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Rapid maxillary expansion
Article in American Journal of Orthodontics and Dentofacial Orthopedics · November 2006
DOI: 10.1016/j.ajodo.2006.08.006 · Source: PubMed
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Rapid maxillary expansion
On the surface, the recent article on rapid maxillary expansion seems like good ammunition for anti-RME faction- ists (Garib DG, Henriques JFC, Janson G, de Freitas MR, Fernandes AY. Periodontal effects of rapid maxillary expan- sion with tooth-tissue-borne and tooth-borne expanders: A computed tomography evaluation. Am J Orthod Dentofacial Orthop 2006;129:749-58). It is also a good example of how not to do rapid maxillary expansion (RME). The following are a just few problems with this very interesting article.
1. Girls with a mean age of 12.4 to 12.6 years could be considered too old by most competent orthodontists to be part of a RME study.1
2. The study neglected to determine beginning and ending skeletal transverse dimensions. Most commonly, those mea- surements are taken lateral to the maxilla at Mx-Mx or at the lateral aspect of the nasal cavity. There are other methods.2-5 3. Actual skeletal expansion is important to determine. If the palatal suture were to be fused, which is highly probable with a 12-year-old girl, all the apparent expansion could be unwanted dental expansion—which has unwanted periodontal effects as detailed in the article. We all know that, when a rapid maxillary expander axle is turned, it does not mean that the maxillary midline suture has opened. We also know that, if the suture has not opened, all the expansion is seen at the teeth, resulting in a combination of temporary increased inclination and trans- lation. If fixed appliances are placed too soon and if the translation is not corrected, temporary becomes perma- nent. And that may become a problem.
4. The eight girls in the study were all treated to 7 mm turnbuckle measurement. Accordingly, it would be rea- sonable to estimate actual skeletal expansion of 2.5 to 3.5 mm.6-8 And that would be true if expansion actually had occurred. Of the 8 patients, did they all need 2.5 to 3.5 mm of skeletal expansion? Did some need more and some less? RME usage without clear skeletal goals in mind, and thus without clear diagnosis, could be considered risky.
5. The study proceeds along a familiar treatment path:
identify a crossbite, use RME to expand, and then, after the crossbite is corrected, place fixed appliances immedi- ately. There are problems with that approach.
● A patient might have a debilitating, narrow maxilla without a crossbite. That patient should also have RME.
● Immediate placement of fixed appliances after RME, although a common treatment,9 should be avoided to let the posterior teeth (those used as abutments for the RME) relapse— back to their prior inclination. Main- taining increased inclination after RME might be peri- odontally detrimental. That problem is easily avoided.
Six weeks of nonretention (no retainer and no fixed appliance) is usually adequate to allow the unwanted RME inclination to disappear.5
● If a crossbite returns after RME removal and after 6 weeks of nonretention, it would indicate that the RME was not taken far enough or that the palate was fused.
● Dental expansion with untoward periodontal conse- quences can occur with improper RME, with improper fixed appliances (eg, a highly flexible archwire placed on crowded teeth), with an expanded palatal bar, or with an expanded headgear, and so on. There might be a periodontal price to pay for dental expansion over the long term. Thus, many appliances might contribute to thinning of the maxillary bone buccal plate.
● It is also possible that the patient’s original presenta- tion, with highly inclined teeth—possibly without crossbite— could also be a long-term periodontal prob- lem, if left untreated with RME.
Contrary to the article, RME, when used correctly and effectively, can improve the long-term periodontal progno- sis.10 Competent RME usage can increase maxillary buccal plate thickness. Because peer-reviewed articles might not be caught up with clinical results, one can use philosophical reasoning: if one can improve the skeletal transverse with RME, then the apical bases will be positioned farther buc- cally. If one were then to allow the posterior teeth (formerly used as RME abutments) to relapse to prior inclinations, then the situation would be different from that detailed by Garib et al. Furthermore, if one were then to move the posterior teeth palatally—with available transverse space—the situation would again be dramatically different from that detailed by Garib et al. In the new position, the posterior teeth would be in a highly protected and improved position—minimal incli- nation with increased buccal plate thickness.
The authors provided vivid documentation regarding what can happen when RME goes wrong because of either misapplication or problems with technique. The same re- search conclusions could have been reached by evaluating several other, more commonly used, orthodontic appliances.
And the same research conclusions could have been reached by evaluating untreated patients with severely inclined pos- terior teeth. The moral of the story: care needs to be taken during diagnosis and treatment to avoid possible future periodontal problems.
John L. Hayes Williamsport, Pa
Am J Orthod Dentofacial Orthop 2006;130:432-3 0889-5406/$32.00
Copyright © 2006 by the American Association of Orthodontists.
doi:10.1016/j.ajodo.2006.08.006
REFERENCES
1. Baccetti T, Franchi L, Cameron CG, McNamara JA Jr. Treat- ment timing for maxillary expansion. Angle Orthod 2001;71:
343-50.
2. Broadbent BH Sr, Broadbent BH Jr, Golden WH. Bolton standards of dentofacial developmental growth. St Louis: C. V.
Mosby; 1975.
3. Ricketts RM, Grummons D. Frontal cephalometrics: practical applications, part I. World J Orthod 2003;4:297-316.
4. Vanarsdall RL Jr. Transverse dimension and long-term stability.
Semin Orthod 1999;5:171-80.
5. Hayes JL. A clinical approach to identify transverse discrepan- cies. Presentation to the Pennsylvania Association of Orthodon- tists; Philadelphia; March 2003.
American Journal of Orthodontics and Dentofacial Orthopedics October 2006 432 Readers’ forum
6. Haas AJ. Rapid expansion of the maxillary dental arch and nasal cavity by opening the midpalatal suture. Angle Orthod 1961;31:73-90.
7. Haas AJ. The treatment of maxillary deficiency by opening the midpalatal suture. Angle Orthod 1965;35:200-17.
8. Fenderson FA, McNamara JA Jr, Baccetti T, Veith CJ. A long-term study on the expansion effects of the cervical-pull facebow with and without rapid maxillary expansion. Angle Orthod 2004;74:439-49.
9. Cameron CG, Franchi L, Baccetti T, McNamara JA Jr. Long- term effects of rapid maxillary expansion: a posteroanterior cephalometric evaluation. Am J Orthod Dentofacial Orthop 2002;121:129-35.
10. Vanarsdall RL, Jr, Secchi AG. In: Graber TM, Vanarsdall RL Jr, Vig KWL, editors. Orthodontics: current principles and tech- niques. 4th ed. St Louis: Elsevier Mosby; 2005. p. 901-36.
Author’s response
We thank John L. Hayes for his interest in our recently published study on periodontal effects of rapid maxillary expansion (RME). His letter allows us to discuss this inter- esting subject further. Most studies on RME—from the first report in 1860 to the present, including the classics—
performed orthopedic expansion on adolescent patients at 11 to 13 years of age or even older. The following are some representative examples. Angell1demonstrated the midpala- tal suture split in a 14-year-old girl; Haas2reintroduced RME as an orthodontic procedure and reported the results of a study of subjects from 9 to 18 years of age; Krebs,3in a remarkable study with implants, used patients 8 to 19 years of age;
Zimring and Isaacson,4to evaluate the forces delivered during orthopedic expansion, selected a sample from 11.5 to 15.5 years of age; Wertz5 and Wertz and Dreskin6 performed reliable studies using samples with ages from 7 to 29 years;
Linder-Aronson and Lindgren7 studied a sample 10 to 21 years of age; Sarver and Johnston8used a sample of patients 7.5 to 21 years of age; Asanza et al9 performed RME in patients from 8.5 to 16 years of age; and Baccetti et al10 compared the RME effects between 2 groups of patients with mean ages of 11 and 13.5 years, respectively.
All these studies proved that the midpalatal suture is still patent during the second decade of life, at least before skeletal maturity. It is also well documented that the orthopedic effect caused by RME decreases as age increases.3,6,10This does not mean that RME can be performed only during the deciduous and mixed dentitions, and should be abandoned in the permanent dentition. During the early permanent dentition, even after the adolescent growth spurt peak, RME can cause transverse skeletal changes (equivalent to approximately a third of the amount of screw activation in contrast with 50%
of skeletal gain when RME is performed earlier3).
Dr Hayes might be painting himself into a difficult corner when he suggested so many restrictions on adolescent RME use. Under his proposed guidelines that would limit the use of RME, what should a “competent” orthodontist do to correct maxillary constriction in a 12-year-old girl with a posterior crossbite? Would he or she use surgically assisted RME treatment for this patient? Or perform slow expansion and
accept the great probability of tooth tipping relapse in the long term? Or must the orthodontist tell the patient it is too late to treat the problem?
RME was successful in opening the midpalatal suture in all of our patient-subjects, as we reported in a previous study on the same sample published in 2005,11which was quoted in the discussion (reference 15). This previous study had the main purpose of evaluating the dentoskeletal effects of RME with computed tomography, and the results can answer questions 2, 3, and 4. It is significant that our expansion protocol replicated methods developed and used in previous studies on RME. Therefore, sharp criticism of this method- ology is the same as dismissing the main body of RME literature for the last 6 decades. Additionally, the periodontal evaluation was performed by comparing pre- and postexpan- sion images, and, in this way, the subsequent fixed appliance therapy had no influence on the results. Furthermore, no patient showed any bone dehiscence before expansion.
Dr Hayes implied in his opening sentence that our work could represent political “ammunition” against RME usage in orthodontics. This negative inference disturbs us. My associ- ate authors and I fully embrace the RME procedure, which we use routinely in our clinics. Our objective was simply to share the results of a carefully designed prospective and controlled study on the periodontal effects of RME to alert clinicians about the risk of gingival recession in the long term12and to emphasize preventive measures to help avoid this sequela.
Daniela G. Garib Bauru, São Paulo, Brazil
Am J Orthod Dentofacial Orthop 2006;130:433-4 0889-5406/$32.00
Copyright © 2006 by the American Association of Orthodontists.
doi:10.1016/j.ajodo.2006.08.007
REFERENCES
1. Angell EH. Treatment of irregularity of the permanent or adult teeth. Dent Cosmos 1860;1:540-4, 599-601.
2. Haas AJ. Rapid expansion of the maxillary dental arch and nasal cavity by opening the midpalatal suture. Angle Orthod 1961;31:
73-90.
3. Krebs A. Midpalatal suture expansion studies by the implant method over a seven-year period. Trans Eur Orthod Soc 1964;40:131-42.
4. Zimring JF, Isaacson RJ. Forces produced by rapid maxillary expansion. III. Forces present during retention. Angle Orthod 1965;35:178-86.
5. Wertz RA. Skeletal and dental changes accompanying rapid midpalatal suture opening. Am J Orthod 1970;58:41-66.
6. Wertz R, Dreskin M. Midpalatal suture opening: a normative study. Am J Orthod 1977;71:367-81.
7. Linder-Aronson S, Lindgren J. The skeletal and dental effects of rapid maxillary expansion. Br J Orthod 1979;6:25-9.
8. Sarver DM, Johnston MW. Skeletal changes in vertical and anterior displacement of the maxilla with bonded rapid palatal expansion appliances. Am J Orthod Dentofacial Orthop 1989;95:462-6.
9. Asanza S, Cisneros GJ, Nieberg LG. Comparison of hyrax and bonded expansion appliances. Angle Orthod 1997;67:15-22.
10. Baccetti T, Franchi L, Cameron CG, McNamara JA Jr. Treatment timing for maxillary expansion. Angle Orthod 2001;71:343-50.
11. Garib DG, Henriques JFC, Janson G, Freitas MR, Coelho RA.
Rapid maxillary expansion—tooth-tissue-borne vs tooth-borne American Journal of Orthodontics and Dentofacial Orthopedics
Volume130,Number4
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