Labial bows

orthodontic wire bending

1. LABIAL BOW

2. Labial bow An component of the removable orthodontics appliance which helps in retracting and retaining the anterior teeth in both mandible and maxilla Contributes for the retention of the appliance Can be passive or active

3. Functions: -Move teeth in a lingual or palatal direction (to reduce overjet and provide an anterior fixation) -Restrains the lip away from the anterior teeth allowing ant. teeth in a more labial direction -Align the anterior teeth to create a harmonious dental arch. -Acts as clasps enhancing the fit of palate -Serves as fulcrum when rotating teeth with springs or screws

4. Components Horizontal bow portion Vertical loops Occlusal crossover section Retentive ends

5. Horizontal bow portion Either contacts or stands slightly away from middle thirds of crowns of incisors(in most appliances) and ends with right angle bends at the distal third of lateral incisor, mesial third of canines, or distal third of canine.

6. Vertical loops Consists of parallel vertical legs joined by a smooth curve. Allows for the adjustments of wire. Constriction of loops shortens wire and opening of loops lengthen it. Repeated bending cause breakage of wire

7. Occlusal crossover section Distal leg of the vertical loop enters the embrasure between canine and premolar or between premolars, crossing the occlusal surface and entering into acrylic

8. Retentive ends A re placed in the palatal or lingual surface 0.5mm-1.0mm gap is placed retentive arm and palatal/lingual surface so acrylic can flow. This prevents dislocation from acrylic base plate

9. Types of labial bow A. With U loops Short Labial Bow Long Labial Bow Split Labial Bow Reverse Labial Bow Fitted Labial Bow B. Without U loops Mill’s Retractor High Labial Bow with Apron Springs Robert’s Retractor

10. Short Labial Bow Made from 0.7 mm round SS wire. contacts the most prominent labial surfaces of the anterior teeth and ends in two U-shaped loops that extend as retentive arm between the canine and premolar before getting embedded in the acrylic base plate . Indication: -closure of spaces mesial to canines -minor overjet reduction -retention

11. Long Labial Bow It is a modification of the short labial bow design The distal arm of the U-loop extends between the two premolars and ends as the retentive arm . Indication: - minor overjet reduction - small amounts of anterior space closure - closure of space distal to canine - guide of canine during canine retraction .

12. Split Labial Bow Modification of the conventional short labial bow in that it is split in the middle. Increase the flexibility of the otherwise stiff short labial bow. The bow is made up of 0.7 mm round SS wire and has 2 separate short buccal arms, each with a U-loop ending distal to canine. Indication: - anterior retraction. - closure of midline diastema (for which it has been modified such that the 2 buccal arms extend across the opposite central incisor and engage onto its distal surface )

13. Reverse Labial Bow The loop is placed distal to the canine and the distal arm is bent at right angles to extend anteriorly as the labial part of the bow. Activation is done by opening the loop which results in lowering of the labial bow in the incisor region. To maintain the proper level of the bow, a compensatory bend is then given at the base of the U-loop . Indication: Minor retraction of incisors Minor crowding

14. Fitted Labial Bow It is adapted to the contours of the labial surface of anterior. It is mainly for retention after completion of fixed orthodontic treatment. The U-loop is smaller compared to the conventional labial bows . Indication: -retention appliance after orthodontic treatment

15. Mill’s Retractor made of 0.7mm SS wire has extensive looping in its design to increase the flexibility and range of action of the retractor . activated by compressing the extended loop and bending the bow palatally Indication: -patients with increased overjet . - Alignment of irregular incissors !! due to difficulty in construction and poor patient compliance, it is not widely used.

16. High Labial Bow with Apron Springs It is made up of a thicker gauge SS wire (0.9-1 mm). extends high into the labial vestibule. support onto which apron springs (made from 0.4 mm wire) help in retraction of one or more upper anterior .

17. two components 1. Heavy base arch wire 2. Apron strings

18. Robert’s Retractor made of 0.5 mm round SS wire extends over the labial surfaces from canine to canine and instead of a reguhelix at the base of the loop adjusted by bending the vertical limb below the coil. as the incisor moves palatally , the bow will drop anteriorly and the level of horizontal part should be adjusted Indications: Retraction of proclined incisors(more than 4mm)