Title: Light-Force Maxillary Expansion in an Animal Model
Achint Utreja (Presenter)
Indiana University School of Dentistry
Carol Bain, Indiana University School of Medicine
Brett Turek, Indiana University School of Dentistry
Robert Holland, Indiana University School of Dentistry
Rawan Alrasheed, Indiana University School of Dentistry
W Roberts, Indiana University School of Dentistry
Objectives: Maxillary constriction is routinely addressed with rapid maxillary expansion (RME). However, the heavy forces delivered by most RME appliances to expand the palate may lead to deleterious effects on the teeth and supporting tissues. The objective of this study was to explore a more physiologic maxillary expansion with light continuous force.
Methods: Twenty, 6-week-old Sprague Dwaley rats were equally divided into EXPT and CTRL groups. A custom-fabricated archwire expansion appliance made from 0.014" copper-nickel titanium (CuNiTi) wire was activated 5mm and bonded to the maxillary molar segments of animals in the EXPT group for 21 days. The force applied to each maxillary segment was 5cN. Fluorescent bone labels were injected 7, 4 and 2 days prior to euthanasia, and micro-CT and histological analyses were used to compare the tooth movement and bone morphology in the midpalatal suture and buccal aspect of the alveolar process between the two groups. Descriptive statistics (mean ± standard error of the mean) and non-parametric statistical tests were used to compare the outcomes across groups.
Results: Compared to the CTRL group, there was a statistically significant increase in buccal tooth movement and expansion of the midpalatal suture. The intermolar width (µm) was significantly greater at the root apex (5737±42.24 EXPT, 5434±54.03 CTRL) and occlusal surface (7868±91.95 EXPT, 7085±35.10 CTRL) (P<0.01). There was no change in the bone morphologic parameters between groups. The mineral apposition rate was significantly higher in the EXPT group compared to the CTRL group in the buccal and suture regions (P<0.05).
Conclusions: Application of light, continuous force resulted in maxillary osseous expansion due to bilateral sutural apposition and buccal drift of the alveolar processes. This animal experiment provides a more physiologic basis for maxillary expansion.
This work was supported by the American Association of Orthodontists Foundatoin (AAOF).