Photobiomodulation After Nonsurgical Root Canal Treatment

Postoperative pain and mechanical allodynia are common concerns after nonsurgical root canal treatment, particularly in teeth diagnosed with symptomatic apical periodontitis. Mechanical allodynia may reduce functional biting capacity and contribute to discomfort even after endodontic treatment.

Photobiomodulation is a noninvasive therapeutic approach using low-level laser energy to stimulate cellular responses without producing thermal tissue damage. It has been studied for analgesic and anti-inflammatory effects, but prior endodontic studies have mainly relied on subjective pain measures. This study combines a patient-reported pain outcome with an objective functional measure of recovery using maximum occlusal force.

This study will enroll 60 adults presenting to the University of Minnesota School of Dentistry Graduate Endodontic Clinic for primary nonsurgical root canal treatment of a tooth diagnosed with symptomatic apical periodontitis. Participants will be randomized 1:1 to adjunctive photobiomodulation or sham photobiomodulation.

All participants will receive standardized nonsurgical root canal treatment in a single appointment. Participants randomized to adjunctive photobiomodulation will receive PBM using the Fotona LightWalker Nd:YAG laser immediately after obturation. Participants randomized to the sham group will undergo an identical simulated laser procedure without laser energy delivery.

Outcome assessments will be completed at baseline, 2 days after treatment, and 7 to 10 days after treatment. Mechanical allodynia will be assessed by measuring maximum occlusal force on the treated tooth and the corresponding contralateral asymptomatic tooth. Postoperative pain will be assessed using the Numeric Rating Scale in response to percussion testing.

• Adjunctive Photobiomodulation (Device), also known as Fotona LightWalker Nd:YAG Laser: Adjunctive photobiomodulation will be delivered using the Fotona LightWalker laser system in Nd:YAG mode immediately after completion of nonsurgical root canal treatment and obturation. The laser will be applied intraorally over the mucosa corresponding to the periapical region using a standardized protocol.
• Sham Photobiomodulation (Device), also known as Simulated Laser Procedure: The sham procedure will simulate photobiomodulation treatment. The laser handpiece will be positioned in the same manner and all aspects of the laser procedure will be replicated, but laser energy will not be delivered. Protective eyewear or a visual barrier will be used to maintain participant blinding.

Primary outcomes

• Change in Mechanical Allodynia Measured by Maximum Occlusal Force Difference [Baseline]: Mechanical allodynia will be evaluated by measuring maximum occlusal force on the treated tooth and the corresponding contralateral asymptomatic tooth. The primary endpoint is the change in the difference in maximum occlusal force between the treated and contralateral teeth from baseline to follow-up.
• Change in Mechanical Allodynia Measured by Maximum Occlusal Force Difference [2 days after treatment]: Mechanical allodynia will be evaluated by measuring maximum occlusal force on the treated tooth and the corresponding contralateral asymptomatic tooth. The primary endpoint is the change in the difference in maximum occlusal force between the treated and contralateral teeth from baseline to follow-up.
• Change in Mechanical Allodynia Measured by Maximum Occlusal Force Difference [7 to 10 days after treatment]: Mechanical allodynia will be evaluated by measuring maximum occlusal force on the treated tooth and the corresponding contralateral asymptomatic tooth. The primary endpoint is the change in the difference in maximum occlusal force between the treated and contralateral teeth from baseline to follow-up.

Secondary outcomes

• Change in Postoperative Pain Measured by Numeric Rating Scale [Baseline]: Postoperative pain will be assessed using the 11-point Numeric Rating Scale in response to percussion testing of the treated tooth. The secondary endpoint is the change in Numeric Rating Scale pain score from baseline to follow-up.
• Change in Postoperative Pain Measured by Numeric Rating Scale [2 days after treatment]: Postoperative pain will be assessed using the 11-point Numeric Rating Scale in response to percussion testing of the treated tooth. The secondary endpoint is the change in Numeric Rating Scale pain score from baseline to follow-up.
• Change in Postoperative Pain Measured by Numeric Rating Scale [7 to 10 days after treatment]: Postoperative pain will be assessed using the 11-point Numeric Rating Scale in response to percussion testing of the treated tooth. The secondary endpoint is the change in Numeric Rating Scale pain score from baseline to follow-up.

Other outcomes

• Adverse Events and Treatment-Related Complications [Treatment visit through 7 to 10 days after treatment]: Participants will be evaluated for adverse events or complications related to nonsurgical root canal treatment, maximum occlusal force measurement, photobiomodulation, or simulated laser treatment.

Sex: All, ages: 18 Years to any

Inclusion Criteria:

* Adults 18 years of age or older
* Able to understand the study procedures and provide written informed consent
* Presenting for primary nonsurgical root canal treatment at the University of Minnesota School of Dentistry Graduate Endodontic Clinic
* A tooth diagnosed with symptomatic apical periodontitis
* A pulpal diagnosis of symptomatic irreversible pulpitis or pulp necrosis
* Study tooth is restorable and appropriate for completion of nonsurgical root canal treatment in a single visit
* Presence of a functional opposing tooth suitable for reproducible maximum occlusal force measurements
* Able to comply with study procedures, including percussion testing and maximum occlusal force measurements
* Able and willing to return for the scheduled follow-up visit 7 to 10 days after treatment

Exclusion Criteria:

* Younger than 18 years of age
* Unable or unwilling to provide informed consent in English
* Pregnant or known or suspected pregnancy
* Previous root canal treatment of the study tooth
* Study tooth cannot be treated and obturated during a single treatment visit
* Non-restorable tooth, vertical root fracture, root resorption, or suspected or confirmed crack extending onto the root surface
* Acute apical abscess requiring incision and drainage or other urgent surgical treatment
* Advanced periodontal disease or tooth mobility that may interfere with maximum occlusal force measurements
* Current chronic opioid therapy or chronic use of medications that, in the opinion of the investigator, would significantly alter pain perception or interfere with study outcome measures
* Unable or unwilling to return for the scheduled follow-up visit
* Any medical, physical, or cognitive condition that, in the opinion of the investigator, would prevent safe participation or completion of study procedures
* Children
* Pregnant women/persons
* Fetuses
* Neonates
* Prisoners
* Adults lacking capacity to consent or adults with diminished or fluctuating capacity to consent
* Non-English speakers
* Individuals unable to read
* Employees of the researcher
* Students of the researcher
* Individuals with a serious health condition for which there are no satisfactory standard treatments
* Individuals with fear of negative consequences for not participating
* Any other circumstance that could increase vulnerability to coercion or exploitation

• Ronald Ordinola-Zapata, Principal investigator, University of Minnesota