Paradigm Shift for Aligners vs. Braces

"Paradigm...a philosophical or theoretical framework of a scientific school or discipline..."

With Traditional Braces:

• Anchorage

1. TADS (Temporary Anchorage Device)
2. Large teeth or groups of teeth

• Effect of Elastic Traction for Class II Correction

1. Distalize a tooth or groups of teeth
2. Alteration of the alveolar process
3. Mandible repositions anteriorly

• Crossbite Correction

1. Lingual turbos
2. Removable bite plates

Let's look at the Paradigm Differences: 

• Paradigm Differences - Anchorage

1. TADS (Temporary Anchorage Device)

When properly placed, TADs can be used to anchor elastic forces effectively for dental and skeletal movements.

    ii. Large teeth or groups of teeth

With traditional braces, large teeth with large or multiple roots are used as anchorage to retract or move smaller teeth or groups of teeth.

   iii. Aligner anchorage

Anchorage in aligner cases does not depend upon:

→Tipping roots

→Large teeth or groups of teeth

→Other methods commonly thought necessary with traditional braces

The aligner tray provides anchorage during the movement of teeth in aligner therapy.

  iv. With traditional braces or TADs, elastics are used to

→Correct horizontal arch changes

→Close open bites

→Extrude teeth

→Correct crossbites

• Paradigm Differences - Elastic Traction

1. Aligner with elastic

With traditional braces elastic traction, in other words, class Il corrections, can affect tooth movement such as; molar extrusion, advancement of the lower anterior, and some distalization of the upper posterior quadrants.

However, the paradigm is different when the elastics are used with clear aligners. Because the teeth are encased in plastic, the elastics really cannot affect any tooth movement that happens with the staging of the aligners. The horizontal corrections we see are a result of the arch movement and/or the repositioning of the mandible. This is true whether the elastics are worn on buttons attached to the teeth or to slits cut into the aligners.

This is an important paradigm to understand if you have anything to do with clear aligner treatment.

ELASTICS ATTACHED TO THE TEETH 

ELASTICS ATTACHED TO THE ALIGNERS  

     ii. Spontaneous intrusion

→The spontaneous intrusion of one or both of the upper lateral incisors is a common form of 'non-tracking'

→Even the presence of an engager (or attachment) cannot prevent the intrusion phenomenon

→Those intruding teeth need to be extruded in order to reach the original treatment goals

Although the actual cause of this phenomenon is unknown, a plausible explanation is that the laterals are 'squeezed' up into the alveolar bone due to the relationship of the interproximal contacts [the Fischer hypothesis].

Because the aligner plastic is stretchable and in situations where the canine or incisor is moved, the stretch causes tightening in the material like an elastic band and in doing so squeezes the lateral incisor upwards.

• Extrusion of the tooth back into the aligner

• Paradigm Differences - Crossbite Corrections

1. Crossbite Correction with Braces

→Lingual turbos
→Removable or fixed appliances
→Allows tooth in crossbite to be corrected without hitting the opposing tooth
→Requires a complex combination of braces and wires to move the tooth

    ii. Crossbite Correction with Aligners

→Lingual turbos, removable or fixed appliances not required 

→Only aligners needed 

→The two opposing occlusal surfaces of the aligners prevent the upper and lower teeth from interdigitating, freeing up the tooth in crossbite to move unrestricted by the opposing teeth

   iii. Crossbite Correction with Arch Correction

Creating space with arch development

→Expansion 

→Uprighting 

→Anterior proclination

→Arch coordination