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Expansion with transpalatal arch or continuous arch mechanics.
Ingrid Müller Ledra1, Luiz Gonzaga Gandini1, Renato Parsekian Martins2
1Department of Orthodontics, Faculdade de Odontologia de Araraquara, Universidade Estadual Paulista, Araraquara, São Paulo, Brazil.
Summary
The transpalatal arch (TPA) and continuous arch (CA) produced different forces for maxillary first molar expansion. TPA caused more rotation in the first molar, while CA affected the second molar.
Area of Science:
- Orthodontics
- Biomechanical Engineering
Background:
- Maxillary first molar expansion is crucial in treating crossbites.
- Understanding the biomechanics of orthodontic appliances is essential for effective treatment.
Purpose of the Study:
- To compare the 3-dimensional force systems of transpalatal arch (TPA) and continuous arch (CA) mechanics during maxillary molar expansion.
Main Methods:
- A patient model with molars in crossbite was used.
- Load cells measured forces (transverse, anteroposterior) and moments on molars with TPA and CA.
- Statistical analysis using independent t tests evaluated the data.
Main Results:
- Both TPA and CA produced distinct forces and moments at the first molar.
- TPA generated greater Mz (-25.09 N·mm) and Net Mz (-22.08 N·mm) at the first molar compared to CA.
- CA produced significant forces and moments at the second molar, which TPA did not.
Conclusions:
- TPA and CA mechanics yield different expansion forces and rotational effects on maxillary molars.
- TPA resulted in greater rotational side effects on the first molar.
- CA exhibited side effects on the second molar.
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