Today I decided to publish a remake of my old blog post from three years ago. Back in the day, it happened to become very popular and was consequently translated into Russian and Italian languages. However it probably was a rather dense read for a non-orthodontist. So I’d like to make the new version more laconic and easy to read for dentists and lay people.

Palatal expansion is a procedure of opening a midpalatal suture. It could be easily done in children since their midpalatal suture is not yet fused. The main goal of this procedure is to correct transverse maxillary discrepancy, a condition when the upper jaw is narrower than the lower jaw. This situation is seen only in about 11% of children [1] and has a potential to self-correct before the age of 7 [2]. Nevertheless there is an ongoing trend to provide palatal expansion to every child indiscriminately. This is often done with good intentions but little knowledge. Here are four common claims used to justify this:

1. Expansion prevents tooth extraction

2. Expansion prevents tooth retention 

3. Expansion stimulates the growth of the lower jaw

4. Expansion cures breathing problems

Let’s look at those claims from a scientific standpoint. 

Does expansion prevent tooth extraction?

Not always. Extraction or expansion could both be a viable option to create space for misaligned teeth. What method to chose depends on the magnitude of space deficit. According to an extensive research data [3], the mean increase of arch width after palatal expansion is about 6 mm. However only 2.4 mm of this expansion are remained long term. This amount of expansion can not prevent tooth extractions in cases with severe space deficit.

Does expansion prevents tooth retention?

It does not. We know that sometimes teeth have problems with eruption and may get stuck in the bone. This is called tooth retention. Current evidence tells us that timely extraction of primarily teeth can prevent this problem with a success rate of 80%. The success rate is the same in patients who do or do not receive palatal expansion on top of the extraction of primarily teeth [4].

Does expansion stimulate the forward growth of the lower jaw?

It does not. We know that the forward growth of the lower jaw is expressed later than the maxillary growth. Usually during the active pubertal growth spurt. Sometimes the proponents of indiscriminate palatal expansion present these natural changes as the effects of their “treatment”. In reality, all studies on this matter show that palatial expansion does not stimulate the forward lower jaw growth [5].

Does expansion enhance breathing?

Not always. The most common risk factors of breathing problems in children are hypertrophic tonsils/adenoids and obesity [6]. As a result, these conditions should be addressed as the first line of treatment. There is some evidence showing that children who initially have a transverse maxillary discrepancy and a diagnosed breathing problem may benefit from palatal expansion [7]. However it doesn’t mean that palatal expansion should be done indiscriminately for prophylaxis purposes. Certainly, children who do not have a transverse maxillary discrepancy should not get an expander to enhance breathing.

What are the common characteristics of transverse maxillary discrepancy?

Transverse maxillary discrepancy is often characterised by a posterior crossbite [picture B]. According to several studies [8,9], if left untreated during the childhood, a posterior crossbite may potentially lead to a development of jaw asymmetry. Transverse maxillary discrepancy can also sometimes be present without a crossbite and masked by the lingual tipping of the lower teeth [picture C]. Regardless of whether transverse maxillary discrepancy is masked or not, it should be corrected to get an aesthetic and stable orthodontic result.

Conclusion

Indiscriminate palatal expansion in children has no justification. There are only a few instances when palatal expansion should be prescribed in the absence of a crossbite. These include transverse maxillary discrepancies masked by the lingual tipping of the lower teeth and situations with mild to moderate space deficit. Actually, those are often the same cases.

References

1. Thilander B, Myrberg N. The prevalence of malocclusion in Swedish schoolchildren. Scand J Dent Res. 1973;81(1):12-21. doi: 10.1111/j.1600-0722.1973.tb01489.x. PMID: 4510864.

2. Khda M, Kiliaridis S, Antonarakis GS. Spontaneous correction and new development of posterior crossbite from the deciduous to the mixed dentition. Eur J Orthod. 2023 May 31;45(3):266-270. doi: 10.1093/ejo/cjac061. PMID: 36203363.

3. Schiffman PH, Tuncay OC. Maxillary expansion: a meta analysis. Clin Orthod Res. 2001 May;4(2):86-96. doi: 10.1034/j.1600-0544.2001.040205.x. PMID: 11553090.

4. Baccetti T, Sigler LM, McNamara JA Jr. An RCT on treatment of palatally displaced canines with RME and/or a transpalatal arch. Eur J Orthod. 2011 Dec;33(6):601-7. doi: 10.1093/ejo/cjq139. Epub 2010 Nov 8. PMID: 21059877.

5. Feres MF, Raza H, Alhadlaq A, El-Bialy T. Rapid maxillary expansion effects in Class II malocclusion: a systematic review. Angle Orthod. 2015 Nov;85(6):1070-9. doi: 10.2319/102514-768.1. PMID: 26516713; PMCID: PMC8612060.

6. Behrents RG, Shelgikar AV, Conley RS, Flores-Mir C, Hans M, Levine M, McNamara JA, Palomo JM, Pliska B, Stockstill JW, Wise J, Murphy S, Nagel NJ, Hittner J. Obstructive sleep apnea and orthodontics: An American Association of Orthodontists White Paper. Am J Orthod Dentofacial Orthop. 2019 Jul;156(1):13-28.e1. doi: 10.1016/j.ajodo.2019.04.009. PMID: 31256826.

7. Pirelli P, Saponara M, Guilleminault C. Rapid maxillary expansion (RME) for pediatric obstructive sleep apnea: a 12-year follow-up. Sleep Med. 2015 Aug;16(8):933-5. doi: 10.1016/j.sleep.2015.04.012. Epub 2015 May 19. PMID: 26141004.

8. Kilic N, Kiki A, Oktay H. Condylar asymmetry in unilateral posterior crossbite patients. Am J Orthod Dentofacial Orthop. 2008 Mar;133(3):382-7. doi: 10.1016/j.ajodo.2006.04.041. PMID: 18331937.

9. Giorgio Iodice, Gianluca Danzi, Roberta Cimino, Sergio Paduano, Ambra Michelotti, Association between posterior crossbite, skeletal, and muscle asymmetry: a systematic review, European Journal of Orthodontics, Volume 38, Issue 6, 1 December 2016, Pages 638–651