Although I believe that all respected orthodontists would do palatal expansion in the presence of a posterior crossbite, there are some orthodontists who do RPE (Rapid Palatal Expansion) in the absence of a posterior crossbite. One of the main advocates of this type of treatment protocol is James McNamara.^1,2 He believes that this type of expansion will do a number of things such as provoke spontaneous expansion of the mandibular arch, particularly the intercanine width, and spontaneous correction of Class II malocclusions. His unsubstantiated argument is that patients are inclined to posture the mandible forward and subsequently mandibular growth will make this initial postural change permanent.

Contrary to this hypothesis are data and evidence provided by Anthony Gianelly, D.M.D., M.D., Ph.D., chairman of the orthodontic department at Boston University, who states³ that it is an enigma to him why anyone would do RPE in the absence of a posterior crossbite. He recently published an article in the American Journal of Orthodontics and Dentofacial Orthopedics⁴ in which he demonstrated again the logic, rationale and literature supporting the principle that rapid palatal expansion in the absence of a posterior crossbite is contraindicated. We also concur with Gianelly's findings.

Like Gianelly, Bowman⁵ argued that expansion in the absence of a crossbite to resolve crowding is unscientific and predisposes patients to periodontal problems, pushes teeth out of the envelope of supporting alveolar bone, and is not stable. He cites Gianelly's research of arch length preservation by the use of Leeway space, E-space (see photo). Leeway space means that the primary second molars are larger than the succeeding permanent second bicuspids. Therefore, if Leeway space can be preserved, you can gain about 4 mm of space/arch length in both upper and lower arches, which is the best way to manage tooth-size-arch-length discrepancies (TSAD). With proper management of Leeway space in the late mixed dentition around 75% of cases with good facial balance can be resolved non extraction. Bowman⁵ further points out that to avoid extractions of 5 mm in each quadrant provided by premolar extractions, would require 12 mm of stable expansion, which is a magnitude larger than anything demonstrated by the orthodontic literature.

Photo - Picture on the left showing a lingual holding arch with primary second molars [yellow arrows] present (E-space, Leeway space). On the right the primary second molars have exfoliated and arch length and anterior crowding have improved by maintaining Leeway space.

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REFERENCES

(1) McNamara JA Jr. Early Intervention in the transverse dimension: is it worth the effort? Am J Orthod Dentofacial Orthop 2002;121:572-4.

(2) McNamara JA Jr, Brudon WL. Orthodontics and dentofacial orthopedics. Ann Arbor: Needhan Press; 2001 p. 57.

(3) White L. JCO interviews Dr. Anthony Gianelly on current issues in orthodontics. J Clin Orthod 1996;30(8):439-445.

(4) Gianelly A. Rapid palatal expansion in the absence of crossbites: Added value? Am J Orthod Dentofacial Orthop 2003;124(4):362-5.

(5) Bowman SJ. More than lip service: Facial esthetics in orthodontics. J Am Dent Assoc 1999;130:1173-1181.