What are the basic ways of preparing instruments with a hand root canal?

Hand root canal preparation instruments are divided into two basic methods: filing and expanding.

File type: Insert the root canal to the working length with a thin root canal file that can reach the working length, and then pull the instrument out against the root canal wall, cutting the dentin wall during the pull-out process. The action of rotating instruments is not included. Repeat the above movements several times along the root canal wall in all directions until the root canal has been enlarged to the extent that the root canal file of a certain number can reach the working length without resistance, and then replace the instrument with the larger one, and prepare the root canal one by one according to this method. The filing method is safe and does not break the instrument easily. However, the linear movement of the root canal instrument being pushed and pulled out in the root canal is similar to the movement of the piston in the cylinder, which is easy to push the dentin debris under the file and the infectious substances in the root canal to the apical direction, and it is easy to block the root canal at the root apex or push the debris and infectious substances out of the apical hole.

Expanded: It is by rotating the root canal file, so that the rotating instrument cuts the root canal wall and drills into the deep part of the root canal. When the instrument rotates clockwise, the debris inside the root canal moves along the thread of the instrument towards the root canal opening. Therefore, the expansion type is beneficial for removing debris from the root canal. Because the expansion type is easy to lead to the device breakage, the combination of expansion and filing is mostly used in clinical use of hand instruments. If the instrument is turned clockwise (< 90° angle), the instrument blade cuts the human dentin wall, then releases, and then pulls the instrument back towards the root canal mouth to cut off the dentin that has been "bitten" by the instrument blade. Repeat until the instrument reaches the working length. Switch to a large one, and so on to complete root canal preparation.

These are of great significance in clinical work, and with the popularity of machine files, the status of hand files has gradually declined, but they are still an indispensable part of clinical work and can be used to treat more complex dental procedures.