Retention & relapse in orthodontics

Retention And Relapse

Retention and Relapse in Orthodontics

Presented by : Chetan BasnetBDS 4th yearRoll no: 02

Contents

• Introduction • Causes of relapse• Why retention required• Schools of thought on retention• Cause of Relapse• Role of 3rd molar• Role of occlusion• Theories of retention• Retainer used in orthodontics• Types of retainers

Retention & RelapseRetention: Maintaining newly moved teeth in a position long enough to aid in stabilizing correction.

-Moyer

Relapse:It has been defined as the loss of any correction achieved by orthodontic treatment.

-Moyer

Why Retention Needed?

1.Gingival and periodontal tissue require time post-treatment to reorganize2.Soft tissue pressures are likely to cause relapse if teeth are placed in an

unstable position3.Growth post-treatment may cause relapse

Schools of Retention

1. The Occlusal School2. The Apical Base School3. The Mandibular Incisor School4. The Musculature School

The Occlusion School

According to KINGSLEY- “the occlusion of teeth is the most important factor in determining the stability in a new position”

The Apical Base School

ALEX LUNDSTROM (1920s) suggested that the apical base is an important factor in the correction of malocclusion and maintenance of the treatment results. Hay’s Nance further concluded that:If a stable permanent result is to be attained, mandibular teeth must be positioned

properly in relation to the basal bone.Arch length may be permanently increased only to a limited extent.Excessive lingual as well as labial tipping must be avoided.

THE MANDIBULAR INCISOR SCHOOL

Grieves and Tweed. In order to maintain stability, mandibular incisors must be placed upright or slightly

retroclined over the basal bone.

THE MUSCULATURE SCHOOL

According to Paul Rojer proper muscle balance is necessary in order to ensure post treatment stability.

Relapse

• Periodontal ligament traction

Teeth moved orthodontically

Streching of periodontal principal fibres and the gingival fibres encircling the teeth

Fibres contract

RELAPSE

• Due to growth related changes

Patient with skeletal problems associated with class II and class III

continued abnormal growth pattern after orthodontic therapy RELAPSE

• Bone adaptation:

Bone during the treatment periods are more responsive to the influence of pressure and relapse may occur if the new position is not stable.

• Failure to Remove Etiology:

Cause of malocclusion not eliminated RELAPSE

• Perioral musculature:

Teeth are encapsulated in all directions by muscles. Muscular imbalance at the end of orthodontic therapy. RELAPSE

Role of third molars: If third molar erupt after the orthodontic treatment .

Exert pressure on the teeth.

Late anterior crowding . RELAPSE

RETENTION

RIEDEL’S THEOREMS OF RETENTION

Theorem 1.“Teeth that have been moved tend to return to their former position”

Theorem 2.“Elimination of the causes of a malocclusion should aid in retention.”Theorem 3.“Over correction of a malocclusion is a safety factor in retention”

Theorem 4.“Occlusion is an important factor in retention”

Theorem 5.“Bone and adjacent tissues must be allowed to reorganize around newly positioned teeth”

Theorem 6.“Lower incisors must be placed upright over the basal bone”

Theorem 7.“Corrections carried out during periods of growth are less likely to relapse”Theorem 8.“The farther the teeth have been moved, the lesser is the risk of relapse”

Theorem 9.“Arch form, particularly in the mandible, cannot be permanently altered by appliance therapy”

Types of Retention

Reidel has grouped retention planning into 3 groups:1. No retention required, Natural2. Limited or short term retention3. Prolonged or Permanent retention

NO RETENTION GROUP

Conditions that do not require retention are:-1. Anterior crossbites.2. Serial extraction cases.3. Posterior crossbites (when axial inclination of teeth remain reasonable after correction).4. Correction achieved by retardation of maxillary growth.5. Dentitions in which teeth have been separated to allow for eruption of previously blocked

out cases.

LIMITED OR SHORT TERM RETENTION

1. Class I, class II div 1 and div 2 cases, treated by extractions.2. Deep bites.3. Class I non-extraction cases with proclination and spacing.4. Early correction of rotated teeth before root completion.

.

PERMANENT OR SEMIPERMANENT RETENTION

Cases requiring permanent retention are:1. Midline diastema.2. Severe rotations.3. Arch expansion achieved without ensuring good occlusion.4. Certain class II, div 2 deep bite cases.5. Patients with abnormal musculature or tongue habits.6. Expanded arches in cleft palate patients.

RETAINERS

RETAINERS

Retainers are passive orthodontic appliances that help in maintaining and stabilizing the position of a single tooth/teeth long enough to permit reorganization of supporting structures after the active phase of orthodontic therapy.

Retainers can be simply classified as-1. Removable Retainers2. Fixed Retainers

Ideal requirements of Retainers

• Should restrain each tooth in its direction of relapse.• Should permit the forces associated with functional activity to act freely on the teeth,

permitting them to respond in as nearly a physiologic manner as possible.• Should be self cleansing and should permit optimal oral hygiene maintenance.• Should be as inconspicuous as possible, esthetic.• Should be rigid enough to bear the rigors of day-to-day usage.

Classification of Retainers

• Removal Retainer HAWLEYS Retainer Beggs retainer Clip on Retainer Wrap around retainer Kesling Tooth positioner Invisible Retainer

• Fixed Retainer Band & Spur fixed Bonded canine-canine Banded canine-canine

Hawley’s appliance

- Designed by Charles Hawley in 1920.• Most frequently used retainer

Components:Acrylic Component:• Acrylic base: supports all elements of the appliance.Wire Component• Adam’s clasps: assures retention of the appliance.• Labial bow: provides anterior stabilization, controls the position of incisors that aren’t meant

to move, or the loops can be adjusted for appliance activation.

Advantages:• Can be used in most cases.• Hygiene not an issue.• Can be modified.

Disadvantages:• Susceptible to fracture• Requires patient compliance.• Visible labial bow.• Interproximal wire may cause opening of spaces.• High incidence of breakage and loss.

Hawley’s appliance modifications

Hawley’s retainer with long labial bow

Simple modification to the original appliance where the labial bow has U- loops on premolar distal to canine.

This modification allows closure of spaces distal to canine.

Hawley’s retainer with C-clasp• Indicated in tight occlusal contacts

Hawley’s retainer with contoured labial bow

Labial bow is contoured to anterior teeth.Has better control over the anterior teeth.

Hawley’s retainer with a Z-spring - In cases of anterior single tooth cross bites, Z-springs incorporated into Hawley’s with posterior bite planes can open the bite sufficiently to allow the incisor to advance without occlusal interference

Begg’s retainer

• Named after late P.R. Begg• The labial bow extends distally posterior to the last erupted molar to be embedded in the

acrylic base plate.• Ideal for cases where settling of occlusion is required, especially in the posterior segments, as

there is no wire framework crossing the occlusion.

Advantage : There is no cross over wire that extends between the canine and premolar thereby eliminating

the risk of space opening.

KESLING’S TOOTH POSITIONER

Described by H.D Kesling in 1945

Made of thermoplastic rubber like material that spans the inter – occlusal space and covers the clinical crowns of the U/L portion of teeth and a small portion of the gingiva.

Disadvantages1. Bulky and difficult to wear full-time.2. Difficulty in speech and risk of TMJ problems3. Do not retain incisor position 4. Overbite increases due to limited patient wear

Osamu’s Invisible Retainers

Plastic removable applianceMade of thin thermoplastic sheets.

Advantages: EstheticWell accepted by patientsHigh strength

Material fully covers the clinical crown and extends partly on to the adjacent gingiva.

FIXED RETAINERS

Used in the situations where intra arch instability is anticipated and “prolonged retention” is planned.

They are generally cemented or bonded to the teeth.

Indications:1. Maintaining lower incisor position.2. Following diastema closure.3. Pontic space maintenance4. Retaining closed extraction spaces.5. Prevention of rotational relapse.

Band and spur retainer

Used in cases where single tooth has been orthodontically treated for rotation correction.

Banded canine to canine retainer

Canines are banded and a thick wire is contoured over the lingual aspects and soldered to the canine bands

The bands predispose to poor oral hygiene and are unaesthetic.

Bonded lingual retainer

Retainers bonded on the lingual aspectS.S wire is adapted lingually to follow the anterior curvature.Recently use of spiral wire is recommended that can be bonded to each tooth individually.Advantages:

• Invisible from front• Reduced caries risk

Holding diastema closed:

• This is another indication for fixed permanent retention, especially if the diastema between the maxillary central incisors has been closed.

• A bonded section of flexible wire can be used, contoured in such a way that it lies near the cingulum to keep it away from the occlusal contact.

• Can prevent bite deepening if lower incisors erupt.

Pontic space maintance:

• A fixed retainer is the last choice to maintain a space where bridge pontic will be eventually placed.

Advantages of Fixed Retainer:• Do not affect speech.• Better tolerated by patients• Recall visits are reduced• Reduced need for patient corporation• Can be used when conventional retainers cannot provide same degree of stability.• Bonded retainers are more esthetic• No tissue irritation unlike what may been seen in tissue bearing areas of Hawley’s retainer• Can be used for permanent and semi permanent retention.

Disadvantages of Fixed Retainers

• More cumbersome to insert• Increased chair side time• More expensive• Banded variety may interfere with oral • Hygiene maintenance.• More prone to breakages• Loss of healthy tooth material

CONCLUSION

After successful orthodontic treatment always retainers are used to prevent RELAPSE

References :• Orthodontics Principles & Practice

-B. S. Phulari• Orthodontics; The Art & Science 5th edition

-S.I. Bhalajhi

• Text book of orthodontics; 2nd edition -Gurkeerat Singh

• Internet sources