How do our patients feel about fixed or removable retainers?
Arguably, retention remains a stubborn final frontier of orthodontic practice. Perhaps, I am being overly optimistic, and it could more accurately be described as one of several frontiers? Either way, Oppenheim suggested that retention ‘is the problem in orthodontia’ in 1934. While technological advancements have led to more user-friendly appliance systems and altered patient experiences over the intervening period. This may be less true of retention.
Successful retention is reliant on patient compliance for wearing removable retainers or in maintaining optimal hygiene and care of fixed retainers over long periods. Given the pivotal nature of retention and the centrality of patient behaviour to its success, there is a surprising lack of data concerning patient experiences associated with fixed and removable retainers.
A team from Gavle, Sweden did this study. The European Journal of Orthodontics published the paper. The authors aimed to shed light on patients’ perceptions of retention with a vacuum-formed retainer and a fixed canine-to-canine retainer after 6 and 18 months. This report is part of a more extensive study incorporating data on the stability of alignment with both approaches. There is also a 5-year follow-up paper.
Authors: Anke Krämer, Mats Sjöström, Mats Hallman and Ingalill Feldmann
Eur. J. Orthod. 2020. doi: 10.1093/ejo/cjaa039
What did they do?
They did a two-group parallel randomised controlled trial with a 1:1 allocation as follows:
Participants: Patients with a range of malocclusion and providers treated with fixed appliances in both arches with and without extractions.
Intervention: A removable vacuum-formed retainer (VFR) in the mandible (1.0 mm Essix C+) covering all erupted teeth from the first premolar to the first premolar. If the first premolar was extracted, the VFR included the second premolar to the second premolar. They asked the participants to wear the VFRs full time the first week and, after that, to wear it only at night for the next 12 months. After 1 year, they reduced the wear-time to alternate nights.
Active Control: Patients received a fixed canine-to-canine in the mandible (0.8 hard Remanium® wire, Dentaurum, Ispingen, Germany).
Importantly, they fitted a VFR (1.0 mm Essix C+) in the maxillary arch covering all erupted teeth for all the participants. They randomly allocated 52 patients to both intervention groups. Data from 95 of them were available at 18 months post-treatment. They concealed the group allocation with sealed envelopes. Finally, they blinded with data analysts to group allocation.
Outcomes: Perceptions of retention based on questionnaires at scheduled appointments: At baseline (2 weeks after debond), after 6 months of retention, and after 18 months of retention.
What did they find?
At both baseline and 18-month follow-up, the patients reported more pain and soreness in the VFR group in the lower arch than in the fixed retention group. Participants in the fixed retainer group also adapted to their retainers more readily. After 18 months, they reported similar rates of adherence to the recommended wear levels in both groups (70.5%: VFR group and 73.9%: Fixed). They found an association between reduced wear-time and perceived discomfort. Overall, the patients reported high levels of satisfaction and self-reported compliance.
What did I think?
I think that this was an excellent body of work providing a holistic comparison of fixed and removable retention. Importantly, this included an evaluation of up to 5 years post-treatment. As such, the whole research provides us with beneficial information. This paper represents a relatively small piece of this research focusing on patient opinions and perceptions. The take-home message, however, appears to be that both fixed and removable retainers are perceived positively in this patient cohort.
They did the study very well and reported it by following accepted guidelines. They undertook a sample size calculation and were able to incorporate data from 85% of participants 18 months after active treatment was completed. This is very impressive and suggests that this was a compliant cohort of patients who understand the importance of retention and the requirement for recall to monitor potential changes.
My chief reservation is that participants in both groups had Essix-type retainers (with an upper VFR provided in the fixed retainer group). As such, I found it difficult to be entirely confident that data relating to perceptions in the fixed retainer group was not ‘contaminated’ by the use of the upper VFR. It would be fascinating to repeat this study on samples having either VFRs or fixed retention, in isolation.
Also, the lower VFR used was relatively small, not extending beyond the premolar region. It is conceivable that this more subtle variant may be associated with less impact (and more positive perceptions) than more conventional designs. It is also noteworthy that a more traditional design was used in the maxillary arch. It is therefore conceivable that the impact of the lower retainer may have been under-estimated.
Finally, it would be interesting to understand the relationship between perceptions of retention and objective wear times. The authors relied on subjective reports in this study; we know that these are notoriously unreliable. Wear duration can be recorded objectively using indwelling sensors. However, these are not without problems. These include potential inaccuracy, higher risk of fracture, as well as associated alteration to the size and appearance of the retainer.
What can we conclude?
The patients reported positive perceptions of both fixed and removable retainers up to 18 months into the retention phase. Nevertheless, slightly more pain and discomfort were associated with removable retainers. While this facet of this study has some limitations, this body of research is very welcome and relevant. If retention is indeed a final frontier, the authors have gone some way to navigating this!
Professor of Orthodontics, Trinity College Dublin, The University of Dublin, Ireland