OPTION 1

Coffin Spring

•            Shape of spring is like a greek letter Omega

 

Indications:

1.           Narrow arch

2.           Crowding to teeth

3.           Expansion of arch in anteroposterior and transverse direction

Design

•            Coffin spring is made up of 1.25 diameter wire or 19 gauge shape of spring is either diamond or pear shaped.

•            In diamond shaped coffin, posterior arm is of 1 cm and anterior arm of 1.5 cm and tag arms are enough to embed in the base plate.

 

 

Position of Spring

•            Anteriorly at intercanine region and posteriorly in the first molar region.

Retention

•            Retention is very important in coffin spring. so four clasps are given. Anterior bends must not be incorporated into acrylic to permit full range of activation.

 

 

An appliance using a Coffin spring to provide bilateral expansion

 

 

Activation and adjustment of coffin:

It is done with three praised pliers or universal pliers.

Anterior and posterior bends are activated to get expansion in anterior and posterior region, reducing the curvature of bends by pliers.

 

 

Functions of Spring

 

1.           Tongue trainer: It helps to correct the deviant swallowing pattern and tongue thrust by causing the base of tongue to seal against soft palate during swallowing; prevents the anterior tip of the tongue from slamming up against the lingual surface of anterior teeth and premaxillary rugae area.

2.           Coffin spring can be used as an effective appliance to push buccal teeth laterally so that cross bite correction is possible.

3.           Coffin spring gives the appliance strength durability and stability in mouth.

4.           Acrylic side plates have interproximal projections of acrylic which face to the teeth. It act as interdental wedges. So by opening the coffin spring the acrylic pushes not only against the teeth but the alveolar bone. It becomes capable of moving the teeth.

Advantage of Coffin Spring :

1.           Cheap as compared to screw.

2.           Permits non—parallel and parallel expansion.

3.           Easy to keep clean for patient.

4.           Patient does not have to adjust the appliance.

 

Disadvantage:

1.           High degree of skill required for preparation.

2.           Excellent retention is necessary.

3.           It can be easily over activated.

 

 

Key concept:

Coffin spring:

•            This appliance was designed by Walter Coffin in 1875.

•            It is a removable appliance capable of slow dentoalveolar expansion. It is an ideal appliance to treat unilateral cross-bites during mixed dentition stage.

•            The appliance consists of an omega shaped wire of 1.25 mm thickness placed in the mid palatal region.

•            The base of the omega is placed posteriorly with the free ends of the omega wire embedded in acrylic plate covering the slopes of the palate. These acrylic plates also contain the retentive clasps.

•            The spring is activated by pulling the two sides apart manually. This should be done first in the premolar region and then in the molar region.