Now that you know about bonded retainers from part 1 of retention, it’s time to see what happens when the patients are in charge of their retention with removable appliances.
We have gathered a collection of thoughts and techniques from various practitioners. Let’s start with Hawley/Wrap Type Retainers.
Why do we love Hawley/Wrap type of retainers?
They allow settling of teeth better than retainers with occlusal coverage. Settling will improve the cusp-fossae relationships over time.
They are more durable than other retainers and last long-term.
They maintain the transverse dimension of the dentition – recommended for expansion cases.
They can be modified with pontic teeth for edentulous sites or active components like finger springs.
They are great for deepbite cases where you can add a passive/active occlusal bite plate to maintain proper OB and OJ.
Clinical tips and designs
Use Wrap retainers in extraction cases to keep spaces closed. Hawley retainers with wires going across occlusal embrasures can re-open the spaces.
In cases with short clinical crowns or erupting second molars it might be challenging to fit the retentive clasps.
In the lower arch, consider occlusal rests on first molars to increase stability especially if the second molars are not erupted.
How to adjust the Hawley/Wrap retainers?
Rinse with water to remove residual monomer.
Once you insert the retainer evaluate the following:
- Indexing of acrylic to teeth: make sure the acrylic is contacting all surfaces.
- Retention of labial bow and clasps: they should fit snug of the teeth.
- Occlusion on wires crossing the occlusal table: it may be necessary to contour the wires passing through the occlusal embrasure with a 3-prong plier to avoid occlusal interferences.
Improve retention by the following methods:
- Tighten the labial bow: squeeze adjustment loops with a three prong plier or pull back on corner of labial bow with a birdbeak (179) plier. Make sure to keep the labial bow parallel to the occlusal plane.
- Tuck Adam’s clasp arrows into embrasures by bending towards tooth center or tightening any other clasps you are using (ball or C-clasps).
What are the downsides of Hawley/Wrap retainers?
Removable retainers with acrylic parts on the palate and lingual space can affect speech. We need to inform the patients and assure them this will be temporary.
They have a tendency to open up extraction spaces if wires pass the contacts on the occlusal.
These retainers are more expensive since they incur a separate lab fee and there is usually a waiting period from debond to delivery.
Thermoplastic retainers are also known as Essix type retainers. There are various types of material available and ideally you would like to have a combination of reasonable thickness to stand occlusal forces and flexibility for comfort.
Why to love them?
Patients tend to like them more because they are more esthetic and comfortable. There is nothing covering the palate and speech is not affected as much.
They are favorable for bruxers or clenchers because they protect teeth surfaces during these parafunctional habits. However these patients can wear trough the occlusal surfaces really fast. In patients with severe bruxism/clenching or heavily restored dentition a customized night guard could be considered as a retainer.
Thermoplastic retainers are great retainers on top of bonded retainers in cases with difficulty in closing extraction spaces and rotations in the lower arch.
Some clinicians recommend Essix retainers for openbite cases. The thickness of the material between posterior teeth is considered to impede extrusion of posterior teeth and prevent the relapse in openbite patients. This effect could occasionally create posterior openbite in adult patients with great compliance.
What are the pitfalls?
Thermoplastic retainers don’t last very long: average life span is 2 years.
They wear down faster and are more prone to fracture or breakage.
They don’t work well with short clinical crowns; they are just not retentive enough.
They don’t allow for settling of teeth.
What can you do?
Some orthodontists make 2 retainers per arch per patient because they don’t last long. You can keep the copy at the office or send it home with patient.
Final word on removable retainers
The main concern with removable appliances is compliance. Patients need to know the consequences of non-compliance.
Many patients lose their retainers when they remove them to eat. We have all heard the story of the retainer that ended up in the trash wrapped in a napkin. Putting the retainer in the box is the key.
Finally what can you do?
Educate the patients about compliance and the possibility of relapse. Give them retainer instructions and a box when you deliver the retainers.
Click the link to download retainer-instructions.
Stay tuned for Part 3 of the wisdom of retention where we offer bonus tips, retention strategies for mixed dentition and discuss whether third molars should be removed to avoid further crowding. It will be thrilling!
Please consider that the preceding article expresses general opinions and thoughts of the author(s), and should not be construed as explicit treatment recommendations for a specific patient. The evidence is constantly changing, and readers are encouraged to continuously update their knowledge base. The post is meant to inform the reader of what is available in the specialty literature at time of publishing.