January, 2008

Fixation and Retention in Orthodontic Treatment and Other Disciplines of Dentistry

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Dr. Mohamad Azhar Ibrahim Kharsa, DDS, PhD Orth

Abstract

In this article, the author discusses fixation and retention in orthodontics, as an important step in maintaining the efforts and results of orthodontic treatment. Retention and fixation are considered major “pillars” in multiple disciplines of dentistry not only orthodontics. The notions of retention and fixation are discussed in light of the multiple factors affecting retention such as periodontal structure, function, occlusion and patient habits.

Key Words: Fixation, Retention, orthodontic active treatment, periodontal fibers, relapse and function.

Discussion

Orthodontic treatment often consists of a long series of actions, steps and stages each one forming an indispensable element in successful treatment. Retention and fixation could be viewed as even more crucial in the overall success of treatment because of its role in preserving the results of all the previous steps. Retention and fixation is ultimately responsible for either preserving or losing the outcome of the treated case. Fixation and retention is discussed within this article from multiple standpoints; each one relevant to a variety of branches in dentistry. While this article categorizes the roles of retention and fixation, the purpose of this categorization is for facilitation and classification. In practical experience, boundaries do not distinctively exist between the various divisions in dental science. The article divides retention and fixation into three major categories:

  1. Retention in periodontal cases.
  2. Retention in adult orthodontic cases.
  3. Retention in interceptive and preventive orthodontic cases.

1. Retention in Periodontal Cases

Fixation and Retention may be indicated in periodontal cases treatment planned for gingival grafts, flaps and even in deep scaling where the periodontium is compromised. Fixation plays a supporting role in stabilization of the periodontium in support of healing or to stop the degeneration of these tissues by preventing undesirable movements. Periodontal fixation can be useful in some orthodontic cases where periodontal issues must be addressed prior to active orthodontic treatment.

Figure 1. A fixed lingual retainer for fixation of the lower incisors during periodontal treatment which includes gingival grafting in the area of the mandibular central incisors.

A fixed lingual retainer for fixation of the lower incisors

Fixation in periodontal cases can be either fixed Figure 1., or removable Figure 2. While removable retainers are not as secure as fixed, they may have other benefits such as lessening the impact of tongue thrusting on the maxillary incisors.

Figure 2. An acrylic plate, with Hawley Arch in a tongue thrusting case. This appliance has been chosen to neutralize the deleterious effect of tongue thrusting on the maxillary central incisors. It is part of the periodontist’s treatment plan to stabilize the case before periodontal procedures are done.

An acrylic plate, with Hawley Arch in a tongue thrusting case

2. Retention in Adult Orthodontic Cases

Retention in adult orthodontic cases should be thought of as a step in the orthodontic treatment, not an addendum to it. The importance of retention per se, is in being not only the “limbo” or transitional step between the active orthodontic treatment and the “braces-free situation”, but also the factor that helps to conserve the treatment results. Retention can be either fixed or removable. Fixed retainers have diverse forms and shapes; nonetheless, they are similar in principle. Lingual fixed retainers are common in daily orthodontic practice, and can be either ready-made or fabricated for the individual by the orthodontist Figure 3.

Figure 3. A fixed maxillary lingual retainer, made by practitioner, consisting of two braided ligature wires.

A fixed maxillary lingual retainer, made by practitioner, consisting of two braided ligature wires.

Figure 4. A fixed retainer that has been installed before debonding, to insure retention, and to avoid a transitional “retention-free” interval.

A fixed retainer that has been installed before debonding, to insure retention, and to avoid a transitional “retention-free” interval.

Figure 5. The same case as Figure 4., with the fixed orthodontic appliance just removed.

The same case as Figure 4, with the fixed orthodontic appliance just removed.

One of the major advantages of the fixed palatal or lingual retainer is that it can be installed just before the debonding procedure to avoid any potential relapse Figures 4. Figure 5. On the other hand, a concern in using the fixed lingual retainer is the need for thorough oral hygiene. To avoid detrimental occlusal forces the retainer must be placed in a cervical position and therefore requires consistent care by the patient. A fixed lingual retainer is supposed to be neutral; consequently, it is necessary that the wire accurately fits the lingual surfaces of teeth to insure that no active forces exist. This should be checked prior to installation.

The time requirements of retention are determined by the case, however, the patient should be informed that the more cooperative and compliant he/she is, the better the result. Retainers for adults have several forms, in addition to the conventional Schwartz acrylic plate and fixed lingual retainers, it seems a positioner can also be effective in retention if the patient is sufficiently compliant Figure 6.

Figure 6. A working model for a positioner retainer, this positioner is still in the laboratory and “under-construction.”

A working model for a positioner retainer

3. Retention in Preventive & Interceptive Orthodontics

Interceptive and preventive orthodontics require retention especially in expansion cases. The same appliance that was used for expansion can act as the retention device if left in place without further activation. This can be left for the desired period of time until active orthodontic treatment resumes Figure 7.

Figure 7. A Hyrax-Type expander left in place for retention.

A Hyrax-Type expander left in place for retention

Figure 8. A Removable Expander that is used as a retention appliance, after expansion has been completed and the crossbite corrected. The Expander is worn without any activation as a neutral appliance for retention until the rest of permanent teeth erupt, and active orthodontic treatment can continue.

A Removable Expander that is used as a retention appliance

As illustrated in Figure 8., a removable expander acrylic plate can be used as a removable retainer after expansion is no longer indicated. It is worn without additional activation to maintain the “neutral” position of the appliance. This can serve to retain the mixed dentition until the next step of orthodontic treatment can be started or until the desired effect of retention is fulfilled according to treatment plan.

Not “all cases” of mixed dentition orthodontic treatments require fixation or retention, nor even “all” adult orthodontics.
Retention is planned independently for each case. Cases of anterior cross bites may be less “in need” for retainers after cross-bite correction Figure 9.

Figure 9. A case of crossbite correction, the photo on left presents the case pretreatment, while the right photograph, the case post-treatment.

A case of crossbite correction

Retention is indicated in pedodontic cases especially when accidental trauma affects one or more of the permanent incisors.
Luxation of incisors is a familiar situation for pedodontists. Reimplantation of a luxated tooth (indicated in most cases, unless too much time has passed) requires fixation and good retention. An orthodontic lingual “or palatal” splint can be a good solution for such cases Figure 10., provided the patient is sufficiently cooperative.

Figure 10. A Luxated maxillary right central incisor, which has been returned to its previous position with a fixed palatal splint installed for good fixation.

A Luxated maxillary right central incisor

Conclusion

Fixation and retention, from an orthodontic point of view is of paramount importance, not only for the orthodontist’s daily practice, but also for other disciplines of dentistry. On the other hand, fixation and retention is not an isolated procedure but a means to conserve the result of orthodontic treatment and/or to assist in compromised cases for better recovery, healing or protection. It is recommended that orthodontists study the retention of each case and make it part of the treatment plan, choosing the best method for future retention. Finally, the more respect that is given to retention and fixation from pre-treatment to post-treatment, the more satisfactory the long term results will be.

References

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Contributed by:

Dr. Mohamad Azhar Ibrahim Kharsa, DDS, PhD Orth
Consultant Orthodontist, King Fahad Hospital. MADINA. Saudi Arabia. Scientist Fellow of American Society for Laser Medicine and Surgery, WFO Fellow AOS Fellow, Member of Saudi Orthodontic Society and Saudi Ortho Club

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