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[A three-dimensional 3-D finite element study on direction of maxillary protraction]
Wei-jiu Lin1, Min Zou, Xiao-lan Liu
1Department of Orthodontics, Stomatological Hospital, Xi'an Jiaotong University, Xi'an 710004, Shanxi Province, China.
Shanghai Kou Qiang Yi Xue = Shanghai Journal of Stomatology
|December 17, 2010
Summary
The optimal angle for maxillary protraction without cranio-maxillary complex rotation is 30°–40°. Angles outside this range risk rotational changes and altered skeletal movement, impacting treatment outcomes.
Area of Science:
- Orthodontics and Dental Anthropology
- Biomechanical Engineering
- Craniofacial Biology
Background:
- Class III malocclusion often involves maxillary retrusion, requiring effective protraction strategies.
- Understanding the biomechanical response of the cranio-maxillary complex to orthodontic forces is crucial for treatment planning.
Purpose of the Study:
- To establish a scientific basis for determining the optimal direction of maxillary protraction.
- To analyze the displacement and stress distribution within the cranio-maxillary complex using a three-dimensional finite element model (FEM).
Main Methods:
- A 3D FEM of the cranio-maxillary complex was created from high-resolution CT scans of a Class III malocclusion patient.
- Anteriorly directed extraoral forces (5N) were applied at various angles (-20° to 50°) to the maxillary canine region.
- Finite element analysis software (ANSYS 10.0) was used to analyze displacement and stress patterns.
Main Results:
- Maxillary protraction between 30° and 40° resulted in pure anterior translation without vertical rotation of the cranio-maxillary complex.
- Angles less than 30° induced anticlockwise rotation, while angles greater than 40° caused clockwise rotation.
- Increasing protraction angles generally decreased anterior displacement while increasing stress within the cranio-maxillary complex.
Conclusions:
- A protraction angle between 30° and 40° is optimal for achieving pure maxillary advancement without rotation.
- Deviations from this optimal angle can lead to undesirable rotational movements and potential risks of deep bite or open bite.
- Higher protraction angles reduce skeletal advancement and increase biomechanical stress, necessitating careful consideration in clinical application.
