SWAMI DEVI DAYAL DENTAL COLLEGE AND HOSPITAL

BARWALA,PANCHKULA.

DEPARTMENT OF ORTHODONTICS AND DENTOFACIAL

ORTHOPAEDICS

SEMINAR

ON

LABIAL BOWS

SUBMITTED BY:-

GURINDER SINGH

MDS 1ST YEAR

LABIAL BOWSBows may be active or passive and will span a number

of teeth.Both ends of bow are incorporated in acrylic

plate.These are components that are used for both

overjet reduction and for providing anterior fixation.

Indications

bows are capable of:

1.Overjet reduction

2.Active bows for incisor retraction

3.Elimination of minor incisor interference

4.retention

5.Flexible bows such as Roberts are suitable

for large overjet reduction

Parts of labial bow

1 .horizontal

2.vertical loop

3 retentive arms

LABIAL BOW FABRICATIONThe Labial Bow fabricated in 0.8mm S.S wire.

The upper model.

A light pencil line is marked on the upper model as a guide to show the position of the Labial Bow and 'U' loops. N.B. The Labial Bow should be mid crown height and level with the occlusal plane.

The following 'spacer technique is not commonly used by experienced dental technicians.A light (1mm) wax spacer may be placed in the 'U' loop area

to create an instant space between the gingival soft tissues / model and the 0.8mm S.S wire. (When forming the 'U' loop, the in 0.8mm S.S wire must contact the wax spacer. Failure to ensure this will result in a greater space between wire and soft tissues, which is undesirable).

A suitable length of 0.8mm S.S wire is cut and an 'ideal arch' is formed using the fingers and thumbs.

The Labial Bow arch is checked on the model and should rest against each anterior tooth passively.

A pencil mark is placed on the 0.8mm S.S wire at the point of the canine eminence, usually at the mid point of the canine and a 90 degree bend is formed.

The 'U' loop is then formed using 'flat round' pliers / 'spring former' pliers. N.B. The length of the 'U' loop should curve just beyond the gingival margin as shown in the image.

As mentioned above, a 1mm space between soft tissues and the 0.8mm S.S wireis ensured for patient comfort. The distal tag wire of the 'U' loop / Labial Box is then formed over the interstitial area of the teeth.

The finished Labial Bow: -

* Contacting all anterior teeth passively and tag arms ending at approximately two thirds into the palate.* 1mm spacing between 'U' loop / tag arm and soft tissues.* The 'U' loop should curve just beyond the gingival margin.* Labial Bow at mid crown height and level with the occlusal plane.

A wide variety of labial bows are available for use in

orthodontics. They are as follows:

1. Short Labial Bow

2. LONG LABIAL BOW

3. Split Labial Bow

4. Robert's Retractor

5. Reverse Labial Bow

6. Mill's Retractor

7. High Labial Bow with

Apron Springs

8. Fitted Labial Bow

Short Labial BowThe short labial bows are made from 0.7 mm round SS

wire. The labial bow is constructed in such a way that

can also bring about minor overjet reduction and

anterior space closure. Their range of action is limited

because of stiffness and low flexibility. For space

closure, the bow is activated by compressing the loops

of the bow by 1-2 mm.

LONG LABIAL BOW

It is a modification of the short labial bow design, in

that it extends from the first premolar of one side to

that of the contralateral side. The distal arm of the U-

loop extends between the two premolars and ends as

the retentive arm. It can be used as an active and

retentive component of the removable appliance. It is

indicated in minor overjet reduction, small amounts of

anterior space closure, closure of space distal to canine

and also for guidance of canine during canine

retraction. It is also activated by compressing the loop

1-2mm so that the bow is displaced palatally by 1 mm.

Modification Labial bow soldered to Adams' clasp. In

extraction cases following orthodontic treatment,

closed spaces can be retained with a Hawley's retainer

in which a long labial bow is soldered to the bridge of

the Adams' clasp. A short labial bow is not feasible in

such cases as the distal arm can cause opening of the

extraction space between canine and premolar.

Split Labial Bow

This is a modification of the conventional short labial

bow in that it is split in the middle. This is done to

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

V-loop ending distal to canine. This labial bow is

effective in anterior retraction. It has also found use in

closure of midline diastema, for which it has been

modified such that the 2 buccal arms extend across the

opposite centra1incisor and engage onto its distal

surface. Activation is done by compressing the 'V' loop

by 1-2 mm.

Robert's Retractor

This labial bow is made of 0.5 mm round SS wire,

which is of a much thinner gauge than the

conventional labial bows. It extends over the labial

surfaces from canine to canine and instead of a regular

loop it incorporates a 3mm internal diameter helix at

the base of the loop. The combination of a thin gauge

wire and a helix makes this labial bow highly flexible

and susceptible to distortion as it lacks stability in the

vertical plane. To overcome this, the distal arms of the

loops are supported in softened stainless steel tubes of

0.5 mm internal diameter.

Along with Adams' clasp on the buccal teeth for

retention, this retractor can be used in patients with

severe anterior proclination as it produces lighter

forces over a longer span of activation. It can also be

used in adult patients for the same reason.

Reverse Labial Bow

This type of labial bow is so called because, activation

of the bow is done by opening the V-loop, instead of

compressing as is seen in the conventional labial bows.

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.The free end of mesial arm is

adapted between the canine and first premolar and

eventually gets embedded in the acrylic base plate.

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 V-loop.

Mill's Retractor

This is a complexly designed labial bow made of 0.7

mm SSwire which has extensive looping in its design

to increase the flexibility and range of action of the

retractor . The anterior part of the bow extends till

mesial of the canine and then forms a complex loop

gingivally before ending in a retentive arm distal to the

canine. This type of a labial bow is indicated in

patients with increased overjet. However, due to

difficulty in construction and poor patient compliance,

it is not widely used.

High Labial Bow with Apron

Springs

As the name suggests, this type of labial bow extends

high into the labial vestibule. It is made up of a thicker

gauge SS wire (0.9-1 mm). The labial bow acts as a

support onto which apron springs (made from 0.4mm

wire) are attached around. Apron springs help in

retraction of one or more upper anteriors. This type of

bow is made highly flexible because of the springs and

is therefore used for retraction in cases with large

overjet.

Apron spring is activated by bending it towards the

teeth, up to 3 mm at a time. Since it generates light

forces, it is also useful in adult patients. However, it is

difficult to construct and can cause soft tissue injury. It

may also lack patient compliance as too much wire is

visible.

Fitted Labial Bow

This type of labial bow is so called, as it is adapted to

the contours of the labial surface of anteriors. It is

mainly for retention after completion of fixed

orthodontic treatment. The U-Ioop is smaller compared

to the conventional labial bows.

References

1.Contemporary orthodontics by proffit

2.Removable orthodontic appliances by

ISAACSON,J.D MUIR&R.T.REED

3. Design, construction and use of removable

orthodontic appliances by C. PHILIP ADAMS

4.Textbook of orthodontics by GRABER and

NEUMANN