Limited evidence for changes of maxillary alveolar width after surgically assisted rapid maxillary expansion


Transverse discrepancies in the maxilla can be treated by rapid maxillary expansion (RME). This is ideally carried out during the pubertal growth spurt, usually before 15 years of age. In older patients surgically assisted rapid maxillary expansion (SARME) has been used.  The aim of this review was to assess the long-term dental and skeletal changes associated with SARME.

A number of electronic databases were searched (SCIRUS, OVID, ISI Web of Knowledge, Cochrane Library, VHL (Virtual Health Library), and PubMed) with no language restrictions.  Papers meeting the following criteria were included; prospective and retrospective human clinical trials; patients undergoing SARME; measurements in dental casts or postero-anterior (PA) cephalometric radiographs; (4) Tooth (TB) or bone borne (BB) palatal distractor appliance; follow-up of at least 1 year after expansion; no other craniofacial surgery.  Selection and grading of the quality of the papers was carried out independently.

Ten studies were included; seven articles were ranked as moderate and 3 as low methodological quality. Those of low quality were excluded leaving & non-randomised clinical trials  (5 prospective and 2 retrospective).  Meta-analysis was conducted using data from the 5 prospective studies.

  • The meta-analysis showed a significant long-term increase in the maxillary alveolar width, and in the inter-canine and inter-molar width in patients submitted to SARME.
  • Alveolar width showed no relapse from just after the expansion until the last follow-up assessment. Although the inter-canine width showed a significant relapse of 1.5 mm, its increase from the initial phase to the follow-up evaluation was highly significant.
  • It may be inferred from these results that the alveolar width changes remain stable and that some relapse is expected in the inter-canine width, thus some over correction may be advisable.

The authors concluded

There is moderate evidence to conclude that maxillary alveolar width and inter-canine and inter-molar width have a long-term significant increase as a result of surgically assisted rapid maxillary expansion. A significant relapse is expected in the inter-canine width after expansion.


While the searches conducted for this review used a number of databases only a small number of studies were identified. This is similar to other reviews in the area.  The fact that several of the included studies had no control groups, no reporting of dropouts and only 3 out of the 10 studies originally selected had the outcomes assessed blindly all impact on the quality of the evidence available to assess this intervention.  The authors also raise the issues of the different ways in which the measurements of the skeletal changes were made which adds another potential bias.  While there have been a number of reviews of different outcomes from RME there is still a lack of high quality randomised trial to guide clinical practice in this area.


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Lagravere MO, Major PW, Flores-Mir C. Long-term skeletal changes with rapid maxillary expansion: a systematic review. Angle Orthod. 2005 Nov;75(6):1046-52. Review. PubMed PMID: 16448254.

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Derek Richards

Derek Richards is a specialist in dental public health, Director of the Centre for Evidence-Based Dentistry and Specialist Advisor to the Scottish Dental Clinical Effectiveness Programme (SDCEP) Development Team. A former editor of the Evidence-Based Dentistry Journal and chief blogger for the Dental Elf website until December 2023. Derek has been involved with a wide range of evidence-based initiatives both nationally and internationally since 1994. Derek retired from the NHS in 2019 remaining as a part-time senior lecturer at Dundee Dental School until the end of 2023.

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