The efficacy of low-level laser therapy versus paracetamol-caffeine in controlling orthodontic separation pain and changes in the oral-health-related quality of life in Class I malocclusions: A 3-arm, randomized, placebo-controlled clinical trial

J World Fed Orthod. 2022 Jun;11(3):75-82. doi: 10.1016/j.ejwf.2022.01.001. Epub 2022 Jan 31.


Background: This study evaluated the analgesic effects of low-level laser therapy (LLLT) and paracetamol-caffeine in controlling orthodontic pain induced by elastomeric separators, as well as changes in oral health-related quality of life (OHRQoL).

Methods: A total of 54 patients (22 male, 32 female; mean age [standard deviation]: 21.68 [±2.77]) participated in the study. Elastomeric separators were placed mesially and distally to the first molars in the upper and lower dental arches. The first group (n = 18) received a single dose of aluminum gallium arsenide (GaAlAs) laser irradiation (808 nm; 350 milliwatts; 3.5 joule/point) with a placebo medication. The laser beam was applied buccally and lingually at the center of the first molar roots and the adjacent teeth (2nd molar and 2nd premolar) in both the upper and lower dental arches bilaterally. The second group (n = 18) received paracetamol-caffeine tablets (3 times daily for the first couple of days after separator insertion, and as needed for the rest of the week), with a placebo light-emitting diode (LED) light; patients in the third group (n = 18) were exposed to the 2 placebo procedures. An 11-point numeric rating scale was used to assess spontaneous and chewing pain perception immediately and at 1 hour, 24 hour, 48 hours, and 1 week after separator placement. The short version of the oral health impact profile (OHIP-14) was used to evaluate OHRQoL at 48 hours and at 1 week after separator placement.

Results: Pain perception reached its peak at 24 hours after separator placement (median values: 3, 3, 6.5 for spontaneous pain, and 6, 6, 8 for chewing pain in the LLLT, drug, and control groups, respectively). LLLT relieved the induced pain more than did the placebo procedures (P = 0.002 for spontaneous pain, P = 0.012 for chewing pain). Orthodontic separators worsened patients' OHRQoL scores during the entire week, especially at 48 hours after placement (median OHIP-14 score: 21, 25, 24 in the LLLT, drug, and control groups, respectively). In comparison with the control group, LLLT slightly increased the "physical pain" domain score (P = 0.015) and the "psychological disability" domain score of the scale (P = 0.010) after 48 hours, as well as the "psychological disability" domain score 1 week after separator placement.

Conclusions: The pain levels were similar in the laser and drug groups. The LLLT group had decreased pain, compared with the placebo group. Paracetamol-caffeine and LLLT were unable to enhance the overall OHRQoL.

Keywords: Chewing pain; Elastomeric separators; LLLT; OHRQoL; Orthodontic pain; Spontaneous pain.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetaminophen / therapeutic use
  • Caffeine / therapeutic use
  • Female
  • Humans
  • Low-Level Light Therapy* / methods
  • Male
  • Malocclusion, Angle Class I*
  • Pain / drug therapy
  • Pain / etiology
  • Pain Measurement / methods
  • Quality of Life


  • Acetaminophen
  • Caffeine