Access Cavity & Instrument Selection

The root canal anatomy should be studied and evaluated before and throughout the treatment, and the proper procedure should be adopted accordingly.

1. Use a diagnostic pre-operative X-ray for initial evaluation of the case.
2. Prepare an endodontic access cavity with clear, unobstructed access to the orifice of each of the root canals.
3. Isolate the tooth properly. It is recommended to use a rubber dam and optionally an additional isolator paste around the tooth. Use an effective suction action to collect the overflow of the irrigant, yet refrain from placing the suction tip too close to the SAF itself, to avoid suctioning of the irrigant before it enters the file's lumen and the root canal.
4. Enlarge and funnel the canal orifice, if required, using the Pre-SAF OS NiTi rotary instrument, using lateral brushing motion, in order to allow a comfortable insertion path for the SAF. Note that the Pre-SAF OS has a short active part, 10 mm long, that should only be operated in the coronal 2-4 mm part of the root canal. Avoid pushing the Pre-SAF-OS too deep into the canal as it might form a ledge if the canal is curved.
5. When used in curved narrow canals (such as mesial roots of mandibular molars), the SAF, similarly to most other motorized endodontic file systems, requires straightening of the coronal access of the canal, to minimize the stress on the instrument. The SAF always requires a direct access to the canal, and should be operated along the vertical axis of the canal. When pushed into the canal in a diagonal manner and not according to the vertical axis, the SAF may buckle, which might lead to ineffective instrumentation of the canal walls and may also result in a mechanical damage to the SAF.
6. Establish the working length of the root canal using an X-ray and optionally also using an electronic apex locator.
7. Select an SAF with the appropriate length and diameter to match the expected working length and diameter of the canal:
   1. Length: Note that the length of the active (mesh) part of the SAF varies between the various file lengths. This active part should be at least of the same length as that of the canal when measured from the canal’s orifice to working length. An SAF with an active part that is too short for a given canal may not be able to reach working length, as the SAFs shaft (tubular part) cannot be compressed inside the canal. An SAF with an active part that is too long for a given canal may not properly deliver the irrigant into the root canal, as the irrigant may escape the file before entering the canal.
   2. Diameter: The diameter of the SAF should allow sufficient compression of the file inside the root canal. The following criteria should be applied:

• • SAF 1.5 mm should be used for canals with initial size of up to ISO #30.
  • SAF 2.0 mm should be used for larger canals, starting from ISO #35 and larger.

The following illustration describes the available SAF sizes: