Three-Dimensional Instrumentation

Transcription

1 Volume 34 No. 10 Page 104 Three-Dimensional Instrumentation The Promise of Minimally Invasive Preparations Authored by Allen Ali Nasseh, DDS, MMSc, and Dennis Brave, DDS Upon successful completion of this CE activity, 1 CE credit hour may be awarded Opinions expressed by CE authors are their own and may not reflect those of Dentistry Today. Mention of specific product names does not infer endorsement by Dentistry Today. Information contained in CE articles and courses is not a substitute for sound clinical judgment and accepted standards of care. Participants are urged to contact their state dental boards for continuing education requirements.

2 Three-Dimensional Instrumentation The Promise of Minimally Invasive Preparations Effective Date: 10/01/2015 Expiration Date: 10/01/2018 About the Authors Dr. Nasseh received his master s in medical sciences degree and certificate in endodontics from the Harvard School of Dental Medicine in He received his DDS in 1994 from Northwestern University Dental School. He maintains a private endodontic practice in Boston (msendo.com) and holds a staff position at Harvard s postdoctoral endodontic program. He has done research in the areas of bone biochemistry and has lectured extensively internationally on endodontic diagnosis, anesthesia and sedation, treatment planning, efficiency of care, and microsurgery. He is the endodontic editor for several dental journals and periodicals and serves as the alumni editor of the Harvard Dental Bulletin. He is the CEO and president of RealWorldEndo. He can be reached at anasseh@me.com or visit the website located at realworldendo.com. Disclosure: Dr. Nasseh is the president and CEO of RealWorldEndo. Dr. Brave co-founded RealWorldEndo in He is a Diplomate of the American Board of Endodontics and a member of the College of Diplomates. He received his DDS from the Baltimore College of Dental Surgery, University of Maryland, and his certificate in endodontics from the University of Penn sylvania. He is an Omicron Kappa Upsilon Scholastic Award winner and a Gorgas Odontologic Honor Society member. He can be reached at dennisbrave@comcast.net or by visiting the website located at the address realworldendo.com. Disclosure: Dr. Brave is a consultant to Brasseler USA. INTRODUCTION For the most part, our clinical judgment about the adequacy of root canal shaping and enlargement has been driven and confirmed by traditional radiography. Al though the limitations of radiographs have long been acknowledged, they continue to be used routinely for this assessment. Further recognizing that, as a 2-D image, we can only visualize canals from a mesiodistal perspective; this perspective has been the basis of our assessment of proper root canal therapy (Figure 1). However, as 3-D imaging has become more mainstream, we have finally come to understand the buccolingual dimension of root canals, which we have long ignored and often failed to clean effectively (Figure 2). The Problem We have long known that most human root canal anatomy is oval or elliptical in cross section (Figure 3). Cleaning and shaping this volume of space, with the intent of removing the majority of the bacteria, has always been the goal of endodontic therapy. However, up until now, almost all instruments recommended for this task (hand or rotary files) have been circular in cross section. Because of this limitation, we have aspired to clean the canal surfaces not directly contacted by these instruments by using sophisticated irrigation protocols. Phys ically touching all canal walls is im portant, since mere irrigation of an established microbial biofilm on canal surfaces may not be adequate to disturb and remove it. The most effective way to remove biofilm is by direct contact with an instrument, disturbing it prior to irrigation. However, the problem with this goal becomes clear when one considers that the area of a circle is related to its radius, but that of an ellipse is dependent on both its major and minor radii. The incoherence of the area occupied by these 2 inherently different shapes is akin to trying to fit a square peg in a round hole (Figure 4). Since our instruments do not adapt to the canal wall completely, and the goal of instrumentation is to effectively touch all canal walls and rid them of tissue and bio film, absence of an adaptive file to this oval canal anatomy limits the instrumentation motion along a circular path. This alludes the most comprehensive method of cleaning elliptical canals. To demonstrate this concept, let s imagine a round file in an oval-shaped canal, or a circle in the middle of an ellipse. The circle will fit within the minor diameter of the ellipse before it makes contact with its internal walls. In order to have the circle touch the walls along the major diameter of the ellipse, the circle would have to be much larger than the minor diameter. In the case of ribbon-shaped human roots, this is generally impossible, since enlarging to the major diameter of the ellipse will cause a perforation of the external surface of the root along the minor diameter of the root (Figure 5) (generally in the mesiodistal direction). As a result of this limitation, we ve come to a clinical compromise where we enlarge the root canal slightly larger than its minor diameter, and count on disinfectants and/or large volumes of irrigant to clean the tissue that has been left along the corridor space of the major diameter. To make the problem worse, the cutting action of root canal 1

3 files and instruments generates large amounts of loose debris, which often gets packed in the empty spaces along the major diameter. This packed debris is a natural by-product of cutting and is found in both rotation and reciprocation motion, although it s been implicated to a higher degree with reciprocation motion. 1 Removal of this packed debris using irrigation alone is not an easy task. Ultrasonics or sonics have been recommended to create agitation and cavitation forces that help in clearing this debris from the canal; but direct touching or disturbance of this canal space is the most effective way to loosen up and irrigate the debris out. a b The Solution Multiple solutions for this problem have been proposed in the past. In 2010, an innovative instrument called the Self-Adjusting File (SAF) was introduced with the hope of addressing the incongruence be tween elliptical root canal anatomy and root canal instruments with a round cross section. The SAF was able to deform and was shown to adjust to the root canal anatomy, and to clean the major diameter of the canal without significant change in the root structure. While research showed promise, 2 the clinical implementation of the SAF met stumbling blocks, and the instrument did not gain popularity due to the requirement of additional handpieces. Furthermore, significant time was required for its successful implementation as compared to rotary instrumentation. Recently, however, a less cumbersome alternative has become available that promises to address those shortcomings by offering a more efficient way of reaching and cleaning the major diameter of the root canal without excessive removal of tooth structure (Figure 6). This instrument is the XP-3D Finisher (Brasseler USA). It is an unique instrument in that it is not associated with a specific cleaning or shaping technique, and therefore enjoys universal application following any instrumentation system. In its capacity as a finisher, the XP-3D finishing instrument will complete the preparation that has been achieved with either a rotary or reciprocating file of any manufacturer, reaching spaces Figures 1a and 1b. (a) The routine, 2-dimensional (2-D) mesiodistal x-ray image of a tooth fails to show the true oval-shaped buccolingual anatomy, (b) creating a flat, 2-D image. a Figures 2a and 2b. The same tooth in Figures 1a and 1b viewed from a buccolingual perspective exhibits the oval-shaped canals in a very different way. These cases would look very different if exposed radiographically in this direction (the oval component of the canal becomes clear). b and canal wall surfaces that were not touched with the standard instrumentation system. The finisher instrument is therefore compatible with all instrumentation systems and promises to complete the incomplete job of physically touching all canal surfaces. This is something that has not been possible with current instrumentation. As a result, the XP-3D Finisher instrument should be considered as a part of the final finishing 2

4 and disinfection protocol at the end of conventional instrumentation and prior to obturation. This file is unique in its implementation of an innovative design, which combined with Max-Wire metallurgy, allows the instrument to be straight at cooler temperatures (room temperature), and to transform into a unique shape with a bulbous tip only after it reaches body temperature (Figure 7). The Finisher has a size 25 tip and no taper (it s parallel!). Furthermore, the file has a patented temperature initiated phase transition and a Booster Tip. 3 When we combine the file s martensitic transformation from a straight file to a bulbous tip at body temperature with its size 25 Booster Tip and parallel taper, the outcome is an extremely flexible file that acts as a whip during rotation. 4 It adapts to the shape of an oval root canal up to 3 mm in major diameter! As a result, the file can touch the walls in a canal space anywhere from a size 25 to 300 file in diameter without removing significant dentin beyond the natural shape of the canal. This is remarkable in reaching and breaking up biofilm and packed debris in places previously unreachable by conventional files. Figure 3. A cross section of the maxillary roots in the mid-root region demonstrates the oval natures of several teeth, including premolars and molars as well as the large diameter of the anterior teeth. Major Radius Minor Radius Radius Figure 4. An elliptical shape has a major and minor radius or diameter, whereas a circle only has one radius and diameter representing different methods to measure the area and perimeter of these 2 shapes. How to Use It? Once instrumentation in a wide or oval-shaped canal has been completed with the clinician s instrumentation method of choice, the XP-3D file is used for one minute per canal and the tooth is irrigated and obturated with the desired obturation technique. It is recommended that the Finisher file be used for 20 to 30 strokes (seconds) of 5 to 7 mm amplitude in the canal and then removed and the canal irrigated. This 20- to 30-second stroke cycle is repeated 2 to 3 times for a total of one minute of instrumentation per canal. A final irrigation protocol should then be carried out to remove the minced loose debris and then the canal dried, the Master Cone fitted, and the tooth obturated with the obturation technique of choice 4 (Figure 8). The XP-3D Finisher is offered in sterilized packaging. The file as delivered is straight and in its m-phase (martensitic) state at room temperature. The file is in a plastic ruler tube that is used to set the working length. The full working length of the Figure 5. A round instrument in an oval canal results in debris remaining in the greater diameter of the canal. Enlarging to the minor diameter does not remove microbes in the major diameter, and enlarging to the major diameter with a round instrument results in a root canal perforation along the minor diameter. canal should be set on the stopper prior to the removal from the sleeve. The root canal is then prepared by suction, drying the pulp chamber while leaving fluid in the canal. The file tip is then quickly placed in the access opening and the tip is inserted in the root canal orifice, and the previously explained stroke cycles are begun. The endodontic handpiece should be operated at 600 to 900 rpm and the file should be in constant up-and-down motion and not be kept static in one place. In operatories where the ambient temperature is high, the 3

5 straight file may undergo early transformation into the bulbous shape. In such cases, using Endo-Ice (Coltene) on a dry gauze pad (running it between your thumb and forefinger to straighten) or spraying the plastic sleeve ruler (with the instrument in it) can help maintain the cooler temperature before introducing the file in the root canal. CLOSING COMMENTS While the XP-3D Finisher shows great promise in all root canals, regardless of the main instrumentation system used to achieve the shape, it is particularly useful for those canals with deformed cross sections created by internal resorptive defects and naturally large, oval, or elliptical canals (Figure 9). This allows us to remove tissue and packed debris from spaces that have previously been considered sanctuaries for microbial debris and biofilms and promises cleaner canals for obturation. Hopefully, this will translate into a higher clinical success rate by addressing persistent endodontic infections that may be due to remaining internal biofilm. However, where this technology appears most promising is in implementation of a more minimally invasive root canal shaping protocol that uses traditional instrumentation up to the minor diameter, and then relies on the Finisher to clean the major diameter without additional removal of internal dentin. This concept will go a long way to preserve the important mesiodistal root structure that promises to simultaneously improve fracture resistance while improving clinical efficiency of shaping. 4 Future research should be directed at assessing the ability of this instrument to clean root canals prepared to smaller Master Files with the hope of saving tooth structure without compromising disinfection and clinical outcomes. References 1. Robinson JP, Lumley PJ, Cooper PR, et al. Reciprocating root canal technique induces greater debris accumulation than a continuous rotary technique as assessed by 3-dimensional Figure 6. The XP-3D Finisher (Brasseler USA) is a new instrument with an innovative flexible design that conforms to the tooth structure and touches walls where traditional instruments cannot reach. Figure 7. The XP-3D Finisher is straight at room temperature and transforms to a special shape at body temperature. This shape provides the file with the ability to touch and clean root canals as large as 3 mm in diameter (equivalent to a size 300 file) without removing significant dentin. Figure 8. The clinical use of the XP-3D Finisher is best visualized in those cases where irregular canals are present. These include immature teeth with blunderbuss apecies, ribbon-shaped roots, as well as teeth with internal resorptive defects such the maxillary left lateral incisor shown here. The internal resorptive defect represents a sudden widening of the normal funnel-shaped root anatomy that can be seen in conventional radiograph as well as the axially sectioned CBCT image. These surfaces are not in direct contact with conventionally tapered rotary files. The unique shape of the XP- 3D file, however, allows such receding surfaces to be contacted directly with the curved tip, thus removing the attached tissue and biofilm. This removal enhances obturation through debridement of the packed debris in the resorptive defect for better adaptation of the obturation material to the canal walls. (Case courtesy of Dr. Gilberto Debelian, Norway.) 4

6 micro-computed tomography. J Endod. 2013;39: Metzger Z, Teperovich E, Zary R, et al. The selfadjusting file (SAF). Part 1: respecting the root canal anatomy a new concept of endodontic files and its implementation. J Endod. 2010;36: Nasseh AA, Brave D. Why do we do what we do? A new standard of efficiency in instrumentation and obturation. Dent Today. 2014;33: Nasseh AA. XP-3D Finisher, a paradigm shift in endodontic instrumentation [video]. realworldendo.com/videos/xp-3d-finisher-aparadigm-shift-in-endodontic-instrumentation. Accessed on August 7, Figure 9. The XP-3D Finisher is particularly helpful in a deformed, oval-shaped, or resorbed canal as it allows touching the canal wall beyond the area of instrumentation by a conventionally round instrument. (Case Courtesy of Dr. Kleber, Carvalho, Brazil.) 5

7 POST EXAMINATION INFORMATION To receive continuing education credit for participation in this educational activity you must complete the program post examination and receive a score of 70% or better. Traditional Completion Option: You may fax or mail your answers with payment to Dentistry Today (see Traditional Completion Information on following page). All information requested must be provided in order to process the program for credit. Be sure to complete your Payment, Personal Certification Information, Answers, and Evaluation forms. Your exam will be graded within 72 hours of receipt. Upon successful completion of the post-exam (70% or higher), a letter of completion will be mailed to the address provided. Online Completion Option: Use this page to review the questions and mark your answers. Return to dentalcetoday.com and sign in. If you have not previously purchased the program, select it from the Online Courses listing and complete the online purchase process. Once purchased the program will be added to your User History page where a Take Exam link will be provided directly across from the program title. Select the Take Exam link, complete all the program questions and Submit your answers. An immediate grade report will be provided. Upon receiving a passing grade, complete the online evaluation form. Upon submitting the form, your Letter of Completion will be provided immediately for printing. General Program Information: Online users may log in to dentalcetoday.com any time in the future to access previously purchased programs and view or print letters of completion and results. This CE activity was not developed in accordance with AGD PACE or ADA CERP standards. CEUs for this activity will not be accepted by the AGD for MAGD/FAGD credit. POST EXAMINATION QUESTIONS 1. We have long known that most human root canal anatomy is oval or elliptical in cross section. 4. In operatories where the ambient temperature is high, the straight file may undergo early transformation into the bulbous shape. 5. The XP-3D Finisher (Brasseler USA) is particularly useful for those canals with deformed cross sections created by internal resorptive defects and naturally large, oval, or elliptical canals. 2. The most effective way to remove biofilm is by direct contact with an instrument, disturbing it prior to irrigation. 3. The cutting action of root canal files and instruments generate large amounts of loose debris, which often gets packed in the empty spaces along the major diameter. 6

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