Orthodontic Elastics

Summarized by Dr. Hani Alhebshi …

The following information are summarized mainly from an article titled “Elastics in orthodontics: a review” by VP Singh
, PR Pokhrael , K Pariekh , DK Roy, A Singla , KP Biswas as referenced at the end of this post.

Elastics are widely used in different clinical situations.

Elastics have an internal diameter usually measured in a unit of an inch like 1/8 of inch.

The thickness of the elastic band will affect the force it delivers.As the thickness increases the force delivered increases.

rubber bands dimentions

How long should the elastics be stretched to get the desired force ?

The standard force index employed by suppliers indicates that at three times the original lumen size, elastics will exert the force stated on the package.

ELASTICS SIZES

 NB: Some manufacturers consider 2 , 3 oz as(light) ,
3 1/2   to 4 1/2 ( moderate) and 5 to 6 (heavy).

 

They can be classified by different ways as follows (Only important ones are showed ) :

A. According to the material

Latex elastics
Synthetic elastics

B. According to the availability 

Different makers have different sizes and force, and
the colour coding and the name is also different.

C. According to the uses

This also can be classified in 2 ways.

a. Extra oral : Recommended force is 16 to 32 oz.

 b. Intra oral

b.1 Class I elastics or intra-arch elastics

Used for space closure in the same arch.

The force recommended is 1 ½ to 2 ½ oz for non extraction cases and 2 to 4 oz. in extraction cases.

b.2 Class II Elastics / interarch elastics.

The force recommended is 1 ½ to 2 ½ oz. in non extraction case and 2 to 4 in extraction cases.

b.3 Class III elastics / interarch elastics.

The force recommended is 1 ½ to 2 ½ oz. in non extraction case and 2 to 4 in extraction cases.

b.4 Anterior elastics

For Open bite up to 2 mm may be corrected with these elastics.  ( Force-1 to 2 oz.).

b.5 Zigzag elastic

Force recommended is 2.5 oz.

b.6 Cross bite elastics

It is placed between the lingual aspect of the lingually placed molar and the buccal aspect of the opposing tooth.Force recommended is 5-7 ounce.

 b.7 Diagonal elastics (midline elastics)

Force used is 1 ½ to 2 ½ ounces

 b.8 Box elastics

These are used to correct the open bite or to decrease the anterior open bite. Elastics attached around the maxillary central and mandibular lateral brackets.

Lateral boxes attached to maxillary laterals and cuspids and mandibular cuspids and bicuspids.

Buccal boxes used to settle in the posterior occlusion or correct a
more posterior openbite. Force used ¼” 6 oz or 3/16″ 6 oz.

b.9 Triangular elastics

Triangular elastics aid in the improvement of CL I cuspid intercuspation and increase the over bite relationship anteriorly by closing open bite in the range of 0.5 to 1.5 mm.

They extended from upper cuspid to the lower cuspid and first bicuspid teeth. Elastics of 1/8″ 3 ½ oz is used.

b. 10 Vertical Elastics (spaghetti)

Force used is 3 ½ oz.

c. Other elastics

1. Asymmetrical elastics

They are usually CL II on one side and CL III on other side. They are used to correct dental asymmetries. If a significant dental midline deviation is present ( 2 mm or more), anterior elastic from upper
lateral to the lower contralateral lateral incisor should also be used.

2. Finishing elastics
like zigzag elastics. .Force recommended ¾” or 2 oz

D. According to the force

1. High Pull
Ranges from 1/8″ (3.2mm) to 3/8″ (9.53mm). It gives 71 gm force (2 ½ oz).
2. Medium Pull
Ranges from 1/8″ (3.2mm) 3/8″ (9.53 mm) it gives 128 gm or 4 ½ oz force.

3. Heavy pull
Ranges from1/8″(3.2mm) 3/8″(9.53 mm) It gives 184 gm or 6 1/2 oz force.

Way of Action Force Recommended
Extraoral 16 oz or 32 oz
Class I intra arch ( power chains ) 1 ½ – 2 ½ oz for non extraction cases.
2 – 4 oz for extraction cases.
Class II iner arch elastics 1 ½ – 2 ½ oz for non extraction cases.
2 – 4 oz for extraction cases.
Class III iner arch elastics 1 ½ – 2 ½ oz for non extraction cases.
2 – 4 oz for extraction cases.
Open bite elastics ( upto 2 mm can be closed) 1 – 2 oz.
Crossbite elastics 5 – 7 oz.
Diagonal ( Midline) elastics 1 ½ – 2 ½ oz.
Box Elastics with Class II or Class III vector 1/2 inch – 6 oz.
3/16 inch – 6 oz.
Triangular elastics ( Canine settling) 1/8 inch – 3 ½ oz.
Vertical ( Spagetti ) 3 ½ oz.
Finishing Elastics ¾ inch – 2 oz.

REFERENCE :

Article : Elastics in orthodontics: a review

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