RETENTION AND RELAPSE �� IN �� ORTHODONTICS

Dr Gazanafer Roshan

Department of Orthodontics,

MES Dental College

CONTENTS

1. Definition
2. Causes of relapse
3. Schools of thought of retention
4. Theorems of retention
5. Raleigh Williams Keys to eliminate lower retention
6. Types of retention
7. Ideal requirements of retainers
8. Types of retainers

Retention

According to Moyer- Maintaining newly moved teeth in position, long enough to aid in stabilizing their correction

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Relapse is loss of corrections achieved in the treatment of malocclusion

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If the underlying etiology is not removed the treatment is destined to Relapse

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Schools of Thought or Philosophies

1. The Occlusion School - Kingsley

Occlusion most potent factor in determining the stability in new position

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2. The Apical Base School –

Alex Lundstrom in 1920’s – apical base

McCauley- inter canine and inter molar

width to be maintained as original

Nance- Arch length cannot be permanently increased to a major extend

3.The Mandibular incisor school

- Grieves and Tweed

Mandibular incisors must be kept upright or slightly retroclined over basal bone

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4.The Musculature School

- Rogers

Proper functional muscle balance is necessary for post treatment stability

CAUSES OF RELAPSE

1. Failure to remove the cause of malocclusion

2. Periodontal ligament traction

3. Relapse due to growth related changes

4. Bone adaptation

5. Muscular forces

6. Role of third molars

7. Role of occlusion

8. Tooth size disharmony

PDL traction

• Periodontal principal fibers and gingival fibers ---stretched --- contract and relapse

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• Pdl fibers 4- 5 months for reorganization
• Gingival fibers 7-8 months or upto 1 year

Relapse due to growth related changes

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• Skeletal problems – class II, class III, open bite , deep bite ---- relapse due to continuation of abnormal growth pattern after orthodontic therapy

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• Treatment during growth--- require prolonged retention until active growth completed

Bone adaptation

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• Teeth moved recently- surrounded by lightly calcified osteoid bone --- teeth not adequately stabilized --- move back to original position

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Muscular forces

• Teeth surrounded by number of muscles in all direction --- muscle imbalance --- relapse.
• Relevant during arch expansion

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Role of third molars

• Erupts late (18-21yrs)
• Erupting 3^rd molar --- exerts pressure --- late incisor crowding --- relapse

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Role of occlusion

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• Good intercuspation of upper and lower teeth

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• Occlusal mannerism such clenching, grinding, lip biting, nail biting --- relapse

• Soft tissue factors - muscular factors

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• Supporting tissue

Reorganisation of pdl fibres & gingival fibres

Alveolar bone adaptation

Occlusal factors

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• Occlusal factors

Third molars

Axial inclination

Tooth size discrepancy

Transverse discrepancy

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• Growth related changes

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Theorems of Retention�( 9 by Riedel + 1 by Moyers)

1. Teeth that have been moved tend to return to their former position. (pdl & ging fibres, alveolar bone)

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• Elimination of the cause of malocclusion will prevent relapse. (thumb sucking, tongue thrusting)

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• Malocclusion should be over corrected as a safety factor (class2, class 3, rotations)

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4. Proper occlusion is a potent factor in holding teeth in their corrected positions.

(proper intercuspation and functional occlusion)

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4. Bone and adjacent tissues must be allowed time to reorganize around newly positioned teeth

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• If the lower incisors are placed upright over basal bone,they are more likely to remain in good alignment

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7. Corrections carried out during periods of

growth are less likely to relapse

(treatment done earlier—better adaptation of tissue—growth modulation—reduces severity of malocclusion)

8. The farther the teeth have been moved the less likelihood there is of relapse

(less evidence, better to minimise tooth movt by guidance of eruption, orthopedic forces, functional appliance)

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9. Archform,particularly in the mandibular

arch cannot be permanently altered by appliance therapy

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10. Many treated malocclusions require permanent retaining devices

Recall

1. Definition
2. Causes of relapse
3. Schools of thought of retention
4. Theorems of retention

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Raleigh Williams - six keys� to eliminate Lower Retention

1. Lower incisor edge should be on or 1mm in front of A-Pog line
2. Lower incisor root should be distal to crown
3. Lower cuspid root should be distal to crown
4. All 4 incisor roots in same labiolingual plane
5. Lower cuspid root buccal to crown
6. Flat lower incisor contact point

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2

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4

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TYPES OF RETENTION

1. No Retention

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• Limited Retention

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• Permanent or Semi permanent Retention

No Retention

1. Corrected Crossbites

Anterior

Posterior- axial inclination reasonable

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2. Serial extraction correction

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• Corrections by retardation of maxillary growth

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• Correction of previously blocked out teeth

Limited retention

1. Cl I non extraction proclination,spacing

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• Cl I & Cl II extraction cases

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• Corrected deep overbites

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• Early correction of rotated teeth

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• Ectopic eruption or Presence of supernumerary

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• Cl II Div2 malocclusion

Permanent or semipermanent retention

1. Midline diastema

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• Severe rotation

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• Arch expansion achieved without ensuring good occlusion.

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• Certain class II, div.2 deep bite cases.

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• Patients exhibiting abnormal musculature or tongue habits.

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• Expanded arches in cleft palate patients.

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Retainers

• Retainers are passive orthodontic appliances

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• help in maintaining and stabilizing the position of teeth long enough to permit reorganization of the supporting structures after the active phase of orthodontic therapy.

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Ideal Requirements of Retainers�(Graber)

1. Restrain teeth in its direction of relapse
2. Permit functional forces
3. Self cleansing and easy to maintain oral hygeine
4. Shoulc be Esthetic
5. Strong

CLASSIFICATION OF RETAINERS

1. HAWLEY’S APPLIANCE :

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• 1920 by Charles Hawley.

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• Classic retainer include clasps on the molars and a short labial bow extending from canine to canine having adjustment loops.

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Modifications :

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• labial bow extended from one 1^st premolar to the opposite 1^st premolar – closes space distal to canine.

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• Solder the bow to the bridge of the Adam’s clasp – avoids the risk of space opening up between the canine and premolars due to cross – over wires.

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• Anterior bite planes can be incorporated to retain or correct deep bite cases.

2. BEGG RETAINER

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• P.R. Begg.

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• Consists of a labial wire that extends till the last erupted molar and curves around it to get embedded in acrylic that spans the palate.

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Advantage :

• No cross – over wire between canine and premolars thereby opening the risk of space opening.

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3. CLIP – ON RETAINER / SPRING ALIGNER:

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• wire framework that runs labially over the incisors and then passes between canine and premolar

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• Both labial as well as the lingual wire segments are embedded in a strip of clear acrylic.

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Uses

• Correction of rotation commonly seen in the lower anterior region.

4.KESLING TOOTH POSITIONER

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• H.D. Kesling in 1945.

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• thermoplastic rubber material that spans the inter – occlusal space and covers the clinical crowns of the upper and lower teeth and a small portion of the gingiva.

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• The tooth positioner needs no activation at regular intervals and is durable.

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5. INVISIBLE RETAINERS/ESSIX RETAINER :

• retainers that fully cover the clinical crowns and a part of the gingival tissue.
• made of ultra thin transparent thermo – plastic sheets using thermoforming sheets
• They are usually given for the 6 anterior teeth

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ADVNTAGES

1.They are esthetic

2.Minimal bulk and therefore does not interfere with speech

3.Devoid of unesthetic metal components

4.Quick to fabricate and relatively inexpensive

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Uses of Fixed Retainers

• Maintenance of lower incisor correction till late mandibular shift
• Diastema closure
• Maintenance of pontic spaces
• Adult patients with compromised periodontal health as a splint
• After severe rotation correction

2.FIXED RETAINERS :

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These retainers are fixed or fitted on to the teeth and cannot be removed and reinserted by the patient.

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1.THE FIXED APPLIANCE:

The fixed appliance that was used for orthodontic correction can be left in place to serve as a retainer.

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2.BANDED CANINE TO CANINE RETAINER ;

• Commonly used in the lower anterior region.
• The canines are banded and a thick wire is contoured over the lingual aspects and soldered to the canine bands.

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3.BONDED LINGUAL RETAINERS :

• They are retainers that are bonded on the lingual aspect.
• Stainless steel or blue Elgiloy wire is adapted lingually to follow the anterior curvature.
• The ends are curved over the canines where it is bonded.

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DISADVANTAGE

1.Anterior teeth can sometimes rotate

4. Band and spur

• rotation correction cases

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• Derotated tooth- banded and spur are soldered on to the bands so as to overlap adjacent teeth

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Possible Questions

• Define retention and relapse
• Enumerate theorems of retention
• Schools of thought of retention
• Short note on Six keys to eliminate lower retention
• Mention different types of retention
• Classify different retainers