Rapid Maxillary Expansion Treatment may Maintain Long-term Dental Changes in Patients with Constricted Arches

Rapid Maxillary Expansion Treatment may Maintain Long-term Dental Changes in Patients with Constricted Arches

REVIEW ANALYSIS & EVALUATION ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION Long-term dental arch changes after rapid maxillary expansion treatment: a sy...

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REVIEW ANALYSIS & EVALUATION ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION Long-term dental arch changes after rapid maxillary expansion treatment: a systematic review. Lagravere MO, Major PW, Flores-Mir C. Angle Orthod 2005;75(2):155-61.

REVIEWER Jorge L. Castillo, DDS, MSD

PURPOSE/QUESTION Does rapid maxillary expansion maintain long-term dental arch changes in patients with constricted arches?


Rapid Maxillary Expansion Treatment may Maintain Long-term Dental Changes in Patients with Constricted Arches SUMMARY Selection Criteria This systematic review included the following inclusion criteria: rapid maxillary expansion (RME) controlled clinical trials, dental arch measurements made from cephalometric radiographs and dental casts, and no surgical treatment that could affect RME effects during the evaluation period. A computerized search was performed using Medline, Medline InProcess, Lilacs, PubMed, Embase, Web of Science, and all EBM Cochrane Research Systems. The key terms used in this literature search were rapid maxillary expansion, RME, tooth or dental changes. Two authors reviewed the articles independently, and the results were compared. If there was any discrepancy, the article was reviewed by all the authors. After collecting all the abstracts, only 41 studies remained. Thirty-five were rejected for methodological reasons. Only 6 articles remained, but 2 were rejected because they did not have a long-term follow-up. Of the 4 final articles, 2 measured the changes through dental casts and 2 through radiographs.

Information not available

Key Study Factor TYPE OF STUDY/DESIGN Systematic review

LEVEL OF EVIDENCE Level 2: Limited-quality, patientoriented evidence

STRENGTH OF RECOMMENDATION GRADE Grade B: Inconsistent or limitedquality, patient-oriented evidence

J Evid Base Dent Pract 2011;11:21-23 1532-3382/$36.00 Ó 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.jebdp.2010.11.015

Review of studies investigating the long-term effects of RME.

Main Outcome Measure The primary outcome was the long-term dental changes (intermolar width, interpremolar width, intercanine width, arch perimeter, overjet, overbite, incisor inclination, and molar extrusion) after the treatment with RME. These changes were measured in dental casts and in radiographs.

Main Results Only 4 studies were identified, and 37 were excluded for various reasons. Among the 4 studies reviewed, 2 studies evaluated changes in dental casts: 1 in a cephalometric radiograph and 1 in a posteroanterior radiograph. No meta-analysis of findings was conducted as part of this review. The authors summarized their findings as follows: (1) a long-term maxillary intermolar width increase (3.7-4.8 mm) can be achieved; (2) maxillary intercanine width expansion was more consistent among adolescents and adults (2.2-2.5 mm); (3) there was significant gain in maxillary (6 mm) and mandibular (4.5 mm) arch perimeter in adolescents treated with RME and edgewise appliances; (4) differences in arch perimeter change with treatment before or after puberty were most likely not clinically significant; and (5) there were no vertical or anteroposterior dental changes associated with RME.

Conclusions The authors concluded that a clinically significant long-term maxillary molar width increase and arch perimeter increase can be achieved with RME.


COMMENTARY AND ANALYSIS Rapid maxillary expansion (RME) (or rapid palatal expansion [RPE]) is defined as an orthopedic procedure that uses a fixed or removable appliance to separate the 2 maxillary bones at the mid-palatine suture.1 Theoretically, this treatment is more effective in growing patients, because the mid-palatine suture may not be completely interdigitated2 or may have lower bone density,3 resulting in children having more skeletal expansion before peak in skeletal maturation than after.4 Although one study in the current review focused only on children, the remaining 3 studies did include adult and non-growing patients. This is important because the younger the patient, the better the treatment outcomes are with RME. Because RME in non-growing patients may be less effective than in patients before their peak of skeletal maturation, more research on longitudinal changes in patients who underwent RME before peak in skeletal maturation is necessary. The 4 studies are summarized as follows: (1) Handelman et al5 studied the long-term effects of RME with a Haas-type appliance, followed by an edgewise appliance. This study used dental casts to evaluate arch changes. There were 47 adults and 47 children assigned to the treatment group and 52 adults assigned to the control group. However, only adult patients were included in the analyses. The expander was removed after an average of 12 weeks, and the long-term evaluation was 5 years (minimum 1 year). The measurements were taken at the lingual cervical margin. They found a net gain of 4.8-mm maxillary and 0.7-mm mandibular molar width. For the upper premolar width, they found a net gain of 4.7 mm. For the upper canine width, they found a net gain of 2.3 mm, and for the mandibular intercanine width, a gain of 0.8 mm. (2) McNamara et al6 studied the long-term changes in the dental arch dimensions in 112 adolescent patients treated with a Haas-type appliance, followed by edgewise treatment. The control group consisted of 41 patients from the University of Michigan Elementary and Secondary School Growth Study. This study also used dental casts to evaluate arch changes. The expander was removed after an average of 65 days, and the long-term evaluation was 6.1 years on average. Although the measurements were made both at the centroid and the junction of the lingual groove with the palatal mucosa, for comparison with the first study, only the measurements at the lingual cervical junction were reported. Compared with the control group, 6.0-mm maxillary and 4.5-mm mandibular arch perimeter gains were achieved in the long term. Compared with the control group they found a net gain of 3.7-mm maxillary and 5.4-mm mandibular molar width. For the upper premolar width, they 22

found a net gain of 3.7 mm. For the upper canine width, they found a net gain of 2.2 mm, and for the mandibular intercanine width, a gain of 1.8 mm. (3) Baccetti et al4 studied the dental long-term effects of the Haas appliance before and after growth peak. In this study there were 62 patients: 42 were in the treatment group and 20 were in the control group. The expander was removed after an average of 65 days. Three posteroanterior radiographs were used to evaluate arch changes (initial, immediately after treatment, and 5 years after treatment). Long-term evaluation was 8 years (minimum 5 years). The early-maturing group (11 year, prepubertal growth spurt) had more intermolar width changes (2.7 mm) than the control. The mandibular change was not significant. The latematuring group had more intermaxillary width changes (3.5 mm) and more mandibular width changes (2.3 mm) than the control. (4) Garib et al7 studied the dental long-term effects of the Haas appliance followed by edgewise treatment on 25 patients (11.0- to 17.4-year-olds). The control group included 26 patients. Three lateral radiographs were used (initial, immediately after full fixed treatment, and post retention) to evaluate arch changes. The long-term evaluation was a minimum of 3 years. When compared with the control group, they found a net overjet decrease of 0.6 mm, and no changes in molar extrusion, incisor inclination, or overbite. The outcome of the Handelman et al study5 was a gain in the maxillary and mandibular molar transarch width; the outcome of the McNamara et al study6 was a gain in maxillary and mandibular arch perimeter and intermolar, interpremolar, and intercanine width; the outcome of the Baccetti et al study4 was a gain in intermolar width; and the outcome of the Garib et al study7 was a change in overjet, molar extrusion, incisor inclination, and overbite. Thus, the main outcome in most of the studies was gains in arch width, which is one of the main objectives of RME (the other major one could be the increase in arch perimeter). Changes in overbite, overjet, molar extrusion, or incisor inclination are not primary objectives of maxillary expansion. All of the reviewed studies included a phase of edgewise appliance therapy. Other authors have used the same sequence.8 Although all the studies included the same protocol (expansion followed by an edgewise appliance therapy phase) that make them comparable, there is the question on how the edgewise therapy may have affected the long-term results of RME, such as better intercuspation or increase in arch width and perimeter after edgewise appliance therapy. For instance, the McNamara et al study6 found a considerable increase in the mandibular intermolar and intercanine width and maxillary and mandibular arch perimeter. The patients started full edgewise appliance after RME, and this may have helped March 2011


in increasing arch width and perimeter, especially in the mandible. The initial severity of the malocclusion of the patients was also not clear, and this may be critical because it may be that the greater the treatment changes, the greater the relapse.9 The terms RME, slow expansion, and semirapid expansion are mentioned throughout the review, but there is no indication of their limits. For instance, how many turns of the expansion screw every day constitute rapid, slow, or semirapid expansion? Or how many times was the expander activated? This information is important to compare the articles presented. All of the articles included in the final pool of articles were studies of the Haas appliance. The Haas appliance is not the only one used for RME. Other appliances are also used for RME, such as the Hyrax and bonded RME appliance.10 It would be interesting to know if there is any difference in the longterm results with other appliances. In the current Lagravere et al systematic review, the authors stated that some articles were rejected because they only evaluated dental changes, but all the articles that were included in this review evaluated dental changes such as interarch width, arch perimeter, molar extrusion, and so forth. Therefore, the selection criteria for the included studies was unclear. As the previous authors mentioned, there is limited information about the retention protocol, and this may be critical to the long-term effects of expansion. The postretention studies at the University of Washington have concluded that with or without expansion, there is always the risk of decrease in intercanine width.11 It is very important to include information on measurement errors, especially in those studies that evaluate changes in casts. Studies have shown that there is a chance for errors with either traditional plaster models or dental digital models.12 All the intra- and inter-reliability measurements should have been included in the review if they were available. In conclusion, this systematic review suggests that clinically significant long-term effects on maxillary molar width can be achieved and there may be significant overall gain in arch perimeter after RME treatment. Because RME produces both dental and skeletal changes, determining how much of the relapse and the long-term effects on changes in width and perimeter can be attributed to skeletal effects warrants a further systematic review. The limitations of the

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studies reviewed show the need for further well-controlled, long-term clinical trials using different appliances, controlling for the protocols of activation, using subjects before and after puberty, controlling for the edgewise treatment, and looking at the retention protocol after RME treatment and after edgewise appliance treatment.

REFERENCES 1. American Association of Orthodontics. AAO Glossary of Terms. Available at: http://www.aaomembers.org/Resources/Library/ glossary.cfm. Accessed September 14, 2010. 2. Melsen B. Palatal growth studied on human autopsy material. A histologic microradiographic study. Am J Orthod 1975;68(1):42-54. 3. Koebmacher H, Schilling A, Puschel K, Amling M, Kahl-Nieke B. Agedependent three dimensional microcomputed tomography analysis of the human midpalatal suture. J Orofac Orthop 2007;68(5):364-76. 4. Baccetti T, Franchi L, Cameron CG, McNamara JA Jr. Treatment timing for rapid maxillary expansion. Angle Orthod 2001;71(5):343-50. 5. Handelman CS, Wang L, BeGole EA, Haas AJ. Nonsurgical rapid maxillary expansion in adults: report on 47 cases using the Haas expander. Angle Orthod 2000;70(2):129-44. 6. McNamara JA Jr, Baccetti T, Franchi L, Herberger TA. Rapid maxillary expansion followed by fixed appliances: a long-term evaluation of changes in arch dimensions. Angle Orthod 2003;73(4):344-53. 7. Garib DG, Henriques JFC, Janson GP. Longitudinal cephalometric appraisal of rapid maxillary expansion effects. Rev Dental Press Ortod Ortop Facial 2001;6:17-30. 8. Gurel HG, Memili B, Erkan M, Sukurica Y. Long-term effects of rapid maxillary expansion followed by fixed appliances. Angle Orthod 2010;80(1):5-9. 9. de Freitas KM, Janson G, de Freitas MR, Pinzan A, Henriques JF, Pinzan-Vercelino CR. Influence of the quality of the finished occlusion on postretention occlusal relapse. Am J Orthod Dentofacial Orthop 2007;132(4):428, e9-14. 10. Weyrich C, Noss M, Lisson JA. Comparison of a modified RME appliance with other appliances for transverse maxillary expansion. J Orofac Orthop 2010;71(4):265-72. 11. Little RM. Stability and relapse of mandibular anterior alignment: University of Washington studies. Semin Orthod 1999;5(3):191-204. 12. Mangiacapra R, Butti AC, Salvato A, Biagi R. Traditional plaster casts and dental digital models: intra-examiner reliability of measurements. Prog Orthod 2009;10(2):48-53.

REVIEWER Jorge L. Castillo, DDS, MSD Department of Dentistry for Children and Adolescents Universidad Peruana Cayetano Heredia Lima, Peru [email protected]