Spontaneous mandibular arch response after rapid palatal expansion:
A long-term study on Class I malocclusion.
Lima AC, Lima AL, Filho RM, Oyen OJ.
The purpose of this study was to investigate the spontaneous mandibular
arch response to rapid palatal expansion as the sole orthodontic
intervention. Particular attention was paid to clinically significant
effects and long-term (mean age, 11.3 years) posttreatment stability
in 30 Class I malocclusion patients treated during the early and
mid mixed dentition. Measurements were made directly on 120 dental
casts obtained at 4 assessment stages: pre-expansion (A1), short-term
follow-up (A2), progress (A3), and long-term follow up (A4). Comparisons
between A1 and A2 showed statistically significant ( P < .001)
increases for intermolar widths (lingual and occlusal values).
During the transition to the permanent dentition, a significant
( P < .001) decrease occurred in arch length and arch perimeter.
There was a 25% intermolar width (occlusal value) decrease from
the initial net gain, whereas the lingual values remained unchanged.
Comparisons between A2 and A4 showed an intermolar width (occlusal
value) net gain of 50% and a significant ( P < .001) decrease
for the arch length and arch perimeter. There was remarkable stability
in intermolar width (lingual value) and intercanine width (occlusal
value), indicating that the increase in the mandibular arch width
dimension was in response to the orthopedic effects of rapid palatal
expansion in the early and mid-mixed dentition and that the stability
was maintained until adulthood.
PMID: 15520690 [PubMed - in process]
Am J Orthod Dentofacial Orthop. 2004 Nov;126(5):576-82.
