Arch width changes with a rapid maxillary expansion appliance anchored to the primary teeth.
OBJECTIVE
To examine the dimensional changes after rapid maxillary expansion (RME) carried out in the transitional dentition with the primary teeth as anchorage.


METHODS
Group A was composed of 31 consecutive transitional dentition patients with posterior quadrant crossbites treated with a Haas-type RME appliance anchored on the maxillary primary molars and canines. No treatment was administered after palatal expansion. Study models were made before RME (T1), at appliance removal (T2), and at least 1 year after appliance removal (T3). A control sample of 60 individuals with posterior quadrant crossbites who had had no orthodontic treatment was categorized into group B (30 individuals with an average age comparable with the treated patients at T2) and group C (30 individuals with an average age comparable with the treated patients at T3).


RESULTS
Permanent molar crossbites were corrected at T2, and this correction was maintained at T3 in all patients. The mean permanent maxillary intermolar width was 42.6 +/- 2.3 mm at T1, 46.7 +/- 1.9 mm at T2 (P < .01), and 46.3 +/- 1.8 mm at T3 (P < .01) in group A; 42.9 +/- 2.7 mm (P < .01) in group B; and 44.4 +/- 3.0 (P < .01) in group C. Premolar and canine widths were slightly wider than the control at T3.


CONCLUSIONS
To avoid undesirable treatment-induced effects on maxillary permanent molars, a stable transverse correction could be achieved with the RME appliance anchored on the primary teeth.
Cozzani
Mauro
M
Department of Orthodontics, University of Ferrara, Italy. maurocozzani@libero.it
Guiducci
Antonio
A
Mirenghi
Stefano
S
Mutinelli
Sabrina
S
Siciliani
Giuseppe
G
D016022:Case-Control Studies; D002508:Cephalometry; D002648:Child; D003724:Dental Arch / Q000033:anatomy & histology*; D003818:Dentition, Mixed; D005260:Female; D006801:Humans; D008297:Male; D008310:Malocclusion / Q000628:therapy*; D052280:Orthodontic Anchorage Procedures; D009967:Orthodontic Appliances; D010155:Palatal Expansion Technique / Q000295:instrumentation*; D013997:Time Factors; D014094:Tooth, Deciduous