A simple and clear paper on orthodontic retention.

Very occasionally, someone writes a paper that is simplistically brilliant and addresses an important area of orthodontic treatment. Today’s blog post is about a publication on the difficult subject of retention.

Simon Littlewood, who is an authority on retention, based in Bradford, Yorkshire wrote this paper. The American Journal of Orthodontics published his paper.

This paper is not open access, so reading the full text is not easy. This is a shame, and I wonder whether the AJO-DDO could make this paper freely available so that this knowledge can be shared?

I would like to declare an interest, as I know Simon Littlewood well. 

His aim in writing this paper was to

“Outline the current status of orthodontic retention, based on the results of clinical research, clinical experience, and patients’ perceptions”. 

There is a large amount of useful information in this paper. It is difficult for me to summarise it all, but I will do my best to outline the main points.

The inevitability of relapse 

We are all familiar with the University of Washington publications from the 1970s. These show that relapse is unpredictable and that it is not possible to predict which patients will remain stable. We also know that relapse may be related to post-retention factors such as facial growth and natural ageing. As a result, we should remember that relapse is inevitable. Nevertheless, we should take steps to retain our final treatment occlusion as far as we can. 

Clinical expertise 

To consider evidence-based retention, we must immediately consider the role of clinical expertise. Although there have been many studies on methods of orthodontic retention, it is clear that the results of these studies are influenced by the operator’s skill and experience. This is similar to most areas of orthodontic treatment. 

Patient values. 

Patients need to consider the effects of their attitudes, expectations, and willingness to undertake certain forms of treatment. This is perhaps the most important factor when we consider retention, as we know our patients need to develop a long-term commitment to reduce unwanted change. 

Importantly, he points out that patients are more likely to wear their retainers if they establish a good pattern of retention wear immediately after the end of their treatment. Furthermore, they report that they wear their retainers because they don’t want to disappoint their clinician, and it is always important for them to have a spare set of retainers in case they are lost. 

Research evidence 

In this section, he draws heavily on the recent Cochrane review, which includes data from 47 randomised trials. Unfortunately, he points out that the evidence on retention remains relatively low, making it difficult to recommend a particular approach at present. There is a clear need for longer-term studies. He uses some of the evidence from this review in the later sections of his publication. 

Types of retainers Fixed retainers 

Most of us have used fixed retainers for our patients. This is because they offer the clear advantage of not requiring compliance to wear them. There is little effect on retention between the different types of wire retainer that can be used. Recently, there have also been developments in CAD/CAM technology. However, there is little evidence to support their increased effectiveness with this new technology. Nevertheless, this may offer clinicians a better and more efficient workflow. 

When we consider the failure rate of bonded retainers. This is surprisingly high, at approximately 35%. Other disadvantages include the potential to increase the risk of plaque and calculus buildup, which may lead to long-term periodontal problems, although long-term studies are lacking. 

The final potentially serious problem with bonded retainers is wire syndrome, in which unwanted bends in the wire cause excessive tooth movement, leading to severe periodontal defects and tooth loss. In this respect, it is essential to regularly review retainers. 

Removable retainers 

In this section of the paper, he outlines the differences in effectiveness between Hawley and clear plastic retainers. Additionally, he points out that high-quality research shows that clear plastic retainers can offer some advantages over Hawley retainers. Moreover, importantly, patients tend to prefer clear retainers because of their better aesthetics. Furthermore, the results of RCTs also show that removable retainers are normally worn at night. They do not need to be worn full time.

When we consider the potential harmful effects of plastic retainers, there are recent concerns about microplastic leaching from these. However, the research is in its early stages, and we urgently need further research in this area. 

Nevertheless, we do need to bear this theoretical problem in mind when discussing retainers with our patients. 

The choice or removable or fixed retainers 

I think one of the major issues in retention is the choice between fixed and removable retainers. I went through several phases, preferring different types of retainers throughout my career, and eventually leaned towards clear removable retainers in my last few years of clinical practice. 

Simon points out that most evidence shows that within the first 6 to 18 months, there’s little difference in the effectiveness of fixed and removable retainers. There are, of course, several advantages and disadvantages of each of these methods, and he has provided this information in a clear table within the article. This provides a useful source of information for discussions with our patients. 

Shared decision making 

The final section of this paper addressed shared decision-making with our patients. Importantly, he points out that shared decision-making means taking treatment decisions with our patients rather than about them, and this has been shown to increase cooperation with treatment regimes. 

This means it is very important for us to discuss the advantages and disadvantages of the different types of retainer with our patients. This also brings me to retention review. It is clear that there is a need for long-term review of any form of retention, and the responsibility is shared among the orthodontist, the patient, and the general dentist.

In this respect, it is not acceptable to discharge patients and inform them that their general practitioner will look after the retainer. A more reasonable approach is to ensure that the general dentist understands the importance of retention, knows how to monitor retainers, and can make repairs. As a result, it is important that knowledge and skills related to monitoring retention should be included in undergraduate and Continuing Professional Development Courses. I cannot help thinking that this is easier said than done and may be the weak link in providing orthodontic retention. 

His overall conclusion was 

“Absolute stability after orthodontic treatment is not feasible, but it is possible to reduce unwanted post-treatment changes with appropriate use of retainers”. 

He has outlined this nicely in this paper. 

What did I think? 

It is unusual for me to review a summary paper. However, I thought this one was so useful that it was worth sharing more of the knowledge it contains. 

If we consider that the three components of evidence-based care are clinical experience, research evidence, and patient perceptions, then Simon has covered these very well in this publication.

Importantly, he has relied heavily on research evidence, much of which comes from randomised trials. He combines this very well with clinical experience and a substantial body of research on patients’ perceptions.

As a result, I feel this is an excellent publication, and we should all consider its conclusions when providing retention care for our patients.