J Oral Maxlllofac
Surg
42 651-655.1984
Surgically Assisted Rapid Maxillary Expansion by Opening the Midpala tal Suture RICHARD A. KRAUT, DDS* The results of surgically assisted rapid maxillary expansion by opening of the midpalatal suture in 25 patients are reported. Osteotomy of the lateral wall of the maxilla combined with pterygomaxillary dysjunction and midpalatal suture separation allowed for successful rapid maxillary expansion in 23 patients. The two patients who did not respond to treatment were found to have unusually thick midpalatal sutures, which were successfully expanded after the midpalatal sutures were osteotomized.
Maxillary expansion is needed to correct real and relative maxillary horizontal deficiency, maxillary collapse, nasal stenosis, and Class III malocclusions, as well as selected arch length problems.‘,’ Nonsurgical rapid maxillary expansion (RME) was used as early as 1860 by Angel13 and continues to be used by orthodontists with a high rate of success for growing children. ‘.2,4-6 Although in growing children RME results in opening of the midpalatal suture, the problem of stability is exceedingly complex following use of this procedure for these patients.4 The expansion due to alveolar bending, periodontal membrane compression, lateral tooth displacement, and tooth extrusion is most assuredly lost.‘,4.6 Haas’ states that for orthodontists the treatment error potential in performing RME is not carrying the expansion far enough; he considers 10 mm to be minimal expansion and 12 mm average, recommending that the mandibular arch be completely contained by the maxillary arch at the conclusion of expansion. Timms” corroborates Haas’s opinion, stating that between one-third and one-half of the expansion is lost before stability is achieved. He
documents the inescapability of relapse, stating that of nearly 1000 patients treated by RME, only two showed no relapse.4 In 1975, Lines? reported three cases of RME in non-growing patients following corticotomy. A year later, Bell and Epker6 reported 15 cases of surgicalorthodontic expansion of the maxilla in which selected maxillary osteotomies were used to facilitate RME to correct five unilateral and 10 bilateral crossbites. Both Lines? and Bell6 stated the reason for failure of nonsurgically assisted RME in adults is the increased rigidity of the facial skeleton; they cited fusion of various combinations of frontomaxillary, zygomaticotemporal, zygomaticofrontal. and zygomaticomaxillary sutures as being the primary anatomic sites of resistance to RME in adults. Messer et al.’ were more definitive and stated, “the midpalatine suture is not the main deterrent to palatal separation.” They directed surgery toward the zygomaticomaxillary complex, reporting relative ease in RME once the “lateral deterrent is removed.“’ Corroboration of this clinical observation can be found in an animal study of RME in adult Rhesus monkeys, which concluded that the major resistance to RME is the zygomaticomaxillary buttress area.s Persson and Thilander9 studied palatal suture closure in 24 humans aged 15-35 years and concluded that great variations exist with regard to age of closure. They agreed with previous authors that with RME most of the resistance to separation is due to circummaxillary sutures and went on to state that, “if a 5% closure is set as a limit for split-
* Colonel, United States Army Dental Corps; Chief of Oral and Maxillofacial Surgery. Brooke Army Medical Center, Fort Sam Houston, Texas. The opinions or assertions contained herein are the private views of the author and are not to be construed as official or as reflecting the views of the Department of the Army or the Department of Defense. Address correspondence and reprint requests to COL Kraut: Box 433. Beach Pavilion, Brooke Army Medical Center. Fort Sam Houston, TX 78234. 651
652
SURGICALLY
FIGURE
I (top /Q?).
FIGURE
2 (hot~o/~
Cast metal palatal
/
holes for circumdental
Palatal
ligatures.
expansion
expansion
Appliance
prosthesis
prosthehk
with
fabricated
RME
IO-mm expander. from autopolymerizing
was designed to exclude
ASSlSTED
acrylic
resin seated prior to placement
canines in this patient due to need for less anterior
of
than posterior
expansion. FlGURE
3 (rctp r-ight).
Cast metal palatai expansion
left side of the prosthesis
contains
expansion
a female
attachment
with minimal
anterior
provides
for posterior
FIGURE
4 (horro,n
right).
maxillary
expansion
while maintaining
Palatal
expansion
prosthesis
with expander
to allow for expansion horizontal
prosthesis
soldered
to only the right side of the prosthesis.
of only the left maxilla.
The anteriorly
placed
The hingt:
movement.
with expander
located
anteriorly
and hinge posteriorly
to allow
anterior
molar width.
ting the inter-maxillary suture, this will not be reached in most patients younger than 25 years of age.“g Timms and Vera”’ reported failure of RME in a l5-year-old girl and Haas] reported failure to separate the midpalatal suture of a IPyear-old young man. Yet in a later publication, Timms recommended three stages of surgical assistance for RME based primarily on the patient’s age: Stage 1 (palatal osteotomy) for patients 25-years-old and older, or younger if RME has been tried and failed; Stage 2 (palatal and lateral maxillary osteotomies) for those 30-year-old and older; and Stage 3 (palatal. lateral maxillary and anterior maxillary osteotomies) for patients 40-years-old and older.4 The purpose of this study was to determine if a standard approach to surgically assisted RME could
be developed. presented.
Experience
Materials
with 25 patients
is
and Methods
Po tier1t Projile
The patient population consisted of all surgically assisted RME procedures performed in the threeyear period from July 1980 to June 1983. There were 14 females, who had a mean age of 24.78 years (range, 15-47 years) and 1 I males, who had a mean age of 22.55 years (range, 17-32 years) in the group. Appliance
Design
Haas’s statement that “anchorage stands alone as the salient characteristic to be considered in de-
653
KRAUT
signing a palate-expansion appliance”” has been supported by success with various appliance designs. Both cast appliances as described by Brudvik and Nelson” (Fig. I) and acrylic appliances (Fig. 2) were used to expand the palates of the 25 patients being reported. Since considerable force is developed by the expansion screw (454-2270 g).” a base-borne appliance is indicated. The appliance is made on a dental cast with 28-gauge relief of the palatal vault from midline to within 2 mm of the free gingiva of the anchor teeth. When the dentition permits. the appliance is ligated to the canine, both premolars. and the first molar. Use of a IO-mm expansion screw minimizes the need to change appliances during treatment. Incorporation of a hinge allows expansion to occur in a selected area of the maxilla (Figs. 3. 4).
The day prior to surgery, a customized RME appliance was inserted. Using general anesthesia, via naso-endotracheal intubation, the left and right maxillary mucobuccal folds were infiltrated with Iidocaine containing 1: 100,000 epinephrine to aid in hemostas,is. Electrocautery was used to develop a horizontal mucoperiosteal incision at the depth of the maxillary vestibule that provided access to the pyriform rim and pterygomaxillary junction (Fig. 5). A 702 tapered fissure bur was used to make a horizontal bone incision 5 mm superior to the apices of the maxillary teeth, from the pyriform rim to the posterior wall of the maxillary sinus (Fig. 6). After completing the same procedure on the contralateral side, a pterygomaxillary osteotome was used to separate the pterygomaxillary sutures. The RME appliance was activated until resistance was encountered. In the 17 cases operated since November 11981.a vertical midline incision has been made in the unattached gingiva, with care being exercised not to include the attached gingiva. A 701 tapered fissure bur was then used to accentuate the midpalatal suture on the anterior surface of the maxilla. A bibeveled osteotome fashioned from a cement spatula was used to separate the midpalatal suture. Use of this ultra-thin osteotome was followed by that of a thicker osteotome, which continued the separation (Fig. 7). The RME appliance was then activated until resistance was felt. In one patient, a 32-year-old man, the proximity of the central incisor roots to the midpalatal suture was such that the midline procedure was omitted. All incisions were closed with 3-O polyglycolic acid suture. Postoperatively. the patients were taught how to activate their appliances and instructed to activate
1
‘) FIGURE
5 (/op).
two is a midline
to the attached FIGURE
gingiva
6 Oniddlc~).
ygomaxillary maxillary
one extend5
from the anteriot
sur-
to the pyriform
rim.
rygomaticomaxillarybuttrexa
face of the Incision
Incision
junction
fissure.
nasal mucosa.
incision
between
from the anterior the maxillary
A Selden elevator protects
(1) seated
(2) is used to protect the
A 702 bur (3) is used to osteotomke
wall 5 mm above the apices of the teeth.
FIGURE
7 thorro~rr).
continued
by changing
suring initiation
The initial direction
to the midpalatal
suture
the angulation
of midpalatal
incisors. at the pter-
the soft tissues of the pterygo-
A no. 9 molt elevator
maxillary
perpendicular
nasal spine
central
(I).
the lateral
of the ohteotome Suture
separation
of the osteotome
is is
(2) in-
suture separation.
them at a rate of 0.5 mm in the morning and 0.5 mm before retiring at night. The rate of expansion was monitored every 48-72 hours and decreased to 0.5 mm per day if the gingiva between the central incisors showed signs of ischemia or detachment. The
654
SURGICALLY
FIGURE ligature
8 (top).
the central
FIGURE
rapid
device,
rapid maxillary
expansion
9 (hottor~).
Occlusal midpalatal
had been completed
with
factor in sur-
expansion.
demonstrating
expansion
maxillary
The gingival tissue between
incisors is used as the rate-determining
gically facilitated
woman
Completed
securing expansion
radiograph suture
of a Wyear-old
separation.
An g-mm
in ten days.
expansion screw was secured with a ligature wire when the horizontal maxillary width was 1.5 mm greater than the desired final result (Figs. 8, 9). Results
Of the 25 patients who underwent surgically assisted RME, ali cases were bilateral expansion except one, in which the patient underwent unilateral expansion, which was accomplished by performing a unilateral osteotomy and pterygomaxillary dysjunction without a midline procedure. Two patients failed to have opening of their midpalatal sutures after horizontal osteotomy, pterygomaxillary dysjunction, and initiation of separation of midpalatal suture with bi-beveled osteotomes. The first was a 19-year-old young man who appeared to respond normally in the operating room, in that after midline separation with bi-beveled osteotomes, several turns were possible on his RME appliance before resistance was felt. Ten days postoperatively. it was apparent that his midpalatal suture was not opening. Since the teeth to which the appliance had been ligated had become mobile, the appliance was removed and the teeth were allowed to stabilize.
ASSISTED
KME
Eight months after his initial surgery, the patient was re-operated. At surgery, it was noted that bone had filled in the lateral maxillary osteotomy sites. In view of previous inability to separate this patient’s midpalatal suture. his appliance was not placed prior to surgery. After the lateral osteotomy. a palatal flap was developed I cm to the right of the midpalatal suture and the mucoperiosteum reflected towards the midline, providing surgical access to the midpalatal suture. An osteotomy was made from the posterior nasal spine to the nasopalatine canal. The midpalatal suture was 7 mm thick in the area opposite the premolars. After bilateral pterygomaxillary dysjunction, all incisions were closed with 3-O polyglycolic acid suture. The RME appliance was inserted, ligated. and activated, resulting in a 2-mm diastema appearing between the central incisors. Half-inch petrolatum gauze was placed between the RME appliance and the palatal vault to support the palatal flap and prevent hematoma formation. The gauze was removed 72 hours postoperatively. The patient had a successful postoperative course and II mm of expansion across the midpalatal suture was achieved. The only other patient who failed to have separation of the midpalatal suture was an l8-year-old young woman. Her appliance was removed five days after surgery, and a midline osteotomy was accomplished on an outpatient basis, using local anesthesia and intravenous sedation. Her midpalatal suture was IO mm thick in several areas. Following palatal osteotomy. her RME was accomplished uneventfully. A postoperative hematoma developed in a l7year-old young man whose blood pressure was poorly controlled during surgery and in the recovery room. Although no bleeding was noted at the time his incisions were closed, he developed a hematoma within the first half hour in the recovery room. The hematoma did not continue to expand after his blood pressure was controlled. and resolution occurred without surgical intervention. Once expanded, all of the maxillae were retained for three months prior to the start of maxillary orthodontics. Discussion
The unpredictability of RME without surgical freeing reported by Haas’ and Timms” also occurred within this group. A 15year-old girl had RME attempted by her orthodontist. When her midpalatal suture failed to open. she was referred for surgical freeing. The standard horizontal osteotomy, pterygomaxillary dysjunction. and midpaIatal suture separation allowed her to undergo successful RME with opening of the midpalatal suture.
655
KRAUT
Lines’ and Bell6 indicate the suitability of lateral maxillary and palatal osteotomies as feasible office procedures using local anesthesia. When the triangle of bone forming the pyriform rim was osteotomized in the 25 patients, several instances of arterial bleeding occurred. The bleeding was from a small artery within the osseous triangle forming the lateral nasal and lateral maxillary walls. Electrocautery successfully stopped the bleeding in all cases. This brisk bleeding may present significant airway problems if encountered in the unintubated patient or if the patient has been sedated. Previous reports on RME indicate the primary resistance to separation of the midpalatal suture is the zygomaticomaxillary buttress.*q6-s Two of 25 reported patients, a 19-year-old young man and an IS-year-old young woman, failed to undergo separation of their midpalatal suture after their zygomaticomaxillary buttresses had been osteotomized. Both of these patients were subsequently found to have unusually thick midpalatal sutures and thus required midpalatal osteotomy to undergo successful R.ME. A recent observation by the orthodontist who has treated the majority of the patients reported is that the expansions are more stable than those achieved without surgical assistance. Consequently, the addition of only 1.O to 1.5 mm is necessary to com-
pensate for relapse in surgically assisted maxillary expansion. References I. Haas AJ: Long-term 2.
3.
8.
9. IO.
II. 12. 13.
posttreatment evaluation of rapid palatal expansion. Angle Ortho 50: 189, 1980 Lines PA: Adult rapid maxillary expansion with corticotomy. Am J Orthod 67:44, 1975 Haas AJ: Rapid expansion of the maxillary dental arch and nasal cavity by opening the midpalatal suture. Angle Ortho 31:73, 1961 Timms DJ: Rapid Maxillary Expansion. Chicago. Quintessence Publishing Co.. I98 I Wertz RA: Skeletal and dental changes accompanying rapid midpalatal suture opening. Am J Orthod 58:41. 1970 Bell WH, Epker BN: Surgical-orthodontic expansion of the maxilla. Am J Orthod 70:517. 1976 Messer EJ. Bollinger TE. Keller JJ: Surgical-mechanical maxillary expansion. Quintessence International 8: 13. I979 Kennedy JW, Bell WH. Kimbrough OL, et al: Osteotomy as an adjunct to rapid maxillary expansion. Am J Orthod 70: 123, 1976 Persson M, Thilander B: Palatal suture closure in man from 15 to 35 years of age. Am J Orthod 72:42, 1977 Timms DJ, Vero D: The relationship of rapid maxillary expansion to surgery with special reference to midpalatal synostosis. Br J Oral Surg 19:180. 1981 Haas AJ: Palatal expansion: just the beginning of dentofacial orthopedics. Am J Orthod 57:219, 1970 Brudvik JS. Nelson DR: Adult ualatal exuansion prostheses. J Prosth Dent 45:315, 1981 ’ ’ ’ Odenrick L. Lilja E, Lindback K-F: Root surface resorption in two cases of rapid maxillary expansion. Br J Orthod 9137, 1983