverse expansion. Release of the pterygoid plates is necessary because they are part of the sphenoid, which is a single bone without a midline suture. Therefore, orthopedic forces cannot widen the pterygoid plates, and they should be separated from the maxillae. SAME can also be used in cases of unilateral or asymmetric maxillary deformities. In this situation, the osteotomies outlined earlier are created on only 1 side, thus allowing a differential anchorage situation with more expansion on one side. As would be expected, on the nonoperated side, buccal bone bending and dental tipping occur. After appliance removal, almost complete relapse occurs on the nonoperated side.
Postoperative care, rehabilitation, and recovery
Box 3. Benefits of the SAME procedure 1. Improved dental and skeletal stability 2. Nonextraction orthodontic alignment of the dentition 3. Improved aesthetics by the elimination of negative space (distance between the corner of the mouth and the buccal surfaces of the posterior maxillary teeth during full smile) and a decrease in the buccal hollowing of the lateral maxilla 4. Improved long-term periodontal health 5. Improved nasal respiration as a result of widening of the nasal cavity and internal nasal valve (this widening results from the lateral repositioning of the lateral nasal walls during maxillary expansion)
Routine follow-up care should be similar to that of the Le Fort I osteotomy, with the exception that liquid diet is followed for only the first week and the diet is advanced from that time forward. After the surgical procedure, the maxilla should remain stationary for at least 5 days before initiation of expansion at a rate of 0.5 mm/d (2 activations of the jack screw appliance a day). This strategy is based on Ilizarov’s work in the extremities, which showed that a healing period of 5 days allows for capillary healing across the bony gap. Reestablishment of this blood supply leads to faster and more complete ossification of the expanded defect. Ilizarov showed that an expansion rate of 0.5 to 1 mm/d does not outstrip this critical blood supply. However, in the maxilla, a rate of 0.5 mm/d is recommended. Expansion rates greater than this may cause gingival recession
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Fig. 4 Palatal (A) and lateral (B, C) views of an adult patient who had previously undergone unsuccessful orthopedic rapid maxillary expansion. The expansion has relapsed and has also resulted in significant buccal gingival recession bilaterally in the canine and premolar regions. (From Betts NJ, Vanarsdall RL, Barber HD, et al. Diagnosis and treatment of transverse maxillary deficiency. Int J Adult Orthodon Orthognath Surg 1995;10:84; with permission.)
on the mesial side of the central incisors, especially if bone and attachment loss is already present. During expansion, the patient should feel little discomfort. If pain is experienced, there is bony interference or inadequate mobilization or the appliance is not functioning properly. However, symptoms of tightness and minor discomfort in the nasal root/glabellar area and posterior orbit can and do occur, with anatomic basis. Pain in the nasal root area can be attributed to an outward rotation of the maxillary halves around an axis of rotation located near the frontonasal suture (because the lateral nasal walls are not osteotomized completely during the surgical procedure) (Fig. 10). The pressure felt in the posterior orbit is caused by the small articulation of the palatine bone, which is not sectioned during the surgical procedure. Palatal expansion must occur within 4 weeks of surgery or the osteotomies may heal before the required transverse dimension has been achieved. During the period of expansion, immature attached gingival tissue should be seen medial to each central incisor tooth. This immature attached gingival tissue arises when skeletal or dental expansion exceeds the ability of the attached gingiva to remodel. It is a sign of successful expansion and should appear bilaterally and be
Fig. 5 Clinical example of a Haas palatal expansion device. (From Betts NJ, Vanarsdall RL, Barber HD, et al. Diagnosis and treatment of transverse maxillary deficiency. Int J Adult Orthodon Orthognath Surg 1995;10:83; with permission.)
symmetric. If gingival recession or gapping occurs between the gingiva and the root surface, the expansion rate should be decreased. In contrast to ORME, overcorrection is not recommended for SAME. Surgical transverse changes are unstable for a longer period than are most other surgical or orthodontic movements. It takes approximately 6 months to achieve bony continuity in the midpalatal osteotomy site. Therefore, some form of skeletal retention is recommended for at least 6 to 12 months after expansion. The expansion device can be retained for this purpose or a palatal coverage retainer can be placed (Fig. 11).
Potential complications Intraoperative complications of SAME are similar to those that occur with Le Fort I maxillary osteotomy. Intraoperative hemorrhage can be limited by respecting the relevant anatomy, carefully elevating nasal mucosa, limiting the lateral nasal wall osteotomies to the first 1.5 mm, and appropriately placing and orienting the pterygoid osteotome. By maintaining the horizontal osteotomy 5 mm above the dental apices, risk of devitalizing the teeth is diminished. The vertical osteotomy
Fig. 6 Hyrax expansion device. (From Betts NJ, Vanarsdall RL, Barber HD, et al. Diagnosis and treatment of transverse maxillary deficiency. Int J Adult Orthodon Orthognath Surg 1995;10:83; with permission.)
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Betts
Fig. 7 Occlusal coverage Haas-type appliance. (From Betts NJ, Vanarsdall RL, Barber HD, et al. Diagnosis and treatment of transverse maxillary deficiency. Int J Adult Orthodon Orthognath Surg 1995;10:83; with permission.)
between the central incisors should be performed with a spatula osteotome to preserve bony coverage of the medial surface of the central incisor roots. Preoperative orthodontics may be useful in splaying the roots in preparation for surgery. Postoperative complications can be divided into those caused by inadequate release of the maxillae (Box 6) and those caused by problems with the expansion device (Box 7, Figs. 12 and 13).
Other caveats (modification of the surgically assisted maxillary expansion procedure) There is increased resistance to expansion with increasing skeletal maturity and age. To achieve stable and adequate
Fig. 8 The maxillary buttresses: nasomaxillary, zygomaticomaxillary, and pterygomaxillary. Resistance to palatal expansion also arises from the midpalatal suture. (From Betts NJ, Vanarsdall RL, Barber HD, et al. Diagnosis and treatment of transverse maxillary deficiency. Int J Adult Orthodon Orthognath Surg 1995;10:85; with permission.)
expansion, the surgeon must perform more extensive surgery in older patients. Older patients often require rechecking of the osteotomies and scoring of the posterior wall of the sinus to achieve adequate mobilization. Palatal tori can be a significant barrier to palatal expansion, because they are composed of dense cortical bone. The presence of a palatal torus in this situation can be approached in 2 different ways. The ideal treatment is to surgically remove the torus 4 to 6 months before the SAME procedure. However, concomitant removal of the torus can be performed if the surgeon is willing to place the expansion appliance intraoperatively. The appliance must be fabricated on a model from
Box 5. Summary of the surgical procedure (see Fig. 9) Box 4. Indications for SAME 1. Skeletal maxillomandibular transverse discrepancy greater than 5 mm (Caucasian patients) 2. Significant transverse maxillary deficiency associated with a narrow maxilla and wide mandible 3. Failed orthodontic or orthopedic expansion 4. Necessity for a large amount (>7 mm) of expansion, or preference to avoid the potential increased risk of segmental osteotomies 5. Extremely thin, delicate gingival tissue or presence of significant buccal gingival recession in the caninebicuspid region of the maxilla 6. Significant nasal stenosis 7. Need for widening of the maxillary arch when no other skeletal deformity is present 8. Widening of the arch to provide space for dental alignment without requiring maxillary extractions to create space 9. Widening of the arch after collapse associated with the cleft palate deformity
1. Vestibular incision 5 mm above the mucogingival junction bilaterally from the first molar area to the midline 2. Bilateral maxillary osteotomy from the pyriform rim to the pterygomaxillary fissure; this osteotomy is created parallel to the maxillary occlusal plane with a step at the buttress and ostectomy performed the buttress to allow expansion 3. Release of the nasal septum (to prevent septal deviation during expansion) 4. Midline palatal osteotomy extended interdentally between the maxillary incisors and from the anterior nasal spine through the posterior nasal spine 5. Osteotomy of the anterior 1.5 mm of the lateral nasal wall 6. Bilateral release of the pterygoid plates 7. Activation of the appliance with a total widening of 1 to 1.5 mm, with evaluation for symmetric expansion 8. Soft tissue closure, including alar base cinch with nonresorbable suture and V-Y closure to control the soft tissues of the nasal base and upper lip
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Fig. 9 Individual steps in the technique of SAME (A) Preoperative state. (B) The Haas palatal expansion device in place before surgery. The appliance has not been activated. (C) Clinical photograph of the surgical incision identical to the one used for the LeFort I osteotomy, above the mucogingival junction. (D) The maxillary osteotomy extending from the pyriform rim to the pterygomaxillary fissure. This osteotomy is parallel to the occlusal plane, with a step and bone removed at the buttress to allow for expansion. (E) Clinical photograph showing the maxillary osteotomies. (F) Release of the nasal septum from anterior nasal spine to the posterior nasal spine. (G) The nasal septal release. (H) The midline palatal osteotomy. The osteotome is first directed inferiorly to split the alveolar bone between the maxillary central incisors and then posteriorly to split the hard palate. (I) Osteotome placement being used to split the alveolar bone between the maxillary central incisors. (J) Separation of the hard palate, with the osteotome directed posteriorly along the palate. (K) The lateral nasal wall osteotomy, which is carried posteriorly for 1.5 mm. (L) Release of the pterygoid plates from the tuberosity of the posterior maxilla. Note that a curved osteotome of less than 10 mm is being positioned in an inferior, anterior, and medial direction. (M) Clinical view of the placement of the curved osteotome to separate the pterygoid plates. (N) Expansion device key used for appliance activation. The key should be attached to floss or string to prevent accidental swallowing or aspiration. (O) Clinical view showing activation of the appliance with the key. (P) Frontal diagram of the completed SAME.
which the torus has been removed. Because a midpalatal incision is necessary to remove the torus, thus compromising palatal blood supply, the lateral, nasal, horizontal maxillary, pterygomaxillary, and anterior midpalatal osteotomies should be performed through vertical incisions in the buccal mucosa combined with subperiosteal tunneling. The torus is then removed by the conventional technique, and parasagittal palatal osteotomies are completed directly through this incision. The expansion appliance is then tested to ensure that it has no direct contact with the palatal tissues. When performing SAME on patients with a skeletal open bite or open-bite tendency, care must be taken to prevent worsening of the open bite with this procedure. If a ramped or angled cut is made from the pyriform rims to the maxillary buttress, the
maxilla preferentially moves inferiorly at the first molar during expansion (Fig. 14A). This movement can cause worsening of an open bite or conversion of an open-bite tendency to a skeletal open bite, therefore mandating a secondary maxillary osteotomy. Prevention of this problem requires modification of the SAME technique to ensure that all osteotomies of the anterior and lateral maxillary walls are parallel to the maxillary occlusal plane. A vertical step is created at the maxillary buttress so that transverse expansion can occur without bony interference in the buttress region. Bone removal of just less than half the desired amount of transverse expansion is completed at each buttress (see Fig. 14B). If a secondary Le Fort I maxillary osteotomy is planned because of the existence of other dentofacial deformities, the osteotomies for SAME should be placed in the
8
Betts
Fig. 9 (continued) (Q) Palatal view of a Haas expansion device in place, with the vectors of expansion shown (R) An alar cinch suture and V-Y closure are used to close the incision to control the soft tissues of the upper lip and nasal base. Clinical photograph of a Boley gauge checking the width of the alar base of the nose after an alar cinch suture has been placed to reposition the tissues to the preoperative value. (S) Clinical photograph showing the use of a Boley gauge set at 10 mm to correctly close the vertical leg of the V-Y closure. (T) Completed V-Y closure. (U) Palatal view of the maxilla with the Haas appliance in place after 2 weeks of expansion. (V) Maxillary occlusal film showing the palatal expansion after 2 weeks. (W) Clinical palatal view of same patient 3 months after expansion with Haas appliance used as a retention device. (X) Haas appliance removed. (Y) Occlusal coverage transpalatal retainer which will be used for the next 3 months to prevent transverse relapse. This patient had preexisting TMJ problems, hence the occlusal coverage. (From Betts NJ, Vanarsdall RL, Barber HD, et al. Diagnosis and treatment of transverse maxillary deficiency. Int J Adult Orthodon Orthognath Surg 1995;10:86e9; with permission.)
location of the planned osteotomy cut of the future Le Fort procedure. This strategy is because the osteotomies in the anterior and lateral maxillary walls seldom completely heal after SAME, and this may compromise future osteotomies or the ability to apply rigid fixation.
Surgically assisted maxillary expansion versus segmental maxillary osteotomy and clinical results in the literature When a patient requires surgical correction of a transverse discrepancy, a decision must be made regarding which surgical technique (SAME or segmental maxillary osteotomy) will be used. Certainly, for a patient who requires a maxillary osteotomy to correct vertical or anteroposterior deformities, consideration should be given to the segmental maxillary osteotomy. There are some difference (other than SAME requiring a second surgical procedure) that merit discussion. The first is postoperative stability. Pogrel and associates studied 12 patients
1 year after SAME (still in orthodontic appliances) and found an 11.8% relapse at the maxillary first molar. Bays and Greco studied 19 patients who had undergone SAME who had completed orthodontic therapy more than 6 months previously and found an 8.8% relapse at the canines, 1% at the first bicuspid, and 7.7% at the first maxillary molar. The reported relapse in the transverse component of segmental maxillary osteotomies has been considerably higher. Stephens found a 30% and 23% relapse at the canine and molar regions, respectively, in 15 patients who had undergone segmental maxillary osteotomies with an average follow-up of 47.5 months after debanding. Phillips and colleagues compared the transverse stability in 39 patients who underwent either a 2-piece Le Fort osteotomy (n Z 26) or a 3piece Le Fort osteotomy (n Z 13). The postorthodontic followup was 14 to 47 months (mean Z 24.4 months). Significant transverse relapse in both groups was observed, ranging from 11% at the canines to 47% at the second molar in the 2-piece group and from 30% at the first premolar to 51% at the first molar in the 3-piece group.
Surgically Assisted Maxillary Expansion
Fig. 10 The outward rotation of the maxillary halves around the axis of rotation located near the frontonasal suture. This situation results from incomplete lateral nasal wall osteotomies, which are not sectioned during surgery and articulate with the skull high in the nasal cavity. (From Betts NJ, Vanarsdall RL, Barber HD, et al. Diagnosis and treatment of transverse maxillary deficiency. Int J Adult Orthodon Orthognath Surg 1995;10:90; with permission.)
The pattern of transverse expansion is different for SAME than for maxillary segmental osteotomies. More expansion occurs at the canines and less at the molars after SAME. In contrast, during segmental Le Fort maxillary osteotomy, more expansion is achieved at the maxillary molars than at the canines. In the SAME procedure, all the maxillary articulations are not osteotomized superiorly and posteriorly (lateral nasal wall and palatine bone); therefore, the greater resistance to expansion in the posterior maxilla accounts for less posterior expansion. The inelasticity of the palatal mucosa is a major limiting factor for segmental Le Fort osteotomy. Widening of more than 6 mm is not stable or feasible. Therefore, transverse expansion greater than 7 mm would be an indication for SAME. SAME is generally performed early in the treatment sequence. Early expansion of the maxilla allows orthodontic alignment in the severely crowded maxillary arch without the need to extract teeth. Treatment plans that include a
9 segmental maxillary osteotomy often include extraction of teeth with partial orthodontic space closure to allow for safe performance of interdental osteotomies. In nonextraction segmental osteotomies, the dentition requires buccal expansion before surgery, which is unstable and prone to postoperative relapse. The major disadvantage of a treatment plan that includes SAME followed by a 1-piece Le Fort maxillary osteotomy is that 2 surgical procedures are required. If a patient who has had a SAME procedure requires a Le Fort osteotomy for correction of concomitant dentofacial deformity, a second procedure must occur after orthodontic decompensation of the maxillary and mandibular dentition. In contrast, a segmental maxillary osteotomy attempts to correct the deformities in all planes of space during 1 surgical procedure. The segmental maxillary osteotomy is a more difficult, more technically sensitive, and potentially more morbid procedure than a 1-piece maxillary osteotomy. Complications such as tooth root injuries, periodontal defects, and vascular compromise are more common in segmental than in 1-piece maxillary osteotomies. The total cumulative time under general anesthesia is approximately the same for SAME followed by a 1-piece Le Fort I as for a segmental Le Fort osteotomy. The potential postoperative morbidity is reduced when SAME followed by a 1-piece Le Fort maxillary osteotomy is performed. Surgical and operating costs are less for the segmental maxillary osteotomy when performed in the hospital, but costs could be less if the SAME were performed in an ambulatory or office setting.
Summary and suggestions regarding the correction of transverse discrepancies in adult patients For patients who require less than 5 mm of transverse expansion with adequate buccal bone present and no gingival recession on the posterior maxillary dentition, orthodontic/orthopedic expansion should be attempted. If the transverse discrepancy is greater than 5 mm, SAME should be performed early in the treatment sequence, after dental decompensation of the mandibular dentition. In a patient requiring a maxillary osteotomy for correction of concomitant dentofacial deformities with a transverse
Fig. 11 (A) Haas expansion device maintained as a retention device after expansion. Note the immature red granulation tissue present bilaterally on the medial surfaces of the maxillary central incisors. (B) Palatal coverage retainer used as a retention device. The acrylic base plate should not touch the anterior teeth and allows for orthodontic movement and closure of the midline diastema. (From Betts NJ, Vanarsdall RL, Barber HD, et al. Diagnosis and treatment of transverse maxillary deficiency. Int J Adult Orthodon Orthognath Surg 1995;10:91; with permission.)
Box 6. Complications associated with inadequate surgery (activation of an appliance against mature, intact sutures) 1. Pain and pressure 2. Dental tipping 3. Periodontal breakdown (as teeth are pushed through the buccal plate) 4. Palatal tissue impingement by the expansion device (possibly with tissue necrosis) 5. Postorthodontic relapse
Box 7. Complication caused by the expansion device 1. Lack of appliance expansion 2. Deformation of the appliance caused by processing errors (see Fig. 12) 3. Stripping or loosening of the midpalatal screw (see Fig. 13)
Fig. 12 (A) Example of an appliance that was overheated during fabrication, leading to deformation of the metal frame rather than expansion. The patient experienced pain from the palate with each activation of the expansion key. Note the absence of a midline diastema, indicating lack of maxillary expansion. (B) Palatal view after removal of the expansion appliance, showing a large ulcer on the plate extending to the alveolar ridge. (From Betts NJ, Vanarsdall RL, Barber HD, et al. Diagnosis and treatment of transverse maxillary deficiency. Int J Adult Orthodon Orthognath Surg 1995;10:91; with permission.)
Fig. 13 Occlusal view showing unequal expansion of a Haas appliance that had a malfunctioning jackscrew, although adequate expansion was achieved. (From Betts NJ, Vanarsdall RL, Barber HD, et al. Diagnosis and treatment of transverse maxillary deficiency. Int J Adult Orthodon Orthognath Surg 1995;10:92; with permission.)
Fig. 14 (A) The result of performing SAME using a ramped cut. As the expansion is performed, the maxilla moves inferiorly at the first molar, worsening an open bite or converting an open-bite tendency into a true open bite. (B) This problem of inferior movement of the maxilla during expansion can be overcome by performing the osteotomies parallel to the maxillary plane and creating a vertical cut at the buttress, with excision of bone in the amount of the planned movement. This allows the maxillary expansion to occur without any bony interference. (From Betts NJ, Vanarsdall RL, Barber HD, et al. Diagnosis and treatment of transverse maxillary deficiency. Int J Adult Orthodon Orthognath Surg 1995;10:92; with permission.)
Surgically Assisted Maxillary Expansion discrepancy of less than 7 mm, consideration should be given to segmental maxillary osteotomy. When a segmental maxillary osteotomy is used in a patient with a transverse discrepancy of greater than 6 mm, complete expansion at the molars is difficult to achieve at the time of surgery, because of palatal tissue inelasticity, and is difficult to retain in the posttreatment period. Therefore, SAME should be performed early in the treatment sequence, followed by a 1-piece Le Fort osteotomy. If 2 separate maxillary surgical procedures are planned, the SAME osteotomies should be performed where the 1piece maxillary osteotomies are projected to be. The diagnosis of maxillomandibular transverse discrepancy may be difficult in adult patients when sagittal and vertical deformities mask the transverse maxillary discrepancy. When appropriate clinical and radiographic assessments are performed, the correct diagnosis and treatment sequences can be applied, resulting in an acceptable and stable outcome.
Further readings Angell EH. Treatment of irregularities of the permanent or adult teeth. Dental Cosmos 1860;1:540e4. 599-601. Bailey L, White RP, Proffitt WR, Turvey TA. Segmental LeFort I osteotomy for management of transverse maxillary deficiency. J Oral Maxillofac Surg 1997;55:728e31. Banning LM, Gerard N, Steinberg BJ, Bogdanoff E. Treatment of transverse maxillary deficiency with emphasis on surgically assisted rapid maxillary expansion. Compend Cont Educ Dent 1996;17: 170e8. Basdra EK, Zoller JE, Komposch G. Surgically assisted rapid palatal expansion. J Clin Orthod 1995;29:762e6. Bays RA, Greco JM. Surgically assisted rapid palatal expansion: an outpatient technique with long-term stability. J Oral Maxillofac Surg 1992;50:110e3. Bays RA, Greco JM, Hale RG. Stability of surgically assisted rapid palatal expansion. A long term study. J Dent Res 1990;69:296. Bell WH, Epker BN. Surgical-orthodontic expansion of the maxilla. Am J Orthod 1976;70:517e28. Bell WH, Jacobs JD. Surgical-orthodontic correction of horizontal maxillary deficiency. J Oral Surg 1979;37:897e902. Bell RA. A review of maxillary expansion in relation to rate of expansion and patient’s age. Am J Orthod 1982;81:32e7. Betts NJ, Lisenby CW. Normal adult transverse jaw values obtained using standardized posteroanterior cephalometrics. J Dent Res 1994;73:298. Betts NJ, Rosenberg M. Two different alar cinch suturing techniques following surgical maxillary expansion. J Dent Res 1995;74:96. Betts NJ, Scully JR. Transverse maxillary distraction osteogenesis. In: Fonseca RJ, Marciani R, Turvey TA, editors. Oral and maxillofacial surgery. 2nd editionvol. III. St Louis (MO): Saunders; 2009. p. 219e37. Betts NJ, Fonseca RJ, Vig P, et al. Changes in the nasal and labial soft tissues after surgical repositioning of the maxilla. Int J Adult Orthodon Orthognath Surg 1993;8:7e23. Betts NJ, Vanarsdall RI, Barber HD, et al. Diagnosis and treatment of transverse maxillary deficiency. Int J Adult Orthodon Orthognath Surg 1995;10:75e96.
11 Betts NJ, Thanasas AG, Lisenby CW, Mosier KM. Evaluation of racial (African-American, Caucasian) and gender differences in skeletal transverse dimension. J Oral Maxillofac Surg 1997;55(Suppl 3):86e7. Buamrind S, Korn EL. Transverse development of human jaws between the ages of 8.5 and 15.5 years, studied longitudinally with the use of implants. J Dent Res 1990;69:1298e306. Crosby DR, Jacobs JD, Bell WH. Special adjunctive considerations: transverse (horizontal) maxillary deficiency. In: Bell WH, editor. Modern practice in orthognathic and reconstructive surgery, vol. 3. Philadelphia: WB Saunders; 1992. p. 2403e30. da Silva Filho OG, Boas MC, Capelozza Gilho L. Rapid maxillary expansion in the primary and mixed dentitions: a cephalometric evaluation. Am J Orthod 1991;100:171e81. Enlow DH. The facial growth process: part 1. In: Enlow DH, editor. Facial growth. 3rd edition. Philadelphia: WB Saunders; 1990. p. 58e76. Haas AJ. Rapid expansion of the maxillary dental arch and nasal cavity by opening the midpalatal suture. Angle Orthod 1961;31:73e90. Haas AJ. The treatment of maxillary deficiency by opening the midpalatal suture. Angle Orthod 1965;35:200e17. Ilizarov GA. Clinical applications of tension-stress effects for limb lengthening. Clin Orthop Relat Res 1990;(250):8e26. Kraut RA. Surgically assisted rapid maxillary expansion by opening the midpalatal suture. J Oral Surg 1984;42:651e5. Krebs A. Midpalatal suture expansion studied by the implant method over a seven year period. Trans Eur Orthod Soc 1964;40:131e42. Lanigan DT, Hey JH, West RA. Aseptic necrosis following maxillary osteotomies: report of 36 cases. J Oral Maxillofac Surg 1990;48: 142e56. Melson B. A histological study of the influence of sutural morphology and skeletal maturation on rapid palatal expansion in children. Trans Eur Orthod Soc 1972;48:499e507. Mossaz CF, Byloff FK, Richter M. Unilateral and bilateral corticotomies for correction of maxillary transverse discrepancies. Eur J Orthod 1992;14:110e6. Persson M, Thilander B. Palatal suture closure in man from 15-35 years of age. Am J Orthod 1977;72:42e52. Phillips C, Medland WH, Fields HW Jr, et al. Stability of surgical maxillary expansion. Int J Adult Orthodon Orthognath Surg 1992;7: 139e46. Pogrel MA, Kaban LB, Vargervik K, Baumrind S. Surgically assisted rapid maxillary expansion in adults. Int J Adult Orthodon Orthognath Surg 1992;7:37e41. Ricketts RM, Roth RH, Chaconas SJ, et al. Orthodontic diagnosis and planning.their roles in preventative and rehabilitative dentistry. Denver (CO): Rocky Mountain Data Systems; 1982. p. 20e5. 42, 50e59, 138, 233e235. Ricketts RM. Perspectives in the clinical application of cephalometrics, the first fifty years. Angle Orthod 1981;51:115e50. Shetty V, Cardid JM, Caputo AA, et al. Biomechanical rationale for surgical-orthodontic expansion of the adult maxilla. J Oral Maxillofac Surg 1994;52:742e9. Silverstein K, Quinn PD. Surgically-assisted rapid palatal expansion for management of transverse maxillary deficiency. J Oral Maxillofac Surg 1997;55:725e7. Stephens CR. An examination of the long-term stability of surgical-orthodontic maxillary expansion [Master’s thesis]. Columbus (OH): Ohio State University; 1986. Turvey TA. Maxillary expansion: a surgical technique based on surgicalorthodontic treatment objectives and anatomic considerations. J Maxillofac Surg 1985;13:51e8.