Fixed retainers fail a lot! A new trial
Retention is one of the most important parts of orthodontic treatment. Surprisingly, we do not have a substantial body of evidence to help us decide our retention regimes. This new trial shows that there is a high level of failure of bonded retainers. It made me think about my retention regimes.
Retention is a “hot topic” in orthodontic treatment at the moment. We need more high-level research into methods of retention. Importantly, these studies need to report on long-term outcomes. The investigators in this new trial looked at important outcomes two years after placing retainers. A multinational team from Poland, Switzerland, and the Czech Republic wrote this paper. The AJO-DDO published it.
What did they ask?
They did this study to answer this question;
“Are there any differences in survival time and periodontal health when using a round or rectangular wire fixed mandibular retainers”?
What did they do?
They successfully did a randomised controlled trial with a parallel-group 1:1 allocation. The PICO was
Participants: Orthodontic patients who needed fixed mandibular retention from canine to canines. One private office did the treatment.
Intervention: Fixed retainer made from 0.0265X0.016 inch 8 strand rectangular braided wire.
Comparator: Fixed retainer constructed from 0.0215 inch round wire
Outcomes: First-time failure and periodontal health.
The retainers were all placed by one experienced operator. The investigators collected data when they placed the retainers at 3, 6, 12,18, and 24 months after placement. They recorded the time to failure and periodontal health with the Periodontal Index, Bleeding On Probing, and Plaque Index.
They used pre-prepared block randomisation and concealment in sealed envelopes. Then, the study coordinator opened the envelopes. This method is a high level of concealment from the operator.
They could not collect the data blind. This issue is important, and I shall return to this later.
What did they find?
They enrolled 133 participants in the study and analysed data from 132.
They found that there was a high failure of retainers in the two years of the study. For example, 37 (56.1%) of the round wire group and 32 (48%) of the rectangular wire had a retainer failure. However, there was no clinical or statistically significant difference between the two interventions.
When they looked at periodontal health, there were no differences between the groups for all the indices. But importantly, they found that periodontal health was good and not influenced by the retainers.
What did I think?
I thought that this was a very nicely done and written-up trial. The authors and the journal used the CONSORT guidelines, which made it easy for me to interpret the findings. If you can access the paper, it is well worth reading it.
The most surprising finding was the very high failure rate of the retainers. We also need to realize that the authors only looked at lower retainers. As a result, I wonder if the failure would be higher if they had included upper retainers? When I think about my clinical practice, I am sure that my retainer failure rate was not this high.
The authors discussed this finding in detail. Their most compelling reason for this finding was that they meticulously looked for any failures in this trial. Furthermore, other studies were retrospective and subject to selection bias. Finally, they felt that other trials reported similar failure rates. However, I could not find a reference for this statement?
I also thought that it was a shame that they did not record any harms from the retainers. For example, unwanted tooth movements. Nevertheless, it was great to see that they are doing this in a longer-term five-year follow-up of these patients.
The authors reassured me that the retainers did not affect the periodontal measurement, which adds to the evidence on this important possible effect of long-term retention.
The results of this trial certainly made me think about fixed retainers. When I was working, I tended to use VFRs because I was concerned about periodontal health and failures. However, this has a “trade-off” of relying on cooperation. Nevertheless, this trial provides us with very useful information on our retainers, and it is a valuable piece of research.
Emeritus Professor of Orthodontics, University of Manchester, UK.
Have your say!
interesting outcome and very high failure rate, they initiated majority were debonds and that IMHO indicates their bonding regime was flawed
My own in house audit consistently finds 13-14% failure in the first 3 months dropping to 1% by 12 mths with a 0.3% ‘total’ failure where the retainer needed replaced.
Their bond failures i would suggest is due to poor isolation/poor preparation.
If they prepared the enamel surface by simply abrading the surface with a round diamond bur increases bond strength by >80% (hadad & hobson Dent Mater 2006 22:870-4). The next difference is you should use Transbond MIP (moisture insensitive primer) and finally use a posterior flowable composite eg 3M Filteck Supreme or Kulzer Venus diamond – they have higher hardness numbers and wear
so as the study does not match my own data and not using same materials/techniques i have to ignore the outcome
Thanks for your insight.Even I have very little failure rates.
Hi doc, thanks a lot for your blog.. yes we face a lot of problem with failure if fixed retainers.. I would like to know what is your advise for fixed retainers? What is best startegy for retention?
The failure rate seems quite high. Looking at the methodology of their intervention, I do wonder if it is related to the technique of placement. I would have loved to see a 3-arm parallel RCT looking at failure rates related to technique of placement of bonded retainers. I think sandblasting the tooth (or another method of roughening) and placing composite under and above the retainer could reduce failure rates.
I only used fixed 3-3 lower retainers when canines have been expanded (rarely) and if the canines were rotated (fiberotomies are a must). If one maintains archform, uprights and at least not flare lower incisors, and maintain lower intercuspid width, then fixed retainers are not needed. After 38 years of practice we have excellent stability without permanent retention. Fixed retainers are a hygiene disaster and do not allow for expected developmental changes. Published studies support this in the AJO.
I hated bonded retainers. They were very technique and equipment dependent, especially the 3 in 1 for drying the enamel. Also patients didn’t notice if a pad became detached until too late, resulting in unwanted tooth movement. No, it was VFR’s for me! A good study though.
Very surprised to see such a high failure rate on a procedure we have excellent long term success, like I see patients in restaurants that come up and show me their lingual retainer still in place after 30 -40 years, honest truth! I always tell patients an upper bonded retainer will eventually debond at the worst possible time so we have an Essix back up. I use a .0175 twist flex precisely bent to the model then never touched without gloves after sandblasting and alcohol cleaning. I use a debonding bur to really clean the lingual canine to canine and then pumice before etching. After etching we use super dry air (no dual water and air syringe which always blow moisture) and a tooth dryer ( hot air) so we are really dry field.(no mouth breathing) I then use 3M Transbond flowable on each lingual surface,and wet the lingual arch with liquid and nest it into the flowable composite. A little tweaking with an explorer to smooth out and accurately position and light cure each tooth. If necessary we add where needed and re cure. Last step it to varnish over the entire lingual surface with liquid and light cure again.All patients are welcome to remove their bonded lingual when they read my obituary in the paper, but I might haunt some of them from the grave if they do.(couldn’t resist the final instructions) John B. Harrison
Jack Sheridan may have had the best rationale for the use of VFRs as retention. He always told patients, ” I am the creator of your smile. You are guarantor of your smile.” At some point patients need to take responsibility for their orthodontic correction, and VFRs provide a reasonable and effective way of doing that.
As others have said, success of bonded retainers is mostly relative to the use of the proper materials, exacting technique, and instruction of patients in the care of them after placement. When I taught students at NYU the placement of mandibular lingual retainers, we used Ortho Flextech Chain by Reliance Ortho which was flat and would lay flat on the lingual surfaces preventing undesirable forces on the teeth as those that may occur with flexible round wire. We also used Assure Plus Enhanced Sealant by Reliance Ortho that we allowed to become slightly cured and “tacky” so it would hold the chain in place while we bonded the chain with the same as Dr. Harrison, 3M Unitek Transbond Lingual Retainer bond adhesive. The exacting technique included plaque and calculus removal on the lingual tooth surfaces first, excellent isolation preventing the tongue from contacting the surfaces at all, controlled etching, placement of Assure Plus, letting it “dry” until tacky, exacting placement of the precut chain to a more incisal position on the lingual surfaces, placement of LR adhesive just over the chain starting at the central incisors, curing the centrals, then moving out to bond the chain at the canines. Floss could also be used to hold the chain in place. After the placement, we showed the patient how to floss under the retainer without pulling it off and had the patient demonstrate the procedure. I used a video PowerPoint to teach this to students online and then worked with the students when they performed the procedure in clinic. We had great success using this method.
In my private practice I tell my patients to expect a ten year life from a fixed retainer, and hope for twenty years. We have very little trouble from fixed retainers, they are very reliable if placed correctly. But it is very technique dependent. There is a serious flaw in this study.
If there is one procedure that is highly technique sensitive in orthodontics it is placement of a lingual bonded retainer. Apart from the technique the different materials used to bond the retainer, in my opinion also makes a difference. I would hence take the results of the study with a pinch of salt.
My method is as follows, I do see some failures few and far between:
1. A week to 10 days before deband the patient gets a good clean. I specifically mention to remove any or all calculus and stains from the tooth surface. If the patient presents for a deband without having the clean the appointment is postponed. A clean done on the same day as deband is a recipe for disaster and we all know why.
Why step no 1: Any calculus or stain on the tooth surface will lead to bond failure
2. On the day of the deband I use a rubber cup to pumice the lingual surface of the lower anteriors, 3-3 non-extraction and 5-5 extraction case. This step is really important as if you use a polishing brush or if you polish overzealously then the gums bleed.
Why step 2: We all know why pumice is used instead of polishing paste
3. Previous appointment to deband lower impression 3-3 is made and an 0.0175 co-axial or twist flex wire is custom made to fit the lingual surface passively and is ready to bond. I personally check each wire to make sure it is bent correctly and make any adjustments before placing it.
Why step 3: A passively placed wire on each tooth surface decreases the amount of glue between the wire and the tooth so chances of failure is reduced.
4. Etch only the area you want to bond, flowing a lot of etch on all the teeth and onto the gums does the following.
– It prepares the teeth to receive the bond and bond and composite flows along the etch lines and can flow interdentally and would not even be visible to you.
– Etch is acidic and stimulates the sublingual salivary glands and thus results in excess saliva just behind the lingual surfaces of the lower incisors.
5. Place the wire using 3 M jigs and bond using 3M transbond flowable composite. Tell the patient not to eat anything too hard for the next 24 hrs.
I perform all the steps myself and delegate no step to anyone else. My retention protocol is lower lingual bonded retainer and upper Essix retainer. My final advise to the patient is based on what Dr Larry White said, Your smile is your responsibility so you need to take care of it.
Please note: It does help to have really well aligned lower anteriors another requisite to avoid bond failures.
It would be foolish to generalise the findings of this study to anywhere beyond this study.
I see almost no bond failures in my thousands of lower fixed retainers in current use.
Bonding to six teeth has three times the chance of failure compared to bonding to two teeth.
I bond two, using foil-mesh pads on the canines with a dead soft (not spring) bar across the span. We clean the canine enamel surfaces with a football shaped multi-fluted composite debonding bur, because almost no other technique removes calculus and proteins, which are much too tenacious for easy removal by brush.
Agree with Larry White quoting Jack Sheridan. Reading the comments above, there are many inconsistencies. The only consistencies I can glean are that bonded retainers present a problem for both clinicians and patients, that they inevitably fail, (albeit some 30 years later) and that they are technique sensitive.
The most glaring conflict is that some clinicians construct a VFR “in case” (inevitable, just a matter of time), the bonded fails.
If we accept that:
– failure of bonded retainers place patients at higher risk of clinically significant tooth movement (we often ignore in research and clinical life that teeth may move significantly even if the bonded does not fail)
– that bonded retainers may fail without patients noticing
– for the back-up VFR strategy to be successful relies on the patient noticing immediately at time of failure, and then undergoes a steep learning curve in compliance
:then this strategy is a Poor Plan B.
Arguably no more successful than constructing a VFR at deband (or prior to using digital technology) , educating patients PRIOR to commencing treatment that they will be responsible for using the VFR as the only insurance for their newly created occlusion / smile, it will hold the entire “bite”/ erupted dentition if worn correctly, it will be easier to floss and to maintain a high standard of hygiene, and retain the upper arch, not just the lower anteriors as is most common in bonded retainer territory.
Yes this is a steep learning curve, but it is the same as what clinicians using the Plan B of VFR together with bonded are asking their patients to climb, simply at an earlier point in treatment when patients are most invested in their result – at deband; not months or years later when most patients are under the illusion that unlike everything else in the universe, their teeth don’t move….
And BTW – this is only a steep learning curve for fixed appliance patients, those using removable orthodontic appliances are already practiced in VFR use.
PS. A benefit of the digital technology used in the construction of the VFR today, if patients do for various reasons – travel, illness, loss, compliance; slip up , we may simply use the original scan to order new VFR (or move into the next one as multiple are supplied), to activate movement in the direction of the original alignment. This digital record allows us to eliminate many retainer “emergencies” of the past.
How can this study show there is no effect on periodontal health?
Since no control group is used where no bonded retainer is in place.
Lower cuspid width maintenance is rightfully sited as a major consideration in lower fixed retention. But the shape of the mandible is a neglected variable. Square or tapered lower arches where standard ovoid archforms are almost always used are particularly vulnerable to retention failure.
Surely bonding technique can be a problem. But I find studies that lack sophistication to incorporate other significant variables to be an even bigger concern to the “science.”
A well isolated area, and restorative composite, proper polished enamel,,,also air dry each tooth again just before placing composite, and then light cure. I have noticed that breath also contaminates the surface of prepared tooth, thus jeopardizing the bonding.