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Ultrasonic instrumentation for root canal treatment lacks evidence.

Heather Hill DDS, MBI .


Systematic Review Conclusion

Because there is no high level evidence to support the clinical effectiveness of ultrasonic instrumentation, dentists must base treatment decisions on their clinical and patient experience.

Critical Summary Assessment

A review that was limited to randomized clinical trials, and had detailed inclusion and exclusion criteria, finds no studies that inform dentists.

Evidence Quality Rating

Poor Evidence

Structured Abstract

Clinical Questions:

What is the relative clinical effectiveness of hand instrumentation versus ultrasonic instrumentation alone or in conjunction with hand instrumentation for orthograde root canal treatment of permanent teeth in adults?

Review Methods:

The authors searched five databases for randomized controlled trials (RCT). Participants had to have a single permanent tooth or multiple permanent teeth with a completely formed apex and no evidence of internal resorption. Patients undergoing re-treatment of a tooth were excluded. The authors included the following types of interventions: 1) "Any ultrasonic devise designed specifically for root canal treatment and capable of the (active or passive) removal of dentine within the root canal, compared to only hand instrumentation using files," and 2) "Hand instrumentation in conjunction with any ultrasonic device" as described above. Both arms of the trial also must have had the same aspects of preparation. The authors assessed the following primary outcomes: proportion of teeth retained, total time required for preparation and number of visits. They assessed the following secondary outcomes: unscheduled revisits or emergency visits’ quality of life and patient satisfaction measures. Adverse effects, such as instrument, tooth fracture, and cost were also included.

Main Results:

Three independent reviewers assessed 226 identified references for relevance. None of the 10 selected studies met the inclusion criteria after the reviewers conducted full-text analysis. The reviewers excluded studies that were not RCTs, those which did not evaluate the preferred outcomes or interventions, or those that were completed on extracted teeth. A nonclinical review article on technology also was excluded. No data were available for analysis.


This review illustrates the current lack of published or ongoing RCTs and the unavailability of high level evidence based on clinically relevant outcomes for the effectiveness of ultrasonic instrumentation used alone or as an adjunct to hand instrumentation for orthograde root canal treatment. Further randomized controlled trials should focus on evaluating the effectiveness of combinations of these interventions with an emphasis on not only clinically relevant but also patient-centered outcomes.

Source of Funding:

None stated.


Importance and Context:

The dentist uses endodontic instrumentation to remove inflamed or necrotic pulp tissue, microorganisms, and microbial byproducts from the root canal system. Traditionally hand instrumentation with files and broaches, along with rotary instrumentation, are used to remove the pulp, and clean and shape the canal. Ultrasonic root canal instrumentation involves the activation of a file with ultrasound (20,000 oscillations per second) to clean and shape canal space. This technique was introduced in the literature in 1976 as a potentially better method to remove tissue and debris, and improve patient outcomes.

Strengths and Weaknesses of the Systematic Review:

The authors presented a clear search strategy with no language restrictions. Three authors independently assessed the abstracts identified by the search. They obtained full copies of all relevant and potentially relevant studies, including those meeting the inclusion criteria and those for which there were insufficient data in the abstract to make a clear decision. The full text papers were assessed independently by the review authors and any disagreements on the eligibility of potentially included studies were resolved through discussion and consensus. After assessment, the reviewers excluded the studies that failed to meet inclusion criteria. Exclusion rationale was noted in the excluded studies table.

Strengths and Weaknesses of the Evidence:

The review was limited to RCTs that evaluated specific primary and secondary outcomes. Because no studies met the inclusion criteria, the review could not make conclusions about the benefit of ultrasonic instrumentation nor offer comparisons about hand and rotary instrumentation. For future studies and reviews, a representative sample of common endodontic interventions would include rotary instrumentation. Standardization of study design, outcomes and reporting would benefit both future trials and meta-analyses.

Implications for Dental Practice:

There are no published randomized controlled trials relevant to this review question. In the absence of any high level evidence clinicians using this technique must exercise vigilance in examining their treatment outcomes. Clinicians should base their treatment decisions on existing low level of evidence, clinical experience, individual circumstances and in conjunction with patients' needs and preferences.

Critical Summary Publication Date:


These summaries are not intended to, and do not, express, imply, or summarize standards of care, but rather provide a concise reference for dentists to aid in understanding and applying evidence from the referenced systematic review in making clinically sound decisions as guided by their clinical judgment and by patient needs. American Dental Association © 2019