Orthodontic treatment with customised fixed appliances – a randomized clinical trial
This guest post is by Martyn Cobourne, Chair of Orthodontics at Kings College, London. It is on a recent trial of customised fixed appliances.
Kevin asked me if I would write a “guest post” for his blog . How could I refuse?
He has also previously mentioned that we both grew up in the same village in England called Hagley. This is in the rural county of Worcestershire. We didn’t know each other in Hagley (Kevin is a decade older than me, although he says you cannot tell) but it is slightly weird to think that two boys who grew up in a small village in the middle of England have both ended up as academic orthodontists. This is a picture of us at School…
Not only that, we seem to have developed the same taste in music! Those aficionados amongst you will have noticed that Kevin likes to use song titles and lyrics for some of the headings contained within his blog posts and seems to be a particular fan of Pink Floyd. Given that he comes from near Stourbridge, he should be using Led Zeppelin or Black Sabbath lyrics a bit more I think! He should also have supported West Bromwich Albion football club and not Manchester United. Anyway, as fascinating as I am sure all of this is to you, I am digressing too much and I will now focus on my contribution!
A randomised trial of customised appliances
As a journal editor and reviewer I have to read and pass comment on a lot of orthodontic research. On the whole, I find this a pretty depressing experience because of the lack of imagination in many of the questions that are asked and the poor quality of the research that is sometimes done. There are too many orthodontic journals needing articles to fill them up. As a result, there is a lot of research being published that probably should not be.
Fortunately, it is not all doom and gloom and occasionally you do see a research study that asks a relevant question and attempts to answer it using the most robust methodology that is reasonably possible. As a result, I was very interested to read this new paper done by a team from the Netherlands. The Journal of Dental Research published this study. This is the highest impact factor dental journal and it publishes papers covering the whole of dentistry. The review process for this journal is very robust. This is reflected in the quality of this investigation.
Penning et al.
J Dent Res 22034517720913. https://www.ncbi.nlm.nih.gov/pubmed/28742420
The advent of digital technology is now providing orthodontists with increased choice in the appliance systems that they can use. Ormco InsigniaTM is a fully interactive custom fixed appliance that uses patient-specific brackets, computer-assisted bracket placement, customised archwires and indirect bonding.
This new system may have some obvious theoretical advantages. These are concerned with overcoming the known shortcomings of direct bonding with off-the-shelf brackets and archwires. It is suggested that these systems reduce treatment time (the current Holy Grail of orthodontics) and give us better treatment outcomes. However, customized appliance systems come at an increased cost for the orthodontist. For example, they require time away from the dental chair for planning treatment.
The researchers for this RCT started with a very simple primary question:
“Does using InsigniaTM customised appliance reduce treatment time”?
To answer this question, they randomised two groups of patients to treatment with fully customized InsigniaTM self-ligating brackets or non-customized DamonQTM brackets. Each orthodontist used archwires selected through the digital planning system or from a range of generic archwires for each group. They saw the patients every 8 weeks during alignment and every 6 weeks thereafter.
They powered the study on the basis that a 4 month reduction in treatment time would be significant. Two operators did the treatment in two private practice settings. Importantly, both operators were experienced users of the appliances.
They randomised 90 subjects within each practice to one of the two appliances. The primary outcome was treatment duration.
What did they find?
They found that there was little difference between the groups at the start of treatment. However, there was a slightly skewed male/female ratio in both samples. Furthermore, the InsigniaTM group had more class III cases and slightly more cases with an increased overjet (although not significant).
There was minimal loss to follow up and they did an intention-to-treat analysis.
Interestingly, there was no significant difference in treatment duration between the groups, both taking just under 1.3 years.
Not surprisingly, the higher the pre-treatment PAR score, the longer the treatment duration, the more visits and the poorer the final outcome. In addition, the orthodontist had a significant effect on both treatment duration and outcome. Importantly, overall treatment outcome was not significantly different between appliance groups.
I thought there were a few other interesting findings. Perhaps not surprisingly, the InsigniaTM group required significantly more planning time for the orthodontist; whilst perhaps more surprising was the finding of significantly more bracket failures in the InsigniaTM group. So overall, there was no evidence that using InsigniaTM reduces treatment time or quality of treatment result. This finding is different to a retrospective study published a few years ago.
What did I think?
A few points to perhaps consider. They started this study in 2011. Since then there has been significant development and refinement of the InsigniaTM system. The participants had relatively mild malocclusions, although this is unlikely to have disadvantaged either system.
What I like about this study is that the investigators asked simple, straightforward and clinically relevant questions about a new technology with a robust experimental design. They did not carry out a complex cephalometric analyses (Kevin will be pleased).
Is InsigniaTM worth the extra planning time, expense and increased bracket failures? Not at the moment according to the best current evidence.
Emeritus Professor of Orthodontics, University of Manchester, UK.