Introduction: In the US, 15 million root canal treatments (RCTs) are carried out annually. Success rates decrease with conventional chemo-mechanical root canal preparation techniques used on teeth with periapical radiolucencies associated with bacterial presence. New irrigation modalities, such as the GentleWave® System (GWS) and Waterlase iPlus® (WL), have been developed to overcome limitations and improve RCT success rates.

Hypotheses: (1) GWS and WL provide superior clinical outcomes compared to conventional RCT using passive ultrasonic activation (PUI). (2) GWS and WL are acceptable treatment modalities for clinicians and patients.

Aims: (1) Estimate probability of success of GWS, WL, and conventional RCT with PUI. (2) Evaluate clinician and patient experiences of the different techniques.

This is a single-blinded, block randomized control trial study, 120 participants will be recruited with 40 participants randomly allocated to the GWS treatment group, 40 randomly allocated to the WL treatment group, and 40 randomly allocated to the control group (CG) receiving PUI treatment (Fig 1). Participants will be selected consecutively based on our inclusion and exclusion criteria. Participants will be recruited and treated at a single site, the University of North Carolina at Chapel Hill Adams School of Dentistry (UNC-CH ASoD) Endodontic Clinic.

There will be an initial baseline/screening appointment that may or may not develop into the first treatment appointment, followed by a potential second treatment appointment to complete treatment as per current treatment protocols in the Endodontic Clinic. Then participants will be followed for 12 months to evaluate clinical and radiographic healing of periapical lesions. Investigators will also assess clinician and patient opinion of the treatment modality employed in addition to calculation of a cost-time ratio.

Patients will receive endodontic treatment for endodontic infections with potential improvements in procedure outcomes, number of visits, and patient intraprocedural comfort. There are the same risks for any root canal procedure that can include intraprocedural or postoperative sensitivity, inflammation infection, numbness, intraprocedural or postoperative pain, reaction to materials used, sodium hypochlorite extrusion, instrument fracture, or perforation. The investigators will manage these risks through execution of proper instrument usage and adherence to clinical protocols.

The investigators do not anticipate difficulty in recruiting the required number of study participants based on the number of patients seen annually. Each week, approximately fifty patients are seen in the ASoD clinic for endodontic treatment, of which at least 50% meet the inclusion criteria for our study. There are nine trained residents in endodontics who carry out approximately five-six treatments per week. Nevertheless, all subjects are free to withdraw from participation at any time, for any reason, specified or unspecified, and without prejudice. A subject may leave at any time if the subject and/or investigator feel that it is not in the subject's best interest to continue.

Study participants will be consecutively recruited from the Endodontic Clinic at UNC-CH ASoD. Specifically, they will be patients seeking endodontic treatment at ASoD. At the consult/treatment appointment, screened potential participants meeting the inclusion/exclusion criteria will be informed of the study and potential treatment modalities by a member of the research team who is not the treating clinician. Patients will be given adequate time to decide if they would like to participate. Once a participant consents/assents to participation in the study, they will be randomly allocated to either the control group, GentleWave treatment group, or the Waterlase treatment group in a block randomized manner. Once a participant is assigned a treatment, the treatment will take place at the same appointment as the baseline/screening appointment or scheduled for another appointment. Treatment will be completed in one or possibly two appointments. Thereafter, the patient will be scheduled for a 12-month follow up visit to evaluate clinical and radiographic healing of the periapical lesion and tooth. This follow-up appointment, depending on the amount of treatment appointments required to complete treatment, may be the second, third, or fourth appointment.

Patients who agree to participate in the study will be randomized to either the GWS, WL, or control groups. As previously mentioned, each treatment group consists of 40 patients. Eight blocks of fifteen treatments (five of each treatment type) will be used. Once a patient consents/assents to participation in the study, a third party will be contacted who has access to the block randomization and they will inform the research team which treatment the patient is to undergo. This will help with organization of the treatment room with the appropriate equipment. Patient details and treatment allocation will be recorded on a password-protected Excel spreadsheet.

Inclusion Criteria:

• Male and female patients 14 years of age or older (maximum of 99 years of age)

  o Participants 14 years of age or older are expected to have permanent teeth erupted in full permanent dentition with close apices

• The subject tooth is indicated for root canal treatment

  • One tooth indicated per participant
  • Permanent tooth requiring root canal treatment which are deemed restorable
  • Teeth exhibiting pulpal pathosis (irreversible pulpitis, pulpal necrosis, previously initiated root canal treatment) and apical periodontitis (with radiographic demonstration of periapical bone loss)

• Patient-signed informed consent/assent form

• Patients display good compliance o Patient is determined cooperative by provider during initial exam and radiographic acquisition

Exclusion Criteria:

• Patients allergic to local or topical anesthetics, heart disease (pacemakers, implantable defibrillators), lung disease, bleeding disorders, immune system deficiency

• Subject tooth is not clinically restorable (prosthetically or periodontally)

  • Mobility scores greater than or equal to 2
  • Periodontal pocket depths greater than or equal to 6mm
  • Cracks with radicular extension, vertical root fracture or horizontal - oblique fracture

• Subject tooth with open or incomplete apices (apical diameter greater than 1mm)

• Subject tooth has insufficient tooth structure to create GWS platform

• Subject tooth has external cervical root resorption

• Subject tooth has signs of dens invaginatus

• Subject tooth has signs of a palatogingival groove

• Subject tooth has root(s) which communicate with the maxillary antrum

• Patient has nonodontogenic facial pain

• Patient requires multiple teeth to be endodontically treated

Deidentified individual data that supports the results will be shared beginning 9 to 36 months following publication provided the investigator who proposes to use the data has approval from an Institutional Review Board (IRB), Independent Ethics Committee (IEC), or Research Ethics Board (REB), as applicable, and executes a data use/sharing agreement with UNC.

Deidentified individual data that supports the results will be shared beginning 9 to 36 months following publication.

Investigator has approved IRB, IEC, or REB and an executed data use/sharing agreement with UNC.

This is a single blinded study. Following randomization, the participant and treating clinician will not be blinded from the treatment. Reviewers of all data collected will be blinded to the treatment modality provided.