Evaluating the Preemptive Analgesic Effect of Photo-biomodulation Therapy on Pain Perception During Local Anesthesia Injection in Children: A Split-mouth Triple-blind Randomized Controlled Clinical Trial

Photochem Photobiol. 2022 Sep;98(5):1195-1200. doi: 10.1111/php.13605. Epub 2022 Feb 17.


To evaluate the impact of photobiomodulation therapy (PBMT) on injection pain perception and compare it with a topical oral anesthetic gel. A total of 30 patients of 6 to 9 years-old seeking pulpotomy treatment of maxillary secondary primary molars of both sides were considered for this split-mouth triple-blind randomized clinical trial. On one side of the maxilla, the low-level laser (diode laser, 808 nm, 250 mW; 16.25 J; 32.5 J cm-2 ) was irradiated upon the buccal gingiva of the tooth, while a Benzocaine 20% topical anesthetic gel was applied on the other side. A gel with the same taste (strawberry) was applied for the placebo. The Wong-Baker Faces Pain Rating Scale was used to evaluate the injection pain and postoperation pain at two timestamps, 1 h and 24 h after treatment. Patients' heart rate was also evaluated. Paired t, Wilcoxon signed-rank test, McNemar and Friedman tests were used for statistical analyses. Results demonstrated that PBMT could significantly decrease the injection pain perception and heart rate alternations compared to the topical anesthetic gels (P = 0.000). However, no significant differences were documented between the two methods concerning the 1-h (P = 0.26) and 24-h (P = 1.00) postoperation pain. PBMT can be an effective nonpharmacological technique for controlling injection pain.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Analgesics
  • Anesthesia, Local* / methods
  • Anesthetics, Local* / pharmacology
  • Anesthetics, Local* / therapeutic use
  • Benzocaine / pharmacology
  • Child
  • Gels / pharmacology
  • Humans
  • Lidocaine / pharmacology
  • Mouth
  • Pain / prevention & control
  • Pain Measurement / methods
  • Pain Perception


  • Analgesics
  • Anesthetics, Local
  • Gels
  • Lidocaine
  • Benzocaine