Orthodontic retainers: impact on periodontal health

The use of retention is necessary to maintain the position of teeth following orthodontic treatment. A range of retention procedures are used although a recent Cochrane review highlighted the lack of evidence to favour one approach over another. Increasingly a need for long-term retention is being recommended and prolonged retention may increase periodontal and hard tissue problems. Consequently, it is important to investigate the impact of fixed and removable retainers on the supporting tissues

The main aim of this systematic review was to determine the influence of fixed and removable orthodontic retainers on periodontal health in patients who have completed orthodontic treatment with fixed appliances.

Methods

Searches were conducted in the Medline/PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), LILACS, BBO, ClinicalTrials.gov, National Research Register, and the ProQuest Dissertation and Thesis database. Randomised and non-randomised controlled clinical trials, prospective cohort studies, and case series with a minimum sample size of  20 patients and minimum  6 months   follow-up were considered. Two reviewers independently selected studies, abstracted data and assessed study quality. The Cochrane risk of bias tool and the Newcastle- Ottawa Scale were used for quality assessment.

Results

24 studies (18 RCTs; 6 prospective cohorts) were included.
11 RCTs and 5 prospective cohorts were considered to be high quality.
7 studies assessed periodontal outcomes and meta-analysis was not possible
There was a lack of evidence to endorse the use of one type of orthodontic retainer based on their effect on periodontal health
The mean failure risk for mandibular stainless steel fixed retainers bonded from canine to canine was 0.29 (95%CI: 0.26, 0.33) and for those bonded to canines only was 0.25 (95%CI; 0.16, 0.33).
Meta-regression suggested that failure of fixed stainless steel mandibular retainers was not directly related to the period elapsed since placement (P = 0.938).

Conclusions

The authors concluded

There is a lack of high-quality evidence to endorse the use of one type of orthodontic retainer based on their effect on periodontal health; risk of failure, patient- reported outcomes, and cost-effectiveness. Further well- designed prospective studies are therefore required to provide further definitive information in relation to the benefits and potential harms of prolonged retention.

Comments

This well conducted review highlights a lack of studies examining the relative outcomes from long-terms orthodontic retention. This might not be surprising given that a recent Cochrane review (Dental Elf- 1^st Feb 2016) looking at evidence for the best retention procedures concluded;

Overall, there is insufficient high quality evidence to make recommendations on retention procedures for stabilising tooth position after treatment with orthodontic braces. Further high quality RCTs are needed.

This current review was focusing more on periodontal health, survival and failure rates, patient-reported outcomes, and cost-effectiveness areas that while important are less frequently examined by researchers. With long-term retention comes the need for long-term studies in order to assess a wide range of outcomes of so while this review had a minimum of 6 months follow up none of the included studies was longer than 3 years. With increasing use of long term orthodontic retention more well designed and reported studies are needed to inform clinical practice.

Links

Primary paper

Al-Moghrabi D, Pandis N, Fleming PS. The effects of fixed and removable orthodontic retainers: a systematic review. Prog Orthod. 2016 Dec;17(1):24. doi: 10.1186/s40510-016-0137-x. Epub 2016 Jul 26. Review. PubMed PMID: 27459974; PubMed Central PMCID: PMC4961661.