Adult rapid maxillary expansion with corticotomy Paul
apid 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, primarily 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 Kronman’ 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 displaccment 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 forward 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 prossure in the region of the zpgomatic.omasillarp suture and some saicl that nressure occurred in the zpgomaticotemporal suture area. llc hclievetl that the reason the maxillae separated from each other in a tipping fashion instead of parallel was the strength of the zygomatic buttresses. \\lcrtz:’ stated that rcsistance of the zygomatic arch prcvcntetl parallel opening of the midpalatal suture. In experiments on monkeys, the z?-gornati~oma?tilla~~, zygomaticotemFrom the Lucerne. *Present
expansion with corticotomy
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, inasmuch 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 repositioning 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 skeleton 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 activations, 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 zygomatic complex to the maxilla appears to be the main restraint to expansion. Because 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 occur. 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 repositioning with a maxillary osteotomy. Steinhauser,l” in 1972, described a tech-
Fig. 1. Dry skull
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 from the skull by cutting the the palate in the midline. The maxilla is srparatc~tl lateral walls of the nose ant1 masill;lr~ sinlls, separation of the xcptum and suture. The vomcr from the palate, a11t1 forced opclling ol’ thr I,tc~r~~c)l~~asilli~r~~ maxilla is split tlown the midline wit I1 tmrs and osteototnes, a ftrr which a triangular 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 relation of the maxilla to the facial skclcton. AS was pointctl out 1)~ IS:~~~SOII ant1 lnit?tillhIry ~~spilllc~ollcagucs,“’ the apposition of hone in the midline (luring rapit occurs as a reaction to the negative pressure in this arc;r pro(lucctl hy the sion 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. in the midline can (‘ausc the apIq$r tells us tllat if the ncgatjiyt> prcssnrc 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 material 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 i11 a(lnlts and rcqqIixing the fact that the rcsistancc to nlaxillary expansion 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.
Fig. 2. Line of the the incisive foramen. Description
expasnsio?z with corticotomy
-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 extending from the piriform aperture across the zygomatic buttress with a mediumsized 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 descending 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 termination 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 midline 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, except 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 mastication 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-
3. Steiger from the
An?. J. Orthod.
bur is tipped palate.
pansion is begun. This interval of time allows the soft tissue to heal and reestablish the blood supply. It is especially important that the midpalatal incision be completely healed before expansion is begun. Expansion can then be initiated 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. Other
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
Fig. 4. buccal zygomatic tion. E, lingual
A, Preoperative occlusion. B, Maxillary mucosal incisions. C, Buccal surgical buttress. D, Amount of expansion Occlusion after 3 weeks of expansion. cusp tips of the maxillary teeth are
mandibular teeth. graph at the time
F, Occlusal of removal
radiograph of retention.
expansion with corticotomy
arch during surgery. Note midpalatal and view demonstrates the bone cut across the attained after 3 weeks of appliance activaNote overcorrection to the point that the in contact with the buccal cusp tips of the
after 3 weeks H, Postoperative
orthodontist. E, Preoperative
Occlusion maxillary 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.
Fig. 6. canines
A, Preoperative and premolars.
maxillary C, Buccal surgery
expamimz with corticotomy
arch. B, Palatal surgery. Note surgery. Note vertical cortical amount
transverse cut between in the
cut between canine and
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 maxillary 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) completion of orthodontic treatment (Fig. 6). Discussion
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.
Am. J. Orthod. January 1975
6. E, Preoperative Maxillary
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 accumulation 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
Fig. 7. porting St. Louis,
Dotted pillars 1965,
line represents of the maxillary The
C. V. Mosby
cut separating [From Sicher,
bone from anatomy,
the main supfourth edition,
on the expanded maxillae is much less at a lesser degree of expansion. Therefore, 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. technique. The corticotomy technique as Adw~etages of fhis corticofor)ly 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 technique 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-
Fmntomaxillary suture Zygoma ticotemporal suture Zygomaticomaxilfar~ suture Pterygcie palatine SUt”UI%
Fig. 8. Sutures where cotomy is used, all Oral anatomy, fourth
slippage but the edition,
must occur in rapid maxillary expansion. pterygopalatine sutures are circumvented. St. Louis, 1965, The C V. Mosby Company.]
the cortiSicher, H.:
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 spacediscrepancy 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 be instances in which the maxillary premolar area modified tecahniyue would was extremely collapsed but where adequate width existed throughout the rest Tt could also be used for unilateral rapid maxillary expansion to of the arch. move only one segment of the maxilla laterally. This procedure is very similar
Fig. 9. Drawing maxilla. (From Company.]
illustrates Sicher, H.:
dotted lines Oral anatomy,
as corticotomy fourth edition,
cuts on St. Louis,
a cross section of the 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 recommended. 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
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
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. REFERENCES
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 midpalatal 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. of rapid maxillary expansion in cleft 8. Isaacson, R. J., and Murphy, T. D.: Some effects 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: 256-269, 1969. 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: 23-25, 1965. 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.