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Inside Dentistry
October 2015
Volume 11, Issue 10

Advances in Endodontics

The equipment, techniques, and products that are optimizing care

One could argue endodontics is an area of dentistry that is often taken for granted. It lacks the glamour of esthetics, the relative novelty of implants, and the reputation for multidisciplinary care of restorative dentistry.

Nevertheless, a 2005-2006 study from the American Dental Association’s Health Policy Resources Center (HPRC) shows just how vital endodontics is to US dentists. The HPRC found that of the 22.3 million endodontic procedures done in the United States annually, 68% (15.2 million) were performed by general practitioners. A survey of Inside Dentistry readers reported similar results, with 71% of respondents reportedly performing endodontic procedures. Endodontics is undoubtedly an incredibly vital and important part of many practices. It is also a field that is continually evolving and improving, though perhaps in a quieter way than some of its specialty counterparts.

This month, Inside Dentistry examines innovations covering four key areas of modern endodontic practice. Dr. Rebekah Lucier Pryles discusses the use of CBCT technology for improved endodontic diagnosis. Dr. Rico Short addresses key issues in treatment planning and deciding between endodontics and implants. Dr. James Bahcall examines advances in nickel-titanium file systems and what they mean for efficiency. Finally, Dr. Allen Ali Nasseh, Inside Dentistry’s Endodontics Section Editor, explores if restorative endodontics is a passing fad or a treatment approach that is here to stay.

These four topics cover all aspects of the endodontic workflow, from diagnosis and treatment planning to final restoration, highlighting the technology and techniques that are moving endodontics forward. As you evaluate each one, consider the ways they can make endodontic treatment more predictable and successful for your practice—and help you provide your patients with optimal care.

DIAGNOSIS | CBCT in Endodontics: 3D Diagnosis and Treatment

Rebekah Lucier Pryles, DMD

Endodontics, by and large, employs technology to solve diagnostic and treatment challenges. For example, the operating microscope, ultrasonics, and rotary instruments have all facilitated the delivery of exceptional patient care. Like these advancements, cone-beam computed tomography (CBCT) technology aids in the diagnosis and treatment of increasingly challenging and complex cases.

The clinical exam and two-dimensional radiography provide foundational diagnostic data. Inconclusive clinical testing or radiographic findings, however, necessitate further diagnostic inquiry. Periapical radiographs are limited in that significant bone is required to visualize apical radiolucencies and because superimposition of anatomical structures further obscures apical pathology. In these instances, CBCT imaging may prove useful, as it detects smaller areas of osteolysis than those visualized by periapical radiographs.

Like obscure apical pathology, root fractures benefit from CBCT diagnostics. While isolated periodontal defects and J-shaped radiographic bony defects suggest fracture pathology, periapical radiographs rarely visualize fractures. CBCT imaging can, in some cases, capture root fractures in the scan volume. In cases where the fracture is not visible on the scan, three-dimensional (3D) patterns of radicular bone loss support fracture diagnostics. As root fractures necessitate extraction, accurate diagnosis is essential to prevent both the maintenance of hopeless teeth and the extraction of healthy teeth.

Similar to fracture diagnostics, CBCT imaging aids in the assessment of dental trauma. The American Association of Endodontists trauma guidelines, which were revised in 2013, recommend CBCT evaluation for traumatized patients. These images discern the extent and direction of dental and alveolar fractures, degree of periodontal ligament damage, and presence of other injuries. This information dictates appropriate treatment and offers more comprehensive prognostic expectations.

CBCT imaging is exceptionally useful in the treatment of resorption. While periapical radiographs depict resorptive defects, they provide little information regarding the extent of the defect and the presence of perforations. CBCT imaging, on the other hand, provides both of these key pieces of information, thus obviating the need for exploratory root canal therapy and better directs clinical resources toward saving teeth with a reasonable expectation of a favorable outcome.

Recurrent pathology in previously endodontically treated teeth is best assessed with CBCT imaging. Retreatment outcomes are most favorable when the cause of failure is identified and corrected. In many cases, failure causes may be obvious based on clinical or radiographic data. When both the restorative and endodontic treatment appears sufficient despite the presence of pathology, however, CBCT scans may visualize the presence of untreated canal anatomy or fracture pathology. Like in cases of resorption, this prevents exploratory treatment and offers more accurate prognostic expectations.

Just as it aids in diagnosis, CBCT imaging facilitates endodontic treatment. In the search for calcified canal spaces, scans discern the exact spatial positioning of the practitioner’s drilling within the tooth relative to the canal space, unlike periapical films, which provide only a mesiodistal orientation. This information directs practitioners in their search for these spaces. In the unfortunate event of an intraoperative complication such as a perforation or instrument separation, CBCT scans evaluate the extent of the issue and allow practitioners to determine the feasibility of correction.

While CBCT imaging provides useful data in many instances, it may not be appropriate in all clinical settings. Clinicians must consider the need for imaging on a case-by-case basis to avoid exposing patients to unnecessary radiation. When used properly, however, its versatility makes it an excellent tool in modern endodontics.

About the author

Rebekah Lucier Pryles, DMD, is in private practice at Upper Valley Endodontics in White River Junction, Vermont. She is also assistant clinical professor of endodontics at Tufts University School of Dental Medicine.

TREATMENT PLANNING | Root Canal or Dental Implant?

Rico D. Short, DMD

If natural teeth cannot be saved, dental implants are an excellent treatment option. In cases where a tooth can be saved, or when a root canal–treated tooth has failed to heal, an implant should not be used as the silver bullet. When it comes to selecting treatment modalities, the general dentist has been somewhat biased against endodontic treatment by a perceived high rate of treatment success and the reported ease of placing single-tooth implants. Economics, marketing, institutional, and other financial factors have pushed many implant manufacturers to persuade virtually all dentists that implants are easy to perform, will last longer than a root canal–treated tooth, and make one’s practice more profitable. As a result, the endodontist occasionally gets isolated from the patient’s overall treatment plan. Unfortunately, the patient is at risk of not getting the proper treatment if he or she does not have an evidence-based opinion on the type of treatment needed from their dentist.

Survival rates of single-tooth implants and restored endodontic treated teeth have been found to be equal,1 although clinical trials directly comparing these treatment approaches are lacking. In fact, studies analyzing these treatments are difficult to compare for a variety of reasons. When assessing relative success or failure of endodontics, for example, most studies use both clinical and radiographic measures, whereas most studies of single-tooth implants focus on survival (ie, implant does not need to be removed). In addition, differences exist when analyzing the anatomy of the case in a follow-up. For a root canal–treated tooth, a continuous intact periodontal ligament all around the root of a tooth represents “success,” whereas osseointegration represents “success” radiographically with an implant.

Postoperative complications are another consideration. An evidence-based study found that although failure rates were similar for endodontically treated teeth and implants, implants had a higher rate of postoperative complications.2 New techniques, in-depth training, microsurgical instruments, new materials, microscopes, and understanding biological principles inside and outside the root canal system have greatly enhanced the endodontist’s ability to successfully treat and/or retreat endodontically involved teeth with fewer complications.

For general practitioners and specialists, the decision to learn to properly place implants is a personal one. In 2008, I attended a practice management seminar for endodontists. The practice management coach told me that my practice would be in jeopardy if I did not start placing implants within the next 3 years. I had to stop and ask myself if I should consider it. It was a very tough question, especially during the economic downturn. Ultimately, I decided that if it were my tooth, I would want the most qualified dentist or specialist to perform the procedure. I decided to focus on being the best endodontist I can possibly be. Despite the rising interest in implants, my practice has been sustained during these rough economic times because people still want to save their natural teeth.

In all areas of dentistry, clinical treatment decisions must always be in the best interest of the patient and should be based on the best, most current evidence-based studies. Because they have similar success rates, the decision to extract a tooth and place an implant or pursue endodontic treatment must be based on more than just statistical outcomes. As practitioners, we are ethically bound to inform patients of all reasonable outcomes, and this includes letting them know that there are specialists with further training and expertise who can handle root canal cases, whether simple or complex.

In my opinion, dental professionals should not give up on a tooth that can be endodontically treated. When clinically indicated, preserving a patient’s natural tooth is more effective from the perspectives of cost, biology, and psychology. However, there are some instances in which the tooth can’t be salvaged, especially with a vertical root fracture, severe periodontal issues, or non-restorability. At that point, an implant would usually be the next best option for a high rate of success and to ensure optimal oral health.

If you are not sure if a tooth can be endodontically treated, refer the case to an endodontist in your area. Finally, ask yourself: Considering the most current and accurate evidence-based information available, what you would want if it was your tooth? Would you want to save your tooth if possible with endodontic treatment or place an implant?

References

1. Iqbal MK, Kim S. For teeth requiring endodontic treatment, what are the differences in outcomes of restored endodontically treated teeth compared to implant-supported restorations? Int J Oral Maxillofac Implants. 2007;22(suppl):96-116.

2. Doyle SL, Hodges JS, Pesun IJ, et al. Retrospective cross sectional comparison of initial nonsurgical endodontic treatment and single-tooth implants. J Endod. 2006;32(9):822-827.

About the author

Rico D. Short, DMD, is in private practice in Smyrna, Georgia. He is clinical associate professor at the Medical College of Georgia School of Dentistry and diplomate of the American Board of Endodontics.

INSTRUMENTATION | Improvements in NiTi Rotary File Systems

James Bahcall, DMD, MS, FICD, FACD

Conventional endodontic treatment has become more efficient and predictable since the introduction of nickel-titanium (NiTi) rotary file instrumentation in the 90s. Due to the superelasticity of the alloy, NiTi files allow for improved tracking around curved canals when compared to stainless steel hand files. In addition, NiTi rotary files also are associated with significantly faster canal preparation, stay centered in a canal better, and do not transport the apex as much as stainless steel hand files. NiTi files extrude significantly less debris apically than hand files and help to reduce ledging and zipping of canals during preparation. Zipping is caused when a file creates an irregular area by opening up the apical region away from the curve of the canal.

Over the past 20 years, endodontic rotary NiTi files have significantly improved in regards to speed of usage (rpm) in the electric slow-speed handpiece, file taper, clinical technique, metallurgy, and file design. The early rotary endodontic files (circa 1995) ran in a slow-speed handpiece at 150 rpm, whereas today’s NiTi files can run at speeds up to 500 rpm. This increase in rotational speed allows for improved file efficiency and effectiveness in removing tooth dentin within a canal. Stainless steel hand file instruments have a 0.02 taper, whereas rotary NiTi files are manufactured with various taper sizes, from 0.04 to 0.12. This increase in taper enables the dentist to efficiently enlarge the canal, thus creating a continuous taper of the canal that improves irrigation flow and canal obturation.

The clinical technique used with rotary NiTi files in endodontic treatment has also changed through the years. The early clinical technique of using rotary files was known as the “crown down” method: working from larger to smaller files as the working length is approached. Over time, this developed into a “modified crown down” technique: after opening the coronal two-thirds of the canal, rotary files are taken to working length and worked up from smaller to larger size files. The last file size that can be taken to working length in a canal is considered the master apical file.

Advancements in rotary NiTi file testing by university researchers and industry have provided a better understanding of the effects that torsional stress and cyclic fatigue have on rotary file separation. Through this dental material science research, file manufacturers have been able to develop files with different NiTi metallurgy preparation through various heat and chemical treatments, along with making changes in file design (eg, flutes, cross-section). These newer rotary files have improved resistance to file separation and enhanced clinical performance.

Another current advancement in NiTi files has been the development of reciprocating (quarter or half rotation motion) files. This change in file design and clinical file motion has helped to reduce the number of actual files needed to properly prepare a root canal system and has also demonstrated significantly less cyclic fatigue stress on the file during clinical usage.

About the author

James Bahcall, DMD, MS, FICD, FACD is professor, department of endodontics at the University of Illinois-Chicago College of Dentistry, and a diplomate of the American Board of Endodontics.

BIOCERAMICS | Restorative Endodontics: A Passing Fad or Here to Stay?

Allen Ali Nasseh, DDS, MMSc

It wasn’t long ago when endodontic clinicians were convinced, unequivocally, that the ideal endodontic shape for obturation is a highly tapered funnel that can accommodate an endodontic plugger or spreader to the apical one third of the root. This wider taper had the primary purpose of achieving gutta-percha condensation in the apical third.

If one asked an endodontist going through specialty training why they tapered canals so wide, they would typically answer, “Because we need to soften and push the gutta-percha at the apex to minimize the sealer interface.” Of course, this axiom of minimizing the sealer interface (MSI) was a byproduct of the limitations of historical root canal sealers available and their poor material properties in achieving and maintaining a long-term apical seal. The ZOE (zinc oxide/eugenol) and resin sealers shrank dramatically, had no bonding properties, and were highly soluble, washing out of the canal in a few years following obturation.

As a result, we condensed gutta-percha because we didn’t have sealers with important qualities of bonding, dimensional stability, nonsolubility, and hydrophilicity. We therefore needed to minimize the sealer interface and replace it with something less soluble, such as gutta-percha.

All these mechanical requirements for MSI came to an end when pure, nano-particulate bioceramics were introduced to the endodontic field and were shown, through research, not to have the same limitations as the old sealers. These products were then developed clinically and became commercially available for surgical and nonsurgical root canal obturation (EndoSequence® BC Sealer, EndoSequence® Root Repair Material and Putty, Brasseler USA, http://brasselerusa.com.)

The superior qualities of bioceramics, addressing all the shortcomings of the previous generations of sealers, marked the end of an era, the era in which MSI ruled endodontic obturation. This led to a fresh discussion over the role of MSI and the logic of removal of excessive coronal dentin merely to accommodate condensers, spreaders, or thermoplastic gutta-percha carriers become the subject of re-examination.

Chemically pure nano-particulate bioceramics have unleashed the power of adhesive endodontics and have allowed us to re-engineer root canal preparation sizes without considering obturation limitations of old sealers. At last, we can count on the sealer to provide its intended function of providing the seal rather than minimizing it.

This shift to a sealer-based obturation technique such as hydraulic condensation has led to the realization that the most conservative preparation required to remove the microbial mass from the root canal is all that’s required to achieve successful obturation. And that endodontic instrumentation can be streamlined and become less dependent on larger tapers. It was then shown that it can be adequately cleaned with 0.04 tapers or even smaller tapers as long as it’s combined with good irrigation. This movement towards minimally invasive tapered preparation has improved the fracture resistance of teeth in the critically important coronal one third of the root. This biomechanically driven endodontic treatment philosophy based on improving the long-term restorative outcome of an endodontically treated tooth is the basis for restorative endodontics. It’s based on the understanding that the restoration of an endodontically treated tooth begins at the apex and the biomechanics left after endodontic therapy is an integral part of the restorative dentistry’s prognosis. Through minimally invasive instrumentation and obturation, restorative endodontics will help us achieve longer term tooth retention due to preservation of the tooth’s original fracture resistance through the idea of adhesive endodontic cements such as bioceramics. In that sense, bioceramics and the resulting restorative endodontics are not fads. They are sound biomechanical concepts laid down in material science that will positively impact the future of endodontic therapy in the years to come.

About the author

Allen Ali Nasseh, DDS, MMSc, is in private practice at Microsurgical Endodontics in Boston, Massachusetts. He holds a part-time staff position at the Harvard School of Dental Medicine postdoctoral endodontic program and is the president and chief executive officer of RealWorldEndo. Dr. Nasseh is the endodontics section editor for Inside Dentistry.

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