Leveling and alignment
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The document discusses various growth trends in orthodontics, specifically type A, B, and C trends affecting facial structure and their implications for orthodontic treatment. It also details the importance of precise bracket placement, techniques for computerized bonding, and principles for alignment arches. Additionally, it covers clinical applications of loop mechanics in tooth movement and emphasizes best practices for orthodontic wire selection and leveling strategies.
Leveling and alignment
- 1. Bracket Positioning, Sequence of Mechanics in Edgewise Mechanics www.indiandentalacademy.com
- 3. Growth trends – Type A growth trend – Type B growth trend – Type C growth trend www.indiandentalacademy.com
- 4. Type A growth trend • The middle and lower face are growing forward and downward in unison, with no change in size of the ANB • Growth is approximately equal in both the vertical and horizontal dimensions • Approximately 25 % of patients www.indiandentalacademy.com
- 5. Type B growth trend • Growth downward and forward with the middle face growing forward more rapidly than the lower face • Growth of the middle and lower face is predominantly in the vertical dimension in most instances • ANB reading 60 to 120 • If ANB is less than 40 prognosis is fair • If ANB is 70 to 120 prognosis is poor • Extraction of all four first premolar mandatory for patients with high ANB angle • Only about 15% patientswww.indiandentalacademy.com
- 6. Type C growth trend • Lower face is growing downward and forward more rapidly than the middle face with a decreases in ANB angle • When FMA ranges upward from 200 , growth is approximately equal in the vertical and horizontal dimensions • When FMA 200 or less, growth predominantly horizontal • When growth is virtually confined to the horizontal dimension with little vertical growth, the growth trend is classified as Type C subdivision. • 60% patients have Type C growth trend www.indiandentalacademy.com
- 7. Anchorage • Tooth anchorage (Anchorage preparation) • Anchorage savers Anchorage preparation • 1st degree • 2nd degree • 3rd degree Anchorage savers • Headgear or palatal bar • Nance button • Delayed extraction • Lip bumpers • Muscular pattern of low FMA cases www.indiandentalacademy.com
- 9. Bracket placement • Precision bracket placement is essential for good leveling and alignment. • Indirect bonding showed better bracket placement. (Koo, Chung, Vanarsdall, 1999) • Light cure bonding also showed better bracket placement than chemical cure. • Bonding with orthocad technology shows more accurate bracket positioning. www.indiandentalacademy.com
- 10. Bracket placement Tweed: Mandibular arch: • Bracket slot should be 3.5mm from incisal edge or cuspal tip • On molars -Between occlusal and middle third Maxillary arch: • Bracket slot 3.5mm from incisal edge of cuspal tip except on lateral incisor (3.0mm) www.indiandentalacademy.com
- 11. Bracket placement Lindquist: Upper arch Lower arch Central 4.5mm 4.0mm Lateral 4.0mm 4.0mm Canine 5.0mm 4.5mm Premolar 4.5mm 5.0mm Molar 3.5mm 4.0mm www.indiandentalacademy.com
- 12. Computerized bonding • Generating digital information defining the shape and location of the malocclused tooth with respect to the patient's jaw • Generating a mathematical model of the malocclused tooth as positioned in the jaw from the digitized information • Calculating the finish position in the jaw to which the malocclused tooth is to be moved from the digitized information www.indiandentalacademy.com
- 13. Computerized bonding • Calculating the placement position of an orthodontic bracket on the malocclused tooth required in order to move the malocclused tooth to its finish position by a preselected orthodontic treatment • A standard bracket is thereafter modified, if desired, individually for the patient, in view of the patient's physical deviations from the statistical averages. • The shape of a bracket positioning jig is calculated and formed www.indiandentalacademy.com
- 14. ALIGNMENT & LEVELING Goals of first phase • Bring the teeth in alignment and correct vertical discrepancies by leveling out the arches • Labiolingual discrepancies (crossbites) • Axial discrepancies (mesio-distal) • Correct rotations www.indiandentalacademy.com
- 15. Loop mechanics • A loop reduces force and increases range by adding wire in inter-bracket span. • A loop may be open or closed type. • Open loops are most efficiently activated through compression of the legs. • The force of any loop may be reduced by coiling the wire at the apex one or more times. • The force developed in loop or arch wire is transmitted to the tooth through the bracket attachment resulting tooth movement. www.indiandentalacademy.com
- 16. Clinical applications of loops Movements Loop Labial - Double vertical- open Lingual - Double vertical- open Elevation - Double horizontal or Box Depression - Double horizontal or Box Rotation - Double vertical- open or box Root tipping- Box or double horizontal Canine Retraction – Ricketts Spring Incisor Retraction T loops /double key hole loops www.indiandentalacademy.com
- 17. Clinical applications of loops 1. Mesial or distal movement (such as midline correction): double vertical loop against bracket or fixed to the contained section of the arch, activated by tying back or compression. Combination of open and closed vertical loops. 2. Space closure (contraction of the arch): closed vertical loop, tied back. 3. Space opening (expansion of the arch): open vertical loop, with stops. 4. Bite opening: T-loops mesial to the canine. Note that the arch wire in anterior section between the two loops should have reverse curve to transmit the pressure equally to all 4 incisors. www.indiandentalacademy.com
- 18. Principles in the choice of alignment arches • Initial arch wires for alignment should provide light, continuous forces to produce the most effective tooth movement. Heavy force in contrast should be avoided. • The arch wire should be able to move freely within the brackets. For mesiodistal sliding along an arch wire, at least 2 mil clearance between the arch wire and bracket is needed, and 4 mil clearances is desirable. www.indiandentalacademy.com
- 19. Principles in the choice of alignment arches • Rectangular wire particularly those with a tight fit within the bracket slot so that the position of the root apex could be affected, normally should be avoided. Cupper Ni Ti or BioForce are the exceptions. • Round wires are preferred for alignment. www.indiandentalacademy.com
- 21. Multiple loop arch wire (0.016”) Molar tie back,Vertical loops, L loops Upper Lower www.indiandentalacademy.com
- 22. Multiple loop arch wire after ligation www.indiandentalacademy.com
- 23. Multiple loop arch wire after movement www.indiandentalacademy.com
- 24. Leveling with 0.016” Arch wire Molar stops First order bends Second order bends upper lower www.indiandentalacademy.com
- 25. 0.016” Arch wire after ligation www.indiandentalacademy.com
- 26. 0.016” Arch wire after movement www.indiandentalacademy.com
- 27. Leveling with 0.018” Arch wire Molar stops, First order bends, Second order bends Curve of spee- upper, Reverse curve of spee- lower www.indiandentalacademy.com
- 28. Typical Upper and lower leveling wire often used in Edgewise appliance just before Insertion of the Edgewise wire. Mild curve of Spee With tip back bends and Molar stops Mild Reverse curve of Spee With tip back bends and molar stopswww.indiandentalacademy.com
- 29. Leveling with 0.020” Arch wire • Molar stops • First order bends • Second order bends • Curve of spee- upper • Reverse curve of spee- lower www.indiandentalacademy.com
- 30. Acknowledgement Sincere thanks to all those staff , PG students, CMET Staff and all others who have directly or indirectly contributed to this presentation www.indiandentalacademy.com