retention and stability

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Dr. Mohammed Alruby
Retention
Relapse
Stability
Prepared by:
Dr. Mohammed Alruby

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Dr. Mohammed Alruby
Retention
Definition:
= it’s an attempts of biological and mechanical preservation of tooth and dental arches in their
new position obtained by active orthodontic treatment.
=It is a continuation of treatment.
=Or it maintaining newly moved tooth position long enough to aid in stabilizing their correction.
Why retention is necessary:
Orthodontic results are potentially unstable; the teeth have a tendency to move in the direction of
original malocclusion after removal of active appliances. Therefore, retention is necessary for
the following reasons:
The gingival and periodontal tissues are affected by the teeth movement and require a time for
reorganization after appliance removal.
The orofacial musculatures are stretched and require time for adaptation to the new position.
The growth changes may alter the orthodontic treatment results, so that the retention should not
discontinued until growth is mostly completed in most cases.
Retention should be considered as a part of orthodontic treatment, and should be applied until
all the tissues in the system: teeth, - alveolar bone, - jaw bone, - muscles, - become in a state of
balance both structurally and functionally to meet a new requirement
The concept and reasons of retention are given by (Angle1972) as:
{after the malposed teeth have been moved into the desired position, they must be mechanically
supported until all the tissues involved in their support and maintenance become modified in both
structure and function to meet the new requirements}
History and schools of retention:
The occlusion school (1880):
According to Kingsly, the occlusion of the teeth is the most potent factor in determining the
stability of the teeth moved to new position.
The musculature school:
According to Rogers 1951, functional muscle balance that maintains the dentition in stable
position is an important factor in retention.
There should be balance between the outer buccal envelop and inner group of muscles such as
tongue musculatures.
The mandibular incisors school:
According to Grieves (1944) and Tweed (1954) the angulation of mandibular incisors is an
important factor in retention, post treatment stability is increased when the mandibular incisors
were slightly retroclined or placed ideally in upright position over the basal bone.
The apical base school: =Alex lundstom 1925 suggested that the apical base (the area between
the alveolar bone and the basal bone), was one of the most important factors in the correction of
malocclusion and maintenance of corrected occlusion.
=McCauly 1944 suggested that inter-canine width and inter-molar widths should be maintained
as originally presented to minimize retention problems.
=Nance noted that arch length may be permanently increased only to limited extent
Theories of retention:
Riedel has been listed a nine theories that explaining retention, the tenth theory was added by
Moyers as an extension to the existing theories.
Theorem 1:

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Dr. Mohammed Alruby
= The teeth that have been moved tend to return to their former position.
=This particularly true for rotation than any other tooth movement, and for anterior teeth than
posterior teeth which have a firm occlusion.
Theorem 2:
=Elimination of the causes of malocclusion will prevent recurrence.
=Many causes of the malocclusion are not known, failure to remove the etiological factors may
be lead to relapse.
=The importance of this factors can be seen in malocclusion associated with abnormal habits
such as thumb sucking tongue thrust, etc.
Theorem 3:
=Malocclusion should be over corrected as a safety measure. This concept has been practiced in
treating certain malocclusion such as rotation, deep bite, class II and Class III.
=Solzman found no advantage obtained by over correction of buccal segment, furthermore over
correction can initiate traumatic occlusion.
Theorem 4:
=Proper occlusion is a potent factor in holding the teeth in their corrected position.
=Angel 1907 believed that, the stability of orthodontic results could be achieved by creating
normal occlusion he stated that (nature always starts out to build a perfect denture in each
person).
= Moyers found that, the occlusal positions that obtained by orthodontic treatment should be
coincide with the unconscious reflex swallowing position which is very important factor in
stabilization of the corrected occlusion.
Theorem 5:
Bone and soft tissues should be allowed an enough time to reorganize around the newly
positioned teeth. This theory is the base for using of retainer after active orthodontic treatment. It
takes a considerable time for the reorganization of bone and collagen fibers of periodontal
ligament and gingiva.
Theorem 6:
If the lower incisors are placed in an upright position over the basal bone, they are more likely to
remain in good alignment.
Up-righting means that, lower incisors are perpendicular to mandibular plane plus or minus 5
degrees, this too difficult to be applied in cases with sever anteroposterior discrepancies.
Theorem 7:
correction carried out during periods of growth are less likely to relapse. This due to the greater
adaptability of the orofacial structures during these period, retention should be maintained till
active growth phase is over.
Theorem 8:
The farther the teeth have been moved, the lesser is the risk of relapse.
This theory is strange in logic and there is no evidence to support it.
Theorem 9:
Arch form, particularly the mandibular arch, cannot be permanently altered by the appliance
therapy. This is particularly true for cases treated with fixed appliance after growth is over,
while treatment in mixed dentition with bite plates, extra-oral or functional appliances may
provide some natural widening of the mandibular arch diameter.
So that, treatment should be directed toward maintaining the arch form.
Theorem 10: Moyer theorem:

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Dr. Mohammed Alruby
This theorem is added by Moyers which stated that, many treated malocclusion require
permanent retention.
Graber pointed out that, the retaining of teeth in an abnormal position by permanent retainers
can causes permanent damage to both teeth and supporting tissue as they attempt to hold them
against the functional forces, so permanent retention is an unhealthy condition.
Keys to eliminate the lower retention:
Williams and Raleigh (1985) put 6 keys to eliminate the lower retention and achieve lower arch
stability after orthodontic treatment:
The incisal edge of the lower incisors should be placed on A-pog line or 1mm in front of it and
this give a good soft tissue balance.
The apices of the lower incisors should be spread distally to the crown, lateral incisors spread
more distal than the central incisors.
The apex of lower cuspid should be positioned distal to the crown.
When viewed in lateral radiograph all four lower incisor apices must be at the same labiolingual
plane.
Lower cuspid root apex must be positioned slightly buccal to the crown apex.
Flattening of lower contact points prevent their slippage.
NB: Centroid theory:
according to Huston (1989) the incisal edge of lower incisors should be anterior to the centroid
of the roots of upper central incisors.
Factors to considered in planning retention phase of treatment:
Periodontal force:
=Widening of the periodontal space and disruption of the collagen fibers supporting the teeth are
the normal response to orthodontic tooth movement, even if the tooth stops before appliance
removal, reorganization of periodontal tissue will not occur as long as the teeth are splinted
together with rigid arch wires, so that holding the teeth with passive arch wires cannot be
considered the beginning of retention.
=Once the appliance is removed each tooth can respond individually to occlusal stress,
reorganization will take place within 3 to 4 months and the slight mobility present at appliance
removal disappear. The teeth normally withstand occlusal force because of the shock absorbing
properties of the periodontal system.
=the gingival fibers are composed of elastic and collagen fibers, both reorganize more slowly
than the other group of periodontal fiber. Collagen gingival fibers remodel within 4 to 6 months,
while elastic supracrestal fibers remodel very slowly, and can exert displacing force upon the
teeth approximately for one year after appliance removal, for this reason some author
recommended Supracrestal fibrotomy before or just after appliance removal in cases of sever
rotations.
=Reitan: in his microscopic studies of post retention changes (1959, 1966, 1967) found that
supracrestal gingival fibers appear histologically altered and directly deviated after rotational
movement, and this condition did not lessen even after years of retention.
=Parker: in clinical study of trans septal fibers (1972) stated that, rotational relapse is a normal
response to an abnormal force, the paralleling of the teeth roots, sectioning of free gingival
fibers, and elongation o retention period are very important in stability aft rated cases.

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Dr. Mohammed Alruby
=Kaplan: 1967: in national survey on the extent of fibrotomy, concluded that, while the surgical
technique is not widely prescribed, it seems problem free and its use will be increasing in the
future.
Muscle force:
Normal function and balance of orofacial musculatures are very important factors in facial
balance and occlusal stability after orthodontic treatment.
Moyers (1965): study the effect of muscle activity on retention, he stated that, failure to deal with
any one or all of the functional problems can lead to relapse. He further emphasized that, if the
results to be stable the treated or new occlusion must be in harmony with muscular pattern.
Tweed: said that abnormal muscle function is a major factor in relapse. The muscle effect is of
great importance after inter-maxillary correction than intra-maxillary correction as in intra-
maxillary the muscles will be stretched behind their normal resting position as a result of new
jaw relation.
In such cases the retention should be for long periods until the muscles accommodate themselves
to the new position and re-stablish their lost balance. The early treatment during active growth
period is advantageous because the muscles are still actively growing, their origin and insertion
are changeable and can easily move in the direction that favorable to achieve.
Rogers (1953-1951): introduce a consideration of necessity to establish proper muscle function
and balance after orthodontic treatment. He introduces an exercise training program for proper
strengthening of the muscles of mastication and facial muscles to aid in treatment as well as
retention. Change in masticatory function brought about by change in dental occlusion require
time for their establishment.
Clinical consideration: muscle aberration should be expected in the following:
Class II and III muscular malocclusion.
Skeletal deep bite and skeletal open bite.
Persistence of abnormal pressure habits.
Over expansion of posterior teeth and procumbancy of anterior teeth.
Growth changes:
Residual growth is troublesome particularly in patients whose initial malocclusion is due to
abnormal growth pattern. Comprehensive orthodontic treatment usually starts in the early
permanent dentition (12years) and take about 18 to 30 months, so it ends at 14 to 15 years but
the growth may continue till 20 years. Furthermore, the long term growth studies have indicated
that, growth takes place at very slow rate during adult life.
It was found that, various facial types have different term of growth and treatment response, as:
Patients with long face syndrome express more backward mandibular rotation which result in
relapse of corrected open bite deterioration of class II treatment results.
Patients with short face express more forward mandibular rotation which can influence the
potential for deepening the bite and contribute to mandibular incisor crowding.
Zaher A, and his colleagues concluded that the facial types does not play a significant role in
stability of orthodontic treatment results.
It extremely important to pay attention to the person’s growth pattern which should be
individualized and not based upon statistics obtained from growth studies in general population,
so that each patient has its own growth pattern that should be taken into consideration.
Timing of pubertal growth spurt:

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Dr. Mohammed Alruby
Nanda and Nanda, found that, the pubertal growth spurts for patients with skeletal deep bite
occur in average 1.5 to 2 years later than the case of open bite so, longer retention period for the
skeletal deep bite
Age of patients:
Early treatment is advantageous for both ease of treatment and stability results due to higher
adaptability of dento-facial structures to the new situation, in addition to the higher rate of
turnover of bone and periodontal tissue.
Sex:
Girls mature earlier than boys so that retention is expected to be longer in boys than in girls.
Type of treatment:
=little et al studied 65 premolar extraction cases for at least 10 years post retention, they report
mandibular arch shortening was seen in 63 cases and post treatment crowding that not
associated with the degree of arch inter canine width changes during treatment.
Kinne: examined 55 patients at least 10 years after serial extraction and showing post treatment
irregularity.
Elms et al: studied a sample of patients with class II division 1 malocclusion who treated without
extraction and with headgear and fixed appliance after 6.5 years post retention and they found
90% irregularities. They concluded that the factors that responsible for the stability seen:
The application of proper mechanics.
Cooperation of patients.
Favorable downward and forward mandibular growth.
Nieke et al: found more significant relapse of crowding and rotation in extraction case than non-
extraction cases.
Length of treatment:
The more rapid the treatment, the higher the tendency to relapse
Mershon: pointed out that, the orthodontic treatment should be carried out in a phases, period
of active treatment followed by period of rest. He stated that if the tissue permitted to adjust
themselves through functional adaptation during the rest periods, no form of mechanical
retention will be required.
Presence of third molars:
Late lower arch crowding was found to be influenced by the presence of 3rd
molars.
Broadbent: was an early advocated of insignificant role played by third molars in lower incisors
crowding either impacted, erupted, missing or extracted.
Niek et al; make a comparison between groups of bilateral erupted or impacted 3rd
molars and
agenesis or extraction revealed no significant difference in post retention changes.
Ades et al; studied groups include absent, present, aligned or extracted 3rd
molars, the results
showing that no significant differences between these groups either in lower labial segment
crowding or in growth pattern.
Alteration of arch form:
It is generally agreed that arch form and width should maintained during orthodontic treatment.
Mills; =found stability after proclination in cases with skeletal deep bite and retroclined incisors.
= inter-canine and inter-molar widths decrease during post retention period, especially if there
is expansion during treatment, so maintenance of arch form rather than arch development is
generally recommended.

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Dr. Mohammed Alruby
=expansion is thought to be better tolerated in class II division 2 cases that show a significant
greater stability to maintain inter-canine expansion than class I and II division 1 cases.
Type of initial malocclusion, pre-treatment:
The needs and duration of retention may differ according to the type of initial malocclusion as
follow:
A= cases requiring minimum or no retention appliance as:
Blocked out canine in class I extraction cases with no incisor crowding.
Class I anterior and posterior cross bite with very steep cusps and no anterior crowding.
Teeth that have been treated with serial extraction.
B= routine cases, extraction or non-extraction should have retaining appliance fixed or
removable, at least until eruption of 3rd
molars.
C= cases that will need indefinite retention:
Class II div. 2 deep bite.
Expansion treatment.
Patients with uncontrolled tongue or muscular habit.
D= cases require an operative procedure with indefinite retention:
Large maxillary teeth which may result in increased over bite or super class I will need stripping
and canine to canine bonded palatal arch.
Larger mandibular teeth which may result an edge to edge bite and spacing of maxillary incisors
will require stripping and permanent bonded lingual retainer.
Lack of incisal stop for any reasons will lead to deepening of over bite unless permanently
retained.
Also the type of retention is influenced by the type of original malocclusion:
Retention after class II correction:
Relapse toward a class II relationship must result from some combination of teeth movement
(forward of upper arch and backward in lower arch) so:
Over correction of occlusal relationship as a finishing procedure is an important step in
controlling tooth movement, that would lead to class II relapse.
Avoid much procumbency of lower incisors as a general guide line, if the lower incisors moved
forward more than 2 mm relapse will occur by the pressure of lower lip unless permanent
retention is applied.
If maxillary growth has been restrained by either extra oral force or functional appliances,
forward growth of maxilla is expected to occur after stopping of active treatment. Part time
headgear should be used in conjunction with retainer to preserve the obtained results. If the
patient is uncooperative, the alternative is to use functional appliances as a retainer to be worn
on a part time basis in conjunction with day time retainer with conventional type.
Retention should be between 12 to 24 months.
Retention after class III correction:
For class III the following must be considered:
Over correction of over jet as a safety measures.
The protraction appliances should be worn at least 3 to 6 months after active treatment as a part
time.
The chin cup should be worn part time until mandibular growth mostly completed.
Frankel 3 or reversed activators should be used as active retainer and at the same time patient
should observed periodically until growth completed.
Retention after deep bite treatment:

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Dr. Mohammed Alruby
Correcting of excessive deep bite is an almost routine part of orthodontic treatment, so wear a
potential bite plane into the retainer which the lower incisors will contact to it because of
vertical growth is continue to late teens.
Retention after open bite:
Relapse can occur by any combination of intrusion of incisors or extrusion of posterior teeth; the
most important aspects are:
Control the habits like thumb sucking or tongue thrust.
Prevent extrusion of posterior teeth particularly the upper molars.
High pull headgear in conjunction with upper and lower conventional retainer for day wear are
effective in preventing relapse. Other alternative is to use open bite activator for night wear and
conventional retainer for day wear from the beginning of retention period.
Retention after incisors alignment:
if the mandible grows forward or rotate downward, the effect carries the lower incisors into the
lip which create force that
=maxillary and mandibular incisors must be present in proper incisal stops.
=a retainer in lower incisor region is needed to prevent crowding from developing until growth
has declined to adult level.
=Reidal 1992, stated that, incisor extraction may give greater stability at this area in absence of
permanent retention.
=Valinot, stated that, incisor extraction cases seem to exhibit less post retention recrowding.
This may be due to the maintenance of these teeth near to their original position where muscle
pressure is less likely to induce instability.
Retention after correction of rotation:
There is a high risk of relapse seen after rotation type of tooth movement due to resiliency of
gingival fibers, so the following should be do:
Long term retention.
Circumferential supracrestal fibrotomy to prevent relapse.
Retention after midline diastema:
A removable simple Hawley’s retainer or bonded fixed bonded retainer from canine to canine on
palatal side.
Retention after cleft palate cases:
Should be of longer duration than the normally used in non-cleft patients and sometimes it may
necessary to maintain for a life time.
Tissue reaction during retention period (post treatment tissue reaction)
Fibrous tissues:
Rearrangement of the fibrous tissues means that, the periodontal fiber bundles are again running
more or less perpendicular to the root surface.
Marginal area:
The fibrous components of the marginal region are the transseptal and free gingival fibers.
= Retain found that, after 28 days some rearrangement was observed on mesial and distal sides
of the root.
= The free gingival and transseptal fibers attached to the labial and lingual aspects of the root
were still under tension after retention period of 232 days.
= Retain, Parker, and others, demonstrate oxytalan fibers in the periodontium of orthodontically
treated teeth. These fibers increase in the area of stress which indicate that the oxytalan fibers is

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Dr. Mohammed Alruby
produced by the body as a safe guard against abnormal forces causing separation and
destruction of the tissues.
These fibers appear originated from soft tissue and inserted into cementum just apical to the
transseptal collagen fibers.
Middle area:
The periodontal fibers in the middle area of the root rearranged in more perpendicular
orientation to the root surface after 147-232 days.
Apical area:
The rearrangement was similar to that of middle region.
NB: the exact mechanism by which the periodontal fibers reorganized and rearranged is still not
fully understood, however several theories explain this process.
Intermediate plexus: Sicher referred to the existence of intermediate plexus that,
= Dissolute the fibrous connection
= production of new fiber.
= formation of new fibrous connection that adapt to the new situation
This theory could not be demonstrating histologically in most experimental studies.
Slippage theory: Postulated by Orban, which the reorientation of the existing collagen bundles
occurs by slippage of some collagen fibers from the parent fiber bundle to join with other
adjacent fiber bundle and thus involved in its lengthening.
Osseous tissue remodeling: The periodontal fibers adapt to the new teeth positions by
progressive osteogenic and cementogenic activities that ply an important role in shortening the
extended fibers and reattachment of new fibers developing during teeth movement.
The alveolar bone:
= In all regions, the alveolar bone showed a very little rearrangement after 15 days
= partial re arrangement occur after 28 days which the new bone formed as a tongue like
spicules surrounded the stretched fiber bundle then laid down to fill the spaces among the
primary bony spicules.
= complete reorganization of alveolar bone and formation of mature bone occur after 147-232
days.
Cementum:
Root resorption is commonly associated with certain types of tooth movement, as
expansion
intrusion
torque
moving the root against the more-dense labial or buccal cortex.
= Shallow resorbed area of the root may be repaired during retention period by new cellular
cementum.
= Extensive resorption of the root is questionable for repair.
Orofacial musculatures:
= Moyers 1960, studied the effect of muscle activity on retention and stated that, “failure to deal
with any one or all of the functional problems can lead to relapse”.
= Tweed said that, “abnormal muscle function is the major factor in relapse, although I do not
know how much one could change muscle function as a result of orthodontic therapy, I would try
to overcome the preserve muscle and tongue habits.

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Dr. Mohammed Alruby
After inter-maxillary correction retention requires longer period until the muscles adapt
themselves to the new position and re-stablish their lost balance.
= Rogers 1935-1951 introduced an exercise training program for proper activation of muscles of
mastication and orofacial muscles to aid in treatment as well as retention, however, his efforts
not always crowned with success because some children were uncooperative.
Clinical considerations:
The Supracrestal fibers still represent a great problem during retention, these fibers are of
special importance in certain tooth movement particularly rotation and closure of extraction site.
Rotations:
A number of clinical measures are introduced to prevent relapse tendency of rotated tooth:
Retain stated that rotation should be corrected as early as possible before complete apical
closure. This permit the root apex to close to close after the tooth moved to the new position with
formation of new apical fibers that aid to stabilize the tooth to the new position.
Rotation should be over corrected as a safety measure.
Occlusal equilibration should be performed immediately before retention to give firm occlusion.
Rotation should be corrected early in the course of treatment to permit longer period of fixation
before turning to retention phase.
Retainer should be inserted immediately after removal of active appliances. Parker among others
stated that 50% of total relapse occurs during first 12 hours.
Corrected rotation should be retained for longer periods, fixed retainer is preferred.
Using surgical techniques as:
Skosporg in 1927 introduced the technique of Septotomy that based on the tension theory of
Walkoff. He believed that remaining tension in the bone tissue after phenomena of resorption and
deposition was the major cause of orthodontic relapse, so the septotomy was designed to relief
this tension.
This technique consists of vertical sectioning of buccal and lingual cortex between the teeth from
the level parallel to the root apex until the alveolar crest.
Thompson in 1959 demonstrate that the apparent success of this technique not due to bone
removal but due to severing the transseptal fibers.
Immediate torsion: Hallett in 1956, de-rotate the tooth by surgical forceps and immobilized with
fixed splints. He believed, that, this method severs the transseptal fibers that regenerate and
adapt to the new position, but this method has a greater risk to pulpal degeneration and does not
appear to reduce relapse significantly.
Kole surgically removed the labial and lingual cortical plates prior to tooth movement.
Brauer and tsopel transecting the Supracrestal fibers in mesial and distal direction with vertical
incision.
Radical gingivectomy introduced by Thopmson by removing all the attached gingiva around the
rotated tooth, reduce the amount of relapse after initial retention period of 4 – 8 weeks.
Edward transecting the Supracrestal fibers all around the tooth (circumferential fibrotomy) by
using No 11 surgical blade to cut all the free gingival fibers to a depth of 3 mm. and below the
alveolar crest. This procedure was performed immediately after 8 weeks of mechanical retention
and no further retention was needed.
Application of soft laser:
Some studies as El-Namarawy and Eid used soft laser during retention period, they found that it
redused the amount of relapse from 100% in control teeth to 43.6% in test teeth.
Closure of extraction space:

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Dr. Mohammed Alruby
When the tooth is extracted, the transseptal fibers at the extraction site are severed, when the
wound heals a newly formed transseptal fibers appears and capping the extraction site. As
extraction space is closed orthodontically the new transseptal fibers coiled and compressed
between the approximating teeth which cause:
= resorption of the alveolar crest which does not re-generate again.
= compression force re-open the extraction space again.
Erickson and co-workers, concluded that, “it is biologically unsound to expect good proximal
contact in areas where dental units have been removed and teeth approximated”.
Burket, commented “the transseptal fibers remained in a coil fashion after extraction to such a
degree that contact is impossible.
Parker concluded that, the key of success in treated cases are:
Paralleling of the teeth roots.
Transection of transseptal fibers.
Adequate time of mechanical retention.
NB: on tension side, mesial to the tooth retracted, the transseptal fibers elongated rapidly and
become stretched, further retraction lead to cutting of fibers or distal migration of tooth medial
to active one, so (incisors should tie together with figure 8 ligature wire during canine retraction.
NB: factors affecting retention:
Factors enhancing retention:
Achievement of proper occlusion:
=proper inter-cuspation
=proper axial inclination.
=normal proximal contact.
=normal overjet and overbite.
=proper alignment of teeth.
=flat occlusal plane.
=proper and early correction of rotation.
=absence of premature contact.
Removal of causative factors.
Proper muscle function.
Proper knowledge about growth.
Good general and oral health.
Post treatment follow up until growth ceased.
Factors interfering with retention: are the same that causing relapse.
Failure to place the teeth in proper occlusion.
Failure to remove the causative factors.
Improper muscle function or failure to adapt the muscle to the new situation.
Persistent pressure habits.
Low rate of periodontal ligament turnover.
Large size of tongue.
Over expanded dental arch.
Improper planning retention.
Lack of clinical experience and basic knowledge.
Factors influencing the length and type of retention:
Age of patient.
Type of orthodontic correction.

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Dr. Mohammed Alruby
Degree and number of rotation.
Health of oral tissues.
The distance that the teeth moved.
Retention period:
Retention is needed for all patients wear orthodontic appliances, it should be:
Essential full time wear for at least 5 months, except during eating (some cases need permanent
splinting)
Continued as part time wear for at least 12 months to allow time for remodeling of gingival
tissues.
If significant growth remains, continued as part time use until completion of growth.
For practical purpose:
all patients treated in early permanent dentition will require retention of incisor alignment until
late teens.
In those patients with skeletal disproportion initially part time of functional appliances or extra-
oral force will be needed.
# Some authors divide the retention into 2 phases
= healing phase for 12 months to allow stabilizing of the teeth to the newly position.
= maintenance phase to guard against the maturational changes in tooth position and need long
time.
NB: as a general rule retention at least should be equal to the treatment period.
Clinical application of retention:
Retention planning is divided into three categories depending on the type of treatment:
Limited retention.
Moderate retention in terms of both time and appliance wear.
Permanent or semi-permanent retention.
Limited retention:
=corrected cross-bites:
Anterior: when adequate overbite has been established.
Posterior: when axial inclination of posterior teeth is good and patient having steep cusps. An
exception is posterior cross-bites treated with either orthopedic or surgical expansion of mid
palatal suture which need over correction and longtime retention.
=dentition that has been treated with serial extraction:
The percentage of complete satisfaction secondary to extraction depend on the degree of
perfection desired by orthodontist. Extraction of 2nd
premolars give more satisfactory results
than extraction of 1st
premolars.
=high canine extraction case.
=corrections that have been achieved by retardation of maxillary growth after the patient is
through growing.
=dentition in which teeth are separated to allow eruption of teeth previously blocked out, as
partially impacted lower 2nd
premolars and maxillary canines.
II- Moderate retention required:
A = Class I non extraction cases characterized by protrusion and spacing of maxillary incisors
these cases require retention until normal lip and tongue function has been achieved.

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Dr. Mohammed Alruby
B = class I or II extraction cases until lip and tongue function can achieved a satisfactory
balance. It is generally desirable to use a maxillary Hawley retainer until normal functional
adaptation occur.
Sometimes desirable to use either maxillary headgear whose force is directed to permanent fist
molars, or labio-buccal type of retainer with cervical or occipital resistance at night. The time
for this type is reduced as patient adapt to new tooth position, proceeding from full time wear to
once or twice each week.
C =corrected deep overbite in either class I or II which require retention in vertical plane.
=Anterior teeth depressed to achieve overbite correction then maxillary bite plane on retainer to
allow prevention of relapse.
=overbite correction is achieved as a result of mandibular clock wise rotation; vertical
dimension should be held at least until growth of mandibular ramus height catches up.
{NB: sever occlusal plane tipping also may require extended retention protocols and possibly
additional maxillary restraint as well.}
D= early correction of rotated teeth to their normal position:
Before root formation has been completed.
In mandibular incisor area, fixed lingual retainer or removable one with labial bow is probably
best. Early correction of rotation, transseptal fibrotomy and long term fixed retention may be
proving to be most satisfactory.
E= cases involving ectopic eruption of teeth or presence of supernumerary teeth require varying
retention time usually prolonged and occasionally a fixed or permanent retentive device such as
bonded lingual retainer.
Excessive spacing between maxillary incisors require prolonged retention after space closure.
Supernumerary teeth may be encountered in the maxillary anterior area and on the removal of
these teeth the maxillary teeth erupt slowly and incompletely.
F= the corrected Class II div. 2 malocclusion generally requires extended retention to allow the
adaptation of musculatures. These cases may have some increase in mandibular inter canine
width and present of malalignment incisors, which needs to be maintained during retention.
III- permanent or semi-permanent retention:
Cases in which expansion has been the choice of treatment particularly in mandibular arch, may
require permanent or semi-permanent retention to maintain normal contact alignment.
Cases with considerable or generalized spacing may require permanent retention after space
closure has been completed.
Cases of sever rotations, particularly in adults or sever labiolingual malposition may require
permanent retention as bonded lingual retainer.
Spacing between maxillary central incisors.
Methods of retention:
Functional:
=Rogers and others have been stressed for the value of muscle exercise in maintaining the tooth
position, particularly lip exercise.

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Dr. Mohammed Alruby
=activator may be used as a functional retainer, it can maintain teeth position and dental arch
relationship.
Natural:
In which the proper inter-cuspation and proper incisor relationship will prevent relapse as
corrected cross-bite.
Appliances:
Removable and fixed retainers.
Requirement of ideal retainer:
Should be restrain each tooth in desired position against the direction of relapse movements.
Should permit the functional forces to acts freely upon the retained teeth permitting them to
respond in physiologic manner as possible.
It should be easily constructed and tolerated by the patient.
It should be strong enough to achieve objective over the required period of use.
It should be self-cleansing and can provide a good oral hygiene.
It should be esthetically pleasant
Removable retentive appliances:
Advantages:
Permit normal function of the teeth and investing tissues.
It is a rigid fixation so allow some root movement, so that, the teeth can respond physiologically
to the functional forces.
Allow the periodontal ligament to rearrange themselves.
It is easily fabricated and non-expensive.
It is more hygienic.
Disadvantages:
Problems of patient cooperation.
Hawley’s retainer:
Designed by Charles Hawley in 1920, it is one of the most commonly used retainer, it can bring
minor tooth movement by activating the labial bow.
Components:
Adams clasp.
Short passive labial arch.
Acrylic base material.
= an acrylic plate to fit the palate, it should be festooned to fit the cervical contour of teeth.
= two Adams clasp om molars or premolars.
= a variety of labial bows can be used, as short labial, long labial, high labial bow.
= the acrylic plate prevents palatal movement of the teeth,
Advantages:
Easy to fabricate because it is simple design.
Good patient acceptance due to reduced bulk.
Can used in maxillary and mandibular arches.
Its acrylic component offers bite plane to control deep over bite cases.
Disadvantages:
Susceptible to fracture or loss.

15. 15
Dr. Mohammed Alruby
Lower Hawley’s retainer difficult to insert in some cases due to due to undercut at premolar and
molar region.
Modification of Hawley’s retainer:
Retainer with C clasp on molars:
This type is used when there is tight occlusal contact and the occlusal arms may cause occlusal
interference, this type is less retention than the conventional one
Retainer with long labial bow:
Incorporation of labial bow from premolar to premolar rather than from canine to canine, used
when there space distal to canine and need to be closed.
Retainer with contoured labial bow:
The labial bow is contoured and fitted on the cervical margin of the anterior teeth, it is used
when more retention is needed in anterior segment, and it gives better control to the anterior
segment.
Retainer with light elastic on incisors:
Use stretched light elastics on anterior segment rather than labial bow, used to close spaces in
anterior segment.
Retainer with labial bow soldered to the bridge of Adams clasp:
The terminal ends of labial bow is soldered to the bridge of Adams clasp, this design allows:
=space closure at the extraction premolar area.
= avoid the risk of space opening between canine and premolar.
Retainer with bite plane:
Bite plane is incorporated to the maxillary retainer lingual to the maxillary incisors, that, allow
maintenance of normal over bite.
Retainer with lingual extension clasp on molar:
Extension of lingual clasp instead of Adams or C clasp but its retentive capacity is less, it is
indicated when there is tight occlusal contact.
Retainer with occlusal rest:
Retainer has occlusal rest on molars instead of Adams or C clasp, indicated when there is tight
occlusal contact.
Begg retainer
It was designed by PR Begg, it consists of extended labial bow till the last erupted molars and
curves around it to embedded in acrylic base.
Advantages:
There is no cross over wire thus eliminate the tendency for space opening.
Less occlusal interference.
Can used in cases of partially erupted molars.
Disadvantages:
Retention is not good.
It can be modified as single arrow head wrap around retainer.
Clip on retainer / spring retainer
Made of wire framework that runs labial over the labial surface of the incisors and then pass
between canines and premolars and then recurved to lie on the lingual surface of incisors, the
both labial and lingual wires are embedded on acrylic. By adjusting the thickness of acrylic pads

16. 16
Dr. Mohammed Alruby
can have used for correction of rotation commonly seen in incisors lower, it can have used as
active retainer.
It is indicated when position of lower incisors must be retained after finish orthodontic treatment.
Wrap- around retainer
It is modification of clip on retainer but it covers all the teeth, it consists of wire that pass along
the labial as well as lingual surfaces of all erupted teeth and embedded on acrylic.
It is indicated in cases of week periodontal condition.
Kesling’s tooth positioner
=Developed by HD Kesling in 1945, it covers the clinical crown of maxillary and mandibular
teeth with spares of inter-occlusal space and small portion of gingiva.
=There are no wire components it is made up of thermoplastic rubber-like material.
=It can be used as active retainer when minor adjustment is required.
Construction:
= an impression is taken after removal of fixed appliance, then poured and duplicated the model.
= the teeth are cut off from the model and then reset in an ideal position.
= the positioner is then fabricated to this relationship.
Advantages:
It is durable.
Not need activation.
Can used as active removable retainer.
Disadvantages:
Difficulty in speech.
Need special equipment for called biostar.
Need patient cooperation.
Invisible retainer (Osamu’s invisible retainer)
Essix retainer
=Retainer fully covered the clinical crowns and part of gingival tissues. It is fabricated from
ultra-thin thermoplastic materials without any wire components.
=It is more esthetic and more accepted by patients, but it requires special equipment called
Biostar.
=Most likely used in maxillary arch, and more accepted by the patients more than other type of
retainer, there are some limitation for this type of retainer:
Thickness of the material over the occlusal surface can cause problem especially of the other
arch use the same retainer, we can overcome that by use only on arch with this type.
Maintain alignment but does not control deepening of the bite.
After few months the retainer tend to crack and discolored.
NB: positioner as a retainer:
Tooth positioner can have used as retainer after serving initially as finishing device. Positioner
does not make a good retainer because:
Pattern of wear of positioner is differ than that for retainer.

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Dr. Mohammed Alruby
Positioner does not retain incisor irregularities and rotation as well as standard retainer.
Overbite tend to increase while wear positioner as a retainer.
Fixed retainer
Retainers that fixed on the teeth and are cannot removed by the patients.
Types:
Passive corrective fixed retainer.
Bonded lingual retainers.
Banded canine to canine retainer.
Band and spur retainer.
Passive corrective fixed retainer
= The fixed appliance that was used for correction can be left passive in place to serve as a
retainer.
Bonded lingual retainer
According to evolution this type classifies into several generations:
Blue Elgiloy of dimension 0.032—0.036 inch that introduced in 1944.
1970 lower fixed retainer soldered to 1st
molars band or canines ban, by 0.032-inch steel wire.
1994 lingual fixed bondable retainer by 0.030—0.032-inch stainless steel which sand-blasted
with aluminum oxide to improve mechanical retention.
Recently 0.0215-inch multistrand wire or 0.030-0.032-inch sand-blasted round stainless steel.
= Fixed retainer that are bonded on the lingual surface of the teeth, most commonly used in
lower anterior region.
= Multi-braided stainless steel or blue Elgiloy wire is adapted ligually to follow the contour of
anterior teeth.
The ends are curved over the canines or premolar as it is bonded.
Advantages:
Invisible and permit good retention with some movements which is essential for the biologic
integrity.
Keep extraction spaces closed and maintain the midline diastema closure.
Favorable to prevent relapse at 5 years and 10 years post retention.
Disadvantages:
Deposition of calculus and plaque around retainer.
Require extra effort to maintain good oral hygiene.
Indication:
Prevent incisor crowding.
Hold the incisor position.
Banded canine to canine retainer
Commonly used in lower anterior segment.
The canines are fitted with preformed bands, then thick wire is adapted over the lingual contour
of anterior teeth and soldered the ends at the canine’s band.
Disadvantages:
Lack of esthetic due to metallic nature of bands and less of hygiene due to food accumulation.
Band and spur retainer
Used in tooth with labiolingual displacement or rotation, the teeth banded using anterior band
material and spurs are soldered onto the bands to overlap the adjacent teeth.
Advantages:
Very conventional in design.
Permit good oral hygiene.

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Dr. Mohammed Alruby
Disadvantages:
Unaesthetic because metallic parts are visible.
Periodontal procedures for successful orthodontic results
Healthy periodontium is very important for successful orthodontic results. After finished
orthodontic treatment periodontal procedures are useful to preventing relapse.
Circumferential fibrotomy:
The more sever rotation, the greater amount of relapse. Supracrestal fibers are considered the
main cause for relapse, so cutting all gingival fibers surrounded the tooth until depth below the
crest of alveolar bone.
It is best performed after correction of rotation prior removal of the appliances. In case of
gingival inflammation, the procedure is postponed until inflammation is subside
.
Maxillary frenectomy:
Highly attached maxillary frenum (closely approximates inter dental margin) considered
responsible for relapse after diastema closure.
When stretching the upper lip, the inter dental tissue is blanching.
Abnormal frenum should be excised before space closure.
This procedure increases the stability of orthodontically closed maxillary midline.
Autogenous gingival graft:
Supra- periosteal dissection to remove epithelium, connective tissue and muscle fibers.
The graft creates adequate zones of attached gingiva, and provide,
= enhance the health of affected area.
= obtain root coverage after recession.

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Dr. Mohammed Alruby
Reorganization of Periodontal and Gingival fibers
Widening of PL and disruption of collagen fibers bundles are normal response to orthodontic
treatment. Even if tooth movement stops before orthodontic appliance is removed, restoration of
PL will not occur as long as the tooth is strongly splinted by rigid orthodontic arch wires.
Once the teeth can respond individually to forces of mastication, reorganization of PDL occurs
over 3—4 months and the slight mobility present at appliance removal disappears. Gingival
fibers are also disturbed by orthodontic tooth movement and must be remodeled to accommodate
the new tooth position.

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Dr. Mohammed Alruby
It occurs more slowly than PDL. It takes 4-6m for collagen fibers to complete their
reorganization.
While the elastic fibers remodel extremely slowly & can still exert forces displacing tooth at a
year after removal of appliance.
Periodontal fibers reorganization takes 3-4m.
Gingival collagen fibers reorganization takes 4-6m.
Gingival elastic fibers reorganization takes 1 year
Therefore, relapse potential can be predicted by evaluation of initial occlusion:
teeth tend to move back in the direction from which they came because of the elastic gingival
fibers and unbalanced tongue-lip force
Relapse:
Definition:
It is the free movement of the teeth toward their original position following cessation of
orthodontic force or the tendency of the teeth to undergo changes of position immediately after
removal of orthodontic appliances.
=Hellman differentiate between relapse and failure as follow:
Relapse: return in whole or in a part to the former state of malocclusion (original position).
Failure: uncomfortable factors which interfere with attainment the successful result as loss of
anchorage or loss of space.
Causes of relapse:
Occlusal interferences.
Placement the teeth outside the area of functional tolerance.
Improper retention period after orthodontic treatment that not allow the temporary bundle bone
that formed to change into permanent lamellated and not allow the periodontal fibers to re-
organize again into the new position.
Abnormal tongue size and position.
Failure to put the incisors over the basal bone, that lead to recrowding and opening of space.
Dento-facial habits.
Over expansion of dental arches.
Low rate of turn-over of gingival and periodontal fibers.
Abnormal proximal contact.
Abnormal axial inclination.
Unfavorable results of retention:
The retaining of the teeth in an abnormal position by permanent retention mat cause permanent
damage of the teeth and their supporting tissues as the retainer hold the teeth against direction of
functional forces.
Recovery after relapse:
If despite the utmost care in treatment and retention, relapse or further post treatment
maturational changes occur then the following suggestion may be useful:
Retreatment may take the form of re-banding or re-bonding some or all teeth. Permanent or
prolonged retention is likely preferable after retreatment.
The mandibular lingual arch may be used to realign teeth and recon touring the arch.
Springs and clasps can be added to removable retainer to assist repositioning and control
labiolingual deviations.

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Dr. Mohammed Alruby
A headgear or functional appliance may be used against the maxillary arch during growth to
provide maintenance or re-correction of relapse toward a class II relationship.
Habit training in the form of myo-functional therapy may be beneficial when abnormal habit
pattern has attributed to orthodontic relapse.
Occlusal adjustment and interproximal reduction may reduce tendency to relapse.
In certain cases, the patients can accept minimal relapse rather than continue with prolonged
retreatment and retention.
Oppenhim, stated, that, retention is one of the most difficult problems in orthodontia; in fact, it is
the problem.
Relapse in orthognathic surgery.
Relapse following orthognathic surgery for correction of skeletal dysplasia may occur due to
defect in functional occlusion, because a stable occlusion is mandatory, the following factors
must take in account t to prevent relapse:
Removal of dental compensation: decompensation.
Correction of tooth mass discrepancies: by interproximal stripping or cosmetic re-contouring.
Correction of transverse discrepancies: that allow proper inter-cuspation
Over extension of tissues, muscles, submucosal tissues allow high tendency of relapse.
In mandibular advancement: the suprahyoid muscle which pull the mandible, so suprahyoid
myotomy is recommended
Relapse in cleft lip and palate
Cases with unilateral or bilateral cleft palate has bony defect in midline or in alveolar segment.
Dento-alveolar expansion is carried out before bone graft is done to:
=Achievement of good inter cuspation
=maintenance the occlusion
=allow apace to restore the missing teeth
= maintain the integrity of the arch
A rigid fixed retainer with wire components extended lingually for all teeth to prevent relapse.
How to minimize relapse
Pretreatment:
Consider extraction of very displaced tooth or rotated tooth
During treatment:
= maintain arch form
= maintain inter canine width
= do not alter the position of lower incisor, teeth must position in neutral zone between the
extrinsic and intrinsic force
=correction of rotation early in treatment
=Interproximal enamel reduction for triangular teeth to increase the area of interproximal
contact
= labial frenectomy before end of treatment
= obtain an adequate centroid relationship
=maximize interdigitation
=Supracrestal fibrotomy for rotated teeth

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Dr. Mohammed Alruby
During retention:
=Bonded retainer.
=active retention for skeletal
Cases most likely to relapse:
Diastemas
Rotations
Open bite
Risk factors for post treatment relapse:
Pretreatment irregularity of maxillary anterior teeth
Incomplete alignment during treatment
Expansion of maxillary arch segment
Rotational displacement
Interdental spacing
Clinical studies of relapse:
Relapse in cases treated with 1st
premolars extraction: Little et al 1981:
=retention period of 2yrs, 65 cases.
=mixed CI and II cases.
=findings after 1Oyrs
=70% became crowded (20% markedly crowded)
=mean crowding was 5.25mm (range 1.96-10.4mm
=Findings after 20yrs (31 cases):
= crowding =1mm on average
= mean crowding t to 6.02mm (range 2.38-11 .48mm)
= arch length and arch widths reduced
Same results in cases with 2nd
premolars extraction
Relapse in cases treated with serial extraction: Little et al 1990a
=15 cases followed for 1Oyrs:
=There was no difference between the serial extraction sample & a matched sample extracted
and treated after full eruption.
Relapse in cases treated by active expansion in mixed dentition: Little et al 1990b
=26 cases followed for a minimum 6 years
=89% demonstrate crowding
=This group showing the worst relapse.
Relapse in cases showing generalized spacing: Little and Riedel 1989
= 30 cases treated with edge wise mechanics.
=satisfactory stability in 50% of crowded cases.
=spacing did not reopen.
Stability
=Long term stability is a major goal for orthodontic treatment, Sadowsky among others were
assumed that, if appropriate orthodontic therapy were provided most of patient exhibit a stable
orthodontic results many years after end of retention.

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Dr. Mohammed Alruby
=the causes of post-retention relapse are multifactorial.
Gorman’s keys for long term stability:
Allow lower incisors to align themselves through serial extraction or by using bumper in early
mixed dentition.
Over correction of lower incisors rotation in early as possible.
Re-approximation of incisors early in treatment and again at retention to enhance stability.
Avoid increase in inter-canine width during active treatment.
Extraction of 1st
premolars when mandibular discrepancy is 4mm or greater except when facial
esthetic dictate otherwise.
The more tooth to move the more likely to relapse.
Up-righting lower incisors at 90 degrees however the profile permits.
Creating flat occlusal plane and over correction of deep over bite.
Supracrestal fibrotomy of severely rotated teeth.
Retention of lower arch until growth is completed.
Retainer must be placed the same day of removal.
Alexander’s keys for stability:
Balanced soft tissue profile.
Good inter-incisal angle.
mandibular incisors upright on basal bone.
Cuspids not expanded.
Normal root tip angulation.
Uprights mandibular molars.
Normal over jet and over bite.
Class I cuspid, cuspid supported occlusion.
Factors affect long term stability:
Careful diagnosis.
Treatment outcome:
At the end of orthodontic treatment and before retention the orthodontist must be sure that the
treated cases fulfill the following criteria:
= teeth are placed over the basal bone.
= teeth with average norm in angulation and inclination.
= no broken contact between the teeth.
= good relationship between the arches and good occlusion.
= lower incisors should place in normal relation to mandible, FH plane, upper dental arch.
= there is no any muscular abnormalities.
= causes of malocclusion removed.
“adequate inter-incisal angle may prevent overbite relapse and good posterior inter-cuspation
prevent relapse of both cross bite and anteroposterior correction”
Growth:
The maxillary and mandibular growth takes place in slow rate during the adult life.
Post pubertal mandibular growth was twice than that of maxilla. According to Bjork the
mandibular growth rotation occurs normally in forward direction, but some individual was
backward.

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Dr. Mohammed Alruby
Normal skeletal cases:
According to Bjork, the forward rotation of mandible causes packing of lower incisors due to the
restraining influences of the upper.
In backward rotation, the lower incisors become retroclined, the posterior teeth not erupted
distally and crowding developed anteriorly.
Mild skeletal cases: border line cases
Depend on the facial type.
Short face type: may show:
=lower incisor crowding
=Deepening of the bite
=Relapse of treated class III
Long face type: may show:
= backward rotation of the mandible
= relapse of corrected open bite and deteriorate the classIII treatment.
Prognathic face:
= mandible grow more forward than maxilla.
= relapse of cases and dished face.
Nanda and Nanda found that, the pubertal growth spurt for patients with skeletal deep bite
occurs in average 1.5 to 2 years later than the cases of open bite. For this reason, a longer
retention period for skeletal deep bite patients is advocated to counteract the continuing effect of
dentofacial growth after the completion of orthodontic treatment.
Clinical application:
Nature and duration of retention should depend on the maturation of individual.
The retention device should be selected according to facial morphology and magnitude and
direction of growth.
Recommended to make over jet more than zero to act as safety valve for mandibular forward
growth
5-Third molars
The etiology of post pubertal mandibular crowding in both treated and non-treated cases is a
multifactorial:
= physiologic mesial drift.
= anterior component force of occlusion.
= presence of developing third molars.
May cause movement of buccal teeth with shortening of the arch and crowding of lower arch.
Richardson 1990 concluded that the presence of developing third molars may affect long term
stability of cases.
Kaplan 1974 concluded that the presence of third molars does not produce a greater degree of
relapse after retention period.
Broadbent was an early advocate of insignificant role played by third molars in late lower
incisor crowding.
Clinical application:
Careful assessment of the developing third molars should be done.
Retention should be continued till eruption of third molars.
6-Type of treatment performed:

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Dr. Mohammed Alruby
Extraction and non-extraction treatment:
Paquette et al, studied the long term stability 10- 20 years post treatment in both extraction and
non-extraction Class II patients, they found:
=the majority of cases in both groups showed less than 3.5 mm of lower incisors crowding
=significant decrease in inter-canine width in extraction group
= the pattern of relapse not related to the type of treatment or post treatment position of denture
Sadowsky et al, studied the long term stability in non-extraction patient with prolonged retention
they found:
= minimal but significant increase in the irregularities of maxillary and mandibular anterior
teeth during the post retention stage
= some degree of relapse in all variables measured including over-bite and over-jet
= the prolonged retention time is an important factor in long term stability
B-Arch form, length and width:
De La Criz et al study Class I and II extraction case found:
=a statistical significant reduction in arch length, inter-canine and inter-molar width.
= increased anterior irregularities.
= arch form tends to change toward its pretreatment shape.
C-Late extraction with full treatment:
Little et al, concluded that, the only way to ensure satisfactory alignment post treatment is the
use of fixed or removal retention for life.
D-Serial extraction without treatment:
Kinne reported post treatment irregularities after 10 years of serial extraction without
appliances.
Person et al, showed re-development of crowding, but less pronounced than before treatment.
E-Serial extraction followed by appliance therapy:
Extraction lead to reduction in arch length and width which unpredictable relative to long term
alignment.
F-Early mixed dentition treatment without fixed appliances:
Early establishment of an inter-molar width and improved occlusion in mixed dentition provides
better long term stability post-retention.
G-Non extraction with spacing:
Mandibular spaces do not open in any case, however the maxillary arch showed more variation,
the midline diastema was the most common areas of space recurrence.
Of all treatment modalities only three showed acceptable long term mandibular incisors
alignment post-retention, these will be:
Early mixed dentition treatment with no fixed appliance therapy.
Non extraction with generalized spaces.
Lower incisors extraction cases.
Basic principles;

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Dr. Mohammed Alruby
The patient pretreatment lower arch form should be maintained during orthodontic treatment as
much as possible.
Original inter-canine width should be maintained as much as possible because expansion of
lower inter-canine width is the most predictable of all orthodontic relapse.
Mandibular arch length decrease with time.
The most stable position of lower incisors is its pretreatment position.
Fibrotomy is an effective means of reducing rotational relapse.
Lower incisors re-approximation shows long term improvement in post-treatment stability
Factors affect arch parameter stability according to Kahl- Nike et al:
Pretreatment anomaly:
Posterior arch constriction
Sever crowding
Greater mesio-distal diameter of the incisors
Increased over-bite
Were associated post retention relapse of the mandibular width
Kind of treatment:
Post retention upper arch constriction was significantly higher in extraction group than non-
extraction group.
Degree of expansion:
Moderate arch expansion during treatment, has greater ability to maintain the arch expansion
than the severely expanded cases.
End of treatment alignment.
Clinical application:
Extraction treatment are more likely to change the arch form during treatment then non-
extraction
Must maintained the original arch form and dimension to enhance stability
Retention should be an important consideration when planning treatment.
7- Muscles:
=The dento alveolar structures are very responsive and adaptive to pressure exerted from
muscles of lips, cheeks and tongue.
= the balance of oro-facial musculature is very important factor in long term stability of
orthodontic outcome.
= Moyers stated that, the new occlusion must be in harmony with the muscular pattern.
= Rogers introduced an exercise training program for proper stretching the muscles to aid in
treatment as well as retention.
Clinical application:
Removal any abnormal pressure habits.
Avoid movement of teeth against the very powerful muscles of cheek and lips in case of over
expansion of anterior or posterior teeth.
Early treatment during active growth is advantageous because the muscles are still growing, and
their origin and insertion is changeable and can easily move in favorable direction.
The orthodontist must know the muscular aberration that associated with class II, III, deep-bite
and open-bite cases.

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Dr. Mohammed Alruby
8-Reorganization of the periodontal tissues:
=Widening of periodontal ligament space and disruption of the collagen fiber bundles that
support each tooth are normal response to orthodontic treatment.
=Reorganization of periodontal ligament in orthodontically moved tooth is very important for
stability.
=it usually occurs over 3-4 months of retention except:
Collagen fibers that need 4-6 months for reorganize.
Elastic fibers that reorganize after one year or more.
Clinical application:
Holding the teeth with passive arch wire ca not considered the beginning of retention.
Retention should be continued at least 12 months to permit reorganization of elastic fibers.
Special consideration for the gingival fibers:
A-Rotation:
The transeptal fibers attached to the labial and lingual surface of the root show tension after one
year of retention that may affect the stability, so, the following should be taken:
= fibrotomy
= early treatment
= longed retention
A-Extraction site:
The transeptal fibers in the extraction site become compressed after approximation of the teeth.
This approximation exert force that tends to open the extraction space, so, the following should
be taken:
= paralleling the roots at the extraction site.
= transection of the transeptal fibers.
= prolonged retention.
9-Age:
Generally, early treatment is preferred because:
Higher rate of cell metabolism, bone and periodontal ligament turn over.
Higher adaptability of the dento-facial structure to the new situation.
In adult patient, the cell population and vascularization is reduced which decrease the rate of
turn over, so the retention should be longer in adult than in adolescence.
10-Sex:
Female patients which suspected to hormonal changes as in pregnancy and postmenopausal,
which have estrogen defect that lead to bone loss and osteoporosis.
11-Duration of retention:
Failure to detect and select the appropriate retention time affect the long term stability.
12-original malocclusion:
Deep overbite cases: relapse tends to occurs in 1st
2 years post retention and maintenance of
inter-canine width is thought to increase stability.
Class II division 1: has slight change in overjet toward pretreatment value when compared with
other malocclusion.

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Dr. Mohammed Alruby
12-Other factors:
= caries.
= abnormal pressure habits.
= improper restoration.
= periodontal problem.
= neglecting the orthodontic annual visits.
Thanks