Retention and relapse
One of the most challenging parts of orthodontic treatment is maintaining post-orthodontic outcomes. The term retention in orthodontics is referred to the procedure of holding of teeth in an ideal aesthetic and functional position allowing reorganization of bone and supragingival/ transseptal fibres, as well as neuromuscular and soft tissue adaptation (Riedel et al., 1969).
Post-orthodontic relapse is mainly due to lack of appropriate retention, occlusal outcomes, soft tissue factors as well as active growth (Fleming et al., 2008, Franzen et al., 2013).
Management of replase
Although several researchers have concluded that relapse is the inevitable outcome after active orthodontic treatment (Thilander, 2000), knowing and understanding different types of retainers, and retention protocols appropriate for their patients are crucial.
To minimize posttreatment relapse, different retainer types, including removable and fixed, have been proposed with varying protocols of retention to minimize relapse (Al-Moghrabi et al., 2018, Kartal and Kaya, 2019, Kaklamanos et al., 2017).
The type of retention protocol depends on many factors, including but not limited to, clinician experience, occlusal outcomes, type of orthodontic movement achieved, background training and patients compliance/ preference (Littlewood et al., 2017).
There is no consensus regarding the optimal appliance and/ or ideal protocol for the upper arch.
European Journal of Orthodontics in their December issue published a good RCT that answered some of these uncertainties. The paper titled: Stability of maxillary anterior teeth after 2 years of retention in adolescents: a randomized controlled trial comparing two bonded and a vacuum-formed retainer. The paper was undertaken by a team from Malmö University in Sweden led by Dr Sasan Naraghi along with very well-known clinical researchers, Niels Ganzer, Lars Bondemark, and Mikael Sonesson.
This 2-year RCT recruited 90 adolescents (54 girls and 36 boys) who had at least upper arch treatment. All patients were randomly allocated to one of three groups:
1. Bonded retainer 13–23,
2. Bonded retainer 12–22,
3. Removable vacuum-formed retainer (VFR) covering the maxillary teeth including the second molars.
The study ticked many of the CONSORT checklists ranging from randomization, allocation, methods used to treat attrition bias and analysis bias.
Though canine rotation was observed in the VFR group, the differences between the three groups were not statistically significant and none of the patients needed retreatment.