How to perform obturation with confidence

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Charlie Nicholas continues his ‘how to’ series, focusing on endodontics. He considers what is needed to fill empty root canals, promote hermetic sealing, and prevent bacterial activity from infiltrating the periapical tissues

Obturation is an interesting step in endodontics. It’s not going to make or break successful treatment. That is down to how well you clean the canal and eliminate bacteria. And yet, it is a fundamental step. Not least because the obturating material is what will be seen on the X-ray. It’s a visual measure of treatment.

For instance, if you see a short root filling, it’s not just that the root filling is short of where it could have gone to. More significantly, it is short of where it should have gone to because you blocked it, or your cleaning is short. 

So, you can usually get your filling as far as you’ve got your cleaning instruments, The X-ray is showing you that there is still debris in the canal, as well as the potential for endotoxins. A need for retreatment is on the cards. 

Obviously, there are exceptions to that, but most of the time that is what a short fill will signify.

Choosing your filling material

So, having clarified what can happen if a fill is short, let’s now look at what is needed to get it done right.

Gutta percha (GP) is perhaps the best-known element of the obturation process, and it has stood the test of time. In 1847, Truman introduced the use of GP as a temporary filling material. As is always the case in dentistry, things moved apace and in 1867 Bowman was the first to use GP to fill root canals.

Since then, GP has been universally accepted for obturation, however there are some challenges with it, especially if you opt for the cold lateral condensation (CLC) technique, which uses pressure to complete the fill. One of the biggest dangers – apart from not achieving a hermetic seal – is that you can fracture a root by putting too much pressure on it. 

In addition, GP does not chemically bond to internal tooth structures, and it is hydrophobic, which can result in an incomplete seal and, ultimately, endodontic failure. 

Warming technique

These issues can be mitigated to some extent using a warming technique. One possibility is the System B method of obturation, created by Buchanan. It uses the continuous wave of condensation protocol, which uses heat but, of course, heated GP will shrink when it cools – by about 4% – which is important to keep in mind.

That caveat mentioned, essentially, you use a cordless backfill obturation device like the Diadent Dia-Duo Complete System, which delivers precise, 3D obturation. 

I particularly like this product over others out there because the Duo Pen offers excellent warm vertical compaction with a quick heating tip. Then the Duo-Gun, with its quick heating system, facilitates fast and perfect obturation delivery. Duo-Gun and Duo-Pen are in one charger, which is a space saver. 

Bioceramic sealer

Aside from GP, a newcomer to the marketplace is the bioceramic sealer. You don’t need new kit to use them, because they are compatible with warm obturation units. Evidence suggests this offers the best of both worlds – biocompatibility and hermetic sealing. 

These bioceramic sealers release hydroxyapatite, which bonds to dentine, and releases calcium hydroxide when they set. That results in a high pH during the setting process, which means it’s antibacterial as it hardens. Plus, bioceramic sealers are hydrophilic, so they will absorb moisture in the dentinal tubules, helping with the bond to dentine.

For me, pre-mixed bioceramic calcium silicate-based MTA Dia-Root Bio Sealer from Diadent is ideal for the job. Its non-shrinking feature and strong bonding ability make it the perfect sealer for permanent obturation and is suitable for all obturation techniques with gutta percha. Bioceramics can be expensive, however this offers really good value combined with great outcomes.

The main caveat is that bioceramic sealers set rock hard, so you can’t fill the entire canal with it otherwise you would never be able to retreat. If you use a GP cone within it, that can act not only as your apical control but also your path to retreat, running your rotary files through that cone.

Cone considerations

While we are on the subject of cones, the classic mistake that people really struggle with is getting that GP cone far enough down the root canal. The good news is there is a simple technique to help eliminate this potential problem. 

Let’s say you have a working length of 20mm. What you don’t want to do is pick up your matching GP cone, pinch it at 20mm and then make sure it fits. This is because you’ve stopped it going any deeper. That cone might want to go further because the end of the root canal is an open hole. 

What you need to do instead is seat the matching GP cone down into the root canal, press it firmly with the top of your finger, pinch it with your tweezers at your reference point, and then take it out and measure how far down the root it is going. 

If it’s going 21mm, it’s going 1mm too far. If you have cut to 20mm without that check, when you take your obturation X-ray you will see that by putting pressure on the filling material you have gone through the end of the canal. Done the right way, you can get the cone to fit spot on within the end of the root canal preparation and you will get a really good tug back. 

The other main issue that people have is their cone doesn’t go far enough. Again, the solution is simple – get eye level with your working length measured on a stopper on your file. By doing that, you can ensure that file goes exactly where you want it to without any mistakes.

Respecting the anatomy

As always during endodontic treatment, respecting the canal anatomy is key to success. We are lucky to be practising in times when advances in materials and technology can help us in our efforts.

The upcoming year is no exception, with the launch of Varyflex Neo files, for example, with their small constant tapers that make them ideal for use in narrow or curved canals. In addition, their fixed taper preparation allows for more predictable cone fit and obturation. They will be a welcome addition to the award-winning Varyflex range of endodontic files, awarded ‘product launch of the year’ at the Dental Industry Awards 2021.  

When combined with the likes of Diadent’s Dia-Duo Complete System and Dia-Root Bio Sealer, you can feel confident you have everything you need for a successful outcome at your fingertips. 

Obturation – simple sequential steps

  1. Apply an effective irrigation regime
  2. Make sure the root canal is patent
  3. Place GP cone in the root canal and firmly seat it down
  4. Pinch it with tweezers and take it out
  5. If it’s long, trim it with scissors or with a scalpel blade, and try it back in until the right length is achieved
  6. Take a confirmation X-ray
  7. Dry the root canals with matching paper points
  8. Put a tiny bit of bioceramic sealer in the top third of the root canal
  9. Clean the access cavity
  10. Place the pre-measured GP cone down into the root canal
  11. Trim the top(s) of the cone(s) carefully
  12. If using the Nyarr technique, pack restorative in the top of the canal.

Find the first article in this ‘how to’ series here.

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