Recidivism and restraint

Recidivism and restraint

 1.Introduction 

The goal of orthodontic treatment is to achieve an aesthetic, functional and stable final result. Despite the progress of our knowledge, relapse still remains, in the opinion of all authors, the most difficult problem to solve in orthodontics.

Nothing is more frustrating than seeing a treatment that has been successfully completed recur after a few months, which, often felt as a failure, is a source of disappointment for the patient, especially since these are disturbances affecting the anterior sectors and are therefore more difficult to accept.

So, to achieve perfection, it would be necessary to first highlight the causes of instabilities, trying to eliminate them, avoid them or counteract them from the clinical examination to the post-therapeutic control.

2. Recidivism  

   2.1. Definition of recidivism: 

Relapse in orthodontics is the return to the initial situation, with the partial or total reappearance of the dental and occlusal characteristics that preceded the treatment.

   2.2. Forms of recidivism: 

There are 3 forms: 

• A rather crude form: intra-arcade.
• A more severe form with deterioration of inter-arch occlusal relationships.
• An ultimate form, leading to the return of skeletal and/or functional disorders.

These different forms can manifest themselves in isolation or in different combinations.

  2.3. Causes of recurrence: 

2.3.1. General causes: 

2.3.1.1. Genetic factors:

Research is focused on one or more genes explaining the appearance of mandibular retrognathia and dolichomandibular dysplasia after treatment of significant Class II and III defects before the end of growth.

2.3.1.2. Skeletal growth:

Growth may be a cause of recurrence if it continues during or after restraint. 

Skeletal growth is said to be “unfavorable” if it worsens a malocclusion. 

In some cases, after orthodontic treatment, unexpected changes in growth both in direction and quantity may occur:

• In direction: a posterior rotation which increases after treatment can be at the origin of the reopening of the gap and an anterior rotation of the appearance or the reappearance of an incisor overbite and of lower incisor crowding.
• In quantity: the growth of the mandible continues longer than that of the maxilla. This phenomenon is favorable to retention in class II cases, and unfavorable in class III cases. (If the treatment of a class III malocclusion in a 13-year-old boy has been completed, by painfully obtaining class I relationships, one should not be surprised to see the relapse appear around 18 years of age).
• The conjunction of the two phenomena, the mandibular incisors are pressed against the maxillary teeth, due to the forward growth of the mandible and its anterior rotation, which can explain the frequency with which malpositions of the mandibular incisors appear after retention.

2.3.1.3. Non-cooperation of the patient: 

Irregular and non-compliance with the wearing of support devices will be the cause of the recurrence.

Recidivism and restraint

2.3.2. Local causes:

   2.3.2.1. Poorly balanced dento-dental pressures: Tooth, denture and dentition:

• The shape of the teeth:

• Relapse of rotation of an incisor with a wide occlusal edge and a round root occurs more easily than a narrow tooth with a flat root.
• The movement of multi-rooted teeth provides better stability.
• Another morphological peculiarity of the crowns of the maxillary incisors can be the cause of recurrence of malpositions of the mandibular incisors. Some maxillary incisors have on their palatal surfaces, protruding marginal ridges which extend towards the occlusal edge. These are called “shovel” teeth.
• Tooth volume:  When teeth are too large to be aligned in the necessary space provided by soft tissue pressure, it is then up to the treatment plan to choose the best solution (expansion of the arch and modification of muscle balance, proximal grinding, or extraction). In either case, if the chosen solution proves to be definitively unsuitable, relapse will be the penalty for a bad decision.
• The meshing: The shorter the cusps, the less deep the meshing and the less the tooth is connected to its antagonists. It will therefore be all the more inclined to move independently of the others.

In the anteroposterior direction, the displacement of one arch relative to the other will be less fixed by a weak cuspal relationship.

• Non-coordination of arch shapes: This lack of coordination is common when the practitioner does not constantly have the desired arch shape design in front of him and does not check, at each adjustment, the conformity of his arches to this outline, as well as their perfect symmetry. 

  Giving all patients the same arch shape, when facial type and muscle behavior are strictly individual, greatly promotes the occurrence of relapse.

• The curve of Spee: The sagittal curvature of the arches is an architectural feature of the face.    

Removing this curve of Spee creates an anomaly. This removal is dangerous for stability, when we suspect the curve of wanting to reform after treatment, according to dental movements that are then uncontrolled. 

• The occlusal plane:

•  Simmons et al, believe that any therapeutic shift in the occlusal plane is likely to relapse.
• Planas argues that a downward and forward tilted occlusal plane directs masticatory forces obliquely, in a way that could push the mandible backward, the maxilla forward, and thus promote the relapse of a Class II malocclusion.
• Occlusal function  : Poor occlusal function can be the cause of relapse .

An example is occlusal dysfunction, which is the cause of recurrence of overbite: it is the insufficiency of the mandibular propulsion movement.

• Dentition (development of wisdom teeth): Do wisdom teeth, and in particular the mandibular ones which give the impression of resting on the Ramus, exert a mesial thrust during their development which results in malpositions or vestibular incisor versions?

Many authors have responded positively (Frajdenrach, Schulhofl, Vego, Theuveney) and even more negatively (Brodbent, Bishara and Andreasen, Little and Riedel and Van der Linden). One can understand the perplexity of those who are trying to make an objective assessment.

2.3.2.2. Functional balance not adapted to the shape given to the dental arches:

• According to Lautrou: “  the stability of the correction of a dysmorphosis will only be achieved if the form (skeleton and teeth) is in harmony with the functions (non-skeletal environment). The recurrence appears if the conflict exists or persists between the two ”.

Functional balance is governed by two components:

• The anatomical peculiarities of the subject, most of which are genetically determined: short or long, thick or thin, levator muscles and facial muscles, large or small tongue, insufficient or abundant lips. These anatomical arrangements can only be modified by surgery or maturation. Treatment that goes against these anatomical imperatives would have a strong chance of being followed by a relapse.
• The functional activities of the subject: the exercise of multiple functions of the face shapes the arcade shape that is strictly adapted to them. Changing this shape without modifying the play of functions that designed it leads straight to relapse.

Misjudgment of the importance of anatomical factors and/or failure to modify dysfunctional behavior leads to relapse.

Recidivism and restraint

2.3.2.3. Tension of desmodontal fibers:

The alveolodental ligament includes the intraseptal fibers also called Sharpey fibers, the supracrestal or gingival fibers.

According to Parker: ”  They respond to the tension caused by orthodontic movement by seeking to return the teeth to their original position  .”

The main difference between the two types of fibers is their duration of action:

• Intraseptal fibers change and reorganize very quickly
• For the supracrestal fibers; according to Reitan quoted by Philippe: “the fibers of the gingival zone are still under tension after 232 days and it would seem that they can remain under tension before completely reorganizing themselves for 3 or 4 years.”

2.3.2.4. Tissue compression:

After the closure of spaces following extractions, a reopening of the extraction site can sometimes be observed. This phenomenon is linked to the existence of an epithelial ridge resulting from the compression of the periodontal tissues with the absence of fusion of the periodontiums when the teeth are brought together. 

2.3.2.5. Iatrogenic causes: 

• Diagnostic error;
• Bad therapeutic choice;
• Treatment completion criteria not met;
• Poorly adapted contention.

To conclude :

Relapses related to growth, occlusion and functional play can be prevented but not contained.

On the other hand, those linked to the desmodontal environment can be contained but not prevented. 

Recidivism and restraint

2.4. Recurrence according to different malocclusions: 

1. CL I malocclusions:
2. Mandibular incisor crowding: The causes that can be mentioned are:

• The shape of the mandibular incisors or their antagonists. This cause often goes unnoticed;
• Mesial migration of the lateral sectors and mesial version of the canines; the evolutionary pressure of the third molar; 
• The progressive decrease in intercanine width, especially if it has been increased by treatment;
• The predominance, within the balance of labio-lingual pressures of the muscular envelope, that is to say of centripetal forces over centrifugal forces;
• Overbite;
• Modalities of the terminal phase of mandibular growth. The late continuation of mandibular growth, combined with a final phase of “anterior rotation”, may be accompanied by pressure from the mandibular incisors on the maxillary teeth.

2. Diastemas: The causes of diastemas are multiple:

• A hypertrophic inter-incisal frenum, 
• Incorrect insertion of the lingual frenulum,
• Consequence of other anomalies, such as proalveolus or open bite.
• Diastemas caused by treatment with extractions must also be considered.
• Reopening of extraction spaces may be due to poor orientation of the dental axes adjacent to the extraction site, or to a stacking of gum between the two close teeth due to poor adaptation of the periodontal tissues forming a true interdental fibrous bridge.
• According to Biourge, the correction of an inter-incisor diastema will only be stable under four conditions:

• The cause must be removed (low-insertion or very short labial frenum, extra teeth, etc.),
• The proximal teeth must ensure continuity of the arch;
• No gap, even distal, should occur on the arch because a diastema can reappear after the loss of a premolar or a molar, especially if there is an incisor overbite;
• There should be no incisor overbite.

3. Rotations:

• Swanson notes variations in relapse depending on the type of tooth: the canine is the tooth that relapses the most in the maxilla and mandible, followed by the lateral incisor in the maxilla and the second premolar in the mandible. 
• On the other hand, the patient’s age, gender, presence of extractions or jaw growth do not affect the recurrence of rotations.
• Edwards describes circumferential supracrestal fibrotomy (CSF) which appears to be more effective in reducing recurrences in the first 4 to 6 years after treatment; moreover, the effectiveness of CSF is less in the mandible than in the maxilla 12-14 years after treatment.

4. Included teeth:

• In general, if the tooth traction has been carried out with light and constant forces, there are no secondary intrusion phenomena once the force is removed.
• If the tooth is positioned in balance on the arch relative to the neighboring teeth and muscular forces, retention is not even necessary.

Recidivism and restraint

5. Anterior infraclusions or vertical gaps:

• The cause of the relapse is probably to be found in the volume or the lingual behavior.
• Stable results were described when “mouth breathing, tongue interposition and dental pain were eliminated.”
• The particularity of the vertical sense is that it does not have any specific effective treatment but often remains influenced by the treatment of the other senses. 
• It is important to respect the vertical dimension during treatment and never lose sight of the reality of the intimate connection between the anteroposterior and vertical senses.

6. Transverse expansion:

• Expansion of the maxillary arch alone is also performed in a number of Class II cases to allow advancement of the mandible since a more posterior, and therefore wider, part of the mandibular arch is placed opposite a narrower, because more anterior, part of the maxilla. This expansion is most often stable, and this, for several reasons:

• Nasal ventilation could be improved by the action of ENT treatment by the mechanical effect of the expansion device (Loreille), by the consequences of the placement of the maxillary incisors (Talmant);
• The anterior parts of the arches are brought back into the occlusal functional circuit, due to the correction of the class II incisor-canine relationship;
• The enlarged maxillary arch can rest on the mandible which has not been modified, and therefore does not risk a relapse.

• Expansion can also be performed on both arches to treat congestion attributed to biendoalveolism.
• However, the transverse expansion of the mandibular arch is particularly unstable. Many studies have shown this.  

• For Château, the recurrence is explained by the fact that the expansion of this arcade is “almost always done by version and that only expansions by gression are stable.” 
• It should be recalled that regarding the long-term stability of expansion treatments, most treated and untreated arches tend to show a decrease in their width, especially in the anterior region of the arch. This slow decrease can be mistaken for a relapse in long-term studies.

2. Class II division 1 malocclusions:

• The stability of the correction of occlusal relationships is favored by the last mandibular growth spurt, which continues longer than the maxillary correction. The longer the growth continues (late puberty), the better the prognosis.
• On the other hand, the change in position of the lower lip which initially passed under the maxillary incisors pushing them upwards and then, after treatment, moves up vestibularly on these incisors, holding them back, most often has a decisive containment action.

3. Class II division 2 malocclusions:

The correction of molar relationships is relatively stable. The problem with this malocclusion concerns the overbite, which all authors consider to be particularly exposed to relapse. (Dake, Sinclair 1989, 20% relapse 4 years later; Sadowski 1993, 73% relapse 20 years later, Vaden 1997 100% relapse rate 15 years later).

4. Class III malocclusions:

• Bad skeletal relationships worsen, more or less, until the complete end of mandibular growth. This often continues, very late, in boys. This is the main cause of relapse.
• Another factor is the volume and lingual activity. It seems that the effect of the tongue lasts less time than that of mandibular growth. The tongue will therefore cause an early relapse, sometimes when the active appliance is removed, and mandibular growth, a late relapse, often after the end of the retention.

4.Contention

4.1. Definition of contention: 

This is the treatment phase that immediately follows the active treatment period. It uses a whole set of procedures and devices designed to stabilize the result obtained and to prevent relapse, that is, the natural predisposition of teeth to return to their original position.

4.2. Purpose of the restraint: 

The aim is to ensure stability by preventing relapse, either permanently if no balance can be found, or until the “environment” reorganises itself around the new position of the teeth and ensures their stability by achieving a natural balance.

4.3. Principles of restraint: 

The choice of the type of restraint must be guided by a few principles: good restraint must be immediate, intelligent, prolonged and whenever possible fixed. 

• Immediate restraint  because recurrence begins as soon as the active appliance is removed. Parker estimated that half of all recurrences occur within the first twelve hours.
• Intelligent retention : This rule was perfectly formulated by Angle: “Since the teeth tend to return to their initial position, the first principle to remember for the design of the retention appliance is that it must oppose the movement of the teeth towards their initial positions, and only this return” 
• Prolonged retention: Retention should be prolonged until the surrounding tissues, teeth and oral functions are adapted to the new position of the teeth and the new shape of the arches. Post-orthodontic retention ends when all treatment-related causes of relapse have disappeared.
• Fixed retention: Not all retention systems can be fixed, but whenever possible, fixed appliances should be preferred. Indeed, a removable plate can be broken, lost or forgotten. An orthodontic treatment represents too much effort, and its result too important for the patient, to be at the mercy of a stroke of bad luck or a movement of impatience.

In conclusion, the most important point to emphasize is that the type of contention must be chosen according to the particularities of each case and each type of treatment, and depending on the possible recurrence.

Recidivism and restraint

4.4. The different types of restraint: 

• The contention can be natural or artificial, active or passive, fixed or removable, uni- or bi-maxillary, temporary or permanent.

4.5. Restraint devices: 

4.5.1. Unimaxillary devices:

4.5.1.1. Removable unimaxillary devices:

• Hawley’s plaque:

Hawley-type removable plates stabilize the teeth using a more or less reinforced resin plate with contact on each tooth in the palatal region and a vestibular stainless steel wire.

They are mainly indicated in cases of endoalveolus treated by maxillary expansion in order to maintain the transverse dimension and the shape of the arch.

There are several variations including:

The plate can be recessed at the palatal level to allow contact of the tongue with the palatal mucosa necessary for lingual function.

• Sved’s plaque:

It is a palatal plate with a resin return encompassing the free edge of the maxillary incisors. The mandibular incisors come into contact with the plate just behind the maxillary incisors on a resin plane.

• The lower removable plate:

The retainer plate in the mandibular arch is more troublesome than in the maxillary arch. It is surprisingly fragile and prone to loss, hence the primary indication for a fixed retainer in the lower arch.

• Thermoformed gutters:

It is a gutter made with a rigid transparent thermoplastic material heated and shaped under vacuum on the plaster cast at the end of treatment.

It is a rigid restraint:

•   Indicated for maintaining arch shape and dental  alignment ; 
•   Prevents the reopening of diastemas or extraction spaces and the reappearance of malpositions and rotations, particularly of the incisors .

2. Fixed unimaxillary devices:

These are devices glued mainly to the lingual surfaces of the teeth. 

Some are for a limited time, others for longer, and some are permanent.

• Semi-permanent bonded retention:

This is the type of retention best suited to preventing recurrences of malpositions (rotation, version, egression) and reopening of spaces after closing an extraction site or a diastema.

There are many variations depending on the nature of the wire and the teeth involved:

Type of thread: Depending on the case, we use:

• either a round wire of fairly large diameter .030 if it is only glued at its ends to the canines;

• or a thinner braided wire .0175 if it is glued to all the teeth . 

Teeth affected. The bonded wire can affect a variable number of teeth:

• In the mandible: the most used is the glued wire from 33 to 43 

• In case of extraction of the first premolars, the wire can be extended on the second premolar in order to prevent the reopening of the extraction site;

• In the maxilla: we mainly use a .0175 braided wire glued to all teeth from 13 to 23 which 

As in the mandible, in the case of extraction of the first premolars, the wire can be extended to the second premolar in order to prevent the reopening of the extraction site.

Recidivism and restraint

• Permanent bonded retention:

In some cases, a permanent post-orthodontic retainer should be considered. 

To choose a bonded cast retainer, three parameters must be taken into consideration:

• The condition of the periodontium: soft tissues, bone and supporting tissue of the teeth  ;
• Integrity of remaining teeth and the presence or absence of restoration;
• Degree of tooth mobility.

  Bonded cast splints in adult teeth:

These are fixed retention systems known as permanent, requiring preparation of dental tissues and their implementation in the laboratory, they include:

• Fiber composite splints 
• Cast metal splints or bridge splints 

2. Bimaxillary devices:
3. Removable bimaxillary devices:

• The KESLING “tooth positioner”

Made of natural rubber, very flexible and very resistant, the appliance is built on a mounting of the patient’s teeth, placed in perfect alignment and in perfect intercuspidation, according to an approximate position of the ATM. The appliance envelops the two arches in the form of a double gutter .

• The “elastopositioners” 

Also called OSAMU, this device resembles the “tooth-positioner”. It is built on a montage of the patient’s teeth, placed in the ideal position.

Its main advantage is that this assembly is itself placed on an adaptable articulator, which allows for high quality intercuspidation; it also provides a solution to the problem of retaining the mandibular arch and eliminates any risk of incoordination between the arches.

The main drawbacks of elastopositioners are their bulk, which makes speaking very difficult, and the difficulty of their development.

Well constructed and well worn, the elastopositioner is, without doubt, the best containment system that can be offered according to PHILIPPE.

• The activator

When an activator is made for retention, it must be as compact as possible. It thus becomes less cumbersome than a tooth-positioner. However, its wearing must be perfectly regular because, if the slightest tooth movement occurs, the appliance can no longer be put back in place.

• Intermaxillary elastics on plates

Two removable plates can be connected by intermaxillary elastics (Class II or III type, carried by arms at the height of the occlusal plane so as not to destabilize the plates).

Easily overactive, these devices should only be worn during periods of contention at night, and with very weak elastics.

2. Fixed bimaxillary devices : 

• The cingulate stops:

These are small masses of composite placed on the cingula of the incisors and often the maxillary canines, intended to prevent the recurrence of the overbite. By increasing the volume of the cingula, they allow them to play the role of lingual cusps which maintain the relationships of the antagonistic incisor groups in the vertical direction and therefore constitute a device with a bimaxillary effect. Most often, the stops are added to the retention wire glued to the maxillary incisors, just as the retention of the overbite is added to that of the alignment of the incisors.

6. Duration of the restraint:

The stability of certain orthodontic corrections increases with the duration of retention ; the desirable retention time varies according to the authors and the anomalies treated:

• IZARD and CHATEAU recommend wearing the device day and night, then a few weeks later only at night to allow the new articulation to be noted.
• According to NANDA (1992), “perhaps the solution to the long-term recidivism issue is long-term restraint.”
• SCHUDY, until the end of the growth and evolution of DDS 

Depending on the anomalies treated:

– for a class I with DDM: one year 

– for a class II: two years 

-for class III; until the end of growth.

5. Conclusion

Relapse, in orthodontics, remains a multifactorial phenomenon of which we do not know and do not control many elements. Relapse is the spur that will force us to move forward 

“Understanding the evolution of the arches and the face over time shows that the stability we seek is only relative. In fact, we want to insert a moment of stability in an evolutionary continuum. This observation joins the conclusion which says that: “contention is not a static but a dynamic maintenance”

Heraclitus said: “Nothing is, everything becomes”

The mistake to avoid for each of us would be to remain motionless, satisfied with our therapeutic method. Nothing like falling into boredom and our cases into relapse.

The world is changing, dental arches are changing, orthodontics is changing. Don’t stay fixed and find your happiness in change.” Julien Philippe.

Recidivism and restraint