November/December 2008, Volume 4, Issue 10
Published by AEGIS Communications
Endodontic Instrumentation: A Technique Review
John C. Comisi, DDS
Endodontic therapy has seen fabulous advances in the past 20 years, and these advances have helped improve the success rate of endodontic treatment. From the lateral condensation technique to rotary nickel-titanium (NiTi) endodontic therapy techniques that incorporated the Schilder vertical warm gutta-percha condensation technique,1 filling the canals has become steadily more predictable for the general practitioner.
However, the first time the author separated a Ni-Ti file, he was shocked and troubled. He had followed the protocol, frequently changed the files, and always irrigated the canals well. Why did it separate? He thought he must have done something wrong. Over the years and many file separations later, he resigned himself to the fact that separated files must be the price to pay for the convenience of using rotary instrumentation.
Recently, a rotary endodontic system helped to change his mind. The Endo-Express® System with SafeSiders® instrumentation (Essential Dental Systems, South Hackensack, NJ) is a simple and versatile system. By following a simple sequence with stainless steel-relieved reamers, a Peeso-like instrument called the Pleezer™ (Essential Dental Systems), and then NiTi files (only a majority of the shaping is done by the stainless steel reamers), the clinician can obtain an easy and predictable endodontic therapeutic result.
Based on the author’s clinical experience, the advantages of these reamers are:
- Two thirds less engagement with the dental walls than with non-relieved files.
- More vertical flutes than those on files and, therefore, more efficiency when used in a rotary-reciprocating fashion.
- Vertical blades that sweep away debris more effectively from the thread line.
- More flexibility than other comparably sized files.
- A cutting tip that allows the reamer to pierce the tooth tissue rather than impact the tissue apically and creating resistance.
- A flat side of the reamer that allows for easier debris removal from the canals.
The reamers easily fit into the reciprocating handpiece, and very efficiently and effectively prepare the root canal system. Typically, each canal can be treated in significantly less time than with rotary NiTi files. With this system, endodontic procedures can be performed without the fear of binding or file separation because of the reamers’ unique design and their use in a reciprocating handpiece, which rotates the reamers in a 30º clockwise–counter clockwise motion. Cutting of the tooth structure is very quick and canal distortion is minimized significantly because of the reamers’ design.
The clinician instruments the canals using the Endo-Express reciprocating handpiece system (Figure 1) with SafeSiders in a straightforward progression of stainless steel reamers (size .08 through size 20) to establish the glide path and working length. Hand instrumentation can be performed in the early stages of treatment if desired; if done in this way, the reamers are used in the typical “watch winding” back-and-forth rotation in the canal.
The handpiece and rotary instrument, when activated by the rheostat, are used in a piston-like up-and-down motion. The use of an apex locator is helpful and can be attached to the reamer while instrumentation of the canals is carried out. Proper irrigation with sodium hypochlorite and ethylene-diamine-tetra-acetic acid (EDTA), as with any endodontic procedure, is advised.
Perhaps the most important thing to understand is that proper access to the canals is critical to the success of any system. This system incorporates a Pleezer reamer (a tapered Peeso drill) that is used to deepen and flare the canals after establishing working length. By straightening the outer wall of the canal with the Pleezer (Figure 2), the tooth structure adjacent to the furcation is protected and kept intact. This flare will help transform even a difficult “C”-curved canal into a more manageable “J”-curved canal and, thus, allow more effective and easier treatment capabilities.
The Pleezer is used after using the size 20 reamer and is used ideally 6 mm from the apex of the canal. After rechecking for patency with the size 20 reamer, instrumentation continues with the size 25 and size 30 reamers to the apex. After these files, a 30/.04 Ni-Ti file is used to the apex and then the size 35 reamer is used to continue to the apex. The size 40 reamer is used short of the apex by 1 mm, and then two NiTi files (25/.06 to the apex, and 25/.08 2 mm short of the apex) are used to complete the instrumentation of the canals. The author has found that he usually will finish instrumentation with the 25/.06 NiTi file and does not need to use the 25/.08 in many cases.
Obturation of the canals is the next step in this procedure. This system uses a single-cone technique. After drying the canals, gutta-percha points are selected and pre-fit to the canals. Then, the EZ-Fill® Xpress epoxy cement (Essential Dental Systems) (Figure 3) is prepared per the manufacturer’s instructions, and the EZ Fill® Bi-Directional Spiral (Essential Dental Systems)2 (Figure 4) is placed on the handpiece.
The Bi-Directional Spiral is then coated liberally with the EZ-Fill epoxy cement in a “corn dog” fashion, sliding the spiral into and out of the epoxy cement. Then, the spiral is placed in the canal, and the handpiece is started. Moving the handpiece with the spiral in an up-and-down piston-like stroke seven to eight times enables the cement to coat the canal laterally, away from the apex. The Bi-Directional Spiral is placed no deeper than 3 mm from the apex. This method of coating the canal is then repeated. After the second coating is completed, the pre-fit gutta-percha is coated with cement in the “corn dog” style and inserted into the canal. This procedure is repeated for each canal being treated.
Extrusion of the epoxy cement is a good sign that the canal is being sealed properly. Then, the gutta-percha point is seared at the endodontic orifice with a heated instrument, and the excess epoxy is removed with a cotton ball and chloroform. The gutta-percha point is then adapted to the coronal opening by tapping with a 1-mm plugger. The plugger should not be used to drive the gutta-percha point apically, but merely to be sure that the point is fully seated in the canal. The endodontic fill is now complete and the final radiograph can be taken.
The unique feature of using epoxy cement and a single gutta-percha point is the stability of the endodontic fill, with little to no shrinkage of the sealer.3 Combining this with the Bi-Directional Spiral makes placement of the sealer and the gutta-percha point very easy. The creation of post room can be accomplished either at the time of endodontic fill or at a later time.
Case 1: Treatment of Tooth No. 20 (Single Canal)
A 86-year-old woman presented with discomfort and mild swelling in the region of tooth No. 20. The tooth was sensitive to percussion, palpation, and cold. A digital radiograph was taken (Figure 5). The diagnosis (irreversible hyperemia) indicated that the tooth required endodontic treatment. When discussing the procedure with the patient, she explained that tooth No. 19 had been removed several months previously and she did not want to lose another tooth at this time. The plan had been to create a three-unit bridge to replace tooth No. 19. With tooth No. 20 becoming a problem, it was important to ensure that the bridge would not have any difficulties in the near future, so endodontically treating the tooth was the treatment modality selected. The patient agreed with this treatment direction.
The tooth was isolated under a nonlatex dental dam (Figure 6), and access was made. Using the Pleezer to create a “glide path” into the tooth helped to improve full access to the canal (Figure 7). After finishing the instrumentation, the canal was filled with a single gutta-percha cone properly fitted to the canal, and E-Z Fill Xpress epoxy cement and Bi-Directional Spiral as described previously. The final fill is seen in Figure 8.
The procedure was completed in approximately 1 hour and was very straightforward. The patient was pleased with the service provided. Subsequently, as planned, teeth Nos. 18 and 20 were prepared for a three-unit fixed bridge, which was delivered and is functioning well.
Case 2: Treatment of Tooth No. 13 (Two Canals)
A 28-year-old woman presented with a badly decayed tooth No. 13, which she reported had been hurting for a week. Examination and a digital radiographic image (Figure 9) revealed deep decay that extended into the nerve of the tooth. She had postponed treatment of this tooth for some time because of financial and personal issues. After discussing the treatment options available with the patient (removal vs endodontic treatment, with eventual post, core, and crown), she opted for endodontic treatment with subsequent post (if needed), core, and crown.
As in the previous case, the tooth was isolated with a nonlatex dental dam, and because the patient required immediate treatment and the schedule allowed only 1.5 hours for the procedure, the SafeSider system was used. With this system, the disease process could be resolved and the patient was treated in an effective and quick manner.
After completing the endodontic therapy (Figure 10), the coronal portion of the tooth was rebuilt immediately (Figure 11) in anticipation of future crown preparation. The entire procedure was performed in less than 1 hour and 20 minutes. In this case, glass ionomer was used as the build-up material. It provided a very good seal of the endodontic access area and portions of the tooth that were destroyed by the decay, plus provided antimicrobial and bioactive protection with its active fluoride release.
This procedure was a great service to the patient, who was able to function on the rebuilt coronal structure immediately. She was pleased that the procedure had been done in such a comfortable and swift manner. The tooth is planned to be restored with a porcelain-fused-to-metal crown in the near future. The author is comfortable in the knowledge that the coronal restoration with the glass-ionomer material will help to protect the tooth until that procedure is performed.
The Endo-Express® System with SafeSiders® instrumentation is a well-thought-out system that provides dental professionals and their patients an outstanding option for all endodontic procedures. It should be considered by all clinicians as the treatment modality of choice for its straightforward ease of use, low-cost per procedure, and reduction of “separation anxiety.”
The author recommends that clinicians begin attaining a comfort level working on single canal teeth as he did, if possible. Mastery of this system can be achieved easily after a few cases are completed.
The author has received no financial support from Essential Dental Systems (EDS).
1. Langford A, Cunningham PJ. An evaluation of Schilder’s endodontic technique. Aust Dent J. 1972;17(5):353-354.
2. Arzt AH. Technique update: improving on the lentulo spiral. American Endodontic Society Newsletter. 1999;87:5.
3. Hata G, Imura N, Matsuda T, et al. Apical sealing ability of the EZ-Fill obturation technique [abstract PR31]. J Endod. 2002;28(3):261.
About the Author
John C. Comisi, DDS
Ithaca, New York