Retention

As the name implies, the purpose of retention is to "retain" the teeth in their finalized positions. Over the years, many retainer designs and retention techniques have emerged as the profession attempts to discover the ideal retainer. Actually, there is no one design that is perfect for all patients. A retainer for the mixed dentition may differ from one for the permanent dentition. Some patients, for special reasons, may need permanently bonded retainers. Some special cases may require a positioner.

In our office, the vacuum-formed invisible retainer is used only as a provisional appliance. This design is fast and inexpensive to produce. The major problem with this approach is that, when the teeth shift slightly, the retainer will no longer fit. The retainer may cause so much discomfort when the patient places it in the mouth that the patient will stop wearing it. Also, this type of retainer is less durable. The material can wear, chip, and crack.

In years past, I have used positioners in specific cases where I wanted to achieve a result closer to ideal or sometimes for open bite patients. These positioners are worn for approximately 3 months before regular retainers are delivered.

Chapter 14 of The Alexander Discipline' describes the basic concepts still used today for retention. The goal of retention is to design a retainer that will hold the teeth in approximately the same position that they occupied at the end of treatment, while allowing them to "settle" into their own physiologically balanced positions.

Principle 18 discussed the phenomenon of "driftodon-tics." This is the uninhibited, mesiodistal self-movement of teeth into extraction spaces. Similarly, when all appliances are removed from the teeth, there will be "vertical" driftodontics. If unencumbered, maxillary and mandibular teeth will move vertically until they reach contact with each other. This settling-in effect will give the patient a more ideal posterior occlusion.

No matter how precise the bracket placement or the use of finishing elastics, occlusal forces will continue to move the teeth into more physiologic positions if the retainer design allows this to happen. Retainer wires that cross the occlusion will prevent the teeth from settling, so this retainer design should be avoided (Fig 19-10).

Conform to the Alexander arch form.


Labial portion and flat lingual portion.


Sors.



Fig 19-14 Small adjustment loops to provide greater control in incisogingival positioning.

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