MTI Clinical: Fiber Post Removal by a New Multi-Tasking Drill, The Gyro Tip

It is important to note that the difficult to remove posts are the new white and translucent posts. If the post is carbon fiber there is no problem. Bisco Dental sells a re-access kit with two drills that will remove the carbon variety. This kit does not work with the quartz fiber, the hardness of the fibers defeats the two drills. Examples of the hardest to drill out posts would be the UM Estheti Plus and the DT Light posts distributed in this country by Bisco Dental and the Achromat System by Axis Dental. These posts are made of pre-tensed quartz fibers imbedded in an epoxy matrix that is milled into the shape of a post. These two systems have a very high concentration of fibers relative to the epoxy binder. Ultradent Products will soon release a post mated to the Gyro Tip so that one drill will do both functions of placement and retrieval.

MTI Precision Products of Lakewood, NJ developed the Gyro Tips in conjunction with me, inventor of the popular Raptor System used for shaping composites. The drills operate on the same principles utilized in lighting a fire by rapidly rotating a sharp stick on wood. The friction of the sharp tip generates the heat necessary to ignite the kindling material. The Gyro Tip drills (Fig. 1) have a unique sharp tip that generates a very small zone of heat capable of melting the epoxy matrix of the fiber post. The tip of the number 1 Gyro Tip is placed in a 1mm deep pilot hole created by a latch-type pilot drill (Fig. 2). The hole must be placed dead-center in the cut-down post so that the Number 1 Gyro Tip spinning at 20,000 rpms will start in a perfectly axial direction. Either air or electric motors can be used provided that the torque is sufficient to keep the Gyro Tip moving when firm pressure is applied. It is critical that the handpiece does not stall out. As the tip of the Gyro Tip follows the path of least resistance created by the melting epoxy, the very hard quartz fibers keep the drill centered in the post. The “lazy flutes” engage the fibers and strip them from the epoxy matrix as the Gyro Tip proceeds down the post following the heat-generated path of least resistance. Above the unaggressive “lazy flute” zone is a plasma spray bonded silica carbide abrasive zone designed to keep heat down if the smooth shank on the upper part of the Gyro Tip should contact coronal dentin and/or enamel. Similar applications of abrasive have been used in implant drills to avoid heat generation by smooth shank portions of bone-burs in contact with bone. This abrasive zone will also aid in creating better straight-line access in placing a new post. Straight-line access will enable the doctor to place a larger post if necessary. It can’t be stated too strongly how important it is to place the pilot hole dead-center in the cut-off post. The dentist should reduce the post and build-up material all the way down to the radicular orifice to assure maximum accuracy. This may necessitate gross removal of coronal tooth or cast restoration keeping in mind that the most important factor is safe removal of the post. The patient should be made aware that this may necessitate placing a crown or replacing an existing crown. Figure 3 shows the perfectly round profile of a post cut down with its build-up material to the lowest radicular orifice position. This adequate exposure assures the dentist of dead-center axially directed pilot holes each time. Again, the pilot drill should penetrate the post at least 1mm to assure good axial tracking and proper heat generation. My endodontist evaluators prefer using a very sharp diamond coated ultrasonic tip such as the number 4 or 5 Pro Ultra by Dentsply Tulsa Dental in molars and second bicuspids. They say that visibility is better with this instrument in the posterior when placing the pilot hole. Indeed, visibility is critical so in the absence of the ultrasonics we recommend the mini latch head by MTI Precision Products for both the pilot drill and the Gyro Tip. Dentists should be using a 3 to 5 power loupe, with good lighting or a surgical microscope if they have it. I use a 5X coaxial lighted surgical telescope by Surgi-Tel Corp. Inc.

When the number 1 Gyro Tip is used in the pilot hole with firm pressure at 20,000 rpms it will travel slowly but surely down the post. When it has penetrated the most apical aspect of the post the soft end-feel of the gutta percha remaining in the canal will signal the stopping point. At this point the number 2 through 4 are used to finish the task. It will probably not be necessary to use the number 5 or 6 unless the doctor has determined that the post is of such a large diameter to require the very large diameters of these accessory Gyro Tips. The number 5 and 6 are used as a means to remove the Vectra central carriers used by Dentsply Tulsa Dental in their gutta percha on a stick obturators. Number 5 and 6 can also aid in removing composite injected into canals as a post and core technique. Figure 4 shows the pre-op radiograph of a bicuspid tooth. Figure 5 shows the results of the pilot drill creating the 1mm deep pilot hole dead center in the post. Figure 6 shows the number 1 Gyro Tip operating at 20,000 rpms with firm pressure following the path created by the pilot hole drill. Figure 7 shows a progress radiograph with the number 1 Gyro Tip in place to assess the axial tracking down the post fibers. Figure 8 shows the number 3 Gyro Tip all the way down the post. The removal is completed by using Gyro Tips number 2 and 3 (Fig. 9).

Placement of a new post is accomplished by using the finishing drill specified by the manufacturer of the new post. If the dentist is placing a post mated to the Gyro Tip he/she simply picks the post size paired to the last drill used in removal. The Gyro Tip Post marketed by Ultradent and manufactured by RTD of France is made to the highest post standards involving the previously mentioned pre-tensed quartz fibers and high percentage fiber content. These two factors are critical in fatigue resistance of the quartz fiber post system. This has become the gold-standard for quartz fiber posts in my opinion and many other experts in this area.

Those dentists who enjoy the Dentsply Tulsa Dental Thermafil Obturators can use this same system to remove the tough Vectra plastic carriers used as the central core of the gutta percha fill. Figure 10 shows the Thermafil size number 45 obturators inserted and ready to be partially removed to create a post space. Figure 11 shows Thermafil carriers with the gutta percha removed on one to illustrate the Vectra plastic central carrier. These central carriers tend to just wrap around conventional burs like the Peezo reamers, Gates Gliddens and other post preparation drills. The Gyro Tip numbers 5 and 6 sizes were created to perform crown-down partial removal of the Thermafil Vectra central carriers in preparation for the post placement. The number 5 and 6 will not slip off the top of the Vectra carrier and if rotating at 20,000 rpms will melt the Vectra carrier with its gutta percha coating rapidly and safely. The dentist should fit stoppers on the numbers 6 through whatever smaller size he/she deems necessary to get sufficient length of the post. The stopper will be set before placement of the Thermafil obturator at the point where the Gyro Tip binds on the canal wall. This will give the dentist an idea of how far to go with each drill. The resistance of the Vectra can mask the binding of the drill as it comes in contact with the walls. It is important to not generate needless heat with a rapidly spinning smooth tip in contact with dentin. If the last drill to bind at a typical 12mm depth in a molar is the number 4 then the number 4 Gyro Tip post will be placed. Figure 12 shows the post space created in the Thermafil obturated canals by the number 6 through 3 Gyro Tip drills. If the dentist desires a longer post space then numbers 2 through 1 would be utilized.

In summary, Gyro Tip sets itself apart from other systems on the market for the following reasons:

1. Creates a post space safely by virtue of its non-end cutting tip and unaggressive flutes minimizing the risk of zipping or stripping

2. Eliminates the need for special finish drills—one drill does all because it is mated with a high fiber content, pre-tensed quartzfiber post

3. Removes the gutta percha very quickly and safely

4. Removes the hardest quartz fiber posts safely and rapidly

5. Removes the Vectra central carriers utilized by Dentsply Tulsa Dental in their Thermafil system

6. Removes the composites that are frequently injected into the root canal as part of an injectable post and core technique.

Dr. Patrick Roetzer is a 1974 graduate of the Marquette University School of Dentistry. Dr. Roetzer founded Carquinez Dental Group in 1976 and North Bay Dental Education Center in 1996. He maintains a full-time restorative dental practice limited to fixed and removable prosthetics as well as esthetic minimally invasive dentistry in Benicia, CA. He has served the dental manufacturing community as a consultant for the last eight years, including MTI.

Dr. Roetzer has lectured on topics ranging from infectious disease to implant restorative dentistry, nationally and internationally. His memberships include the: California Dental Association, American Dental Association, American Academy of Cosmetic Dentistry, International Congress of Oral Implantologists, and the Academy of General Dentistry.

Dr. Roetzer can be reached at (707) 745-8002.