Cleaning and shaping of the apical part of the root canals
The coronal third of the root canal has already been prepared. Now it is relatively simple to clean the rest of the root canals when the right instruments are available.
If possible, the pulp chamber is always full of hypochlorite solution.
Using Rotary-files and hand files the canals are prepared crown down, till hand file 015 reaches the working length (already determinated with the apex locator).
Now a radiograph will be made with hand files 015 in the root canals.
Whilst waiting for the radiograph to be developed, cleaning and shaping is continued.
When the pulp chamber is full of hypochlorite solution, it is almost never necessary to clean the Rotary Files. This is because the centrifugal forces (at least 300 rpm), the files get cleaned when they are pulled back a little.
With the Operating Microscope it is good to see how the cleaning of the Rotary Files works.
When the radiograph confirms the length which was already measured with the apex locator, cleaning and shaping with Rotary Files will be continued until the main file has reached the determinated length. In between a small hand file is used to prevent blocking and forcing debris peri apically.
When the preparation is ready and sufficient hypochlorite solution has been used, rinse for at least 1 minute with EDTA 17% is necessary to remove the smear layer from the canal walls. Also lateral canals are filled better with gutta percha and sealer. After the use of EDTA, hypochlorite will be used again to remove the EDTA and clean the dentin tubules. Now the hypochlorite will be aspirated from the root canals. It is simple to do this by using the syringe which has been used to apply the hypochlorite solution. The needle gets deep into the root canal and after one second of aspirating the canal is empty. When root canals are connected (e.g. mesial canals lower molar), aspirating one canal emptis both canals. The use of one or two paperpoints is enough to completely dry the canals.
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Tip: Coloured paperpoints are handy to determine if there is any hypochlorite solution left in the apical part of the root canal. The paperpoint will be discoloured when there is still some hypochlorite solution in the root canal.
Tip: When the pulp chamber is full of hypochlorite solution, Rotary Files can be cleaned easily by the centrifugal forces of the File in the hypochlorite solution.
Tip: By using Chlorhexidin digluconate 2% for minimally 1 minute in the root canals, Enterococcus Feacalis (may be responsible for many failures)will be eliminated. Be careful when using the combination of hypochlorite and Chlorhexidine, because the dentin gets brown and it is difficult to discolour afterwards. EDTA in between prevents some of the browning but not completely!
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- Operating Microscope
- Gutta Percha Points
- Hand Files
- Paper-Points
- Rotary Files
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Length determination
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Obturate the root canals
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