Why is it that most Endodontists use warm GP for obturation?
Well, According to Schilder, 1967, the root canal system is best obturated in a three dimensional way. Most canals have an oval shape, where-as GP has a rounded cross section. Thus using a single cone technique is simply not going to fill a canal in three dimensions.
The cold lateral condensation (CLC) technique is also limited and unable to fully obturate oval shaped canals, lateral canals or isthmuses (Wu, Kaštáková, & Wesselink, 2001).
Warm GP is therefore the current way to go!
There are many systems and techniques including, warm vertical condensation/compaction, thermafill/guttacore etc. Lets focus on the most common – warm vertical condensation.
Step by step guide to warm vertical condensation/compaction
- Get the equipment! You need x2 units – one heated plugger and one back fill unit. (e.g. B&L SuperEndo Alpha and Beta Kit or System B and Obtura) – An endodontic plugger/S Kondensor is essential!
- Make sure the canals are prepared adequately, cleaned well and dried.
- Choose your master apical point based on the minimum size of the apical constriction and ensure there is good true apical tug back – see Apical Gauging
- Choose a plugger tip and insert it into the canal. Mark the depth at which it binds to the canal with a rubber stopper. (Try to choose the largest plugger that goes to within 4-5mm of your working length, although it may not always be possible to get that deep in every case)
- Insert a coated matching gp point into the canal and trim off the excess at orifice level
- Condense the GP at the orifice left with the large end of an endodontic plugger (S Kondensor)
- Insert the heated plugger into the canal whilst activated, applying firm pressure – stop 1mm from the marked stopper.
- De-activate the heat, whilst still maintained apical pressure for approximately 8-10 seconds
- Activate the plugger and push apically the final 1mm and swiftly pull the plugger out – this step should be done quickly in 1-2 seconds – you should have pulled out a “bite” of GP, leaving an apical .
- Condense the apical GP with the fine end of an endodontic plugger (S Kondensor)
- Place the backfill unit (Obtura or alternative) into the canal as close to the apical portion of GP. Squeeze and express GP but let the pressure GP draw the tip out of the canal, do not pull back as you can get voids
- Condense the expressed GP into the canal carefully with an endodontic plugger.
It takes practice and doesn’t always go to plan! Practice on extracted teeth first to gain confidence. If things don’t go well, you can always start again!
Note: there are variations to this technique but the principle remains the same; three dimensional obturation.
Schilder, H., & Hargreaves, K. M. (2006). Filling root canals in three dimensions. Journal of Endodontics, 32(4), 281–290. https://doi.org/10.1016/j.joen.2006.02.007
Wu, M. K., Kaštáková, A., & Wesselink, P. R. (2001). Quality of cold and warm gutta-percha fillings in oval canals in mandibular premolars. International Endodontic Journal, 34(6), 485–491. https://doi.org/10.1046/j.1365-2591.2001.00463.x