Retention and relapse for orthodontists by Almuzian

UNIVERSITY OF GLASGOW
Retention, stability & relapse in orthodontics
----------------------------------------------------------
Mohammed Almuzian
Personal note, 2013

Mohammed Almuzian, University of Glasgow, Personal note, 2013 1
Table of contents
Definition..................................................................................................... 3
Relapse ........................................................................................................ 3
Retention...................................................................................................... 3
Method to measure relapse............................................................................ 3
Reasons of relapse ........................................................................................ 3
Rationale of retention.................................................................................... 4
Normal age related dental changes................................................................. 5
Factors related to retention and should be considered at the TP stage .............. 6
1. Informed consent ............................................................................... 9
2. Original malocclusion ........................................................................ 9
3. Adult Patients .................................................................................... 9
4. Occlusion .......................................................................................... 9
5. Growth.............................................................................................. 9
6. Periodontal health: ........................................................................... 10
7. Soft tissue features ........................................................................... 10
8. Type of treatment & teeth movement ................................................ 16
9. Patient wishes, oral hygiene and cooperation. .................................... 17
10. Associated habits .......................................................................... 17
11. Adjunctive soft or hard tissue procedures ....................................... 17
12. Type of retainer............................................................................. 17
13. Duration of retention.. ................................................................... 17
Factors that will help minimize relapse.......................................................... 6

Types & design of retainer .......................................................................... 17
Relapse Due to Growth and methods to maintain them................................. 33
Retention: Class II ...................................................................................... 33
Retention: Class III..................................................................................... 34
Retention: Deep Bite................................................................................... 34
Retention: Anterior Open Bite..................................................................... 34
Retainer, what type and how, evidences based ............................................. 35
Parameter to help in determining the position of the best stability of LLS ..... 37
1. Lower incisor edge- root centroid relationships ................................. 37
2. Lower incisors to A-Po line .............................................................. 38
Theories of LLS crowding .......................................................................... 38
Indications for removal of wisdom tooth (SIGN Guidelines) ........................ 39

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
Retention
Moyers (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
Reasonsofrelapse
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 promotereorganization 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 relateddental 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. Sinclairand 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 GrowthStudyby 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 presentpre-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 createdduring 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 roottorque & 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 relatedto retention and should be consideredat the treatment
planning (TP) stage
1. Informed consent about the possibility of relapse and the rationale of
retention.
2. Growth
3. Age (Adult Patients)
4. Original malocclusion
 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
9. Type of treatment & teeth movement
 Extraction/Non-extraction
 Serial extraction
 Changes in the intercanine width
 Change in lower incisor position
10. Type of retainer.
11. Adjunctive softor hard tissue procedures to enhance stability.
12. Duration of retention.
13. Patient wishes, oral hygiene and cooperation.

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 + postbite 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. Occlusionat 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 crossbitewith 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. Periodontalhealth:
 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 softtissue 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
7. Original malocclusion
 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. Skeletalpattern
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 skeletallycorrectedproblems
should continue until growth is ceased.
C. Lower incisorirregularity
 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. Sadowsky1994
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 supportthis. Proffit 1992
F. Anterior crossbite
It is retained by the +ve overbite otherwise permanent retention is mandatory to
maintain the results.
G. Posteriorcrossbite
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. Generalizedspacing
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 supracrestalfiberotomy)
to reduce postretention relapse of derotated teeth is beneficial in the first
4-6 years posttreatment. 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 probehas 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 contactpoints 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 contactpoints 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 (Popovichet al 1977).
 Sullivan et al (1996) found that 2/3rds of diastema closure was stable 12
months postretention. 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 spaceclosure is recommended to use the
scar as natural retainer (Edwards, 1977, Profitt, 2010)
8. Type of treatment & teeth movement
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.

Intercaninewidthchanges
• De Lacruz 1995 showed that it is highly related to relapse.
• Active intercanine expansion shows 89% relapse
Changein Lower incisorposition
 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 descriptionat the end of this
note.
9. Patient wishes, oralhygiene and cooperation.
10. Associatedhabits which should be stopped to avoid relapse.
11. Necessityfor adjunctive softor 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 & designof 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 constructand use
 Cheap,
 Vacuum-form retainers can also be used for active tooth movement.

 They provide good aesthetics and better controlof 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 custommade (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 occurin 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/softliner 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 approachis to use Activator or Twinblock designs. In the
case of the latter, it is appropriate to constructthe 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
Types
1. The fixed appliance can be left as retainer
2. 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
compositeand bonded to acid-
etched enamel. This technique
has the advantage of reducing
the bulk of the retainer.
The proposedadvantages ofthe
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 A. Six loweranterior teeth

design
B. Extend to lowerpremolars
 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 retention
1. Restoration present lingually.
2. Deep bite.
3. Extraction cases to prevent space
reopening
4. Labial to upper incisors in mixed
dentition after early incisor alignment
5. 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 physiologicalmovement of the teeth,
7. Do not seem to produceany 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 offixed 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 poorcompliances 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 effectchoosing 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 cuspalinterdigitation, inclination of buccal
teeth, adequate buccalOB & 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 casesofhigh chances ofrelapse (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 ofrelapse) is recommended instead of CSF
(Ahrens et al.,1981).
 It is contraindicated in LLS, poorOH and medical contraindications
2. Surgical gingivoplasty: removing softtissue 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 spacecan be created at each contact point by means of
diamond abrasive strips or guarded discs

2. In the buccalsegments, up to 0.75mm of spacecan 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. Spaceis provided when needed
Disadvantages
1. Technique sensitive (too wide or 'v' shaped spaces, orgingival 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 contactpoint 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. Mechanicalwith 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. Chemicalerosion
 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. BuccalSegments
Air RotorStripping (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 spacebetween the posterior teeth.
How much enamel to remove?
1. Labial Segments
 In the anterior part of the mouth, 0.3 to 0.5mm spacecan be created at each
contact point
 Thus, a total of 1.5 to 2.5mm of spacecan be created from the five anterior
contact points.
2. BuccalSegments
 The enamel thickness is greater in the buccalsegments and 0.5 to 0.75mm
spacecan be created at each contactpoint.

 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 ofaligning 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: DeepBite
 Achieve positive incisor stop
 Normal lower incisor centroid relationship
 Constructupper 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
removable)
Artun et al 1997 compared bonded
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 them
Fleming 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 2006
There 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 months
Rowland 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 incisorposition
 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 softtissue 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
• Conceptintroduced 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 ofLLS 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 componentof 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 assessmentby 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
opposingor contralateral

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