Effects of low level laser therapy on injection pain and anesthesia efficacy during local anesthesia in children: A randomized clinical trial

Int J Paediatr Dent. 2022 Jul;32(4):576-584. doi: 10.1111/ipd.12936. Epub 2022 Feb 8.


Background: The use of low level laser therapy (LLLT) to reduce injection pain associated with dental local anesthesia is reported in a limited number of studies in adults, but research on the effects of LLLT in children is needed.

Aim: This study aimed to evaluate the effects of topical anesthesia + LLLT on injection pain, anesthesia efficacy, and duration in local anesthesia of children who are undergoing pulpotomy treatment.

Design: The study was conducted as a randomized, controlled-crossover, double-blind clinical trial with 60 children aged 6-9 years. Before local infiltration anesthesia was administered, only topical anesthesia was applied in one side (control group/CG), and topical anesthesia plus LLLT (a diode laser: 810 nm; continuous mode; 0.3W; 20 s; 69 J/cm2 ) was applied in the contralateral side (LG) as pre-anesthesia. The injection pain and anesthesia efficacy were evaluated subjectively and objectively using the Wong-Baker Faces Pain Rating Scale (PRS) and the Face, Legs, Activity, Cry, Consolability (FLACC) scale respectively. Data were analyzed for statistical significance (p < .05).

Results: The "no pain" and "severe pain" rates in the PRS were 41.7% and 3.3% for the LG and 21.7% and 11.7% for the CG, respectively, during injection. Similarly, in the FLACC data, the number of "no pain" responses was higher for the LG than the CG (40%, 33.3%) and no "severe pain" rate was observed in both groups. The only statistically significant difference found for the PRS was p < .05. The median pain score was "0" for the LG and the CG in the FLACC data for the evaluation of anesthesia efficacy, and there was no statistically significant difference between the groups in terms of pain and anesthesia duration (p > .05). Also, most of the children preferred injection with topical anesthesia + LLLT (66.7%).

Conclusions: It has been determined that the application of topical anesthesia + LLLT with an 810-nm diode laser before local infiltration anesthesia reduced injection pain and did not have an effect on anesthesia efficacy and duration in children.

Keywords: anesthetic efficacy; child; dental local anesthesia; injection pain; laser analgesia; low level laser therapy.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Anesthesia, Dental*
  • Anesthesia, Local
  • Anesthetics, Local
  • Child
  • Humans
  • Low-Level Light Therapy*
  • Pain / etiology
  • Pain / prevention & control
  • Pain Measurement


  • Anesthetics, Local