retention in orthodontics (dentistry)

RETENTION in Orthodontics

S a r a n g S u r e s h H o t c h a n d a n i

INTRODUCTION

▪ If excellent long term results are to be obtained, the orthodontic control of tooth position & occlusal relationship must be withdrawn gradually, not abruptly.

▪ Re t e n t i o n i s m e t h o d o f m i n i m i z i n g o r p r e v e n t i n g R E L A P S E .

▪ DEFINITIONS OF RELAPSE▪ Return following corrections.

▪ Any change from final tooth position at the end of treatment. S.S Hotchandani 2

WHY is Retention Necessary?

▪ The gingival & periodontal tissues are affected by orthodontic tooth movement and require time for reorganization when appliance are removed.

▪ The teeth may be in an inherently unstable position after the treatment, so that soft tissue pressure constantly produce relapse tendency.

▪ Changes produced by growth may alter the orthodontic treatment results after removal of appliance.

S.S Hotchandani 3

CAUSES of Relapse

• The major causes of relapse after orthodontic treatment include the

• elasticity of gingival fibers

• cheek/lip/tongue pressures,

• jaw growth.

• Gingival fibers and soft tissue pressures are especially potent in the first few months after treatment ends, before PDL reorganization has been completed.

• Unfavorable growth is the major contributor to changes in occlusal relationships.

S.S Hotchandani 4

Reorganization of the Periodontal & Gingival Tissues.

▪ Passive archwire used for stabilization of multiple teeth during orthodontic treatment cannot be considered the beginning of retention.

▪ Restoration of PDL structures will not occur as long as tooth is strongly splinted to its neighbours with help of orthodontic arch wire.▪ Once each tooth can be displaced slightly relative to its neighbour as the patient chews,

reorganization of PDL will start.

▪ Reorganization of PDL occurs over 3 – 4 month period.

▪ Reorganization of Gingival Fibers occurs slowly than PDL.▪ Collagen fibers of gingiva take 4 – 6 months.▪ Elastic Supra crestal fibers takes approx. 1 year.

S.S Hotchandani 5

Why REORGANIZATION OF PDL is Important for Stability of Tooth in Preventing Relapse.

▪ PDL contribute to equilibrium that normally CONTROL TOOTH POSITION within its socket.

▪ Teeth tolerate occlusal forces because of SHOCK ABSORBING CAPACITY of PDL.

▪ RESISTANCE OF TOOTH MOVEMENT caused by prolonged imbalance in tongue – lip – check pressure or pressure from gingival fibers occur by ACTIVE STABILIZATION OF PDL.▪ Orthodontic force reduces the active stabilization of PDL to cause tooth

movement. S.S Hotchandani 6

PRINCIPLES of Retention

▪ The direction of potential relapse can be identified by comparing the position of teeth at the end of treatment with their original position. ▪ Teeth will move tend to move back in the direction from which they came, primarily

because of elastic recoil of gingival fibers but also because of unbalance tongue – lip force.

▪ Teeth require essentially F U L L T I M E R E T E N T I O N after comprehensive orthodontic treatment for F I R S T 3 – 4 M O N T H S after fixed orthodontic appliance removed.▪ To promote reorganization of the PDL, however, the teeth should be free to move

individually during mastication, as the alveolar bone bends in response to heavy occlusal load during mastication.

▪ This can be achieved by removable retainer appliance worn full time except during meals.

S.S Hotchandani 7

PRINCIPLES of Retention

▪ Retention should be continued for at least 12 months (because of slow

response by gingival fibers) if teeth were too much irregular initially.▪ But this retention can be performed in parts as under;

▪ Full time wear initially for 3 – 4 months

▪ Part time wear after 3 – 4 months.

▪ Retention should be discontinued after approx. 12 months in non growing patient.

▪ Permanent retention is provided in those cases in which you think tongue – lip – cheek pressure inevitably cause relapse.

▪ In growing patients, retention should be provided until growth stops. S.S Hotchandani 8

Occlusal Changes Related to Growth

▪ Malocclusion caused by skeletal growth pattern alwaystend to relapse as long as patient is growing.▪ Long term relapse in transverse dimension are less of clinical

problem because transverse growth completes 1st.

▪ Clinical changes from later antero posterior & vertical growth aremore problematic in growing patient.

▪ Following are conditions mentioned which tend to relapsein their life after completion of orthodontic treatment;▪ Class II, Class III

▪ Deep Bite, Anterior Open BiteS.S Hotchandani 9

RETENTION in CLASS II

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Retention in CLASS II

▪ Causes of Relapse in Class II

▪ Tooth movement (forward in maxilla, backward in mandible)

▪ Differential growth of maxilla relative to mandible.

▪ Methods to Control Relapse in Class II Patient;

▪ Overcorrection of occlusal relationship to control tooth movement.

▪ Fixed appliance approach.

▪ Functional appliance.

S.S Hotchandani 11

Overcorrection of Occlusal Relationship

▪ Even with good retention 1 – 2 mm of antero posterior relapse always occurs, that’s why we have to overcorrect the position of teeth to prevent it.

▪ Too forward movement of lower incisors is avoided because;▪ Lip pressure will cause uprighting of protruding incisors, leading quickly (within few months) to

crowding, overbite & overjet.

▪ If MORE THAN 2 MM FORWARD MOVEMENT OF LOWER INCISORS occurred

during treatment, PERMANENT RETENTION will be required.

S.S Hotchandani 12

Fixed Appliance Approach

CONTINUE HEADGEAR to the upper molars on reduced basis

(at night for instance) in conjunction to WITH A RETAINER to hold the

teeth in alignment.

Remove all brackets except molar band in which head gear will be placed.S.S Hotchandani 13

Functional Appliance Therapy

▪ Use a functional appliance of activator & Bionator type along with conventional retainer to hold both tooth position & occlusal relationship.

▪ The construction bite is taken without any mandibular advancement for retention.▪ Goal is to prevent Class II malocclusion

from recurring, not to treat one that is already treated.S.S Hotchandani 14

RETENTION in CLASS III

S.S Hotchandani 15

Retention in CLASS III

▪ If the face height is normal or excessive after orthodontic treatment

& relapse occurs from mandibular growth, SURGICAL CORRECTION after growth is completed is only option.

▪ In MILD CLASS III, A FUNCTIONAL APPLIANCE OR POSITIONER may be enough.

S.S Hotchandani 16

Retention after DEEP BITE Correction

▪ Using a removable upper retainer made so that the lower incisors will contact the acrylic base plate of upper retainer & upper incisor teeth contact the facial surface of lower retainer.

▪ Patient should wear only at night to maintain the bite depth

S.S Hotchandani 17

Retention after Anterior Open Bite Correction

▪ Relapse into anterior open bite results from Any Combination Of Intrusion (Depression) Of Incisors & Extrusion (Elongation) Of The Molars from;▪ Thumb sucking, tongue thrusting, placement of objection b/w anterior teeth, downward & backward

rotation of mandible.

▪ In patients who do not place some object b/w front teeth, in them return of open bite results from elongation of upper molars.

▪ Controlling the eruption of posterior teeth during late vertical growth is the key to preventing open bite relapse.

S.S Hotchandani 18


There are two major approaches to accomplishing this:

▪MAXILLARY RETAINER WITH BITE BLOCKS

▪HIGH-PULL HEADGEAR. ▪ either must be continued as a nighttime retainer through the late teens.

S.S Hotchandani 19


▪ MAXILLARY RETAINER WITH BITE BLOCKS (or a functional appliance)▪ Open Bite Activator or Bionator appliance is

used.

▪ to impede eruption, as shown here in a patient soon after his severe open bite was corrected.

▪ Create separation b/w posterior teeth

▪ better choice for most patients for two reasons: ▪ controls eruption of both the upper and lower molars, and

▪ usually it is better accepted because it is easier to wear.S.S Hotchandani 20


A patient with sever open bite problem is particularly likely to benefit from having conventional maxillary and

mandibular retainers for daytime wear and open bite Bionator as night time wear.

S.S Hotchandani 21

Retention of Lower Incisor Alignment

▪ Continued skeletal growth also affects the position of teeth along with occlusal relationships.

▪ If mandible grows forward or rotates downward due to continued growth, the effect will be that lower incisors will be carried into lips, which creates a force causing tipping of lower incisor lingually or distally.

▪ so that’s why we place retainer in lower incisor crowding treatment also - FIXED LINGUAL BAR

S.S Hotchandani 22

Timing of Retention: SUMMARY

▪ Retention is needed for all patients who had fixed orthodontic appliance to correct their malocclusion.

▪ Patient should wear retainer full time for first 3 – 4 months. Continued on part time basis for at least 12 months to allow remodelling of gingival tissues. If growth is remaining, wear until growth stops.▪ Removable retainer should be removed during eating.

▪ Fixed retainer should be flexible so that individual tooth movement can occur.

S.S Hotchandani 23


▪ NO RETENTION CASES;▪ Anterior cross bite, with positive overbite and overjet following correction; and

▪ Spontaneous alignment following extractions and no active treatment.

▪ MEDIUM-TERM RETENTION: Medium-term retention usually means a period that allows reorganization of the soft tissues and periodontal ligament, and for adolescent growth and dental development to be completed, including eruption of the third molars▪ De-rotation

▪ Diastema

▪ Deep Over Bite

▪ Sk. Discrepancies

▪ Expansion cases

▪ ALMOST ALL CASESS.S Hotchandani 24


▪ PERMANENT RETENTION

▪ Severe rotations;

▪ Midline diastema and spacing; and

▪ Periodontal compromised teeth with bone loss

▪ Proclination of the lower labial segment;

▪ Expansion of lower inter canine width;

▪ Alignment of palatally displaced maxillary lateral incisors in the absence of a positive overbite at the end of treatment;

▪ Correction of an anterior open bite by extrusion of incisors; and

▪ Correction of an overjet with lip incompetence at the end of treatment.

S.S Hotchandani 25

TYPES of Orthodontic Retainers

Ort

ho

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ner RemovableRemovable

Hawley applianceHawley appliance

Begg RetainerBegg Retainer

Wraparound (Clip) Retainer

Wraparound (Clip) Retainer

Vacuumed Essix Retainer

Vacuumed Essix Retainer

PositionersPositioners

FixedFixed

ActiveActive

Functional AppliancesFunctional Appliances

Barrer ApplianceBarrer Appliance

HeadgearHeadgearS.S Hotchandani 26

REMOVABLE RETAINERS

S.S Hotchandani 27

Hawley Retainer

▪ The classic Hawley appliance consists of an acrylic baseplate with Adams clasps placed on the first molars and a labial bow with U-loops

▪ It can be used in both the upper and lower arches and has the advantage of being durable.

▪ M O D I F I C AT I O N S E X I S T I N C L U D I N G U S E O F ;

▪ a labial bow with acrylic to maintain correction of rotations,

▪ a reverse U-loop to improve canine control, and a

▪ labial bow soldered to the bridge of the Adam clasps for holding the extraction site of premolar closed.

▪ The baseplate can be modified into a U shape to minimize palatal coverage and improve comfort and speech.

▪ An anterior bite plane can be included for maintenance of deep bite correction.S.S Hotchandani 28

Hawley RetainerHawley

Retainer

S.S Hotchandani 29

A. A Hawley retainer for a patient with

maxillary premolar extractions, with the

anterior bow soldered to Adams clasps on

the first molars so that the extraction site is

held closed.

B. The adjustment loop of the Hawley anterior

bow often keeps the wire from having full

contact with the canines. If good control of the

canines is needed, as in this patient whose

canines were facially positioned before

treatment, a wire that extends across the

canines can be soldered to an anterior bow

that crosses distal to the lateral incisor.

C. In a patient whose second molars have

erupted, a wraparound outer bow soldered

to C-clasps on the second molars provides

a way to avoid interference as the retainer

wire crosses the occlusion, but a bow with

such a long span will be quite flexible.

D. For a mandibular retainer, the wire Hawley bow

is less effective than a wire-reinforced acrylic

bar that tightly contacts the lower incisors. This

Moore design has almost completely replaced

the Hawley design for lower removable

retainers that extend to the posterior teeth.S.S Hotchandani 30

Begg Retainer

is a modified version of the Hawley retainer

that does not incorporate Adams clasps and therefore allows greater molar

settling.

S.S Hotchandani 31

Wraparound (Clip – on) Retainer

▪ Consists of plastic bar (usually wire reinforced) along the labial and lingual surfaces of teeth.

▪ A removable clip-type retainer that controls alignment of only the anterior teeth (3-3 clip or

as shown here, 4-4 clip) often is preferred as a removable lower retainer because if the lower posterior teeth were well aligned prior to treatment, retention of these teeth usually is unnecessary, and undercuts lingual to the lower molars make it difficult to place a lower retainer that extends posteriorly.

S.S Hotchandani 32

Wraparound (Clip – on) Retainer

▪ An anterior clip retainer in the maxillary arch is

particularly useful when it is necessary to keep spaces from reopening. It also can be used to

prevent re-rotation of maxillary incisors, but contact of the lower incisors with a maxillary clip retainer often becomes a problem.

▪ Anterior clip retainers in both arches for this patient, who had maxillary and mandibular anterior spacing prior to treatment.

S.S Hotchandani 33

Clear (Vacuum Formed) Retainers

▪ These retainers are clear, heat softened plastic.

▪ Construct by heating a sheet of clear plastic, which is then sucked down onto a dental cast by a vacuum.

▪ The material of this retainer is transparent & thin.

S.S Hotchandani 34


▪ Advantages of Vacuum Formed Retainers;

▪ Superior aesthetics

▪ Less interference with speech

▪ More economical and quicker to make

▪ Ease of fabrication

▪ Superior retention of the lower incisors

▪ Both Hawley and vacuum-formed retainers are equally successful in the upper arch, but the VACUUM-FORMED RETAINERS ARE BETTER AT PREVENTING RELAPSE IN THE LOWER ARCH.

Description in Notes

S.S Hotchandani 35


▪ Vacuum-formed retainers only need to be worn at night, every night.

▪ It is important that the patient is instructed never to drink with the vacuum-formed retainer in situ , particularly cariogenic drinks ▪ The retainer can act like a reservoir, holding the

cariogenic drink in contact with the incisal edges and cuspal tips and leading to decalcification

▪ Vacuum-formed retainers are CONTRAINDICATED IN PATIENTS WITH POOR ORAL HYGIENE. This is because these types of retainers are retained by the plastic engaging the undercut gingival to the contact point. If the oral hygiene is poor, then hyperplastic gingivae can obliterate these areas of undercut.

Cariogenic drinks and vacuum-formed retainers. It is vital

that patients are instructed not to wear vacuum-formed

retainers when eating or drinking. This patient wore a

vacuum-formed retainer full-time (a), while regularly

drinking fizzy drinks, leading to substantial tooth surface

loss and caries (b).

Cariogenic drinks and vacuum-formed retainers. It is vital

that patients are instructed not to wear vacuum-formed

retainers when eating or drinking. This patient wore a

vacuum-formed retainer full-time (a), while regularly

drinking fizzy drinks, leading to substantial tooth surface

loss and caries (b).

S.S Hotchandani 36

Positioners

▪ They are excellent finishing devices but sometimes can be used as retainers.▪ For routine use they are not good retainers.

▪ It is a device with inherent elasticity to move the teeth slightly to their final position as the patient bites into it.

S.S Hotchandani 37

Disadvantages of Positioners

▪ Pattern of wear does not match the pattern usually desired for retainers.

▪ Patients have difficult due to its bulk.

▪ They are worn less than 4 hours per day.

▪ Does not retain incisor rotation

▪ Increases overbite▪ Good for open bite cases

▪ Not good for deep bite patients

S.S Hotchandani 38

F I X E D R E TA I N E R S

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Indications of Fixed Retainers

Keeping Extraction Spaces Closed in adultsKeeping Extraction Spaces Closed in adults

of Pontic or Implant spaceof Pontic or Implant space

Diastema MaintenanceDiastema Maintenance

Maintainace of Lower Incisors Position during Late mandibular growthMaintainace of Lower Incisors Position during Late mandibular growth

S.S Hotchandani 40

RETAINERSfor Maintainace of Lower Incisors Position during Late mandibular growth

▪ FIXED LINGUAL BAR▪ Attached only to canines or canines & premolars.

▪ Rest against the flat lingual surface of lower incisors above cingulum.

▪ Prevents lingual tipping & rotations of incisors.

▪ This bar is made From Heavy Wire Of 28 – 30 Mil Stainless Steel with loop bend in the end of wire to improve retention.▪ Alternative is 17.5 – 19.5 mil stainless steel twisted/braided

wire. (Described in Next Slide)

Description in NotesS.S Hotchandani 41

RETAINERSfor Maintainace of Lower Incisors Position during Late mandibular growth

Alternative to Fixed Lingual Bar (Braided Wire)

A. Bonding a wire to all the mandibular anterior teeth (canine-to-canine or premolar-to-premolar) is indicated if spaces existed in the lower anterior segment prior to treatment, or if severe rotations were corrected. A light wire (17.5 or 19.5 mil twist) should be used. A retainer of this type must be kept under observation because a bond failure on one tooth is unlikely to be noticed by the patient and severe decalcification can occur in that area.

B. A section of twist wire, usually bonded just on the four incisors, also can be used to maintain alignment of maxillary teeth that were severely displaced. Bonded attachments on the lingual of the upper incisors also can serve to prevent deepening of the bite as lower incisors erupt.

S.S Hotchandani 42

RETAINERSDiastema Maintenance – Bonded Lingual Retainer OR Solid Wire

Bonded lingual retainer for maintenance of a maxillary central diastema.

A. 17.5 mil twist wire contoured to fit passively on the dental case.

B. A wire ligature is passed around the necks of the teeth to hold them tightly together while they are bonded. The wire retainer is held in place with dental floss passed around the contact, and

C. composite resin is flowed onto the cingulum of the teeth, over the wire ends.

A. Note that the retainer wire is up on the cingulum of the teeth to avoid contact with the lower incisors.

B. A Hawley retainer can be worn to stabilize other teeth and maintain vertical control in the presence of a bonded segment of this type.

S.S Hotchandani 43

RETAINERSDiastema Maintenance – Bonded Lingual Retainer OR Solid Wire

Solid Wire

▪ An alternative design for a bonded retainer for the maxillary incisors, using a heavier wire.

▪ The wire is contoured so that flossing is not impeded, and the bonded attachment areas also serve to keep the bite from deepening, but the patient will have to tolerate more tongue contact with a retainer of this type, and ▪ overgrowth of palatal gingiva can become a

problem

S.S Hotchandani 44

RETAINERSMaintenance of Pontic or Implant Space

▪ For Posterior Teeth missing space;A – Splint.

▪ For anterior teeth missing space, artificial tooth in a removable retainer.

De

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in N

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S.S Hotchandani 45

Fixed Retainers

▪ Advantage▪ they are not dependent on patient compliance for wear.

▪ Disadvantages▪ difficulty with oral hygiene,

▪ localized relapse and

▪ Decalcification following partial debond.

S.S Hotchandani 46

AC T I V E R E TA I N E R S

S.S Hotchandani 47

Active Retainer

▪ It is misnomer, since a device cannot actively move teeth & provide retention at the same time.

▪ However sometimes relapse or growth after orthodontic treatment lead to change in treated position, so in that case we will need a an appliance which initially correct the relapsed tooth position followed by providing retention.

▪ That’s why active retainer are mostly given in following conditions;▪ Realignment of irregular incisors with spring retainer (Barrer Spring)

▪ Management of class II or Class III relapse with functional appliance▪ Headgear

▪ Activator or Bionator type

S.S Hotchandani 48

Realignment of Irregular Incisors: Spring Retainers

▪ Re-crowding of lower incisor is the major indication for active retainer to correct the incisors position.

▪ If the irregularity is moderate, spring retainer of choice is canine to canine clip on retainer.

▪ If the irregularity is more than moderate, retreatment with fixed appliance is treatment of choice.

S.S Hotchandani 49

Canine – to –Canine Clip –On Retainer for Realignment of Irregular Incisors (STEPS)

1) Reduce inter proximal width of incisors & apply topical fluoride to the newly exposed enamel surface.

▪ Enamel can be removed with following devices▪ Abrasive strips

▪ Thin discs in hand piece

▪ Thin flame shaped diamond stones

▪ Maximum enamel which can be removed is 0.5 mm on each side of tooth.

2) Prepare Laboratory Model on which teeth can be reset into alignment.

3) Fabricate canine to canine clip on appliance.

S.S Hotchandani 50

Removal of interproximal enamel to facilitate alignment of

crowded lower incisors.

A and B, Before and after use of a carbide coated

strip to remove enamel. The surfaces are polished after the

stripping is completed. Topical fluoride should be applied

immediately after stripping procedures because the fluoride-

rich outer layer of enamel has been removed.

C, A canine-to-canine clip-on retainer (now; initially an aligner)

immediately upon placement must be worn full time until theteeth are back in alignment.S.S Hotchandani 51

Steps in the fabrication of a canine-to-canine clip-on appliance to realign lower incisors.

A. Re-crowded incisors in a patient who decided to “take a vacation” from retainer wear. After the teeth have been

stripped appropriately, an impression is made for a laboratory cast.

B. A saw-cut is made beneath the teeth through the alveolar process to the distal of the lateral incisors, and cuts

are made up to but not through the contact points.

C. The incisor teeth are broken off the cast and broken apart at the contact points, creating individual dies, and

the cast is trimmed to provide space for resetting the teeth; then the teeth are reset in wax in proper alignment

and 28 mil steel wire is contoured around the labial and lingual surface of the teeth as shown, with the wire

overlapping behind the central incisors. A covering of acrylic is added over the wire, completing the aligner,

which then looks exactly like a canine-to-canine clip-on retainer. As an aligner, however, full-time wear is

essential.S.S Hotchandani 52

Fixed Appliance Therapyfor Realignment of Irregular Incisors

For this patient, who was concerned about crowding of lower incisors several years after orthodontic treatment,

excessive stripping of interproximal enamel would have been required to gain realignment with a clip-on removable

appliance. In that circumstance, a partial fixed appliance with bonded brackets only on the segment to be realigned is

the most practical approach.

A, Bonded appliance from first premolar to first premolar, with a coil spring on 16 steel wire to open space for the rotated and

crowded right central incisor. B and C, Alignment of the incisors on rectangular NiTi wire after space was opened, which was

completed 4 months after treatment began. At this point a fixed lingual retainer can be bonded before the brackets and archwire

are removed. S.S Hotchandani 53

References

▪ Cobourne, M. T. (n.d.). Handbook of Orthodontics. Mosby.

▪ Gill, D. (n.d.). Orthodontics at a Glance.

▪ Mitchell, L. (n.d.). Introduction to Orthodontics (4 ed.).

▪ Proffit, W. R. (n.d.). Contemporary Orthodontics (6 ed.).

S.S Hotchandani 54

THANKSSarang Suresh HotchandaniFinal Year BDS, Bibi Aseefa Dental College, SMBBMU.Larkana, Sindh, PAKISTAN.Email: [email protected]: www.twitter.com/fetusdentistaS.S Hotchandani 55

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retention in orthodontics (dentistry)

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