2. Goals of orthodontic treatment
-To improve the patient’s life adjustment by enhancing:
- dental and jaw function and
- dentofacial esthetics.
- To obtain optimal proximal and occlusal contact of the teeth
(occlusion) within the framework of normal function and
physiologic adaptation,
- acceptable dento-facial esthetics and self-image, and
- reasonable stability.
Optimal function
Acceptable dentofacial esthetics
Reasonable stability
3. Stability
Ability of the teeth and skeletal structures to remain
permanent in an orthodontically treated position.
Relapse
Any change in the position of teeth and skeletal structures
from which they were placed by the orthodontic treatment.
Retention
The holding of teeth in ideal esthetic and functional positions.
The holding of teeth following orthodontic treatment in the
treated position for the period of time necessary for the
maintenance of the result.
4. Retention is not a separate item apart from orthodontic
treatment …. but that …….. it is a continuation of what we
are doing during treatment.
Stability has become a prime objective in orthodontic
treatment ……for without it, either……. ideal function, ideal
esthetics, or both…...may be lost.
5. Malocclusion is stable
….. Unless it is intervened by the orthodontic
treatment
….. The teeth that have been moved through the bone
by mechanical appliances…But they
have a tendency to return to their former positions.
Nobody would like to spend even a penny
for an unstable result
6. -The occlusion of the teeth is the most potent factor in
determining the stability in a new position. (Kingsley)
-The apical base was one of the most important factors in the
correction of malocclusion and maintenance of a correct
occlusion. (Lundström)
-The mandibular incisors must be kept upright and over
basal bone. (Tweed)
-Establishment of proper functional muscle balance is
necessary to prevent relapse. (Rogers)
7. To prevent relapse ……
care must be exercised to establish the following conditions: …
Occlusion
1- proper occlusion within the bounds of normal muscle
balance
2- Proper occlusion is a potent factor in holding teeth in their
corrected positions.
- Proper intercuspation of teeth is the most potent factor in
retention of teeth in corrected position.
- However, an excellent functional occlusion is desired for the
health of the periodontium and temperomandibular joint.
8. Apical base
3- careful regard to the apical bases available and
the relationship of these apical bases to one another
Causes of malocclusion
4- Elimination of the cause of malocclusion will prevent
recurrence.
There is no problem in defining and eliminating the cause of
malocclusion associated with habits.
However, the causative factors for malocclusion resulting from
growth and developmental variation may be difficult to define.
9. Treatment time (early treatment)
5 - Corrections carried out during the periods of growth are less
likely to relapse.
-There seems to be little direct evidence to substantiate that
orthodontic treatment should be instituted at the earliest age.
6 - However, institution of early treatment can prevent
progressive , irreversible tissue or bony changes, maximize the
use of growth and development with concomitant tooth
eruption, allow interception of the malocclusion before
excessive dental and morphologic compensations, and allow
correction of skeletal malrelationships while sutures are
morphologically immature and more amenable to alteration.
10. 7 - It may be more desirable through guidance of eruption and
early interception of skeletal dysplasia to minimize the need for
future extensive tooth movement with less impact on functional
environment and supracrestal fibres.
Overcorrection
8 - Malocclusion should be overcorrected as a safety factor.
It is a common practice to overcorrect the, overjet, overbite
and rotation problems.
11. Mandibular incisors
9 - If the lower incisors are placed upright over basal bone, they
are more likely to remain in good alignment.
Functional muscle balance
10 - his concept is based upon the presumption that the mature
bone will assure greater stability for the teeth.
The present day concept regard bone as being a plastic
substance and consider tooth position to result from an
equilibrium of the muscular forces surrounding the teeth.
.
12. Mandibular arch form
11- It was believed that the mandibular arch form plays a more
important role in stable mandibular tooth alignment than does
the relative anteroposterior relationship of mandibular
denture to basal bone.
12- Arch form particularly in the mandibular arch, cannot be
permanently altered by appliance therapy.
The scientific evidence showed that attempts to alter
mandibular arch form in the human dentition generally meet
with failure.
Therefore, treatment should be directed toward maintaining
the arch form presented by the malocclusion as much as
possible.
13. Retention
13 - Teeth that have been moved tend to return to their former
positions.
- the teeth should be held in their corrected position for
sometime after treatment although there is little agreement in
the cause of its relapse.
14 - Bone and adjacent tissues must be allowed time to reorganize
around newly positioned teeth.
- Bone and periodontal tissues around the teeth are altered
during orthodontic treatment and therefore considerable time
should be given to allow for complete reorganization.
14. Adjustive periodontal surgery
15- to reduce rebound from elastic fibers in the gingiva .
eg - Papillary split or
- CSF (Circumferential supracrestal fibrotomy)
- It is important to hold the teeth in good alignment while
gingival healing occurs.
- It should be done before a few weeks before removal of the
orthodontic appliance or
- If it is performed at the same time the appliance is removed ,
a
retainer must be inserted almost immediately.
Indication – to control rotational relapse in severely rotated
tooth or teeth.
Contraindication – for patient with crowding without rotations.
16. Reasons for retention
1 - To allow time for reorganization of gingival and periodontal
fibers that are affected by orthodontic treatment.
2 -The teeth may be unstable because it may not be in a zone
of balance between the lip, cheek and tongue after
treatment.
3 - The position of teeth may change because of growth.
Why do teeth need to be retained after orthodontic treatment?
17. To allow time for reorganization of gingival and periodontal
tissues
- Orthodontic tooth movement is brought about by the
periodontal ligament and the alveolar bone.
- The periodontal ligament is constantly destroyed and repaired
throughout the treatment.
- As a result there are widening of periodontal ligament space
and the disruption of the collagen fibers that support each
tooth.
18. The normal healthy periodontium is important for the stability of
the teeth because :
- it anchors the teeth firmly in alveolar socket,
- the shock absorber-like action of the periodontal ligament provides
resistance to heavy, short duration forces like mastication.
- the force thought to derived from the PDL metabolism contributes to active
stabilization of teeth against the light , prolonged forces from the lip, cheek
and tongue
-Therefore, immediately after orthodontic appliances are removed, teeth will
be unstable in the face of occlusal and soft tissue forces which would
otherwise can be
19. Even if tooth movement stops before the orthodontic appliance is removed,
restoration of the normal periodontal architecture will not occur as long as a
tooth is strongly splinted to its neighbors, as when it is attached to a rigid
orthodontic archwire (so holding the teeth with passive archwires cannot be
considered the beginning of retention).
20. Teeth may not be in a zone of balance after orthodontic
treatment.
- The teeth, after entering into the oral cavity, is guided by the lip, cheek and
tongue into the position where these muscular forces are neutral or balanced.
- Orthodontic treatment should, in fact, moving the teeth from the existing zone
of balance to another zone of balance so that the teeth will be in a stable
position. However, the teeth may not remain stable if the new position after
orthodontic treatment is not in a balanced zone.
- Therefore, teeth need to be retained, for a certain period of time after
treatment, for the soft tissues to settle in.
21. The position of teeth and skeletal structures may change
because of growth
- The arch length becomes shortened mesial to first permanent molars and
lengthened posterior to it during growth.
-The arch width particularly intercanine and intermolar width increased together
with the eruption of permanent canines and molars.
-The interocclusal space is occupied by the teeth eruption and vertical growth
of the alveolar bone which occurs with it.
-Therefore, relapse is likely to occur if the orthodontic treatment ends before
the
growth has completely stopped.
-Even after the growth has stopped the dental arch length gradually shortens
with potential to the development of incisor crowding.
22. - The nasomaxillary complex and the mandible grows rapidly at
the onset of puberty and gradually slowing down after puberty.
- Generally, the direction of growth of the maxilla and the
mandible
is downward and forward.
- Orthodontic patients usually have skeletal dysplasia with
unfavourable growth pattern.
- If orthodontic treatment has stopped early during the period of
growth, the continued unfavoural growth of the jaws would
23. Retention plan
- The requirements for retention , the type of retentive measures
and the duration of its use - are often decided at the time of
diagnosis and treatment planning.
- Retention depends on what is accomplished during treatment.
- Retention planning is divided into three categories depending
on the type of treatment instituted.
1. No retention.
2. Limited retention –in terms of both time and appliance
wearing.
3. permanent or semipermanent retention.
24. No retention required
- Corrected crossbites –
When adequate overbite has been established and reasonable
axial inclination has been achieved.
- Condition that have been treated by serial extraction.
- Conditions that have been achieved by retardation of maxillary
dental and skeletal growth and the patient has passed the
growth period.
- Previously blocked out tooth which was moved into occlusion.
25. Limited retention
- Class I nonextraction cases characterized by protrusion and
spacing.
- Class I and class II extraction cases especially where
anteroposterior position of teeth have been corrected.
- Corrected deep overbites.
- Early correction of rotated teeth.
- Cases involving ectopic eruption of teeth or the presence of
supernumerary teeth.
26. Permanent or semipermanent retention
- Cases treated by expansion
- Cases of generalized spacing the cause of which is tooth
size-jaw-size discrepancy.
- Severely rotated teeth.
- Spacing between maxillary central incisors in otherwise
normal occlusions.
27. Retention appliances
Fixed type
Bonded lingual retainer
Removal type retainer
Hawley type retainer
Active retainer
Spring retainer
Circumferential type retainer
Tooth positioner
Functional appliances – monobloc,
-- activator appliances
28. Retention appliances
Hawley retainer
- Most commonly used retainer for both arches
- Made of acrylic and stainless steel wire.
- The acrylic portion covers the palatal or lingual mucosa and contacting
the lingual surfaces of the teeth.
- A labial bow or round stainless steel wire (0.7 to 0.8 mm) is constructed to
contact the labial surfaces of four or six
anterior teeth.
- The labial bow passes across the occlusal surface through mesial or
distal to the canine to enter into the acrylic.
- Modification of a labial bow, acrylic plate or addition of a clasp or pontic
may be made depending upon the restraints required.
29. fig : Hawley retainer.
• This Hawley retainer has been adapted – with acrylic facing over the labial
bow – to improve stability.
• The patient had the upper first premolars extracted as part of their treatment,
so the labial bow was soldered to the clasps on the first molars.
• This avoids wire work passing over the contact points between the canines
and premolars, which could lead to relapse with the extraction space
reopening after treatment
33. • Removable Wraparound (Clip) Retainers
• the wraparound or clip-on retainer, which consists of a plastic bar
(usually wire-reinforced) along the labial and lingual surfaces of the
teeth .
• A full-arch wraparound retainer firmly holds each tooth in position.
• This is not necessarily an advantage, since one object of a retainer
should be to allow each tooth to move individually, stimulating
reorganization of the PDL.
• In addition, a wraparound retainer, though quite esthetic, is often less
comfortable than a Hawley retainer and may not be effective in
maintaining overbite correction.
• A full-arch wraparound retainer is indicated primarily when
periodontal breakdown requires splinting the teeth together.
36. • A variant of the wraparound retainer,
• the canine-to-canine clip-on retainer, is widely used in the
lower anterior region.
• This appliance has the great advantage that it can be used to
realign irregular incisors if mild crowding has developed after
treatment ,but it is well tolerated as a retainer alone.
• An upper canine-to-canine clip-on retainer occasionally is useful
in adults with long clinical crowns but rarely is indicated and
usually would not be tolerated in younger patients because of
occlusal interferences.
37. • In a lower extraction case, usually it is a good idea to extend a
canine-to-canine wraparound distally on the lingual only to the
central groove of the first molar .
• This is called a Moore retainer. It provides control of the second
premolar and the extraction site but must be made carefully to
avoid lingual undercuts in the premolar and molar region.
• Posterior extension of the lower retainer, of course, also is
indicated when the posterior teeth were irregular before
treatment.
45. ESSIX RETAINERS
An Essix retainer:
• is a light, clear ‘aligner’ type appliance
• does not have any wires
• is a vacuum-formed appliance made from thermo-plastic
material
These are:
• lighter
• less visible
• not worn for eating and drinking
• often worn just at night
Essix retainers are sometimes used in the lower arch if:
• it might be hard to get good retention using a Hawley retainer
• the patient would tolerate it better
• an adult patient would find it socially more acceptable
47. Vacuum - formed retainer.
•This vacuum - formed retainer is covering all the upper teeth.
• An area has been cut away over the gingival third of the upper
canine teeth to allow the patient to more easily insert/remove the
retainer.
• Vacuum - formed retainers are contraindicated in patients with
poor oral hygiene.
• This is because this these retainers are retained by the plastic
engaging the undercut gingival to the contact point. If the oral
hygiene is poor, then hyperplastic gingivae can obliterate these
areas of undercut.
50. Positioners
• are sometimes fitted at the end if treatment.
• These are flexible splints which are mildly active
• They continue to correct any small or mild irregularity which
still remains after the active appliances have been removed
51. Retention period
- Various literatures suggest from no retention to permanent retention.
- However , retention should be maintained until completion of growth and
consideration should be given to the use of retainers on an as-needed basis
indefinitely to ensure maintenance of tooth position and relation.
- Generally, removable retainers are worn day and night for three months
followed by three months only on night time and gradually reducing the
wearing time.
- However, clinical signs of relapse should be judged to decide whether to
continue or discontinue the retainer.
52. A common regime , used to retain dental alignment is to use
removable retainers.
-Warn full time for 3-6 months , and
-For 12 hours per day for a further 6-8 months.
-Therefore , the retaining appliances can be gradually withdrawn
2 months - night time only wear,
2 months - alternate night time wear
to assess the stability of the result.
-The patients who have experienced significant orthopedic
changes during treatment after require more elaborate retention
appliances to maintain inter-arch relationships during continued
growth.
53. • This timetable for soft tissue recovery from orthodontic
treatment outlines the principles of retention against intra-arch
instability.
• These are:
1- The direction of potential relapse can be identified by
comparing the position of the teeth at the conclusion of
treatment with their original positions.
Teeth will tend to move back in the direction from which they
came, primarily because of elastic recoil of gingival fibers but
also because of unbalanced tongue–lip forces .
54. 2- Teeth require essentially full-time retention after comprehensive
orthodontic treatment for the first 3 to 4 months after a fixed
orthodontic appliance is removed.
To promote reorganization of the PDL, however, the teeth
should be free to flex individually during mastication, as the
alveolar bone bends in response to heavy occlusal loads during
mastication.
This requirement can be met by a removable appliance worn
full time except during meals or by a fixed retainer that is not
too rigid.
55. 3- Because of the slow response of the gingival fibers, retention
should be continued for at least 12 months if the teeth were
quite irregular initially but can be reduced to part time after
3 to 4 months.
After approximately 12 months, it should be possible to
discontinue retention in nongrowing patients.
More precisely, the teeth should be stable by that time if they
ever will be, and in most patients some degree of re-crowding
of lower incisors long term should be expected.
56. Some patients who are not growing will require permanent
retention to maintain the teeth in what would otherwise be
unstable positions because of lip, cheek, and tongue pressures
that are too large for active stabilization to balance out.
Patients who will continue to grow, however, usually need
retention until growth has reduced to the low levels that
characterize adult life.
57. • As a general guideline, if more than 2 mm of forward
repositioning of the lower incisors occurred during treatment,
permanent retention will be required.
• The slower long-term relapse that occurs in some patients who
did not have inappropriate tooth movement results primarily
from differential jaw growth.
• The amount of growth remaining after orthodontic treatment will
obviously depend on the age, sex, and relative maturity of the
patient, but after treatment that involved growth modification,
further growth almost surely will result in some loss of the
previous correction as the original growth pattern persists.
58. Timing of retention
Retention is needed for all patients who had fixed orthodontic
appliances to correct intra-arch irregularities. It should be :
Essentially full time for the first 3 to 4 months , except that
removable retainers not only can but should be removed while
eating and fixed retainers should flexible enough to allow
displacement of individual teeth during mastication (unless
periodontal bone loss or other special circumstances require
permanent splinting )
continued on a part – time basis for at least 12 months to allow
time for remodeling of gingival tissues .
If significant growth remains , continued part time until
completion of growth.
59. • For practical purposes , nearly all patients treated in the early
permanent dentition will require retention of incisor alignment at
least until their late teens , and in those with skeletal
disproportios initially part - time use of a functional appliance or
extraoral force probably will be needed.
