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Continuous forces are more effective than intermittent forces in expanding sutures
Sean Shih-Yao Liu1, Hee-Moon Kyung, Peter H Buschang
1Department of Orthodontics and Oral Facial Genetics, Indiana University School of Dentistry, Indianapolis 46202, USA. SSLiu@iupui.edu
European Journal of Orthodontics
|January 8, 2010
Summary
Continuous forces are more effective for midsagittal suture expansion than intermittent forces. This study found continuous force application resulted in greater sutural separation and bone formation in rabbits.
Area of Science:
- Orthodontics
- Craniofacial Biology
- Biomaterials
Background:
- Suture expansion is a common orthodontic procedure.
- The optimal force delivery method (intermittent vs. continuous) for suture expansion remains unclear.
Purpose of the Study:
- To compare the effectiveness of intermittent and continuous forces in expanding midsagittal sutures.
- To evaluate sutural separation and bone formation rates under different force application modes.
Main Methods:
- 18 juvenile rabbits underwent midsagittal suture expansion using nickel-titanium (NiTi) open coil springs (50 g) and miniscrew implants (MSIs).
- Two groups were established: intermittent force (5 days on, 1 day off, repeated 5 times) and continuous force (29 days).
- Biometric and histomorphometric analyses assessed sutural separation and bone formation.
Main Results:
- Continuous forces yielded significantly greater sutural separation (1.3 mm) compared to intermittent forces (0.8 mm).
- Intermittent forces achieved only 61% of the sutural separation seen with continuous forces.
- Continuous forces demonstrated significantly higher mineral apposition and bone formation rates between days 7 and 17.
Conclusions:
- Continuous force application is more effective for midsagittal suture expansion than intermittent force application.
- Greater sutural separation and enhanced bone formation support the use of continuous forces in orthodontic expansion.
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