1. Adult rapid maxillary expansion
Paul A. lines, D.D.S., KS.*
Rapid maxillary expansion was used as early as 1860 by E. II. Angell,l
and it has been utilized even more in the last decade. The procedure fell into
disuse by practitioners in America shortly after the turn of the century, primar-
ily because the concept of dentoalveolar expansion and bone growth was popular
at the time, and it was thought that the risks involved did not justify the use of
such an unknown technique.
Eapid maxillary expansion has been shown to he an cstrcmely valuable aid
in the orthodontic treatment of young patients exhibiting maxillary collapse,
maxillary retrusion, and/or a pseudo Class III malocclusion. Davis and Kron-
man’ reported that, with the exception of those wearing headgear, all patients
in their study demonstrated a forward repositioning of point A following rapid
maxillary expansion, Wertz3 and Biederman” believed that the forward displacc-
ment of the maxilla during rapid maxillary expansion was tluc to the disjunction
of the pterygopalatine suture. In t,hc experimental rapid maxillary expansion
of monkeys, Gardner and Kronman” found the spheno-occipital sync~hondrosis
to open. They thought this to bc the causative factor for the downward and for-
ward movement of the maxilla.
IIaas” explained that the downwartl and forward movcmrnt of the maxilla
during rapid maxillary expansion occurred becausr of the location of the
maxillocranial sutures. He stated1 that half of his patients being treated with a
rapid maxillary expansion appliance said that they felt the sensation of pros-
sure in the region of the zpgomatic.omasillarp suture and some saicl that nres-
sure occurred in the zpgomaticotemporal suture area. llc hclievetl that the rea-
son the maxillae separated from each other in a tipping fashion instead of
parallel was the strength of the zygomatic buttresses. lcrtz:’ stated that rc-
sistance of the zygomatic arch prcvcntetl parallel opening of the midpalatal
suture. In experiments on monkeys, the z?-gornati~oma?tilla~~, zygomaticotem-
From the Department of Oral and Maxillofacial Surgery, Kanton Hospital of
*Present address: 2415 South Kurul Ed., Tcmpc, Ark. 85382.
2. Adult rapid maxillary expansion with corticotomy 45
poral, and midpalatal sutures, as well as all other maxillary articulations, were
found to have an increased cellular activity when rapid maxillary expansion
was used53 7
Isaacson and Murphy8 reported the use of rapid maxillary expansion in five
cleft palate patients in 1964. In one of these patients, a 22-year-old man, no
expansion between the maxillae occurred. The inability to spread the maxillae
apart in the midline was obviously not due to a sealed midpalatal suture, inas-
much as no such suture exists in the cleft palate patient. Therefore, it was
concluded that the rigidity of the facial skeleton was a more important factor
than was ossification of the midpalatal suture in those cases in which attempted
rapid maxillary expansion failed. Subtelny and Brodie” reported that reposi-
tioning of bony segments in cleft patients occurred more slowly in adults, and
this was probably due to suture closure.
In a second article,l” Isaacson and his co-authors stated that the facial skele-
ton of younger patients was less resistant to expansion, and they concluded that
the facial skeleton must therefore increase its resistance to orthopedic forces with
age. Zimring and Isaacson proved this theory in 1965. A strain-measuring
device was incorporated into the rapid maxillary expansion unit, so that forces
produced by expansion could be measured. They found that their oldest patient
a&umulated a higher level of resistance pressure over a smaller number of acti-
vations, required more time to dissipate pressure loads, and accrued higher
residual loads than the other patients.
Haaslz reported that the midpalatal sutures of two patients, aged 1’7 and 19,
did not separate, and only alveolar remodeling and orthodontic tooth movement
were possible in these patients. Wertz3 also found that older patients exhibited
less skeletal change. One of his patients, a 16-year-old girl, showed no midpalatal
suture opening after attempted rapid maxillary expansion. Cleall and associates,13
in experiments involving rapid maxillary expansion in monkeys, deduced that
the best reaction time would be during the period that the midpalatal suture is
still growing. This deduction is in agreement with a statement by Haa@ that
orthopedic forces are most ideally used during the growth spurt.
From these various reports in the literature, we reach two conclusions : (1)
that rapid maxillary expansion has been used with a relatively high rate of
success in growing children and (2) that its failure when attempted in adults
can be primarily attributed to the increased rigidity of the facial skeleton and
to the sealing of the frontomaxillary, zygomaticotemporal, zygomaticofrontal,
and zygomaticomaxillary sutures. The rigidity of the articulation of the zygo-
matic complex to the maxilla appears to be the main restraint to expansion. Be-
cause of the increased rigidity of the facial skeleton in adults, it has been
stated8 that when one is contemplating rapid maxillary expansion in an adult,
he should acknowledge the fact that basal or alveolar bone movement may not
Until recently, rapid maxillary expansion has been mostly limited to the
treatment of growing children. Maxillary expansion in adults has been confined
either to orthodontic tooth movement and alveolar remodeling or to surgical re-
positioning with a maxillary osteotomy. Steinhauser,l” in 1972, described a tech-
3. Fig. 1. Dry skull showing line of corticotomy cut through the lateral wall of the maxillary
niquc for a maxillary expansion ost,eotomp. Basically, the surgical intervention
invol-es a TieFort I typo of ostcotomy in coml)ination with surgical splitting of
the palate in the midline. The maxilla is srparatc~tl from the skull by cutting the
lateral walls of the nose ant1 masill;lr~ sinlls, separation of the xcptum and
vomcr from the palate, a11t1 forced opclling ol’ thr I,tc~r~~c)l~~asilli~r~~suture. The
maxilla is split tlown the midline wit I1 tmrs and osteototnes, aftrr which a tri-
angular unicortical iliac graf’t is insrrtctl into the voicl crratctl I)?- the cspansion.
It is prohahlc that the long-term Ability of this tcc+liniqiit~ is primarily
(Icpcndcnt not upon the mitllinc gl*il ft hut, rather, upon the nc~vly c*rcatcd rela-
tion of the maxilla to the facial skclcton. AS was pointctl out 1)~ IS:~~~SOII ant1
c~ollcagucs,“’ the apposition of hone in the midline (luring rapit lnit?tillhIry ~~spilll-
sion occurs as a reaction to the negative pressure in this arc;r pro(lucctl hy the
SpK’fXt~illg ilpilrt of tlIc maxilla. Thc~- rcportctl that, ape” ;i~P~~liallc~c l’(‘mOV?ll, ZIS
much as 20 JW~ cent, immediate relapse occurred. This was due to the residual
forces still prcscnt in the expanclcd Cacial skclcton.
Iq$r tells us tllat if the ncgatjiyt> prcssnrc in the midline can (‘ausc the ap-
position ot’ hone, then the positive rcsitI~al pressure of the facial skeleton cw~ld
cause resorption of’ hone in thr mitllinc. Thcrcforc, the placement of graft ma-
terial in the midline with Stcinhauscr’s tcchniyuc is nc~ssar~- for the initial
midline hone growth and it adds temporary stability to the surgical procedure,
but the long-term stability comes from the relationship of the maxilla t,o the
facial skeleton and the lack of residual forces to initiate it dlaps~.
After realizing that the zygomatic huttrcss was the cause of most OF the
rcsistancc to nlaxillary expansion i11 a(lnlts and rcqqIixing the fact that the
midline graft is not essential for tllc Iong-term staLlit>. of a surgic’nl result, the
conclusion was drawn that rapid maxillary expansion in atlults was possible with
the use of a corticotomy as an atljunc*t to mechanothcrapy. The corticotomy used
to weaken the rigid facial skeleton ant1 surgicall?; oprn the midpalatal suture in
atlults will now he descrihetl.
4. Adult mapid maxillury expasnsio?z with corticotomy 47
Fig. 2. Line of the palatal cut on the dry skull extends from the posterior nasal spine to
the incisive foramen.
Description of technique
-The lateral incision is made in the depth of the vestibule from the canine to
the tuberosity. A mucoperiosteal flap is raised, and the lateral wall of the
maxillary sinus is exposed. The cortical plate is then severed along a line ex-
tending from the piriform aperture across the zygomatic buttress with a medium-
sized Steiger bur, which is basically a cross-cut fissure bur with a rounded
head that does not damage the sinus mucosa. The distal cut is extended into
the tuberosity area, but it is not necessary to extend it into the pterygomaxillary
fissure area; therefore, the danger of damage to the pterygoid plexus and de-
scending palatine artery is reduced (Fig. 1). The incision is then closed with a
continuous mattress 2-O Supramid suture.
The midline incision is made from behind the incisive papilla to the termina-
tion of the hard palate. Because the incision is not extended into the incisive
papilla, the nasopalatine nerves and vessels are left intact. The palatal tissue and
periosteum are elevated 3 to 4 mm. on each side of the incision. The sealed mid-
line suture is then opened with a small Steiger bur from the posterior nasal
spine to the incisive foramen (Fig. 2).
The bone cut need not extend interdentally; thus, the risk of damage to the
roots of the central incisors is eliminated. The bur is tipped to separate one side
of the maxilla from the septum and vomer, and then the other (Fig. 3). The
palatal incision is then sutured with 4-O Dexon and covered with a previously
fabricated protective acrylic plate. The acrylic plate is made from study models
taken prior to the surgical procedure and is similar to a Hawley retainer, ex-
cept that it has no labial arch wire. The purpose of the acrylic stent is to cover
the palatal incision so that it will not be opened by the tongue during mastica-
tion and swallowing.
The Supramid sutures are removed in 10 days to 2 weeks. Two to 3 weeks
after the corticotomy, the rapid maxillary expansion unit is cemented and ex-
5. 48 Lines An?. J. Orthod.
fig. 3. Steiger bur is tipped in the midline cut to sever the septum and the vomer articula-
tion from the palate.
pansion is begun. This interval of time allows the soft tissue to heal and re-
establish the blood supply. It is especially important that the midpalatal incision
be completely healed before expansion is begun. Expansion can then be ini-
tiated with one complete rotation of the expansion screw (0.8 mm.) the first day,
followed by two quarter-turns (0.4 mm,) each day thereafter until the desired
expansion has occurred. The expansion is then retained for a period of 3 to 6
months, as with rapid maxillary expansion in growing children.
After successfully using corticotomies to adjunct the rapid maxillary
expansion of three nongrowing patients, I made an extensive review of the
literature to determine whether or not corticotomy for rapid maxillary expansion
in adults had previously been reported. It was found that only two techniques
had been described, and they were both for maxillary alveolar expansion.
Koele,l” in 1959, reported performing a corticotomy in one patient to weaken
the maxillary alveolus, thus permitting warpage of the alveolus in slow maxillary
expansion. His technique differed from that described here in that he did not
extend the buccal cut to the piriform aperture but, instead, made a vertical cut
distal to the canine. The palatal cut w&s made at the junction of the alveolus
and the hard palate. This cut extended from the major palatine foramen to the
distal aspect of the canine, where it was joined to a vertical cut between the
first premolar and the canine.
In 1969 Converse and Horowitz*G mentioned the use of a corticotomy for
dentoalveolar expansion and illustrated the use of the technique in a patient with
6. Adult rapid maxillary expansion with corticotomy 49
Fig. 4. A, Preoperative occlusion. B, Maxillary arch during surgery. Note midpalatal and
buccal mucosal incisions. C, Buccal surgical view demonstrates the bone cut across the
zygomatic buttress. D, Amount of expansion attained after 3 weeks of appliance activa-
tion. E, Occlusion after 3 weeks of expansion. Note overcorrection to the point that the
lingual cusp tips of the maxillary teeth are in contact with the buccal cusp tips of the
mandibular teeth. F, Occlusal radiograph after 3 weeks of expansion. G, Occlusal radio-
graph at the time of removal of retention. H, Postoperative occlusion.
7. 50 Lines
Fig. 5. A, Preoperative occlusion. B, Occlusion at the time the patient was referred back
to her orthodontist. C, Preoperative maxillary arch. D, Maxillary arch at time of retention
removal. E, Preoperative cephalometric film F, Postoperative cephalometric film.
bilateral palatal clefts. The tcchniqutr was identical to that reported by Koelc
except that no vertical bone cuts wcrc necessary bcvause the clefts extended
interdentally between the canines and incisors. Several mucosal incisions were
made buccally and lingually. Osteotomes were then place~l in these incisions and
malleted to weaken the cortex, after which orthodontic forces were applied by
either a lingual or a labial appliance. Neither the report by Koele nor the article
by Converse and Horowitz mentioned the age of the patient.
8. Adult rapid nwxillnry expamimz with corticotomy 51
Fig. 6. A, Preoperative maxillary arch. B, Palatal surgery. Note transverse cut between
canines and premolars. C, Buccal surgery. Note vertical cortical cut between canine and
premolar. D, Model surgery showing amount of expansion needed in the premolar region.
Patient I;. H. was an 18-year-old girl with open-bite, maxillary collapse, and
mild maxillary retrusion. The treatment plan consisted of (1) rapid maxillary
expansion after corticotomy, (2) a period of retention, (3) surgical closure of
the open-bite, and (4) completion of the case orthodontically (Fig. 4).
Patient E. B. was a 17-year-old girl with open-bite, maxillary collapse, and
moderate root resorption. She was referred from her orthodontist for surgical
closure of the open-bite. The treatment plan was identical to that of the first
patient (Fig. 5).
Patient F. H., a 20-year-old man, had a Class III malocclusion with maxil-
lary arch collapse, particularly in the area of the premolars. The treatment plan
consisted of (1) rapid maxillary expansion after corticotomy, (2) a period of
retention, (3) surgical correction of the mandibular prognathism, and (4) com-
pletion of orthodontic treatment (Fig. 6).
Operative ami! postoperative course. In two of the patients upon whom the
corticotomy7 procedure was performed general anesthesia was used; in the other
only local anesthesia was employed.
The length of time required to complete the corticotomy was between 45
minutes and 1 hour in each case. This operating time is short enough to negate
the necessity for general anesthesia. Therefore, I suggest the use of local
anesthesia with premeditation.
9. 52 Lines Am. J. Orthod.
Fig. 6. E, Preoperative occlusal radiograph. F, Occlusal radiograph during retention phase.
G, Maxillary arch at initiation of retention phase.
Bleeding was light to moderate, and none of the patients required transfusion
of blood. Swelling was moderate and remained to some degree for about a week.
The postoperative course in all instances was uneventful. The procedure can be
performed on an outpatient basis.
Expa.n.sion. The appliance therapy employed in the rapid maxillary expansion
of these patients was the same as that. commonly utilized in growing children.
The study of forces used during rapid maxillary expansion,ll showed the ac-
cumulation of extremely high levels of pressure in adults during expansion. To
aid in the dissipation and to decrease the total residual load, the authors of that
article suggested that a reduced expansion schedule be used in adults. It would
be interesting to see if the force levels are actually reduced in the adult who
has had a corticotomy when compared to the adult who has not undergone a
corticotomy. Assuming that the corticotomy does aid in reducing this force
level, the adult patient could maintain the same expansion schedule that was
used in this report. If, on the other hand, the corticotomy does not appreciably
reduce the pressure load accumulation, then a reduced expansion schedule
should be used for all adult patients.
Retention. As pointed out by Isaacson, and supported by a statement by
Haas, the best method of retention is overcorrection. The residual force load
10. Adult rapid maxillary expansiovl with, corticotonLy 53
Fig. 7. Dotted line represents corticotomy cut separating basal bone from the main sup-
porting pillars of the maxillary skeleton. [From Sicher, H.: Oral anatomy, fourth edition,
St. Louis, 1965, The C. V. Mosby Company.)
on the expanded maxillae is much less at a lesser degree of expansion. There-
fore, if one overcorrects and retains the overcorrected position for some time
before allowing some of the overcorrection to be lost, much of the residual force
load is dissipated. Once collapse back to the amount of desired expansion has
occurred, these rcsitlual forces should have been dispersed.
Cleall and co-workers’” demonstrated that the midpalatal suture, even though
radiographically it appeared nearly normal after 3 months of retention, was still
histologically disorganized and poorly calcified. It was not until 6 months had
elapsed since expansion had been completed that the suture was repaired to a
normal state, both histologically and radiographically. I also recommend this
6-month period of retention, but it posts some problems for patients who require
intcrmaxillary fixation when their malocclusion is surgically corrected, as in the
second patient tlcscribcd here. This patient would have had inadequate space
for the tongue if she had been placed in intermaxillary fixation with a rapid
maxillary expansion unit still in place. In this instance, the expansion unit was
removed after only 1 month of retention. On the same day that the expansion
unit was removed, a palatal and intermaxillary splint was inserted to maintain
the maxillary arch width.
Adw~etages of fhis corticofor)ly technique. The corticotomy technique as
described separates the basal bone of the maxilla from the main supporting
pillars of the maxillary skeleton (Fig. 7). The articulations of the rigid facial
skeleton are isolated from the basal section of the maxilla by the corticotomy.
The only remaining suture that must be opened orthopedically with this tech-
nique is the pterygopalatine suture (Fig. 8). After completion of the corticotomy,
the maxilla is joined to the base of the skull via three remaining anatomic con-
Fig. 8. Sutures where slippage must occur in rapid maxillary expansion. When the corti-
cotomy is used, all but the pterygopalatine sutures are circumvented. (From Sicher, H.:
Oral anatomy, fourth edition, St. Louis, 1965, The C V. Mosby Company.]
nections-the very thin and pliable lateral wall of the nose, the cartilaginous
articulation of the premaxilla to t,hc septum, and the pterygopalatine suture
(Fig. 9). The maxillae arc still linked in the midline by the interdental bone
hctwecn the central incisors. It is usually an advantage to have the maxillae
connected via the intcrincisor bony bridge because the bridge adds an additional
restraint to an area where, in most ceases,rotaCon is desirable, rather than a
large opening. JIaas* and WerW I7 stated that t,hc opening of the midpalatal
suture occurs in a scissorslike fashion. This type of opening produces more
interincisal expansion than intcrmolar expansion. Only in extreme space-
discrepancy cases is the scissorslike opcniug dcsirahle. In the third clinical case
described here, the corticotom,v technique differed slight,ly from t,hose of the
first two cases. The buvc*al bone cuts WW~~identical to those in t,hc first, two cases,
except that they cxtendcd vertically distal to the canines ins&ad of extending
horizontally to t,he piriform aperture, similar to the Kocle technique. The
lingual cut was different in that, thr niitlpalatal suture was opened surgically
from the end of the hard palate to the area behind the canine, where it joined a
bone cut running across the palate from the distal aspect of the left to the distal
aspect of the right canine.
The modified procedure used in the third case has fewer indications than
the corticotomp used in the first two patients. The main indicat,ion for this
modified tecahniyue would be instances in which the maxillary premolar area
was extremely collapsed but where adequate width existed throughout the rest
of the arch. Tt could also be used for unilateral rapid maxillary expansion to
move only one segment of the maxilla laterally. This procedure is very similar
12. Volunze 67
Adult rapid maxillary expansion with corticotomy 55
Fig. 9. Drawing illustrates dotted lines as corticotomy cuts on a cross section of the
maxilla. (From Sicher, H.: Oral anatomy, fourth edition, St. Louis, 1965, The C. V. Mosby
to that of Koele and also to the Converse and Horowitz techniques. The main
difference is in the placement of the palatal bone cut.
The corticotomy used in the third case surgically opens the midpalatal
suture, whereas the other techniques separate the alveolus from the palate at
the junction of the alveolus, palate, and lateral wall of the nose. One advantage
of surgically opening the midpalatal suture is that the danger of damaging the
palatine vessels is reduced. A disadvantage is that, as a result of the midline
corticotomy used in this report, the lateral wall of the nose must be moved
orthopedically. However, the lateral wall of the nose is very thin and is capable
of bending rather than disarticulating,4 and, therefore, offers little resistance
to lateral expansion. Through use of the midline expansion, the nasal capacity
is increased6, 7yI7 This increase does not occur when only the alveolus is
expanded, as in the other techniques.
Future considerations. As previously mentioned, the forces required to
expand the maxillae in the patients in this report were unknown. Forces as
high as 2295 pounds have been reportedly used in nongrowing patients.lO The
forces necessary for expansion in patients who have undergone corticotomy
should be measured so that a physiologic Rctivation schedule could be recom-
mended. The possible use of the corticotomy for unilateral expansion was also
mentioned. This is one area in which a corticotomy might be employed in both
growing and nongrowing patients.
There are few cases of maxillary expansion with corticotomy reported in
the literature. It would seem imperative that larger numbers of such cases be
reported before any comparisons between techniques and their results can be
13. made. The oldest, patient in this report was 20 years of age. The actual valuer
of’ the corticotomg cannot be properly tliscerned unt,il after it lliis Len uscc1 in
older patients and in a greater number of cases.
Summary and conclusions
A corticotomy to weaken the maxillary osseous structure for widening was
employed in three nongrowing patients, after which the maxillae were separatetl
in the midline by the application of orthopedic forces via a cdementcd rapid
maxillary expansion &vice. The postoperative courses were uneventful and gave
no contraindication to the use of the corticotomp in adults. The conclusion
drawn was that an expansion of the rnaxilla can bc attained in nongrowing
patients following corticotomy.
1. Haas, A. J.: Rapid expansion of the maxillary dental arch and nasal cavity by opening
the midpalatal suture, Angle Orthod. 31: 73-90, 1961.
2. Davis, W. M., and Kronman, J. H.: Anatomical changes induced by splitting of the mid-
palatal suture, Angle Orthod. 39: 126-132, 1969.
3. Wertz, R. A.: Skeletal and dental changes accompanying rapid midpalatal suture opening,
AM. J. ORTHOD. 58: 41-66, 1970.
4. Biederman, W.: Rapid correction of Class IIT malocclusion by midpalatal expansion, AM.
J. ORTHOD. 63: 47-55, 1973.
5. Gardner, G. E., and Kronman, J. H.: Cranioskeletal displacements caused by rapid palatal
expansion in the rhesus monkey, AM. J. ORTHOD. 59: 146-155, 1971.
6. Haas, A. J. : Palatal expansion: Just the beginning of dentofacial orthopedics, AM. J.
ORTHOD. 57: 219-255, 1970.
7. Starnback, K. H., and Cleall, J. F.: The effects of splitting the midpalatal suture on the
surrounding sutures, AM. J. ORT~~OD. 50: 923, 1964.
8. Isaacson, R. J., and Murphy, T. D.: Some effects of rapid maxillary expansion in cleft
lip and palate patients, Angle Orthod. 34: 143-154, 1964.
9. Subtelny, J. I)., and Brodie, A. G.: An analysis of orthodontic expansion in unilateral
cleft lip and cleft palate patients, AM. J. ORTHOD. 40: 686-697, 1954.
10. Isaacson, R. J., et al.: Forces produced by rapid maxillary expansion, Angle Orthod. 34:
Il. Zimring, J. F., and Isaacson, R. J.: Forces produced by rapid maxillary expansion, Angle
Orthod. 35: 178-186, 1965.
12. Haas, A. J.: The treatment of maxillary deficiency by opening the midpalatal suture,
Sngle Orthod. 35: 200-217, 1965.
13. Cleall, J. F., et al.: Expansion of the midpalatal suture in the monkey, Angle Orthod. 35:
14. Steinhauser, E. W.: The midline-splitting of the maxilla for correction of malocclusion,
J. Oral Aurg. 30: 413-422, 1972.
15. Korle, H.: Surgical operations on the alveolar ridge to correct occlusal abnormalities, Oral
Surg. 12: 515529, 1959.
16. Converse, J. M., and Horowitz, S. L.: The surgical orthodontic approach to treatment of
dentofacial deformities, AM. J. ORTHOD. 55: 217-243, 1969.
17. Wertz, R. A.: Changes in nasal air flow incident to rapid maxillary expansion, AM. J.
ORTHOD. 53: 705-706, 1967.