Retention After Nonextraction Treatment in a Patient With a Tongue Thrust and Relapse Risk
A woman aged 31 years has completed 22 months of nonextraction treatment for moderate crowding. The upper and lower arches are aligned, overjet is 2 mm, and overbite is 2 mm. She has a history of a tongue thrust with an anterior open bite that was closed during treatment, and she has a high-arched palate and a large tongue. She is a professional singer and is concerned that a fixed retainer will affect her articulation. She asks whether she can have a removable retainer only, and whether the open bite will return.
1. Assess her relapse risk and recommend a retention regimen, justifying each component.
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Her relapse risk is high for several reasons. First, the anterior open bite was closed during treatment in a patient with a tongue thrust and a large tongue, and tongue pressure against the incisors during swallowing and speech can reopen the bite. Second, the high-arched palate and large tongue suggest a habitual posture that will continue after appliances are removed. Third, the crowding was moderate and the treatment was nonextraction, so there is no residual space to absorb relapse and the teeth will tend to return to their original positions. Fourth, she is an adult, and adult patients have a higher risk of relapse of the lower incisors in particular.
The recommended regimen is a combination of fixed and removable retention. A bonded lingual retainer from canine to canine in the lower arch, and preferably in the upper arch as well, provides continuous resistance to relapse of the anterior teeth without affecting speech significantly. The fixed retainer should be placed with a small-diameter multistrand wire and composite pads on the lingual surfaces, with careful attention to the occlusion so that the retainer does not interfere with the opposing teeth. A removable vacuum-formed retainer should be worn full-time for the first 3–6 months and then nights long-term. The fixed retainer protects the anterior teeth during the day, and the removable retainer provides full-arch coverage and can be adjusted if relapse occurs.
Regarding her singing, a well-fitting vacuum-formed retainer covering the palate may affect articulation temporarily, but most patients adapt within a few weeks. A bonded retainer on the lingual surfaces of the anterior teeth has minimal effect on articulation. She should be advised to practise speaking and singing with the retainer and to report any persistent speech difficulty. Myofunctional therapy for the tongue thrust should be considered, because retention alone will not control tongue pressure.
2. She asks what will happen if the open bite recurs and whether she should have had extractions. How do you answer?
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If the open bite recurs, the first step is to determine why. Recurrence may be due to tongue pressure, to incomplete correction of the vertical dimension during treatment, or to growth, although growth is unlikely at her age. A small relapse can sometimes be managed with a removable retainer adjusted to apply a small intrusive force to the incisors, or with a short course of aligner or fixed appliance therapy. A significant recurrence may require retreatment, which could include intrusion of the posterior teeth, a tongue crib or myofunctional therapy, or, in extreme cases, orthognathic surgery. The earlier the relapse is detected, the easier it is to manage, which is why regular retention reviews are important.
Regarding extractions, the decision not to extract was reasonable if the crowding was moderate and the profile was acceptable. Extractions would have created space but would not necessarily have prevented open bite relapse, because the open bite is related to tongue posture rather than to arch length. In some patients with severe crowding and bimaxillary protrusion, extractions can improve stability and profile, but they are not a guarantee against relapse. The patient should be told that the treatment plan was individualized and that the outcome, not the extraction decision, determines whether retreatment is needed. She should also be told that her tongue habit is the main modifiable risk factor and that myofunctional therapy is likely to be more useful than a change in the original extraction decision.