Bows and retractors for Undergraduates

Undergraduate level seminar on orthodontic bows and retractors.

1. Bows and Retractors Dr. Miliya Parveen

2. BOWS Labial bow is an essential component of removable orthodontic appliances . The principle function of the bow is to retrude the anterior teeth . It can also be used for retentive purposes. Two groups: With U-loops & without U-loops.

3. Components : The incisor segment . Vertical loops. The retentive ends. The occlusal or cross over section. D D

4. Placement of the incisor segment :

5. Types : Short labial bow Long labial bow Roberts retractor Reverse labial bow Begg’s labial bow Mills labial bow Fitted labial bow High labial bow with apron springs Split labial bow

6. Short labial bow (0.7mm)

7. Labial segment - placed at the junction of the incisal and middle third . Vertical segment - starts from mesial third of canine, should be perpendicular to the incisor segment and should be away from gingiva . Occlusally - passes between canine and premolar. Retentive ends – adapted to the lingual or palatal side .

8. Indications: Closure of spaces mesial to canine Retraction of anteriors Proclination with a nterior spacing Overjet reduction Retention post fixed treatment Activation: By compressing U-loops

9. Long Labial Bow 0.7 mm (A) and 0.9 mm (P)

10. Indications: Anterior space closure Overjet reduction in case of anterior spacing Closure of the space distal to the canine Retaining device at the end of fixed T. Guidance of canine using palatal retractor Same as short labial bow, BUT: Occlusaly it passes between two premolars. Also activated by compressing of the U-loop.

11. Roberts Retractor (0.5 or 0.6mm)

12. Designed by G. H. Robert Labial segment of wire is placed at the junction of the incisal and middle third . Extends only two thirds of the MD width of the lateral incisors . A coil of 3mm internal diameter placed mesial to canine. The mesial arm of the coil is towards the tissue surface. Distal part is supported in a SS tubing .

13. Activation: Closing the coil OR giving palatal bend at emergence of the coil . Indication: Severe anterior proclination with overjet of over 4mm In adult patients as the box is highly flexible it generates lighter forces

14. Reverse labial bow (0.7mm)

15. U-Loops are placed distal to the canine. The free ends of the U-loops are adapted occlusally between the premolar and canine. Activation: First the U-loop is opened, this r esults in lowering of the labial bow in the incisor region . A compensatory bend is given at the base of the loop Indications: Retaining tooth positions Minor tooth movements

16. Begg’s labial bow (0.9 mm) Wrap around or Around the globe bow

17. Popularized by P. R. Begg . Consists of labial wire that extends till the last erupted molar. U-loop is incorporated at the premolar and molar area to close the band spaces. Advantage: Since there is no cross-over wire between the canine and premolar, it eliminates the risk of space opening up. Indication: As a retainer after fixed ortho treatment

18. Mill’s retractor (0.9mm) Extended labial bow

19. Extensive looping of the wire → Flexibility↑ & Range of action↑ • Patient acceptance: poor • Design: complex Indications: Large overjet Alignment of irregular incisors

20. Fitted labial bow (0.7mm)

21. Indications: To secure incisors firmly after incisors de-rotation Retainer NOT USED in a ctive tooth movements

22. High labial bow with apron spring (0.9 mm)

23. Is very similar to a Roberts retractor Highly flexible Light force Fabrication: A heavy base arch of 0.9 to 1mm wire extends into the buccal sulcus , with vertical arms incorporated and relived in the areas of labial frenum . Apron springs are the active components which are attached to the base arch by winding a few turns in horizontal arms. made of 0.4mm wire is attached to the high labial bow.

24. Activation: Bending the upright arms of the apron spring towards the teeth. (3mm activation at a time) Disadvantages: Difficulty in construction & tissue injury. Indications: Retraction of one or more teeth Large overjet

25. Split labial bow

26. Used for retraction; effective for incisors retraction. • Used for median diastema closure; in this type, the free ends of labial bow meet each other. • Not effective for overjet reduction • Activation is same as short labial bow. Indications: Retraction of anterior teeth Closure of midline diastema

27. Retractors Canine retractors are a type of spring. Used to move canine in distal direction. CLASSIFICATION: I. Based on location - buccal or palatal II. Based on presence of - helix or loop III. Based on mode of action - push type or pull type

28. Buccal Self Supported Canine Retractor (0.7mm) Buccally placed canine to be moved palatally and distally. The 3mm coil is placed just distal to long axis of tooth with the active arm away from the tissue.

29. May be supported (0.5mm with SS tubing) or self-supported (0.7mm). Activation: By 2mm in supported and 1mm in self-supported Distal -closing the loop Palatal -anterior limb is bent towards the tooth after it emerges from the coil Uncomfortable to patient Stability increased - flexibility compromised

30. Reverse Loop / Helical Canine Retractor Has a coil of 3mm diameter (placed 3-4mm below gingival margin), active arm(towards tissue) and a retentive arm. Can be used in shallow sulcus esp. in mandibular arch. Activation: By opening the helix by 1mm Cut off 1mm from the free end & readapt it Opening the coil

31. ‘U’ Loop Buccal Canine Retractor Can be used in sallow sulcus . For minimal retraction (1-2mm) U-loop with base 2-3mm below cervical margin. Activation: The U-loop is closed or free end is cut by 1mm & readapted . Requires frequent adjustment but is easy to fabricate and isn’t bulky.

32. Palatal Canine Retractor Canines placed palatally requiring distal and buccal movements. Active arm placed mesial to canine. Coil of 3mm placed between the initial & final position of canine. Activation: Opening the helix by 2mm

33. The End