10
If the canal is partially or completely invisible on the radiograph:
The canal is considered narrow = use an R25.
If the canal is completely visible on the radiograph:
1. Take an ISO size 30 hand instrument; insert it passively into the
canal. If it reaches working length, the canal is considered large =
use the R50.
2. If an ISO size 30 hand instrument does not go passively to working
length, try an ISO size 20 hand instrument. If this goes passively to
length, the canal is considered medium = use an R40.
3. If a size 20 hand instrument does not go passively to length,
the canal is considered narrow = use an R25.
Passively means that the instrument goes directly to working
length with a gentle watch winding movement (small right left
rotations) but without filing action.
• Preparation with the R25 – Getting started:
Prior to preparation with an R25, estimate the working length with the
help of a pre-operative radiograph. Set the stopper at 2/3 of that length.
To Next Page
Loading...