Endodontics - A Quarterly Newsletter on Dental SpecialtiesJADA Specialty Scan

Diagnosing pulp necrosis

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Scientists at the University of Athens in Greece found a reliable way to diagnose more cases of pulp necrosis before the final cementation of a crown.

As a result, they said, “a number of root canal treatments can be performed in time, preserving the longevity of the prosthetic restoration.”  The findings are published in the June 2014 issue of International Endodontic Journal.

The procedures involved in preparing a tooth for a crown—desiccation of dentine and production of frictional heat and exothermic reactions of impression materials, acrylic resins and cements—are known to pose a potential threat to the pulp. Permanent pulp damage of teeth with crowns is a significant reason for restoration failure. But research on pulp necrosis after crown placement shows a wide range of findings, with irreversible pulpitis in 2 percent to 33.8 percent of teeth after an observation period of one to 25 years.

Limitations to the evidence are due to the nature of the studies, according to the current report. Most of this research was performed retrospectively. Initial status of the teeth was not documented using pulp sensibility tests. Pulps were assumed to be healthy because patients were asymptomatic, and periapical tissues appeared normal on radiographs. At the recall examination, pulp status was determined by the combined absence of clinical symptoms and periapical lesions because proper pulp sensibility tests were not possible in most cases after crown placement.

Radiographic absence of a periapical lesion does not ensure pulp health, and pulp necrosis is not always accompanied by clinical symptoms.

In this research, the scientist were interested in evaluating the incidence of asymptomatic pulp necrosis during crown preparation up to the final cementation stage and seeking to assess the positive predictive value of electric pulp testing (EPT).

To investigate, they enrolled 33 patients scheduled for crowns at the undergraduate prosthodontic clinic and used a sample of 120 teeth with healthy pulps that remained asymptomatic during the prosthodontic process.

The teeth were divided into two groups according to preoperative crown condition (intact teeth and teeth with preoperative caries, restorations or crowns) and then into four groups according to tooth type: maxillary anterior, maxillary posterior, mandibular anterior and mandibular posterior.

Electronic pulp testing was taken before treatment, at the beginning of the impression-making session and just before the final cementation of the crown by the same operator.

Results showed that of the 120 teeth that remained without symptoms throughout the dental procedures, 9 percent were diagnosed with pulp necrosis. Six of the cases were diagnosed during impression making and the remaining five cases were diagnosed just before permanent cementation of the crown.

The overall incidence of pulp necrosis in intact teeth was 5 percent, whereas in teeth with preoperative caries restorations or crowns, the incidence was 13 percent. The positive predictive value of the electric pulp testing was found to be 1.00, as no false negative responses were recorded.

The authors said the results highlight the possibility of pulp necrosis in teeth with initially healthy pulps and positive response to EPT, which are slated for crown preparation.

The authors noted that previous research has found a possibility that the incidence of pulp necrosis may be underestimated, as deterioration of pulp status may occur and remain undetected due to lack of radiographic changes, and clinical signs and symptoms. This condition was confirmed in the present study, according to the authors, as 10 of 11 cases with necrotic pulp did not show it on radiographs after the third-stage measurement (just before the final cementation of the crown).

Authors said the second important finding was that an unfavorable prognostic factor was clearly identified. The presence of preoperative caries, restorations or crowns was correlated with a significantly higher risk of pulp necrosis. The odds of pulp necrosis of teeth with preoperative caries, restorations or crowns were eight times higher than those of intact teeth.

This finding “is of utmost clinical significance and supports the need for an accurate clinical examination and consequently an appropriate treatment planning of the abutment teeth before final crown cementation,” authors said.

“It is imperative for the clinician to re-examine teeth during the period until final cementation of a crown,” the advised. “The electric pulp tester is a reliable diagnostic tool to disclose pulp necrosis before final cementation of the restoration.”



Consulting Editor: Dr. Susan Wolcott
Diplomate, American Board of Endodontics

Improving anesthetic success?

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Many of the basic mechanisms of local anesthetic action are based on preparations of isolated nerves. But because anesthetic can’t be applied directly to the nerve in the clinical setting, desired anesthetic effect isn’t always attained.

A randomized clinical trial published in the September 2014 issue of the Journal of Endodontics explored the mechanisms of local anesthesia and the inferior alveolar never block (IAN).

Theoretically, because of the higher number of anesthetic molecules and higher pH value, 3 percent mepivacaine would provide more of the base molecules for the IAN initially and possibly boost the effect of a second cartridge containing 2 percent lidocaine with 1:100,000 epinephrine.

To test the rationale, a team of researchers at Ohio State University conducted a prospective, randomized, double-blind study of 100 asymptomatic patients. In terms of injection pain, onset time and pulpal anesthetic success, the combination method—one cartridge volume of 3 percent mepivacaine plus one cartridge volume of 2 percent lidocaine with 1:100,000 epinephrine—wasn’t more effective than administration of two cartridges containing 2 percent lidocaine with epinephrine.

“In the clinical situation, the anesthetic cannot be applied directly to the nerve because it must diffuse through the surrounding tissue before it has an action on the nerve membrane,” study authors said. “In addition, once injected, the anesthetic solution may diffuse away from the nerve, resulting in a decreased concentration.”

The authors reported extensively on previous research and considerations for further study.


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Bond strength and glass fiber posts

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Glass fiber reinforced (FRC) posts often are the first choice of treatment for endodontically treated teeth—but one of their main advantages is also a limitation. Although they can be easily removed from the root canal if treatment fails, the most common cause of their failure is post-treatment debonding.

Finding little information on the long-term effect of chlorhexidine digluconate (CHX) on adhesion of fiber posts in root canals with various cements, authors publishing in the March 2014 issue of the European Journal of Prosthodontics and Restorative Dentistry were moved to research. In their study, they investigated the effect of 2 percent CHX and two different adhesive luting systems on the bond strength of glass FRC posts to root dentine after a six month period.

They used 40 extracted premolars that were endodontically treated for their research. The teeth were divided into two groups according to luting system, and each of the two groups was further divided into two subgroups: those that had received a CHX application and those that had not. The scientists evaluated bond strength values according to the type of luting agent and CHX irrigation.

Among the results, they found that application of CHX before the luting procedure with etch-and-rinse/chemical cure luting agent of glass FRC posts improved long-term bond strength between glass FRC posts and root dentine.



Investigating conservative endodontic cavity design

Findings that support revised guidelines for endodontic cavity design in premolars and molars were reviewed in the August 2014 issue of the Journal of Endodontics.

The report made a potential case for the preservation of coronal dentin through conservative endodontic cavity (CEC).

Although consistent with the concept of minimally invasive dentistry, CEC has not influenced mainstream endodontics. Neither the benefits of tooth structure conservation nor the possible drawbacks have been well supported by research.

Canadian and Swiss scientists conducted a study to assess the potential benefits and risks associated with CEC. Their aims were to characterize canal instrumentation performed through CEC and traditional endodontic cavity (TEC) in three matters:

To investigate, the scientists used 90 previously extracted noncarious, mature, intact teeth of which 30 were maxillary central incisors, 30 mandibular second premolars and 30 mandibular first molars, to represent the three main tooth types. For each tooth type, 20 teeth were equally assigned to one of two groups—CEC and TEC—and 10 teeth were assigned to fracture testing only.

Results showed the benefit of increased fracture resistance in both mandibular molars and premolars. Scientists also observed conservation of coronal dentin in all three tooth types, whereas the risk of compromised canal instrumentation was found only in the molar distal canals.

“Medicine and dentistry have been moving toward minimally invasive procedures that may benefit patients,” the authors noted. “Although technological advances such as CBCT imaging, operating microscopes, and nickel-titanium instruments enable this progress, clinicians have to adapt their skills to meet the challenge of working effectively in confined spaces.”

The scientists also observed that CECs are likely to benefit patients, that the treatment is challenging for clinicians and that clinicians have been shown to meet the challenges.

“It may be appropriate for the larger endodontic community to revisit endodontic access cavities in premolars and molars to better align them with CEC,” they said.


Essential Dental Seminars ready for 2015

Essential Dental Seminars, a division of Essential Dental Systems, Inc., has announced dates for its 2015 hands-on, two-day endodontic course. Its “Intense Endodontics: A 2-Day Hands-on Workshop” has received rave reviews.

“Best course I have ever taken. Best hands-on course,” declared Dr. Anthony Coarello of Cranford, N.J. To read what others had to say and learn more about the course, visit http://www.essentialseminars.org

Updated AAE Guide will help dentists plan treatments, save teeth

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An updated version of “Treatment Options for the Compromised Tooth: A Decision Guide,” a publication of the American Association of Endodontists (AAE), is available as a free download to dentists.

The guide encourages dentists to save natural teeth by assessing all possible endodontic treatment options before recommending extraction. The full-color, revised clinical resource includes 13 new cases and more than 100 images demonstrating successful endodontic treatment in difficult clinical situations.

The guide also willhelp dentists evaluate conditions using case examples with radiographs and clinical photographs, clinical considerations, and guidance for successful outcomes based on prognosis. It aims to increase collaboration between general dentists and endodontists to work as partners in developing treatment plans to save natural teeth.

The AAE mailed the revised guide to about 32,000 ADA members this summer. A version can also be downloaded for free from the AAE website at www.aae.org/treatmentoptions.


ADA offers discount on revised root canal brochure

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Now through Nov. 30, the ADA is offering members a patient education brochure on understanding root canal treatment at a 15 percent discount.

Members can order “Root Canal Treatment” (W117, new Spanish version, W244) through the ADA Catalog, using promo code 14363E.  The eight-panel brochure is available in packets of 50 for $27; retail price $40.50. Discounts also are available at higher quantities.

The brochure explains the benefits of endodontic treatment from start to finish, helping patients understand the tooth-saving benefits of root canal with step-by-step illustrations. It also encourages patients to return for a permanent restoration.

Members can preview this and other ADA brochures online at adacatalog.org. Orders can be placed online or by calling the ADA Member Service Center at 1-800-947-4746.

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What is Specialty Scan?

This is one in a series of quarterly newsletters updating dentists on selected specialties in dentistry. Information presented is aggregated and summarized from previously published materials, each item attributed to its publication of origin. This issue of JADA Specialty Scan focuses on endodontics, the third in the series on this topic for 2014. Other Specialty Scan issues are devoted to periodontics, orthodontics, oral and maxillofacial radiology and prosthodontics. The ADA has engaged the specialty organizations in these areas as well as its own divisions of Science and Legal to assist with these newsletters. We welcome your feedback on this and all Specialty Scan issues.

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