In the last AAO meeting I was exposed to an interesting shift in terminology regarding post-treatment retention: from stability to maintainability.
I find it a very honest way to present facts to our patients. While studying dentistry I was exposed to a wide crowd of treated patients in their 30s-40s who were complaining that “Orthodontics has been useless” as a minor crowding was disrupting their smile or altering the lower incisors alignment. I was sad of being exposed to such a common disappointment (that actually produces a lot of invisalign-work… very often for a different colleague, as nowadays teens rarely spend the rest of their life where they grew up). Furthermore I found unacceptable not to be able to guarantee stable (or should I say maintainable?) results to my future patients. Since then the post-treatment maintenance of the results has been a major concern of mine. I cannot stand the idea that one of my patients could say that my work has been useless.
In the very first years of my orthodontic career I was using a lower fixed 3-3 retention and an upper removable plate. This seemed to me to be a careful approach, evidence driven and inspired to Little’s studies, pointing at the lower arch as the weak one in term of stability. Anyway patients are more prone to accept a minor to average lower incisors crowding rather than accept a minimal change into their smile. That’s why I felt obliged to re-treat some of my well finished Class I cases for free. They commonly presented some sort of minor rotation on the upper incisors in the follow-up period after gradually abandoning their upper removable retention according to my instructions (1.5 years on average after the end of treatment). Of course after fixing alignment I was bonding an upper fixed retainer, that is easier to be kept clean with respect to the lower, but it’s also weaker due to wear induced by chewing. Even if we carefully avoid direct occlusal contacts, the upper wire and the composite points fixing it to the teeth will always be subject to some sort of wear, much more than the lower one. The only dangers for the lower one are small particles of food (I hated peanuts for that reason) entering in between the wire and the interdental embrasures. My experience of former orthodontic patient with a lower retention made me hate peanuts and any other food of that kind, not to say mango and it’s fibers having some hateful hanging points that gave me a lot of extra cleaning work. As far as calculus would be the only burden to pay, I think that could be a good deal, but unfortunately that’s not all. I experienced the weakness of the traced wire on my self and a good number of my patients. The weakest point are interdental space where the wire is not covered by composite glue.
A standard retainer for one of my old patients
What if I cannot trust completely into fixed retention due to material properties?
I tried many wires from many companies, I did them my self, I bonded them directly and indirectly (I prefer anyway a lab-built indirect transfer jig, but to take an alginate impression with brackets and a wire on is pretty much annoying). I wasn’t anyway able to find something who made the difference and let me sleep quiet sleeps. until I saw this video of a special kind of wire.
The Memotain video that attracted me
I was literally enchanted and I was willing to try it on myself as it has been ages that I wanted to get rid of my old lower wire. In fact some years ago it broke between a lateral incisors and a canine, inducing a minor shift between them. This was the occasion that allowed me to experience the invisalign system as a final customer (something that was and still is extremely useful to understand the patients point of view). The aim was to get teeth straight and place a Memotain (https://ca-digit.com/en/produkte/memotain/). I was my first memotain case =)
Me with my old odd retention and a displaced 43 due to a never repaired breakage of the wire
Me with Memotain (and after invisalign lite, willing to test both of them on my self)
The wire perfectly adapts to interdental embrasures that in the lower arch are naturally minor, so that no particle of food can get stuck. It’s laser cut from a piece of Nitinol after designing a cad-version of it. It thus had a flexibility that allows physiologic toot movement and the precision of a customized virtual appliance.
Memotain entering into interdental embreasures
The personalization is particularly appreciated in the upper wires where anatomy of the teeth is naturally more complicated. The company gives a two years warranty on the wire in case of breakage, which is rare due the the material properties. It’s now two years that I am using it on any single patient and I experienced two breakages out of 150 wires installed (and it was in two patients with a crazy anatomy). In this case the company produce a piece exactly equivalent to the previous one to allow an easy rebonding.
The possibility of giving to my patient a really good and effortless chance of maintainability has no price, as it’s the price of my quiet sleeps =)
Stay tuned for the second part of this article to see how to manage the order and the bonding of such a great tool…
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