If you do root canals, you’ll use the kind of sealer you were trained to use, or the kind you’re used to using, or the kind that seems to work best for you. We’re largely creatures of habit.
But sealers aren’t all the same.
Ideally, every sealer should be easy to mix, and should adhese nicely, and should seal well, with no shrinking or staining. It shouldn’t dissolve over time, but it should be soluble enough that you can take it out easily if you need to. it should be bacteriostatic, and it should show up clearly in radiography. Above all, it should be as biocompatible as possible, so it doesn’t irritate periradicular tissue.
There is no sealer that does all these things perfectly. There are now half a dozen different types on the market, and each of them has its relative advantages and disadvantages. Some of these sealers are zinc oxide-eugenol-based, some are resin-based, or glass ionomer-based, or they’re silicone-based, or calcium hydroxide-based. The ones that aren’t these are the bioactives. (We’ve got the range of them at Sky Dental, and you can have a look.) Chemically, these sealers are built differently, so they work in different ways. That makes them difficult to compare. In the end, clinicians generally just choose the ones they like best overall.
The problem of irritation does come up a lot when our customers talk to us about how to choose. It’s not for us to tell you how to manage your patients, of course, but we do know quite a bit about the in vitro cytotoxicity studies out there, and the in vivo biocompatibility studies too. There’s been quite a lot done in this field. It’s pretty scattered, though, and the studies vary enough methodologically that easy conclusions about which sealer is kindest to tissue aren’t really possible yet.
Still, it’s worth knowing the rundown of the studies generally, on biocompatibility and the different kinds of root canal sealer.
Broadly speaking, without mentioning brand names, it seems warranted to say that in vitro toxicity is lowest in bioactives. The problem is, however, that the studies vary tremendously in parameters like setting time (ranging from an hour to a month), setting condition (freshly-mixed vs. set materials), and extract concentration. It seems that freshly-mixed and longer-setting materials are more cytotoxic, though nobody’s sure quite why. Higher concentrations, logically enough, also seem more cytotoxic, though it’s not clear how or if this translates into clinical practice.
In vivo? All sealers elicit inflammatory response. No sealer has shown itself to be unacceptable for clinical use in this respect, however. Interestingly, the severity of response – read this carefully – is, so far, independent of type. This seems surprising, on an intuitive level.
It’s worth saying that the methodology of these trials, as in the in vitro ones, is heterogeneous. Some studies assess periapical response, others assess subcutaneous response, others assess intraosseous response. Some focus on the influence of exposure time. (Inflammation seems to subside, but data actually conflict on this.) Across all the studies, whatever their focus, there is consistently high risk of bias. That’s a problem. In a number of the studies, it’s not even clear how randomized they were, or whether they were blinded properly, or even how they measured outcomes. The apparent findings of in vitro studies, to say it bluntly, have not been confirmed definitively by in vivo studies so far.
That isn’t to say that the answer isn’t forthcoming. There just isn’t enough data yet, harvested in methodologically sound ways. We’ll keep you posted on studies that compare similar conditions and concentrations, in clinical settings, or at least using human fibroblasts instead of animal ones (which is another problem). It will be a while yet, until we know – really know – which kind of root canal sealer to use if biocompatibility is your big criterion of choice.
In the meantime, if you’re shopping with us, you might have a look at a popular bioceramic sealer called BioRoot RCS, from Septodont. It’s mineral-based, for permanent canal obturation. It doesn’t stain, and there’s no post-op sensitivity. It’s easy to use, it stays leak-free for a long time, and because it’s got a high pH, it keeps the bacteria down. It’s biocompatible, in other words, and it’s even resin free. We offer it in a 35-application pack, with pipette and spoon, ready to use.