Int. J. Oral Maxillofac. Surg. 2006; 35: 481–487 doi:10.1016/j.ijom.2006.01.025, available online at http://www.sciencedirect.com
Invited Review Orthognathic Surgery
Dental and skeletal changes following surgically assisted rapid maxillary expansion
M. O. Lagrave`re, P. W. Major, C. Flores-Mir Orthodontic Graduate Program, Faculty of Medicine and Dentistry, University of Alberta, AB, Canada
M. O. Lagrave`re, P. W. Major, C. Flores-Mir: Dental and skeletal changes following surgically assisted rapid maxillary expansion. Int. J. Oral Maxillofac. Surg. 2006; 35: 481–487. # 2006 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. Abstract. The aim of this study was to evaluate skeletal and dental changes after surgically assisted rapid maxillary expansion (SARME). Clinical trials were carried out that assessed skeletal and dental changes through cephalograms, computer tomographs or dental casts. No other simultaneous treatment during the active expansion period was accepted. Electronic databases (Pubmed, Medline, Medline In-Process & Other Non-Indexed Citations, All Evidence-based Medicine Reviews, Embase, Web of Science and Lilacs) were searched. Abstracts which appeared to fulfil the selection criteria were selected by consensus. The original articles were then retrieved and evaluated with a methodological checklist. Their references were hand searched for possible missing articles. Only 12 articles fulfilled the selection criteria. All presented methodological flaws. An individual methodological analysis of these articles was made. Expansion was greater at the molars and diminished progressively to the anterior part of the dental arch in all the evaluation periods. Vertical and sagittal skeletal changes were nil or not clinically significant. The nasal portion of the maxillary complex showed an increase in dimensions thereby improving nasal patency. An overall dental relapse of 0.5–1 mm is reported after 1 year of orthodontic treatment. The conclusions should be considered with caution because only a secondary level of evidence was found.
Several treatment alternatives for posterior crossbites exist6,28,30. Some benefits associated with maxillary expansion treatments have been the correction of the maxillary constriction and the creation of additional arch perimeter space to relieve crowding16,26. From the available literature, rapid maxillary expansion (RME) appears to be the treatment of choice for growing adolescents. This technique has however been shown to have a limited effect on 0901-5027/060481 + 07 $30.00/0
mature teenagers and adult patients.36 This is explained by progressive midpalatal sutural closure that increases the resistance of the maxilla to expansion during the late teen years18,29. When RME does not appear to be feasible, surgically assisted rapid maxillary expansion (SARME) becomes the treatment of choice in non-growing adolescents and adult patients. This procedure allows for the splitting of the midpalatal suture and widening of
Key words: surgical; rapid maxillary expansion; rapid palatal expansion. Accepted for publication 27 January 2006 Available online 29 March 2006
the maxilla. SARME has been reported to be successful in achieving a clinically significant expansion in non-growing patients15; however, this type of treatment has not been able to eliminate tipping and extrusion of the anchorage teeth12,14,23. Although widening the maxilla is an unstable procedure when compared with other surgical procedures, SARME has been advocated to improve stability compared with non-surgical RME31,32.
# 2006 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
Lagrave`re et al.
Table 1. Sensitivity of electronic databases searched Database Medline PubMed Medline, in process Embase All EBM reviews (Cochrane Database of Systematic Reviews, ASP Journal Club, DARE and CCTR) Web of Sciences Lilacs Reference lists
Percent of total selected abstracts (n = 62)
Keywords (1) (3) (1) (3) (1) (3) (1) (3) (1) (3)
Rapid maxil$ expan$.mp; (2) rapid palat$ expan$.mp; Surg$.mp; (4) 1 or 2; (5) 3 and 4 Rapid maxil* expan*; (2) rapid palat* expan*; surg*; (4) #1 or #2; (5) #3 AND #4 Rapid maxil$ expan$.mp; (2) rapid palat$ expan$.mp; Surg$.mp; (4) 1 or 2; (5) 3 and 4 Rapid maxil$ expan$.mp; (2) rapid palat$ expan$.mp; Surg$.mp; (4) 1 or 2; (5) 3 and 4 Rapid maxil$ expan$.mp; (2) rapid palat$ expan$.mp; Surg$.mp; (4) 1 or 2; (5) 3 and 4
(TS = rapid palatal expansion or TS = rapid maxillary expansion) and TS = surgical (1) Rapid maxillary expansion; (2) rapid palatal expansion; (3) #1 or #2 NA
* and $, truncation of the word. .mp, codification of OVID based databases for searching the search term as is inserted. EBM, Evidence-based Medicine. ASP, American Association of Physicians. DARE, Database of Abstracts of Reviews of Effects. CCTR, Cochrane Controlled Trial Register.
Various studies have reported dissimilar dental and skeletal changes after SARME but no published systematic review has been found covering dental and skeletal structural changes after SARME treatments. The purpose of this systematic review was to evaluate immediate and long-term skeletal and dental changes associated with SARME. Methods
Terms used in the literature search included rapid maxillary expansion, rapid palatal expansion, surgical and their respective abbreviations, specifically selected according to the search engine used with the help of a senior librarian specialized in health sciences’ databases (Table 1). Inclusion criteria for the selection of the appropriate articles from the published abstracts consisted of (1) human clinical trials and (2) measurements made from cephalograms, computer tomograms and/or dental casts. An electronic search for skeletal and dental changes after SARME was conducted using the following databases: Medline (from 1966 to week 4 of May 2005), Medline In-Process & Other NonIndexed Citations (from week 4 of May 2005 to week 1 June 2005), Lilacs (from 1982 to May 2004), Pubmed (1966 to week 4 of May 2005), Embase (from 1988 to week 23 2005), Web of science (1945 to week 4 May 2005) and all Evidence-based Medicine Reviews
(Cochrane Database of Systematic Reviews, ASP Journal Club, DARE and CCTR) (to the second quarter of 2005). Articles identified by each search engine were determined as eligible by reading their respective title and abstract. Selection of the articles to be collected was made by 2 researchers. Any discrepancies were settled through discussion. All the articles that appeared to meet the inclusion criteria based on their abstract information were selected and collected. Table 2. Flow diagram of the literature search
Articles were also obtained when enough information was not provided in the abstracts to determine if inclusion criteria were met. The final selection process was independently completed by the researchers reading the complete selected articles and comparing their results. The goal of this selection stage was to evaluate if any of the selected articles did not actually fulfil the selection criteria. Any discrepancies were again settled through discussion.
SARME: Systematic Review Table 3. Methodological score for the clinical trials
influence of key components of methodological quality individually17,21,35. A summary of the sample size, error method, exams and evaluation periods is presented in Table 5. In general, sample sizes were very small, the error method was almost never reported, and the reported changes were not consistently stated.
I. Study design (9H) A. Objective—objective clearly formulated (H) B. Population—described (H) C. Selection criteria—clearly described (H); adequate (H) D. Sample size—considered adequate (H); estimated before collection of data (H) E. Baseline characteristics—similar baseline characteristics (H) F. Timing—prospective (H) G. Randomization—stated (H) II. Study measurements (5H) H. Measurement method—appropriate to the objective (H) I. Blind measurement—blinding (examiner H, statistician H) J. Reliability—described (H), adequate level of agreement (H)
III. Statistical analysis (6H) K. Dropouts—dropouts included in data analysis (H) L. Statistical analysis—appropriate for data (H); combined subgroup analysis (H) M. Confounders—confounders included in analysis (H) N. Statistical significance level—P-value stated (H); confidence intervals (H)
Eight studies7,13,27,31,33,37,38,40 analysed immediate dental changes after SARME. The mean expansion obtained in the first molars was 8.5 mm27, 7.1 mm (5.7– 8.5 mm)40, 7.5 mm (6–13 mm)31, 33 and 8.7 mm 8.3 mm (4.8–12.3 mm) (7.3–10.1 mm)7. For the 2nd molars the mean expansion obtained was 7.1 mm (3.4–11.4 mm)27 and 5.5 mm (3.0– 8 mm)7. The mean expansion obtained in the canines was 4.9 mm (0–8.4 mm)33 and 5.2 mm (3.9–7.5 mm)7; while for first biscuspids it was 7.8 mm (6.3–9.3 mm)40 and 8.1 mm (6.3–9.8 mm)7. Even though STROMBERG’s study33 included patients with surgical treatments other than SARME, only subjects with solely SARME were included in the present review. NEUBERT’s study27 reported a midline diastema of 7.0 mm (4.2–11.1 mm) immediately after expansion; whereas ZOLLER & ULLRICH40 reported 5.9 mm (4.4–7.4 mm). All these measurements were made from dental casts. Frontal cephalograms have also been used to evaluate the transverse dental changes. GILON et al.13 reported a first molar expansion of 3.9 mm (3.5– 4.3 mm) whereas ZHOU et al.38 reported a first molar expansion of 5.6 mm (3.9– 7.3 mm). BYLOFF & MOSSAZ7 reported a mean molar tipping of 9.68 (2.2–178).
Maximum number of Hs = 20
Reference lists of the selected articles were also hand-searched for additional relevant publications that may have been missed by the search-engine searches. In cases where specific data were necessary for the discussion and not specified in the article, efforts were made to contact the authors to obtain the required extra information.
The search results and the initial number of abstracts selected, according to the selection criteria, from the various databases are provided in Table 1. From the 62 studies initially selected to be eligible based on their title and abstract, 48 studies were eliminated. Most of these were case reports or articles describing surgical techniques. Only 14 studies actually fulfilled the initial selection criteria after reading the complete article. After hand searching the reference lists of the 62 studies, no
other study appeared that had not been shown in the electronic search. Of the 14 remaining articles, one9 was rejected because the results presented were mixed with those of subjects treated with non-surgical RME, and another39 because it used the same sample as another of the selected studies (Table 2). Thus, finally, there were only 12 articles that met the inclusion criteria. Coincidentally, all 12 studies used a tooth-anchored device to achieve expansion. A methodological quality checklist (Table 3) was used to evaluate the selected articles and the application of this checklist is provided in Table 4. The scoring process was a modified version of one previously used in a systematic review about maxillary expansion using different treatment alternatives24. No attempt was made to imply that this evaluation was validated. Previous reports have shown that there is no sound evidence of the validity of the use of quality assessment of clinical trials, and they recommend that researchers examine the
Table 4. Methodological score of initial selected articles Authors
STROMBERG & HOLM33 BAYS & GRECO4 POGREL et al.31 WRIEDT et al.37 CAPELOZZA FILHO et al.8 NEUBERT et al.27 BIERENBROODSPOT et al.5 GILON et al.13 ZOLLER & ULLRICH40 ZHOU et al.38 BYLOFF & MOSSAZ7 ANTTILA et al.2
H X H H X X H X X H H H
X H H X H H X X X X H H
X 6¼ 6¼ HH 6 ¼ X 6 ¼ X X HH X X
X X X X X H X X X X X X
X X X X 6 ¼ X X X X X X X
X X X X X X X X X X X X
X X X X X X X X X X X X
H H H H X H H H H H H X
X X X X X X X X X X X X
X X X HH X X X X X X HH X
X X X X X X X X X X X X
X X X H X X X H X H X 6¼
X X X X X X X X X X X X
X X X X X X X HH X H X X
Total number of checks
Percent of the total
2 2.5 2.5 7 2 3 3 4 1 6 5 2.5
10 12.5 12.5 37.5 10 15 15 20 5 30 25 12.5
A–N: methodological criteria in LAGRAVE`RE et al.24 (H) fulfilled satisfactorily the methodological criteria (1 check point); (6¼) fulfilled partially the methodological criteria (0.5 check point); (X) did not fulfill the methodological criteria (0 check point).
1 year post-expansion
2 years minimum Yes (1.5 years; 10 months-3.5 years)
Yes (6 months) No Yes, but no tx time specified No Dentals casts, frontal cephalometric X-ray Dental casts
1–1.5 years post-expansion No
Yes, but no tx time specified No
No Few days
No After Cx Qx
Frontal and lateral cephalometric X-ray Frontal cephalometric X-ray Acoustic rhinometry, dental casts and sonography Dental casts
No 3.5 weeks (11–59 days) Dental casts
Yes No No Dental casts
3 years 6 months (7 months-8 years) post-orthodontic tx No
No No 3.5 weeks Dental casts
Dental casts, submentovertex variation Not clear
but no tx specified but no tx specified
Yes, but only 22 patients No No
Yes, time Yes, time No
Five studies7,13,27,37,38 analysed immediate skeletal changes after SARME. NEUBERT et al.27 reported maxillary changes immediately after the surgery. No vertical or sagittal maxillary displacement was found. They found a skeletal maxillary expansion of 1.7 mm and a nasal expansion of 1 mm. GILON et al.13 reported a maxillary expansion of 5 mm (1.5–8.5 mm) and a nasal expansion of 4.4 mm (2.2–6.6 mm). Vertically, they also found a significant anterior rotation of the palatal plane of 1.58 (0.6 to 3.6 mm) and sagitally a decrease of the SNB angle of 1.788 (0.2 to 3.8 mm). Regarding the maxillary base, an expansion of 3.8 mm (2–5.6 mm) has been reported38 while another study37 found a transverse increase in the anterior width of 5.9 mm and posterior width of 7.5 mm. BYLOFF & MOSSAZ7 reported a mean skeletal expansion of 1.3 mm measured at the maxillary alveolar level. Volumetric and area changes
In one study37 nasal and palatal dimensions were measured with the use of acoustic rhinometry, dental casts and sonography. The results obtained from these were a total increase in nasal volume of 4.7 cm3, anterior nasal volume of 0.8 cm3, midnasal volume of 1.7 cm3 and posterior nasal volume of 2.2 cm3. Palatal vault volume increased by 2.1 cm3. An increase in the area of the nasal valve of 0.14 cm2 and in the area of the apical base of 3.4 cm2 was found.
ANTTILA et al.
BYLOFF & MOSSAZ7
BIERENBROODSPOT et al.5
WRIEDT et al.37
ZHOU et al.
tx, treatment; CxQx, Orthognatic Surgery.
3 females and 4 males (27.6 years; 18–40 years) 5 females and 5 males (19.6 years; 16–33 years) ? females and ? males (28.5 years; 16.9–43.6 years) 5 females and 2 males (23.2 6.7 years; 15–31 years) 3 females and 11 males (27.2 years; 18.5–41.8 years) 14 females and 6 males (30.6 years; 16.2–44.2 years) 38
STROMBERG & HOLM33
CAPELOZZA FILHO et al.8
POGREL et al.31
GILON et al.13
No BAYS & GRECO
ZOLLER & ULLRICH40
19 females and 20 males (15–35 years) 12 females and 6 males (28.1 years; 4.3 years) 16 females and 3 males (30.2 9 years) 8 females and 4 males (23 years; 16–32 years) 3 females and 2 males (30.4 years; 22–44.9 years) 5 females and 7 males (36 years; 18–59 years)
After expansion retention
NEUBERT et al.27
End of orthodontic treatment After retention Immediate changes Exam Method error reported Sample Authors
Table 5. Description of initial selected articles
2.4 1.3 years (post-orthodontic tx) 1 year post-expansion
Lagrave`re et al.
Only one study7 measured changes once the expansion retention phase (6 months following expansion completion) was completed. They reported a mean relapse of 0.5 mm in first molar expansion, 0.2 mm for second molar expansion, 0.7 mm for first bicuspid expansion and 0.2 for canine expansion. Concerning molar tipping, they found a mean relapse of 3.38. Skeletal changes
The same study7 reported a mean relapse of 0.1 mm when measuring the maxillary posterior alveolar level on PA cephalograms. After orthodontic treatment
Four studies2,4,8,27 measured dental changes at the end of orthodontic treat-
SARME: Systematic Review ment with SARME. NEUBERT et al.27 measured a mean maxillary molar expansion of 6.2 mm, a premolar expansion of 5.7 mm, and a canine expansion of 4.2 mm. BAYS & GRECO4 reported a maxillary arch molar expansion of 7.5 mm, a premolar expansion of 8.75 mm and a canine expansion of 2.5. For the mandibular arch, a molar expansion of 2.1 mm, a premolar expansion of 0.25 mm and no canine expansion were reported. CAPE8 LOZZA FILHO et al. reported a 3.8-mm (2.8–8.0-mm) maxillary molar expansion after completion of orthodontic treatment. Finally, ANTTILA et al.2 reported an average maxillary molar expansion of 7.2 mm (2.9–13.0 mm) when measured at the occlusal level and 6.4 mm (3.3– 11.0 mm) when measured at the gingival level. They also found a mean canine expansion of 4.1 mm (1.6–8 mm) at the occlusal level and 4.2 mm (2.1–8.1 mm) at the gingival level. For the first bicuspid, they found a mean expansion of 6.8 mm (3.2–10.1mm) at the occlusal level and 6.0 mm (3.2–9.5 mm) at the gingival level. Long-term changes
Six studies2,4,5,7,31,33 reported changes as follow-up to the orthodontic post-expansion treatment. POGREL et al.31 reported a maxillary molar expansion relapse of 0.88 mm (0.4–1.36 mm) after 1 year of post-expansion. After 1 year of postexpansion, BYLOFF & MOSSAZ7 reported a maxillary molar expansion relapse of 2.6 mm, 2.0 mm for the first bicuspids, and 0.9 mm for the canines. They also found a molar angulation relapse of 68. BAYS & GRECO4 reported a mean molar expansion of 5.78 2.68 mm with 0.45 0.69 mm relapse, a mean premolar expansion of 5.76 2.56 mm with 0.64 1 mm relapse, and a mean canine expansion of 4.5 3.28 mm with relapse of 0.39 0.79 mm, 2.4 1.3 years after orthodontic treatment. STROMBERG & HOLM33 reported a mean molar expansion of 7.3 mm (3.8–11.9 mm) and a mean canine expansion of 5.4 mm (0.4 to 8.1 mm) for a follow-up of 3 years, 6 months (7 months–8 years) after orthodontic treatment. When comparing their results to the immediate expansion changes, a relapse of 0.9 mm for molar expansion and 0.5 mm for canine expansion was found. ANTTILA et al.2 reported after 5.9 years (3.1–11.5 years) an average molar expansion of 5.9 mm (0.7– 12.3 mm) when measured at the occlusal
level and 5.8 mm (1.7–11.3 mm) when measured at the gingival level. They also found a mean canine expansion of 3.7 mm (2.1–6.5 mm) at the occlusal level and 3.8 mm (2.1–6.1 mm) at the gingival level. For the first bicuspid, they found a mean expansion of 6.0 mm (1.6–8.4 mm) at the occlusal level and 5.9 mm (3.3–8.1 mm) at the gingival level. In the overall results, they report a mean relapse of 0.5 mm on the canines, 0.7 mm (occlusal level) and 0.2 mm (gingival level) on the first bicuspids, and 1.3 mm (occlusal level) and 0.6 mm (gingival level) on the first molars. Finally BIERENBROODSPOT et al.5 reported a retained cuspid expansion of 4.7 mm (3– 6.4 mm) and a molar expansion of 5.6 mm (2.4–8.8 mm) after 1–1.5 years. Skeletal changes
BYLOFF & MOSSAZ7 reported a mean relapse of 0.3 mm measured through PA cephalograms at the maxillary posterior alveolar level. Discussion
RME has been successfully used in growing children and young adolescents25, but when attempting this treatment on adults its success rate diminishes significantly. This can be attributed to the increased rigidity of the facial skeleton, and mechanical interlocking of the midpalatal suture and other circum-maxillary sutures as reported by KOKICH22; with increasing age, bony projections or interdigitations at the sutural sites occur. ISAACSON et al.20 demonstrated that facial skeleton resistance increases with age and that the midpalatal suture is not the major resistance to expansion; rather it is the zygomatic articulations with the maxilla that restrain expansion. Due to this, when RME is being applied in a young adult there is a possibility that basal or alveolar bone movement may not occur19,25. For these reasons, maxillary expansion in adults has been directed toward orthodontic tooth movement and alveolar remodeling or toward skeletal expansion with surgical repositioning using a maxillary osteotomy, such as SARME25,34. No previous systematic review or metaanalysis has been published regarding the dental and skeletal effects of SARME. Even though studies have been published on SARME, the majority consisted of case reports, descriptions of different surgical techniques and studies involving SARME jointly with other surgical treatments. After reviewing all the published material on SARME, only 12 articles satisfied
the inclusion criteria of human clinical trials and reporting changes solely due to SARME. When the methodological checklist was applied, the selected articles received very low quality scores and had definitive methodological failures. From the final 12 articles, 87,13,27,31, 33,37,38,40 evaluated immediate dental changes after SARME. All studies used tooth-anchored devices as used in traditional RME treatments to achieve the necessary expansion. All found a greater expansion at the molar level with a progressive reduction in expansion at the cuspid level. Three articles7,13,27 reported immediate skeletal changes. All found significant transverse expansion. One27 found neither vertical nor sagittal changes while another13 reported a significant change in the palatal plane inclination (1.58) and a sagittal decrease in SNB (1.78). Although these values were statistically significant, their clinical importance may not be significant. Using acoustic and sonographic measurements, WRIEDT et al.37 found volumetric changes on the nasal portion of the maxillary complex. The increased dimensions of the nasal airway13,27,37 may result in an improvement in nasal patency.37 Only one study7 reported relapse during the retention phase immediately after expansion. Their methodology involved a 2-week expansion period, leaving the tooth-borne expander in for 3 months, and retrieving it so that for the next 3 months there was no appliance or retainer. Changes reported can be considered clinically insignificant. Although this protocol is not used traditionally in the clinical environment, it demonstrates the possible relapse of the expansion treatment. Four studies2,4,8,27 evaluated the SARME effects at the end of the orthodontic treatment. All reported greater molar expansion with a progressive concomitant anterior reduction up to the cuspids. Only one study8 reported a significant lower molar expansion. These changes were less than the ones reported by MCNA26 and BACCETTI et al.3 with MARA et al. RME in growing adolescents. This may be a result of reduced adaptive potential of the mandibular structures in non-growing patients. Long-term expansion effects have been reported by 6 studies2,4,5,7,31,33, covering from at least 1 year after expansion treatment. Again, all reported a greater molar expansion when compared to the cuspid expansion. Concerning relapse, it has been
Lagrave`re et al.
reported that the long-term stability of this technique is primarily dependent not upon the midline graft but, rather, on the new maxilla–facial skeleton relation20. ISAAC20 mentioned that the apposition SON et al. of bone in the midline during RME occurs as a reaction to the negative pressure in this area produced by the spreading apart of the maxilla. They reported that, upon appliance removal, an immediate relapse of as much as 20% occurred. This was due to residual forces still present in the expanded facial skeleton. CLEALL et al.10 demonstrated that the midpalatal suture, although radiographically normal after 3 months of retention, was histologically disorganized and poorly calcified. It was not until 6 months had elapsed following expansion treatment that the suture was repaired to a normal state. The long-term studies4,5,31,33 reported up to 1 mm relapse of molar and cuspid expansion. Since the relapse is relatively minor, the amount of overcorrection required for SARME is less than for RME25. When comparing SARME to RME procedures in adult and non-growing patients, a good point to consider is the discomfort associated with the treatment1. Even though surgical intervention is aggressive, the expansion occurs without excessive forces on other midface structures and there is less force applied to the dental support8. This review did not include quantification of secondary adverse effects such as parasthesia, postoperative bleeding, sinus healing complications, root resorption, periodontal changes or loss of tooth vitality. These are important clinical factors in determining the most appropriate treatment approach. Unfortunately, the final selected studies included in this review failed to attain the high level of scientific evidence which would be obtained through randomized clinical trials11. In the absence of a high level of evidence, clinicians have to make decisions based on lower levels of evidence. Thus, as in any clinical environment, clinicians will have to rely on their experience, expert opinions and the presented limited evidence concerning SARME effects. Future research should involve a randomized controlled clinical trial methodology, evaluate dental as well as skeletal changes immediately after SARME and continue follow-up for possible relapse. The following conclusions from this systematic review should be considered with caution because only a secondary level of evidence was found. In summary, expansion is greater for molars and diminishes progressively at the premolars
and cuspids in all phases of SARME orthodontic treatment. Vertical and sagittal skeletal changes are nil or not clinically significant. The nasal portion of the maxillary complex presented an increase in its dimensions probably to be improving nasal patency. Finally, an overall relapse of 0.5–1 mm is reported after 1 year of orthodontic treatment. Acknowledgement. Special thanks to Linda Seale for her professional assistance in the database search.
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