A month ago I wrote a blog on creating a glide path for endodontic treatment and tried to keep the description easy for the more regular endodontic cases.
Two weeks ago I reviewed the C+ handfile which is useful for some of the more challenging cases when creating a glide path. This week I want to review yet another very helpful bur to be used in even more challenging cases. Specifically I want to review this bur as a tool to be used for hard to find canals; canals that have receded deeper into the canal system and within teeth that do not have a defined pulp chamber space. See examples in the figures 1 and 2 below.
The Munce Discovery Bur is a great tool for a more careful approach to uncovering these challenging canals. The unique part of this bur is that they are very long as they are available in both 31mm and 34mm lengths from tip to shaft top. As a comparison the standard bur length from tip to shaft top is 19mm and a long neck bur is 25mm. (See figure 3). The burs tips come in 6 sizes including #1/4, #1/2, #1, #2, #3, and #4. However we will rarely use any tip larger than a #1.
As is obvious the primary benefit to this bur is the length. This allows for deep troughing of the canal spaces and still offers visibility beyond the dental handpiece head. Shorter burs limit that visibility considerably. Thus there is less risk in using a bur at an improper angle and less risk in creating perforations when searching in difficult to reach locations within a tooth as compared to a standard bur (19 mm) or even a long neck bur (25mm). Additionally, I find that the bur can works quicker than ultrasonic instrumentation. Ultrasonic instrumentation often takes quite a while to clear a path of dentin. On a side note, this bur does not replace the usefulness of ultrasonic instrumentation; rather I find that it delays the need for ultrasonic instrumentation. The use of ultrasonics becomes necessary once the Munce Discovery Bur cannot find the canal space and for other accessory applications. Additionally, the dentin floor or wall is easier to read/view through enhanced magnification as a Munce Discovery Bur leaves a smooth contour of the dentin vs. ultrasonic tips that tend to gouge or ledge dentin. Searching for a canal on a smooth surface is indeed easier than on a roughened dentin surface. See the linked video below.
We find that these burs are even better when searching deeply on posterior roots that have divergence. For example, the palatal or distal buccal root of an upper molar or the distal root of a lower molar can usually accommodate a Munce bur very well. The advantage in these specific roots is that the length of the bur is not prohibited as much by the limited patient jaw opening. The divergence of the root form allows the handpiece head to be tilted thus allowing easier use of this long bur and improved visibility down the length of the bur itself. In the case of a lower molar distal root we can angle the bur head towards the distal and the handpiece head towards the mesial side to get the handpiece head out of the way of our view path (see figure 4). This is not always the case in the mesial buccal root of an upper molar or the mesial root of a lower molar where the bur and handpiece need to be more upright. In those roots the patient opening can and often does limit how long of a bur we can use unless the patient has a large mouth opening.
I also find the Munce Discovery Bur to be very effective in anterior teeth where we can easily use longer burs and adjust our angle of view with the mirror to accommodate improved visibility.
Lastly we will often use this Munce Bur to trough between canals that are nearby to each other. Very often in a lower molar where there are two distal canals there is pulpal debris between the two orifi. This is often found in a two canalled premolar as well. These burs are very effective at careful removal of this narrow dentin space to remove that pulp tissue (see figure 5 and 6). Obviously the mesial roots of molars will also have a narrow strip of pulp debris between the canals, but remember this long bur has some limited use in this root with patients that have a limited jaw opening. If the opening is large enough then this bur can work great (again see the video linked above).
Ultimately, I would advise having these burs in your endodontic armamentarium. You may not use them often, but when you need them, they will be quite useful.
Thanks for visiting Tri City and Fallbrook Micro Endodontics of San Diego, CA.