retention and relapse by almuzian

University of glasgow

Retention, stability & relapse in orthodontics

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Mohammed Almuzian

Personal note, 2013

Table of contents

Definition

Relapse

Retention

Method to measure relapse

Reasons of relapse

Rationale of retention

Normal age related dental changes

Factors related to retention and should be considered at the TP stage

1. Informed consent

2. Original malocclusion

3. Adult Patients

4. Occlusion

5. Growth

6. Periodontal health:

7. Soft tissue features

8. Type of treatment & teeth movement

9. Patient wishes, oral hygiene and cooperation.

10. Associated habits .

11. Adjunctive soft or hard tissue procedures

12. Type of retainer..

13. Duration of retention..

Factors that will help minimize relapse

Mohammed Almuzian, University of Glasgow, Personal note, 2013 1

Types & design of retainer

Relapse Due to Growth and methods to maintain them

Retention: Class II

Retention: Class III

Retention: Deep Bite

Retention: Anterior Open Bite

Retainer, what type and how, evidences based

Parameter to help in determining the position of the best stability of LLS

1. Lower incisor edge- root centroid relationships

2. Lower incisors to A-Po line

Theories of LLS crowding

Indications for removal of wisdom tooth (SIGN Guidelines)


Retention, Stability & Relapse in Orthodontics

Definition

Relapse It is defined by the BSI in 1983 as “The return, following correction, of the

original features of the malocclusion.”

But the more updated definition is unfavourable change (s) from the final tooth

position at the end of orthodontic treatment

RetentionMoyers (1973) defined orthodontic retention as “The holding of teeth in the

treated position, following orthodontic treatment, for the period of time

necessary for the maintenance of the result”.

Method to measure relapse

1. Direct assessment

2. PAR index

3. Little index

4. Digital superimposition of the study model

5. Photograph or sterophotogrammetry

6. Cephalometric or 3D radiograph

Reasons of relapse Hixon, 1969

1. Periodontal or physiological recovery due to elastic recoil of the

periodontal tissues (principal fibres of PD ligament, collagenous fibres of the

gingiva, elastic fibres of the gingiva (supracrestal fiber) and alveolar bone )


2. Pressure from the surrounding orofacial tissues when the neutral

equilibration zone disturbed or due to soft tissue maturation with aging (Poffit,

1978).

3. Unfavourable growth and/or growth changes (growth relapse).

4. Pressure from occlusion (Poffit, 1978).

5. Continuous habits

6. Iatrogenic cause of relapse (called true relapse) due to poor outcomes e.g.

changing intercanine width (Felton et al. 1987). This could be considered as

iatrogenic cause of relapse since the teeth are placed in purely evidence based

unstable position.

7. Idiopathic cause of relapse like relapse after treating a high angle class II

malocclusion due to idiopathic condylar resorption

8. Combination

Rationale of retention

1. Reitan 1967 mentioned that one of the main rationales behind retention is

to allow reorganization of the gingival and periodontal tissues affected by

orthodontic tooth movement (resist physiological relapse). His study showed

the following:

• The principal fibres of PD ligament take 3 months to reorganize

• The collagenous fibres of the gingiva take 6 months.

• The elastic fibres of the gingiva (supracrestal fiber) take 232 days.

• Alveolar bone takes 1 year.

NB: Masticatory stimulation of PDL promote reorganization so that advise

removing the retainer appliances during meal and avoid use of rigid retainer

2. To prevent unwanted movement resulting from growth changes (resist

growth relapse).


Retain if possible until growth ceases.

Prolonged retention of the lower labial segment until the end of facial

growth may reduce the severity of future lower incisor crowding (Sadowsky et

al. 1994).

3. To prevent relapse tendency of teeth that have been moved to an

inherently unstable position (resist true relapse and soft tissue maturation

changes).

Normal Age related dental changes

These changes are normal but might be confused with relapse by a patient who

has received orthodontic treatment. Two studies for these changes are below:

A. Sinclair and Little (1983)

1. A decrease in arch length.

2. A decrease in inter-canine width (especially females aged 13-20).

3. Intermolar widths were fairly stable

4. Small decrease in overjet and overbite.

5. An increase in lower incisor irregularity. No variables that could predict

those individuals who would experience increasing dental irregularity.

B. Iowa Facial Growth Study by Bishara et al. (1997 and 1998)

1. Maxillary & Mandibular arch length &intercanine width all increase until

age 13 years then it decreases especially females

2. Mandibular & maxillary intermolar width increases until 13 then become

static with little decrease in female.


Relapse Risk Factors

A. Factors present pre-treatment

3. Class III in growing patient with family history or unfavourable growth

4. Class II div 2

5. AOB

6. Hyperactive mentalis

7. High lower lip

8. Incompetent lips

9. Primary tongue posture

10. Slipped contacts and rotations

11. Median diastema

12. Spacing in adults

13. Palatal canines

B.Factors created during treatment -

1. Incisor advancement

2. Incisor retraction (if tongue thrust)

3. Incisor extrusion

4. Intercanine expansion

5. Extraction spaces in adults

Factors that will help minimize relapse: (Destang and Kerr 2003):

1. During TP

Consider extraction of severely displaced teeth in the plan of extraction

pattern


2. During active treatment

Maintain existing arch form.

Maintain intercanine width.

Avoiding posterior expansion

Maintain A-P position of lower incisors.

Move upper incisors to within lower lip control.

Correct rotations early in treatment. Tuverson (1980) suggests reshaping

of contact points to aid stability.

Over-correction of the malocclusion.

3. During finishing stage

Maximize interdigitation.

Correct incisors to achieve normal edge-centroid relationship.

Correct root torque & ensure root parallelism.

Consider IPS for triangular teeth

Labial fraenectomy prior to debond to minimise re-opening of diastema

CFS within 4-6 months after debonding

4. During retention phase

Prolong retention (Bonded retainer) for PDL compromised cases and

cases of high risk of relapse

Retain if possible until growth ceased

Elimination of the habits.

Factors related to retention and should be considered at the treatment planning (TP) stage1. Informed consent about the possibility of relapse and the rationale of

retention.


2. Growth

3. Age (Adult Patients)


Incisor relationship

Skeletal pattern

Anterior deep bite

Anterior crossbite

Posterior crossbite

Generalized spacing

Diastema

Rotations

Lower incisor irregularity

5. Soft tissue features

6. Periodontal health

7. Associated habits

8. Occlusion at the end of treatment


Extraction/Non-extraction

Serial extraction

Changes in the intercanine width

Change in lower incisor position

10. Type of retainer.

11. Adjunctive soft or hard tissue procedures to enhance stability.

12. Duration of retention.


In details


1. Informed consent

According to the BOS advice sheet, it is the responsibility of the treating

clinician to explain in details the possibility of relapse and the rationale of

retention before commencing and orthodontic treatment.

2. Growth

• Facial growth continues throughout life, generally in the same direction

as that occurring during adolescence, but to a much smaller degree (Behrents,

1985).

Recommendation:

Retain if possible until growth cession with:

Long term removable or fixed retainer to avoid LLS crowding Sadowsky

1994

• For class II skeletal discrepancy: modified activator appliance or URA

with postured inclined bite plane (FABP) or HG (Wieslander 1993)

• For class III either Frankle III, chin cap, PFM,

• High pull HG + post bite block after correcting AOB

• For deep bite use ABP

3. Age (Adult Patients)

Slow tissue remodelling and soft tissue-age related changes in adult might be a

reason for permanent retention to avoid relapse. However, there is no evidence

for that.

4. Occlusion at the end of treatment

The occlusion can aim in retention and stability.

• It is also a widely held belief that a well-interdigitated class I occlusion

aids stability at the end of treatment and there is some evidence for this (Kahl-


Nieke et al, 1995) this is because achieving good occlusal relationship will aid

in providing favourable dentoalveolar compensation.

• Correction of an anterior crossbite with a positive overbite following

treatment requires no retention.

• Normalization of the lower incisor to centroid relationship claimed to be

a reason for good retention in deep overbite (Houston 1989).

• Normal lower incisor edge to Apo line claimed to be a reason for good

retention in deep overbite. (Williams, 1969).

• Normalization of II angle claimed to be a reason for good retention in

deep overbite (Mills, Bjork 1947)

5. Periodontal health:

For those with minimum to moderate disease, permanent retention is

advised. Zachrisson 1997

There is evidence of an increased risk of deterioration of lower incisor

alignment post-retention in cases with root resorption or crestal bone loss.

Sharpe et al., 1987

6. Soft tissue features and its relationship to the stability of treatment

To a large extent the soft tissues define the limitations of orthodontic tooth

movement. Any change in the position of the teeth that move them out of the

zone of soft tissue balance can increase the chance of relapse. These include

A. Lip competency,

B.Lip form,

C.Lip size

D. Lip tonicity

E.Tongue size and position.


For this reason the arch form, particularly of the lower arch, is not

amenable to any significant change. If expanded during treatment, especially

across the intercanine width, this will be very prone to relapse.

Vertically, the lower lip position is very important in the stability of

overjet reduction. If the lips are competent following treatment and the lower

lip rests labially to the upper incisors, there is greater stability.

An endogenous tongue thrust is primarily neurological in origin, resulting

in anterior position of the tongue and excessive force exerted on swallowing. If

the anterior open bite is corrected, the tongue activity is normalized and the

result will be stable. However, if a true tongue thrust is present, no treatment

will guarantee stability, as the primary aetiological factor will remain

It is possible that with age the soft tissue pressures may change, which

may lead to relapse.

A soft tissue features indicative of stable overjet reduction (Melrose and Millett

1998):

I. Competent lips

II. Normal lower lip to upper incisor coverage

III. No lip trap

IV. Normal activity of the lips

V. Absence of persistent tongue thrust


Incisor relationship

Skeletal pattern

Lower incisor irregularity

Anterior deep bite

Anterior open bite


Anterior crossbite

Posterior crossbite

Generalized spacing

Rotations

Diastemas

In details

A. Incisor relationship

Class II D2 is the higher in the relapse than others.

B. Skeletal pattern

Most of the skeletal changes are relapsed after 1-2 years according to the

evidences:

• Early treatment of class 2 skeletal patterns was associated with loss in the

skeletal changes by the end of fixed appliance treatment when compared with a

control group. Tulloch et al, 2004.

• A long term follow up study of patients receiving early treatment of class

2 malocclusions with HG and Herbst showed that mandibular protrusive effect

was lost and maxillary growth inhibition had continued. Weislander 1984.

• Chin cup treatment of class 3 malocclusions (Sugawara et al 1996) were

not stable as skeletal changes were lost with growth.

For the above reasons, the retention of skeletally corrected problems

should continue until growth is ceased.

C. Lower incisor irregularity

Lower incisor irregularity take place by the middle of the third decade.

Richardson 1998.


The presence of LLS crowding increase the risk of posttreatment relapse.

For each 1mm of LLS crowding there is a chance of 4-18% of relapse (Fudalej

2008).

It has been suggested that prolonged retention of the lower labial segment

until the end of facial growth may reduce the severity of lower incisor

crowding. Sadowsky 1994

For the above reasons, Patients’ expectations of the stability of their lower

incisor alignment should be considered on completion of orthodontic treatment.

If an individual is unwilling to accept any deterioration in lower incisor

alignment following orthodontic treatment then permanent fixed or removable

retention may have to be considered.

D. Anterior deep bite

Loss of positive incisor stops considered an aetiological factor in deep

OB. Kim and Little 1999 found that the more upright the teeth, the high risk of

relapse.

Achieving normal lower incisor to centroid or normal II angle claimed to

be effective in stability of OB (Houston 1989). However Kim and Little 1999

disagree with this.

The use of RA with anterior bite plate until completion of growth (Proffit

1992) is recommended. This may be particularly useful when there is evidence

of an anterior mandibular growth rotation. Nielsen 1993

E. Anterior open bite

In general: AOBs tend to relapse in approximately 20% of treated cases.

(Huang, 2002)

Extraction: There is also evidence of greater stability of open bite

correction when orthodontic treatment is undertaken with extractions (Janson et

al., 2006).


Extrusion or intrusion: In treatment resulting in molars intrusion, the rate

of relapse ranges from 17 to 30%: whilst in treatments with incisor extrusion,

relapse may be even greater, reaching sometimes 40% of treated cases.

(Suguwara 2011)

The use of retainers incorporating posterior bite blocks has been

recommended for prolonged retention of anterior open bite malocclusions with

unfavourable growth patterns, however, there is currently a lack of scientific

evidence to support this. Proffit 1992

F. Anterior crossbite

It is retained by the +ve overbite otherwise permanent retention is mandatory to

maintain the results.

G. Posterior crossbite

It is highly prone to relapse. The recommended strategies by Kaplan 1988 are:

(but it is weak evidence)

• Minimum period of 3-month's retention after active expansion and before

starting FA

• Further stabilization can be achieved by slight expansion of the archwire.

• Posterior intercuspation should be sufficient to maintain the correction.

H. Generalized spacing

It is highly prone to relapse and needs permanent retention. Joondelph 1994

I. Rotations

• Surbeck et al (1998) stated that pre-treatment irregularity or rotation of

maxillary incisors and incomplete alignment are a significant risk factor for

post-retention relapse.

• Following orthodontic tooth movement, the tissues of the periodontal

ligament and gingivae remodel to the new position of the tooth. Whilst

collagen fibres in the periodontal ligament take between three to four months to


remodel, those in the gingival tissues take slightly longer, at around six

months. The slowest turnaround occurs in the elastic supracrestal fibres, which

take up to one year. This has important implications for teeth that were rotated,

Recommendations to reduce the risk of relapse after de-rotation

Overcorrection.

The amount of relapse for an individual tooth is probably related to the

degree of rotation (Swanson et al., 1975), to the effectiveness of the

fiberotomy procedure, or to the stage of development of the transseptal

fibers. So that all fibers will be sectioned during the fiberotomy, the

original point of insertion of the transseptal fibers must be known. Early

de-rotation, before the transseptal fibers have fully developed (Furstman

and Bernick, 1972; Schacter and Bernick, 1976), will probably diminish

the amount of relapse. Kusters et al (1991) stated that transeptal fibres

developed only when the AEJ of the developing teeth erupted to the

height of the alveolar bone. He therefore advocated early correction to

allow normal formation of the fibres.

Edwards (1970) suggested CSF (circumferential supracrestal fiberotomy)

to reduce post retention relapse of derotated teeth is beneficial in the first

4-6 years post treatment. CSF can be undertaken in the conventional way

using a surgical scalpel to transect the gingival fibres or by using a laser-

aided probe. It is thought that the laser-aided probe has a number of

advantages such as less bleeding, minimal swelling and no apparent

damage to the supporting periodontal structures (BOS guidelines 2013)

Zachrisson believed that broken contact points are a starting point for

later crowding in untreated malocclusions. So that, interdental stripping

producing near parallel sides may be associated with greater stability than

triangular teeth (Peck and Peck 1972) although this has been contested by

Gilmore & Little in 1984.


Tuverson (1980) advocated reshaping the contact points to make them

larger to improve stability.

J. Diastemas

Incidence of maxillary midline diastema varies in the literature from 8%.

Edwards (1977) proposed that their presence was associated with

abnormalities of the frenum but that view is disputed (Popovich et al 1977).

Sullivan et al (1996) found that 2/3rds of diastema closure was stable 12

months post retention. He found no significant predictors for relapse but

considered that abnormal fraenum or intermaxillary osseous clefts may play a

role in diastema relapse.

Cheashua and Artun 1999 no difference

Recommendation

It needs permanent retention.

The frenectomy before complete space closure is recommended to use the

scar as natural retainer (Edwards, 1977, Profitt, 2010)


Extraction/Non-extraction

Paquette et al 1992 found no clinically significant difference in relapse between

treated extraction and non-extraction borderline class 2/1 malocclusions. This

finding has been supported by similar studies (Luppanapornlarp and Johnston

1993, Kahl-Nieke et al 1995).

In contrast, Artun et al (1996) reported a greater mean mandibular incisor

irregularity for extraction group but this was not statistically significant.

Serial extraction:

• Little 1990 found no difference in the LLS irregularity with serial

extraction and other gp.


Intercanine width changes

• De Lacruz 1995 showed that it is highly related to relapse.

• Active intercanine expansion shows 89% relapse

Change in Lower incisor position

Mills 1968 advised to preserve the original position of LLS

Any change of more than 2 mm in anterioposterior direction needs

permanent retention. (Proffit 1990). See more description at the end of this

note.


10. Associated habits which should be stopped to avoid relapse.

11. Necessity for adjunctive soft or hard tissue procedures to enhance

stability. See more comprehensive discussion below.

12. Type of retainer. See more comprehensive discussion below.

13. Duration of retention. See more comprehensive discussion below.

Types & design of retainer

A. Removable retainers

Types

Hawley retainer

Spring or Barrer retainers

Begg retainer

Thermoplastic retainer VFRs

Positioner


Damon Splint

HG, FABP, functional appliance, modified activator

In details

1. Hawley retainer

Types

U-loops

Reverse U-loops which provides better control of the canines

Labial bow soldered to the molar cribs which means that there are fewer

wires to interfere with the occlusion.

Advantage

Facilitating posterior occlusal settling in the initial three months of

retention. Sauget 1994.

A bite plane can also be incorporated to maintain overbite reduction.

Acrylic tooth can be added to temporarily replace a missing tooth.

Can be activated to close residual spaces

Maintain lateral expansion

2. Spring or Barrer retainers carry acrylated bows both labially and

lingually. The original appliance extended only to the canines; however, due to

the risk of swallowing or aspiration, a modification which includes cribs on the

first molars has been described. These retainers can be used to realign minor

lower incisor relapse if the teeth are realigned on the working model by the

technician.


Modified Barrer to avoid inhalation

3. Begg retainer labial bow soldered to thinner wire.

Its principal advantage is that

It has no clasps and therefore there are no wires

crossing the occlusion which is therefore free to settle

during the retention period.

A bite plane can also be incorporated to maintain overbite reduction.


Can be activated to close residual spaces

Maintain lateral expansion

4. Thermoplastic retainer VFRs

Full coverage of all teeth until the half of the second molar.

Usually for short time otherwise it will interfere with settling of the

occlusion.

It is fabricated from 1.5mm polyvinylchloride sheets by heating to 475

degree and vacuum pressure of 1.5b for 50 second.

Advantage

Aesthetic appliance

Easy to construct and use

Cheap,

Vacuum-form retainers can also be used for active tooth movement.



They provide good aesthetics and better control of incisor alignment than

Hawley type retainers (Rowland et al, 2007)

Disadvantages

Ineffective to retain expansion cases unless it is supported by thick wire

Ineffective to retain intrusion or extrusion movement

No settling of the occlusion

If partial Essex which cover incisor and canine is used, the patient may

develop AOB

Increase the risk of decalcification in the presence of a cariogenic diet.

5. Positioner

Features

• Elastomeric or rubber removable retainers

• Preformed or custom made (the custom made are made on articulated

models in which the teeth have been sectioned and realigned to achieve the

desired result. The appliance is then formed around the teeth and the coronal

part of the gingiva)

Uses

Provide further minor correction following deboned and thus "guide" the

settling of the occlusion.

They were particularly beneficial at the end of Begg treatment in which

stage III (the finishing phase) is difficult.

They may also be useful in instances when the desired finish was not

achieved or the case had to be discontinued early.

As a retainer

Instruction on the uses


• The patient is advised to wear the appliance and practice repeated cycles

of clenching then relaxation to encourage the desired tooth movements.

• These should occur in the first 3 weeks so that the positioner soon

becomes a passive retainer.

Problems

• It is costly to make,

• Do not hold rotational or overbite corrections well

• Not popular with patients whose compliance is poor.

6. Damon Splint

Basically, upper and lower Essix

retainers connected

Can be made using hard pressure

formed, dual hardness/soft liner and elastic

silicone

Advantages

Holds teeth and arches in corrected

position

Retentive splint for Class II, Class III,

bilateral crossbite treatment & orthognathic cases.

Assists in tongue training

7. Hawlix or ‘aesthetic’ retainer

When maxillary expansion has been undertaken, Hawley type retainers,

introduced by Charles A. Hawley (1861–1929) in 1908, are preferable as the

palatal acrylic helps to maintain the expansion and prevent transverse relapse. An


alternative is a combined retainer, the Hawlix or ‘aesthetic’ retainer, which

combines the anterior aesthetic advantage of the Essix retainer and the palatal

acrylic of the Hawley retainer. This retainer is particularly useful following

treatment in cleft lip and palate patients in order to improve the aesthetics of

anterior maxillary dentoalveolar cleft defects (Collins et al 2010).

8. HG, FABP, chin cup, functional appliance, modified activator

Indications

After orthopaedic correction of sever skeletal problems in growing patient.

To complete treatment in cases where it is thought appropriate to debond in the

presence of 2 or 3mm Class II discrepancy.

Procedure

Bonded retainers should be fitted to retain alignment prior to taking

impressions for the functional retainer.

Although some clinicians advocate inclined biteplanes,

A more positive approach is to use Activator or Twinblock designs. In the

case of the latter, it is appropriate to construct the appliance to an edge to edge

relationship, reduce the vertical opening to 3mm, and to keep the block

interfaces vertical, at 90°.

B. Fixed retainer

Types1. The fixed appliance can be left as retainer2. Dental bridge like resin bonded or fixed-fixed bridge used in hypodontia cases.3. Banded retainer. Bands placed on the lower premolars with a connecting soldered, heavy archwire (0.030’’), closely adapted to the LLS.4. Bonded A. Rigid (bond on canines only with rigid touching but not

bonded to lower incisors). Bearn 1995 considered the following to be indications for placement of a bonded canine-to-canine retainer:


Severe pretreatment lower incisor crowding or rotation; Planned alteration in the lower intercanine width; After advancement of the lower incisors during active

treatment; After nonextraction treatment in mildly crowded cases; After correction of deep overbite.

B. Flexible retainer bonded on each individual tooth. They allow physiological tooth movement. The materials used are:

.015, 0.0175, 0.0195 or even 0.0215 inch multistrand.

0.030 - 0.032 inch (0.6-0.7 mm) sandblasted round stainless steel wire.

Orthoflex chain made from gold or ss

Reinforced fibres. The fiberglass strips are soaked in composite and bonded to acid-etched enamel. This technique has the advantage of reducing the bulk of the retainer.

The proposed advantages of the use of multistrands wire are that

1. the irregular surface offers increased mechanical retention for the composite without the need for the placement of retentive loops,

2. The flexibility of the wire allows physiologic movement of the teeth, even when several adjacent teeth are bonded. (Bearn 1995)

Less failure rate than round because of the flexibility Al-Nimiri 2009 found no difference between multistrand or round wire except more plaque accumulation with the first one.

Artun 1997 studied the failure rate over 3 years and found that thick multistrands retainer showed 30%, thin multistrands 27%, thick canine-canine 9%.

Bonded retainer design

A. Six lower anterior teeth


B. Extend to lower premolars Where vertical step between

canine and premolar before treatment

Where the inter premolar width has been increased in non-extraction treatment

To prevent slipped contacts between 3-4 where labial segment has been advanced

Extraction cases to prevent space reopening

C. Labial/buccal retention1. Restoration present lingually.2. Deep bite.3. Extraction cases to prevent space

reopening4. Labial to upper incisors in mixed

dentition after early incisor alignment5. Temporary retention, while dentist makes

palatal maryland splint or bridge.

Sandler technique 2001

Advantage of fixed retainer

1. Easy & well tolerated by the patient

2. Do not compromise on aesthetics

3. Not interfere with speech

4. Less reliant upon compliance than removable retainers.

5. It may reduce the risk of development of LLS (Sadowsky et al 1994)

6. Allow some physiological movement of the teeth,


7. Do not seem to produce any long-term periodontal problems, although

calculus can build up around them, particularly in the lower incisor region.

8. Effectiveness: Same result of RA (Artun et al 1997)

Disadvantage of fixed retainer

1. Their placement is time-consuming

2. Technique-sensitive

3. Interference with the bite specially in deep OB

4. PDL diseases due to plaque accumulation, (not significant)

5. Caries

6. Prevent settling of occlusion,

7. Do not retain transverse expansion.

8. High failure rates 23% (Artun et al 1997).

9. It might fail without patient knowing until relapse occur. So, It is a

completely the clinician responsibility if any relapse occur. While with RA it is

the patient own responsibility to wear the retainer and maintains it.

10. It might be active and result in teeth movement

11. A back-up removable retainer should also be supplied to the patient to

preserve tooth position if the fixed retainer fails.

Indication

1. Use in prolong retention

2. PD compromised cases

3. Adult cases due to poor compliances with RA

4. CLP patient and in this cases bonded retainer is combined with RA to

maintain transverse relationship.

5. Lack of anterior occlusion (e.g. AOB)


6. Retention of AOB specially if it is extended to the molars.

7. Palatal canines

8. Diastema and generalized spacing

9. Extraction space closure in adults

10. Cases with proclined LLS incisors

11. Alteration in intercanine width

12. Retain corrected severely displaced teeth

13. Prophylactic in the lower arch, provided alignment is good, when upper

arch treatment only is carried out before age of 16 or even 18 years

Method of constructing the bonded retainer (Bearn 1995)

1. Direct using orthoflex

2. Direct bending of the wire It is useful to take all the activity out of the

wire by very quickly annealing the wire with a gas torch (Sandler 2005)

3. Lab bended wire that fitted by hand, seps, or transfer jig

4. Indirect bonding same like Incognito

Factors effect choosing the type of retainer:

1. Age.

2. Type of malocclusion and its aetiology.

3. Type of treatment and tooth movement.

4. Presence of restoration that might prevent the use of bonded retainer.

5. PDL status.

6. Duration of retention.

7. Patient motivation.


Duration of retention

There are many strategies for retention duration

A. No retention :

This is the exception rather than the rule, and is only applicable in cases

where the occlusion will hold the correction or where no active treatment was

undertaken.

Malocclusion that do not need retainer (Natural retainer) Kaplan 1988

1. Anterior Xbite with adequate OB, retroclined or upright tooth &

favourable growth.

2. Post Xbite with adequate cuspal interdigitation, inclination of buccal

teeth, adequate buccal OB & favourable growth.

3. Cases relying on spontaneous alignment following “interceptive”

extractions only

B. Medium-term retention :

Medium-term retention usually means a period that allows

1. Reorganization of the soft tissues and periodontal ligament,

2. Allow growth and dental development including eruption of the third

molars to be completed (for adolescent).

In reality this means retention into the late teenage years or early twenties

and is usually indicated in most routine cases.

Alshawesh and Mandal 2010 compare the effect of full time and night

time wear of Hawley; they found no difference between them.


Thickett et al 2010 to evaluate the effectiveness of VFR night only versus

full time, they found no difference between them no difference ex

C. Permanent retention and cases of high chances of relapse (RCSEng.

Guidelines, Johnston 2008)

1. Spacing & Midline diastema

2. Rotation

3. AOB

4. Expansion of lower intercanine width

5. Changing position of LLS

6. PDL compromised cases

7. Hypodontia cases

8. CLP with scar

9. Alignment of palatally displaced maxillary lateral incisors in the absence

of a positive overbite at the end of treatment.

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

Additional information:

1. Insufficient data to support the period of optimal retention however it

should be at least 7 months

2. 1 year retention better than 6months retention (Kerr, 2003)

3. Better stability achieved after 2 years retention since most of the relapse

occurs during that period (Tofeldt)

4. Increase retention will reduce relapse (Littlewood, 2004)


5. Part time wear similar to full time wear of the removable retainer.

(Thickett et al 2010, Alshawesh and Mandal 2010)

Adjunctive procedures to improve stability and retention

1. Pericision or circumferential supracrestal fiberotomy (CSF):

The principle is to cut the interdental and dentogingival fibres above the

level of the alveolar bone.

It has been shown to reduce relapse (especially when combined with RA)

in the first 4-6 years by up to 30%. however additional long-term benefit is

small (Edwards 1970).

Where attached gingiva is thin, the papilla dividing procedure (because

the gingival fibers are the cause of relapse) is recommended instead of CSF

(Ahrens et al.,1981).

It is contraindicated in LLS, poor OH and medical contraindications

2. Surgical gingivoplasty: removing soft tissue at the extraction site.

3. Fraenectomy: described by Edward 1977 which involve repositioning of

the frenum and sectioning the transeptal fiber with gingivectomy.

4. Interproximal stripping: Peck & Peck 1972 found better stability of lower

incisor after IPS due to their square shape compared to triangular original one.

Better result after IPS appear if combined with CSF

Inter-dental enamel reduction

1. up to 0.5mm space can be created at each contact point by means of

diamond abrasive strips or guarded discs


2. In the buccal segments, up to 0.75mm of space can be gained through a

process known as 'air rotor stripping'.

3. It is always necessary to re-polish the enamel surfaces after reduction

with diamond abrasion in order to recreate a smooth enamel surface.

Indication 1. Can be used to replaces extractions

2. Closure or reduction of gingival triangular spaces

3. Correction of inter-arch tooth size discrepancies

4. Re-shaping of tooth anatomy (e.g. Upper canine to lateral incisor)

5. Correction canine to lateral incisor conversion

6. Correction of triangular morphology

7. Increase area of contact (keystoning) that improve stability Peck & Peck 1972

Advantages 1. It provides the right amount of space

2. Reduced mesio-distal root movements required (especially important if bone

loss)

3. Shorter treatment

4. Space is provided when needed

Disadvantages 1. Technique sensitive (too wide or 'v' shaped spaces, or gingival ledges must be

avoided)

2. Cannot be done if contact points are gingival or sub-gingival

3. Cannot be done on narrow parallel sided incisors (triangular morphology

required)

4. Cannot be done between overlapping teeth (only if good contact point between

the teeth)

5. Almost invariably requires fixed appliance control.


6. Harmful effects of disking:

a. Periodontal disease: It allows the adjacent roots to come closer together will

lead to periodontal problems and bone loss.

b. Caries

The fluoride rich superficial layer of enamel has been removed

The enamel surface has been roughened

Again, much work has been reported (El-Mangouri et al) and this does not show

any additional risk of developing caries following enamel reduction. In fact,

some evidence suggests that the abraded enamel has more remineralisation

potential.

Nonetheless, it is appropriate to ensure that the enamel surface is left as smooth

as possible

A further and desirable refinement is to apply 37% phosphoric acid etchant gel

to the strip so that combined mechanical and chemical polishing takes place.

The use of subsequent fluoride mouthwash is also recommended

Clinical techniques

A. Labial Segments

1. Mechanical with diamond abrasion By Hand: This is laborious and involves the use of diamond coated metal

abrasive strips.

By Disking: Guarded disks have the advantages of having a circular continuous

motion that makes it comfortable for patients..

By 'Woodpecker':This handpiece, supplied by Kavo, provides an in/out sawing

motion that is less comfortable for the patient.


2. Chemical erosion This is like the manual abrasion strips described above but with the addition of

applying a slurry or paste of pumice and etchant.

The technique is relatively inefficient and slow but does leave the enamel

smooth with excellent potential for remineralisation with the assistance of

fluoride rinses.

B.Buccal Segments

Air Rotor Stripping (ARS) This technique has been advocated by Sheridan 1982. This involves the use of a

long tapered `safe tipped' diamond bur that has no abrasive component near its

tip and this therefore reduces the likelihood of cutting a groove inadvertently.

Unfortunately, these burs are a little too wide and tend to create too much space

between the teeth and exceed the 1mm limit. It is therefore good clinical

practice to fit separating elastics a week before air rotor stripping is undertaken

to create some space between the posterior teeth.

How much enamel to remove?1. Labial Segments

In the anterior part of the mouth, 0.3 to 0.5mm space can be created at each

contact point

Thus, a total of 1.5 to 2.5mm of space can be created from the five anterior

contact points.

2. Buccal Segments

The enamel thickness is greater in the buccal segments and 0.5 to 0.75mm space

can be created at each contact point.

Sheridan claims up to 8mm per arch can be gained (4mm per quadrant) but this

includes reducing enamel between the first and second molars which we would

not advocate.


Planning enamel reduction Enamel reduction should only be undertaken once adjacent teeth have a good

contact point relationship. It is not desirable to carry out enamel reduction if

the teeth are rotated or overlapping.

It should be remembered that the process of aligning the teeth to achieve good

contact points leads to proclination. In turn, proclination leads to the gingival

migration of the contact points which, in turn, makes enamel reduction more

difficult.

It is therefore better to reduce the enamel at a contact point once it becomes

available.

Relapse Due to Growth and methods to maintain them

Class II, Class III, Deep-bite and Open-bite cases are most likely to

relapse due to continued growth

Retention: Class II

Dental changes

1-2mm of A-P change tends to occur immediately following treatment,

especially when Class II elastics are used.

Forward movement of lower incisors more than 2mm will require

permanent retention

Overcorrection is important in preventing relapse

Skeletal changes

Depends on age, sex, and maturity

If original growth pattern continues, treatment that involved growth

modification will most likely result in loss of at least some correction

Continue headgear at night along with retainer


Use a “passive” functional appliance (activator/bionator) to hold position

at night and conventional retainers during day (continue for 12-24 months)

Patients most likely to require these treatments:

1) The younger the patient at the end of treatment

2) The greater the initial Class II problem

Retention: Class III

Relapse occurs mainly from mandibular growth

Not as effective as maintaining Class II

If relapse occurs in normal or excessive face height patients: may need

surgical correction after growth.

In less severe Class III cases: Utilize functional appliance or positioner

1. Will maintain occlusal relationship in these cases

2. May position jaws down and back to prevent relapse

Retention: Deep Bite

Achieve positive incisor stop

Normal lower incisor centroid relationship

Construct upper removable retainer with a baseplate to prevent lower

incisors from over-erupting while posterior occlusion is maintained

Retention: Anterior Open Bite

High-pull headgear with use of conventional removable retainers

Appliance with posterior bite blocks (open bite activator or bionator) at

night and conventional retainers during the day.

Retainer, what type and how, evidences based

Which type of retainer (Fixed or Artun et al 1997 compared bonded


removable) retainer and RA and showed no difference in their failure rate.McDermott and Millett 2007 and 2008, showed that patient prefer bonded retainer and it is better in mainiting LLS position than PFR.Atack 2007 showed no difference between themFleming 2013 systematic review compare light and chemical cure and found no difference and the failure rate is 40%

Which type of fixed retainer Al-Nimiri 2009 found no difference between multistrand or round wire except more plaque accumulation with the first one.Pandis 2013 RCT showed that bonding with chemical or light cure is similar

Which type of removable retainer Tibbetts, 1994, No difference between positioner with bonded lower 3-3, Essix retainer, and Hawley retainer.Settling of occlusion: Cochrane Review by Littlewood 2006There is also a (weak) suggestion that a Hawley retainer, worn full time, allows more settling of the occlusion than a clear overlay retainer, worn at night, after 3 monthsRowland 2007 No difference between Hawley with Essix, they found Essix retain teeth better in lower arch by maintaining a better contact but similar result in the upper arch

Full time or night time Alshawesh and Mandal 2010 No difference between full time and night time wear of Hawley if the patients are not at high risk of relapse (like diastema, spacing, rotation)


Thickett et al 2010 No difference between full time and night time wear of VFR if the patients are not at high risk of relapse (like diastema, spacing, rotation

Adjunctive procedure Cochrane Reviewby Littlewood 2006(CSF) reduces relapse when combined with a full-time removable retainer, when compared to a full-time removable retainer alone.

Change in Lower incisor position

Mills 1968 advised to preserve the original position of LLS

Any change of more than 2 mm in anterioposterior direction needs

permanent retention. (Proffit 1990). See more description at the end of this

note.

There is exception for this rule including:

1. Mild Class III with positive OJ and OB after retracting the LLS.

2. Lower incisors trapped behind the upper incisors in Cl 2D2 with mild

crowding. This had been advocated by Selwyn-Barnett (1996) who points out

that the lips cannot ‘know’ which incisor is touching them and that we can

therefore procline the lower incisor in class 2 division II cases to touch the

lower lip at the same A-P position as was occupied before treatment by the

extruded upper incisor.

3. Lower incisors trapped in the palate due to deep OB

4. Lower incisors trapped by digit sucking habit

5. Lower incisors trapped by the lip in class II D1 with increase OJ.

6. Bimaxillary proclination with competent lip at the end of treatment.

7. Cl1 with very mild crowding


8. De-compensation prior to orthognathic surgery. Artun et al (1990) found

that substantial (>10 degrees) proclination of lower incisors was not associated

with greater subsequent relapse than a group treated without proclination. This

is due to the change in the soft tissue environment by surgical repositioning of

the jaw, the usual soft tissue effects do not seem to apply.

There are two parameter to help in determining the position of the best stability

of LLS

1. Lower incisor edge- root centroid relationships

• Concept introduced by Houston (1989).

• It is particularly useful in evaluating the tooth movements required for

stable overbite reduction in class II cases.

• The upper incisor root centroid is located at the midpoint of the long

axis of the root.

• The edge-centroid relationship is measured as the distance between

the perpendicular projections of these points onto the maxillary plane. The

distance is positive whenever the lower incisor edge is in advance of the upper

root centroid, and negative otherwise.

• For maximal chances of OB stability, the upper root centroid should

be at least 2mm behind the lower incisal edge.

• Houston found that Lower incisor edge- root centroid relationships is

more strongly related to overbite depth than interincisal angle, particularly in

class II div II malocclusions where it accounted for 61% of the variance in

overbite depth while interincisal angle accounted for 28%.

• It is also a simple and useful guide when treatment planning for stable

OB reduction.

2. Lower incisors to A-Po line

• The Diagnostic line or A-P line(Williams., 1969)


• It was suggested that for a harmonius facial profile and lip balance the incisal

edge of the lower incisor should lie near or on the A-P line. It has been used as

useful aids in TE and Begg technique by (Cadman., 1975) to determine the

need for extraction.

• If the alignment, levelling , or the mandibular growth change the location of

LLS incisor edge to the A-Po line, it is likely that extractions or tooth size

reduction may be necessary.

Theories of LLS crowding

1. Iatrogenic causes: due to proclination of LLS and expansion of

intercanine width during orthodontic treatment.(Little et al 1981)

2. Growth theory: Late mand growth (Bjork 1972)

3. Occlusal forces: Equivocal evidence due to anterior component of force

4. Normal PDL fibres action: mesial drift of teeth due to transeptal fiber

traction

5. Loss of interproximal attrition: Dietary evolution and lack of

interproximal attrition, more common in Triangular incisors (Peck & Peck

1972)

6. Soft tissue causes: Lower lip hyperactivity, maturation or scar

7. Inflammatory causes: PDL diseases and pathological migration (Profitt

2010)

8. Third molar (no evidences)

No difference in LLS crowding or growth pattern between different gp

with absent 8s, impacted 8s, aligned 8s, extracted 8s (Ades el al 1990)


No justification for removal of 8s (NICE 1998, Harradine 1998).

Yu et al in 2013 (Cochrane review) showed that This review has revealed that there was no evidence from RCTs to show that one intervention was superior to another to manage the relapse of the alignment of lower front teeth using any method or index, aesthetic assessment by participants and practitioners, treatment time, patient's discomfort, quality of life, cost-benefit considerations, stability of the correction, and side effects including pain, gingivitis, enamel decalcification and root resorption. There is an urgent need for RCTs in this area to identify the most effective and safe method for managing the relapse of alignment of the lower front teeth.

Indications for removal of wisdom tooth (SIGN Guidelines):

1. One or more episodes of infection

2. Pulpal/periapical pathology

3. Unrestored caries of 8s

4. Caries in the adjacent.

5. Periodontal disease.

6. Dentigerous cyst formation or other related oral pathology.

7. External resorption of the third molar or of the second molar

8. For autogenous transplantation to a first molar socket.

9. Fracture of the mandible in the third molar region or for a tooth involved

in

10. Tumour resection.

11. Prior to denture construction or close to a planned implant.

Other recommended indications are:

1. Medical complications associated with removal of third molars (e.g. prior

to radiotherapy or cardiac surgery).


2. General anaesthetic is to be administered for the removal of at least one

third molar consideration should be given to the simultaneous removal of the

opposing or contralateral


retention and relapse by almuzian

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