The separation of an endodontic file within a root canal is a challenging complication for any dental practitioner. Fortunately, modern ultrasonic technology, such as the Satelec P5 unit with its specialized endodontic tips, provides a reliable and minimally invasive method for retrieval. This guide outlines the clinical protocol for removing broken instruments.
Initial Assessment and Tip Selection
First, a radiograph is essential to accurately determine the position of the fractured instrument within the root canal.
Next, measure the estimated length from the occlusal surface to the apical end of the broken file fragment. This measurement will dictate the initial selection of ultrasonic tips:
- For fragments less than 18mm deep: A combination of the ET20 and ET25S tips is recommended.
- For fragments approximately 18-22mm deep: A combination of the ET20 and ET25 tips should be used.
- For fragments deeper than 22mm: A combination of the ET40 and ET25L tips will be necessary.
Creating Access: The Staging Platform Technique
The key to successful retrieval is creating adequate access to the broken instrument. This involves preparing a “staging platform” or trough at the coronal end of the fragment. The goal is to create a space that fully exposes the cross-section of the broken file, allows direct visualization (and light to reach it), and provides straight-line access for the smaller, active ultrasonic tips.
This staging preparation can be initiated with endodontic files or manual instruments, but the ET20 tip is highly effective for this task. Use the ET20 to carefully remove dentin around the file fragment until its surface is flush with the surrounding canal wall. In most cases, the wider ET20 (or the longer ET40 for deeper canals) works in synergy with the slimmer ET25 series. The wider tip creates the platform, allowing the thinner tip to be inserted alongside the fragment to dislodge it.
Instrument Retrieval
Once the staging platform is complete and the fragment is exposed, the finer tip is brought into play. Insert a tip from the ET25 series (e.g., ET25S) into the space created, alongside the broken file. Activate the ultrasonic unit, moving the tip in an apical direction to vibrate the fragment and work it loose from the canal walls.
It is rare to successfully retrieve an instrument with a single ultrasonic tip. A combination of at least two tips—one for staging and one for retrieval—is almost always required. The specific choice of tips ultimately depends on the clinical situation and the unique anatomy of the root canal.
Recommended Tip Combinations
Based on the location of the fracture, the typical tip pairings are as follows:
- Coronal or Middle Third: ET20 and ET25S
- Middle Third: ET20 and ET25
- Apical Third: ET20 or ET40 and ET25L
To be prepared for any instrument retrieval scenario, it is highly recommended that a dental practice has the following tips available:
- ET20
- ET40
- ET25S
- ET25
- ET25L
For a comprehensive endodontic retreatment armamentarium, the kit should also include:
6. ETBD (for locating calcified canals)
7. ETPR (for removing filling materials)
Managing Curved Canals
Removing instruments from curved canals presents a unique challenge. The ET25 series tips are designed with the necessary flexibility and durability for this task. These tips can be pre-bent to match the canal’s curvature, allowing them to navigate the curve and reach the broken fragment.
When using a pre-bent ET25 tip in a P5 Newtron unit, a power setting of 8 to 10 is effective for generating the ultrasonic energy needed to vibrate the instrument loose. For example, a pre-bent ET25S is an excellent choice for retrieving a file fractured in the apical third of a curved mesiobuccal root canal.