Endodontics — January 17, 2020

Regenerative protocols and immature teeth

Three cases with the same repair pattern after regenerative endodontic procedures to treat maxillary incisor immature tooth necrosis led researchers to determine that the regenerative protocol can induce a healing pattern that might repair cervical level hard tissue of the access opening and strengthen the immature tooth. They reported their study findings in the October issue of Journal of Endodontics and called for further scientific investigation and modulation.

The Greek and Dutch researchers first addressed clinician reticence toward regenerative endodontic procedures in developing teeth. Conventional endodontic treatment procedures are challenging in immature teeth where pulp necrosis has led to cessation of maturation and arrested root development, leaving the tooth weakened and fracture prone.

“The strengthening of immature necrotic teeth is considered a major challenge in dentistry,” researchers wrote. “Incompletely formed teeth with thin dentin walls have been shown to experience higher incidences of cervical root fracture, which lead to reduced long-term overall prognosis.”

Clinicians seek more evidence and better biological outcomes to feel confidence in incorporating regenerative endodontic procedures in their everyday practice, the researchers declared.

In their study, the researchers aimed to report outcomes of regenerative endodontic procedures in 3 cases of maxillary incisors immature tooth necrosis, which successfully resulted in continuous root development, dentinal wall thickening, and cervical level biological repair of the access openings in close continuity with axial walls.

To conduct the study, the researchers used regenerative endodontic procedures to treat 3 maxillary central incisors in 2 young patients—teeth nos. 8 and 9 in a 9-year-old boy and tooth no. 9 in an 8-year-old girl. The incisors had become necrotic after traumatic dental injuries resulting in dentin enamel fractures.

Clinicians treated the teeth with single or multiple visit regenerative endodontic procedures. “The 5- and 9-year follow-up evaluations revealed similar continuous root development, dentin wall thickening, and hard tissue biological repair of the wide access cavities,” according to the study.

In the case of the 8-year-old girl, some “grey cervical discoloration” resulted and was successfully managed. “The 10-year follow-up clinical and radiographic evaluations revealed healthy tissues and satisfactory esthetic result,” researchers wrote.

Regenerative endodontic procedures are defined in the article as biologically based procedures aimed at the elimination of the infection (primary goal, essential), continuous root development/dentin wall thickening (secondary goal, desirable), and regeneration of the pulpal-dentinal complex within a previous empty, but infected, root canal space (tertiary goal).

Researchers noted that biological repair of the access cavity in the cervical root level with hard-tissue bridge is not reported as a direct goal of regenerative endodontic procedures, although it is included as a favorable outcome.

“Interestingly enough, most of the regenerative literature focused on the continuous root development and the dentin wall thickening potential of the different regenerative protocols to strengthen the root, and little attention was given to the cervical area,” researchers wrote.

“However, cervical level access opening repair might be a more important biological outcome than continuous root development and dentin wall thickening, leading to the true strengthening of the immature teeth.”

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Apical periodontitis and systemic health

A literature review and meta-analysis revealed an association between apical periodontitis (AP) and elevated systemic inflammation, with researchers concluding that AP can increase risk of developing other pathology. The researchers reported on their findings in the November issue of Journal of Endodontics.

Researchers defined AP as an inflammatory response around the root tip of teeth to an insult. They explain that AP can present itself in various ways clinically, from asymptomatic (with just a periapical radiolucency on an intraoral radiograph) to great clinical signs of inflammation (such as pain, swelling, redness, and loss of function).

“Over the past 5 to 6 years, the possible consequences of AP in general health have received great interest from scientists. ... The current systematic review and meta-analysis were conducted with the aim to evaluate whether the continuous attention to this topic has resulted in new insights,” researchers wrote.

Researchers designed their systematic review in accordance with Preferred Reporting Items for Systematic reviews and Meta-Analyses and the Cochran handbook and registered it with PROSPERO. Databases included MEDLINE-PubMed, Embase, and Cochrane, with searches conducted up to and including February 2019.

Their inclusion criteria allowed for all prospective clinical trials, case-control studies, and cross-sectional or cohort studies assessing symptomatic or asymptomatic AP written in English, Dutch, German, French, or Greek (the language skills of the team of authors). “Studies should compare subjects with AP before and after any treatment or compare subjects with AP with subjects without AP. All studies should have been conducted on systemically healthy adults, and the inflammatory mediators in peripheral blood should have been quantified,“ researchers wrote.

They excluded in vitro studies on cell cultures and animals, studies that evaluated local inflammatory mediators of periapical lesions or gingival crevicular fluid, studies involving medically compromised people or participants with periodontitis, and studies quantifying only Igs (antibodies).

“The aim of this systematic review was to summarize the existing evidence on the influence of AP on the peripheral blood levels of inflammatory mediators and markers of systemic stress,” researchers wrote. They focused on the question, “In healthy individuals, does AP add inflammatory mediators and other systemic stress markers to the peripheral blood concentrations?”

They found 20 studies, all heterogeneous designs, that ultimately met the inclusion criteria. Of the 20, data from 11 studies were available for a meta-analysis. “The meta-analyses revealed statistically significant differences in C-reactive protein, interleukin 6 and asymmetric dimethylarginine levels between AP subjects and controls in peripheral blood,” researchers wrote.

They also found that concentration of C3 complement fragment in peripheral blood was significantly lower after treatment and resolution of AP than before.

High variation in study designs was a limitation of the study, and future studies should be conducted with similar methods, stricter inclusion criteria, and clearer presentation of data, researchers wrote. They also offer various other suggestions for future study design on the systemic consequences of AP on general health.

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Ultrasonic irrigation, bacteria and endotoxins

In a Brazilian randomized controlled trial (RCT), ultrasonic activation was more effective than a nonactivated irrigation protocol for reducing the number of bacteria but not the endotoxin levels in root canals of teeth with apical periodontitis, researchers determined in a study published in a January 2018 special issue of International Endodontic Journal.

“Studies evaluating the effect of chemo-mechanical procedures on endotoxin levels have indicated that the use of rotary nickel-titanium files and irrigant significantly reduced endotoxin content but was not able to eliminate it from root canals,” researchers wrote. “Therefore, alternative approaches have been proposed to supplement the antimicrobial effect of chemo-mechanical preparation in infected root canals, including a final irrigation protocol using additional ultrasonic activation of the irrigant.”

Researchers declared that they found no RCTs comparing the antibacterial effectiveness of ultrasonic and conventional irrigation using molecular based methods or any RCTs assessing the effectiveness of ultrasonic activation in reducing endotoxin from infected root canals with apical periodontitis.

“It is possible that mechanical agitation of the irrigant could improve bacterial DNA and endotoxin reduction after root canal preparation,” they wrote.

With a null hypothesis that the irrigation protocol used after the chemo-mechanical preparation does not influence the reduction of bacteria and endotoxin within the root canal system, the researchers designed a single-blinded, 2-arm RCT with the main goal of evaluating the effect of ultrasonic activation on the reduction of bacterial and endotoxin levels in root canals compared with a nonactivated irrigation protocol using quantitative polymerase chain reaction and the limulus amebocyte lysate assays.

Also, the antibacterial effect of each step of the endodontic therapy was evaluated, including chemo-mechanical preparation, final irrigation protocols, and calcium hydroxide intracanal medicament.

They ultimately evaluated 50 patients aged 18 through 65 years (37 women; 13 men) reporting in 2 visits to the postgraduate endodontic clinic from January 2014 through July 2016 with necrotic pulps and asymptomatic apical periodontitis.

Inclusion criteria were patients who had asymptomatic teeth with necrotic pulps confirmed by a negative response to sensitivity pulp tests and radiographic evidence of apical periodontitis in single rooted teeth or in 1 root with a single canal from multi-rooted teeth.

Exclusion criteria were patients who had received antibiotics during the previous 3 months or had any general disease, teeth that could not be properly isolated with rubber dam, nonrestored teeth, periodontal pockets depths greater than 4 millimeters, and radiographic evidence of previous endodontic treatment, open apex, crown/root fracture, root resorption, or calcifications. In addition, teeth with root canal curvatures greater than 20° and roots shorter than 15 mm or longer than 25 mm were excluded.

After root canal preparation, the researchers randomly divided teeth into 2 groups according to the final irrigation protocol used after chemo-mechanical preparation: an ultrasonic irrigation (UI) group (n = 25) and a needle irrigation (NI) group (n = 25).

Extracted microbiology samples fell into 4 categories: before the root canal preparation (S1); after the root canal preparation (S2); after the irrigation protocols (S3); and after the removal of the intracanal medication (S4). “Total bacteria counts were determined by [quantitative polymerase chain reaction] and the endotoxin levels by the [limulus amebocyte lysate] assay. Intragroup analyses were performed using the Wilcoxon test for related samples, whereas intergroup analyses were performed using the Mann-Whitney U-test (P < 0.05).”

Key results were that significant drops in bacterial counts occurred in microbiology samples following each irrigation protocol. From S2 to S3 in both groups samples were UI: 4.29 x  10³ and NI: 1.08 x  10⁴. “Intergroup analysis revealed a significant difference between irrigation methods regarding bacterial counts in S3 samples (P > 0.05).”

In contrast, no significant differences were observed between groups for endotoxin levels (P  > 0.05).

“The findings of this study indicate ultrasonic activation is more effective than needle irrigation in removing bacteria from root canals in a clinical setting, as predicted by previous laboratory studies comparing various irrigation techniques,” researchers wrote. They offered the caveat, however, that results of molecular studies have not yet been correlated with treatment outcomes, and thus their findings might not be clinically relevant.

Nitrous oxide sedation, anxiety and pain

Nitrous oxide inhalation sedation effectively treats anxiety and pain during endodontic procedures in patients, researchers determined after conducting a prospective randomized controlled study. They published their findings in the July/August issue of Journal of Conservative Dentistry.

“Avoidance of dental treatment because of anxiety and fear of pain is acknowledged to be the major deterrent to oral health,” researchers wrote. “Dental treatment has been ranked fifth among the commonly feared situations. One of the dental procedures which is feared by many people is endodontic treatment.”

Researchers designed an in vivo study to determine the effectiveness of nitrous oxide in alleviating patient anxiety and pain during endodontic treatment of a vital mandibular tooth with irreversible pulpitis. The study involved 60 patients from the outpatient department of Gènesis Institute of Dental Sciences and Research at Ferozepur, Punjab, India.

Inclusion criteria were that patients were older than 18 years, needed root canal treatment of a vital mandibular molar with irreversible pulpitis, were anxious and fearful as indicated by scoring on the preoperative Modified Dental Anxiety Scale, fell into the American Society of Anesthesiologists category I or II, were willing to accept nasal hood and showed no impediments to adequate nasal breathing, and were not pregnant.

Participating patients had a Modified Dental Anxiety Scale score of 19 or greater. Also, patients reported pain using the Heft-Parker visual analog scale. Researchers randomly established a control group and intervention group with 30 patients in each. The control group patients received local anesthesia for access opening and pulp extirpation while intervention group patients underwent access opening and pulp extirpation under local anesthesia and nitrous oxide sedation.

Statistical analysis was achieved using analysis of variance and paired t tests to assess the anxiety levels of patients before and after treatment and pain during administration of local anesthetic and access opening in a mandibular molar with and without nitrous oxide sedation.

“The results show that nitrous oxide sedation did alleviate the anxiety and pain of patients during endodontic access opening including a significant reduction in pain during administration of local anesthesia, and therefore, it might be a useful technique to add to the armamentarium used in the treatment of teeth with symptomatic irreversible pulpitis,” researchers wrote.

Researcher said that nitrous oxide sedation is titratable and therefore preferable to oral sedation in patients with irreversible pulpitis of a mandibular tooth and severe anxiety, as patients would not be sedated beyond the length of the appointment and would not require a driver to accompany them home.

Endodontics courses scheduled for 2020

Essential Dental Seminars has recently added additional hands-on endodontic courses to its expanding curriculum. Courses include its flagship 2-day seminar and various nationally held courses.

Examples of the many course reviews:

• Excellent Course! Best I've taken. Lots of instruction
  - Robert Schneider, DDS Fort Myers, FL
• This was an excellent course. Endo confidence went way up with this course. Thanks!
  - Todd Anderson, Springfield, MO
• This Course was fantastic! It will make me a better dentist after 30 years of doing endo!
  – Chris Nix, DDS, McCook, NE

2020 dates just announced. For additional reviews and complete info visit www.essentialseminars.org.

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• Minimally Invasive Exodontia Techniques
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Visit ADACEOnline.org to find out more information about these and other endodontics courses.

The consulting editor for JADA+ Specialty Scan — Endodontics is Dr. Susan Wood, Diplomate, American Board of Endodontics.