JOSNA THANKACHAN FINAL YEAR PART I

AL-AZHAR DENTAL COLLEGE

RETENTION APPLIANCES

INTRODUCTION THEORIES OF RETENTION RALEIGH WILLIAMS KEYS TO ELIMINATE LOWER

RETENTION TYPES OF RETENTION RETAINERS CLASSIFICATION REMOVABLE RETAINERS FIXED RETAINERS ACTIVE RETAINERS CONCLUSION REFERENCES

CONTENTS

What is retention?has been defined by

Moyers as “Maintaining newly moved teeth in position long enough to aid in stabilizing their correction”.

INTRODUCTION

Why is retention necessary?

Retention is necessary for 3 main reasons1. The gingival and periodontal tissues are

affected by orthodontic tooth movement and require time for reorganization when the appliances are removed.

2. The teeth may be in an inherently unstable position after the treatment,so that soft tissue pressures constantly produce a relapse tendancy.

3. Changes produced by growth may alter the orthodontic treatment.

If teeth are not in an inherently unstable position and if there is no further growth, retention still s vitally important until gingival and periodontal organization is complete.Retention cannot be abandoned until growth is essentially completed.

What is relapse?

Relapse implies loss of any correction achieved by orthodontic

treatment.

CAUSES OF RELAPSEL

Text book of orthodontics,SRIDHAR PREMKUMAR

SCHOOLS OF THOUGHT PERTAINING TO RETENTION/HISTORY OF RETENTION

There are 4 schools of thought pertaining to retention:-

1. Occlusion school of thought(kingsley) A/C to this,proper occlusion of teeth is a potent

factor in maintaining the stability of the teeth. At the end of active orthodontic treatment there

should be proper intercuspation and interdigitation.

There should be cusp to fossa relationship between maxillary and mandibular teeth.

2. Apical base school of thought(Axel lundstrom)

A/C to this,apical base is one of the most important factors in both correction of malocclusion as well as maintenance of correct occusion.

Intercanine and intermolar width should be altered to prevent relapse.

Nance advised to increase the arch length only to a minimal extent.

3. Mandibular incisor school of thought(Grieve and Tweed)

This theory postulated that the mandibular incisors should be placed upright and over the basal bone.

4. Musculature school of thought(Roger’s) Establishing proper functional muscle balance

is a must to achieve stable occlusion. Improper muscle balance leads to relapse.

THEOREMS ON RETENTION There are 10 theorems of which 9 are put

forward by Riedel and the last one by Moyer. THEOREM 1

“Teeth that have been moved tend to return to their former positions”

THEOREM 2 “elimination of the cause of malocclusion will

prevent recurrence”

THEOREM 3 “Malocclusion should be overcorrected as a

safety factor” THEOREM 4

“proper occlusion is a potent factor in holding teeth in their corrected positions”

THEOREM 5 “bone and adjacent tissues must be allowed to

reorganize around newly positioned teeth”.

THEOREM 6 “if the lower incisors are placed upright over

basal bone,they are more likely to remain in good alignment”

THEOREM 7 “corrections carried out during periods of growth

are less likely to relapse” THEOREM 8

“the farther teeth have been moved ,the less likelyhood of relapse.

THEOREM 9 “arch form particularly in the mandibular

arch,cannot be altered permanently by appliance therapy”.

THEOREM 10 “many treated malocclusions require permanent

retaining devices”.

PRINCIPLES OF RETENTION Relapse potential may be predicted by

evaluation of initial occlusion; teeth usually want to return to their original position; this is due to gingival fibers and unbalanced lip-tongue forces

Full-time retention is required for 3-4 months to allow for reorganization of PDL

Retention should continue for at least 12 months in non-growing patients or until growth has ceased in growing patients

TYPES OF RETENTION

natural/no retention Limited or short term retention Medium term/moderate retention prolonged/permanent/semi permanent

retention

NATURAL RETENTION--Occlusion is self retentive--an upper incisor is moved over the bite, no retention is

required--Conditions that do not require any retention anterior crossbite Serial extraction procedures Blocked out or highly placed canines in class I

extraction cases Posterior crossbite in patients having steep cusps

SHORT TERM RETENTION Limited retention-3-6 months Class I non-extraction with dental arches

showing proclination and spacing Deep bite Class I,Class II div 1 and div 2 cases treated

by extraction

MEDIUM TERM/MODERATE RETENTION

Supporting tissue will take longer time to adapt

Retention may extend between 1-5 years Class I non extraction cases,with protrusion

and spacing of maxillary incisors Corrected deep bites in classI or class II

malocclusion Corrected class II div 2 malocclusion

PROLONGED/PERMANENT/SEMI PERMANENT RETENTION

Cases treated by expansion particularly in the mandibular arch

Generalized spacing with arch length excess Severe rotatation Midline diastema Cleft palate cases Adult patients with periodontal problems Severe labiolingual malposition

RALEIGH WILLIAMS KEYS TO ELIMINATE LOWER RETENTION.

6 keys:-1. Incisal edge of the lower incisor should be placed on the A-P line or 1mm infront of it. This position of the lower incisor ensures stability following treatment. It also creates optimum balance of soft tissues in the lower third of the face.

2. The lower incisor apices should bespread distally to the crowns more than is generally considered appropriate and the apices of the lower lateral incisors must be spread more than those of central incisors. In otherwords the lower incisor roots should be diverging.

3. The apex of the lower cuspid should be positioned distal to the crown4. All 4 lower incisors apices must be in the same labolingual plane5. The lower cuspid root apex must be positioned slightly buccal to the crown apex.6. The lower incisors should be slenderised as needed after treatment

RETAINERS

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

IDEAL REQUIREMENTS FOR RETAINERS(GRABER) It should restrain each tooth that has been

moved in to the desired position It should be easily cleanable It should allow functional forces to be

transmitted to the retained teeth if worn It should be self cleansable It should be inconspicuousIt should be strong enough to achieve the

objectives of retention

CLASSIFICATION

Hawley retainer and modifictions

Wrap around retainers Canine to canine clip

on Tooth positioners Essix/invisible

retainers Functional appliances

Banded canine to canine retainers

Bonded canine to canine retainers

Diastema maintenance

Antirotation band Band and spur Pontic maintenance

REMOVABLE FIXED

REMOVABLE RETAINERS Effective for retention against intra arch

stability Effective in growth problems

HAWLEY RETAINER

Most common removable retainer

Developed in 1920s

Clasps on molars, palatal coverage, and labial bow with adjustment loops

Can incorporate biteplate for deep bite patients

MODIFICATIONS Labial bow can be made to extend from 1st

premolar to the opposite 1st premolar. The design helps in closing spaces distal to canine.

Solder the bow to the bridge of the Adam’s clasp.This design avoids the risk of space opening upbetween the canine and premolar due to the crossover wires.

Fitted labial bow offers excellent retention Anterior bite planes can be incorporated to retain

correct deep bite cases. Advantages

Ease of fabrication Minimal patient discomfort Acceptable to most patients.

Popularized by P.R.Begg Consists of labial wire that extend till

the last erupted molar and curves around it to get embedded in acrylic that spans the palate

Advantages:there is no cross over wire between the canine and premolar thereby eliminating the risk of space opening up.

BEGG’S RETAINER

CLIP-ON RETAINER/SPRING ALIGNER Made of a wire framework that runs labially

over the incisors and then passes between the canine and premolar and is recurved to lie over the lingual surface. Both the labial as well as the lingual wire segments are embedded in a strip of clear acrylic.

Used for correction of rotations commonly seen in the lower anterior region.

WRAP AROUND RETAINER Extended version of the spring aligner that

covers all the teeth. It consists of a wire that passes along the

labial as well as lingual surfaces of all erupted teeth which is embedded in a strip of acrylic.

APPLICATION Stabilizing a periodontally week dentition.

WRAPAROUND MODIFICATION: “3-3 CLIP-ON”

Used mainly for lower anterior area

Can realign incisors and/or maintain lower incisor space closure

Used if posterior teeth were well aligned pre-treatment

KESLING TOOTH POSITIONER Described by H.D.Kesling in 1945 It is made of a thermoplastic rubber like

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.

Needs no activation at regular intervals and is durable.

Drawbacks include difficulty in speech and risk of TMJ problems.

ESSIX/INVISIBLE RETAINERS

Developed in 1993

Plastic removable appliance

Advantages: Esthetic Patient is more likely to wear Inexpensive Quick fabrication Minimal bulk High strength No adjustments Usually does not interfere with speech or

function

Studies have determined that Essix retainers are as efficient as Hawley-type or bonded wire retainers

Graber, Orthodontics, 2005

POSITIONER

Can be made as retainer or used for finishing and then maintained as retainer

Disadvantages as a retainer:1. Bulky and difficult to wear full-time

2. Do not retain incisor position as well as a conventional retainer because patients usually wont wear full-time

3. Overbite increases due to limited patient wear

Advantages as a retainer:1. Reestablishes normal tissue when

gingival hyperplasia is present

2. Maintains occlusal relationship and intra-arch position

3. Unlikely to break

4. Can be made with jaws rotated down and back to prevent Class III relapse

5. Can be constructed to prevent relapse in skeletal Class II and open bite cases Growth control is less effective than

part-time functional appliance or headgear

DAMON SPLINT

Basically, upper and lower Essix retainers connected

Retentive splint for Class II, Class III, and bilateral crossbite treatment

Assists in tongue training

Holds teeth and arches in corrected position

Designed By Dr. Dwight Damon

Can be used by adults or patients in mixed dentition

Minimal vertical opening to allow for air slot

Esthetic

Can be made using:hard pressure formed, dual hardness/soft liner and elastic silicone

FIXED RETAINERS Utilized in cases where stability is

questionable and prolonged retention is planned

Four main indications:1. Maintaining lower incisor position2. Holding diastema closed3. Implant or pontic space

maintenance4. Retaining closed extraction spaces

BONDED CANINE TO CANINE RETAINER Commonly used in lower anterior region. 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 unesthetic.in addition when these retainers are removed band spaces are seen around these bands.

These drawbacks of the banded retainers have made them less popular than the bonded retainers.

BONDED LINGUAL RETAINERS They are retainers that are bonded on the

lingual aspect. Stainless steel/elgiloy wire is adapted

lingually to follow the anterior curvature. The ends are curved over the canine where it is bonded. Disadvantage : anterior teeth can sometimes

rotate This is overcome by using bonded retainers

that are bonded to each of the anterior teeth from canine to canine.

In case extractions have been done as part of the orthodontic treatment it may be advisable to extend the retainer to include the 1st premolar of both the sides.

Alternatives Use of etched or perforated metal cast bars that

can be bonded on the lingual side of the teeth. Braided or multistranded wire that can be

bonded individually to each tooth in a segment.

Advantage All individual teeth are retained with no

possibility of rotation of the incisors. Use of lighter braided wires permit physiological

movement of the teeth within the periodontal ligament.

Disadvantage The bonding of the lingual retainers on the

lingual surface of the teeth can be accomplished by direct or indirect bonding.

BAND AND SPUR RETAINER Used in cases where a single tooth has been orthodontically

treated for rotation,correction or labiolingual displacement. The tooth that has been moved is banded and spurs are soldered on to the bands so as to overlap the adjacent teeth.

In case it is used to retain a tooth that has been blocked partially,the spurs are made on the labial aspect so that tooth doesnot onceagain get displaced palataly.In derotation cases ,one spur is placed labially and the other lingually to avoid relapse.

ACTIVE RETAINERS Spring retainer: realign malpositioned

incisors Modified functional appliance: manage

relapse potential in Class II or Class III cases

ACTIVE RETAINERS Spring retainer: realign malpositioned incisors

Will usually need to perform IPR prior to appliance placement to prevent proclining incisors into unstable position

IPR flattens contacts increasing stability

Can reduce incisors 0.5 mm/side

If teeth are severely crowded, retreatment with bonded brackets is recommended; followed by fixed retention

Modified functional appliance: manage relapse potential in Class II or Class III cases

Activator or Bionator: Upper and lower retainers joined by inter-

occlusal bite blocks Maintain teeth within arch while slightly altering

occlusal relationship Example: If adolescent slips back 2-3 mm into

Class II after early correction, this appliance can be used to recover proper occlusion

No value if used in adults (as no vertical growth remains)

Moves teeth (no skeletal change)

Can only be used if no more than 3mm correction is needed

Goal: Hold maxillary posterior segment and allow for eruption of mandibular posterior segment anteriorly (Class II)

CONCLUSION Goals of occlusion are predefined prior to

start of orthodontic treatment.Procedures should be conducted with extreme care to minimize iatrogenic effects on dental hard tissues and periodontium.

REFERENCES CONTEMPORARY OF ORTHODONTICS

BY WILLIAM PROFITT,HENRY W FIELD,DAVID M SARVER

ORTHODONTICS ART AND SCIENCE BY S.I BHALAJHI