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Change in crown inclination accompanying initial tooth alignment with round archwires
Mona A Montasser1, Ludger Keilig2, Christoph Bourauel2
1Mansoura University, Faculty of Dentistry, Orthodontic Department (Mansoura/Egypt).
Dental Press Journal of Orthodontics
|July 6, 2022
Summary
Orthodontic leveling and alignment mechanics significantly impact tooth inclination. Conventional brackets with elastomeric rings minimize unwanted crown movement, while multi-stranded archwires offer more predictable results across combinations.
Area of Science:
- Orthodontics
- Biomaterials Science
- Dental Mechanics
Background:
- Crown inclination changes are critical during orthodontic leveling and alignment.
- Understanding the influence of various archwire-bracket-ligation systems is essential for predictable treatment outcomes.
- In-vitro studies provide controlled environments to isolate variables affecting tooth movement.
Purpose of the Study:
- To quantitatively assess the in-vitro changes in crown inclination during simulated orthodontic leveling and alignment.
- To compare the effects of different archwire materials, bracket types, and ligation methods on tooth movement.
- To identify optimal combinations for minimizing unwanted inclination during orthodontic treatment.
Main Methods:
- Four archwire types (0.012-in stainless steel, 0.0155-in stainless steel multi-stranded, 0.012-in nitinol Orthonol®, 0.012-in nitinol Thermalloy®) were tested.
- Five orthodontic bracket types (SmartClipTM, Time3®, Mini-Taurus®, Victory SeriesTM, Synergy®) were evaluated with various ligation methods (stainless steel, elastomeric).
- Simulated malocclusion involved 2.0mm gingival and 2.0mm labial displacements of a maxillary central incisor, with Y-axis rotation measured.
Main Results:
- The greatest lingual crown inclination was observed with nitinol wires (Orthonol®, Thermalloy®) combined with self-ligating (SmartClipTM) or conventional-low friction (Synergy® with stainless steel ligatures) brackets.
- Minimal lingual crown inclination occurred when nitinol (Thermalloy®, Orthonol®) or multi-stranded wires were used with conventional brackets (Mini-Taurus®, Victory SeriesTM) secured by elastomeric rings.
- Multi-stranded archwires generally resulted in less rotation compared to other archwires across most bracket-ligation combinations.
Conclusions:
- All tested archwire-bracket-ligation combinations induced lingual crown inclination.
- Conventional brackets ligated with elastomeric rings demonstrated the least amount of unwanted tooth inclination.
- The choice of archwire-bracket-ligation system significantly influences crown inclination during leveling and alignment, necessitating careful consideration in treatment planning.
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