Effects of low-level laser therapy on burning pain and quality of life in patients with burning mouth syndrome: a systematic review and meta-analysis

Abstract

Background: Burning mouth syndrome (BMS) is a complex chronic pain disorder that significantly impairs patients' quality of life. Low-level laser therapy (LLLT) uses infrared or near-infrared light to produce analgesic, anti-inflammatory, and biological stimulation effects. The aim of this systematic review is to evaluate the effect of LLLT on burning pain, quality of life, and negative emotions in patients with BMS.

Methods: The PubMed, Embase, Cumulative Index of Nursing and Allied Health Literature (CINAHL), Cochrane Library, Web of Science, and Scopus databases were searched up January 2023 to identify relevant articles. All randomized controlled trials that were published in English and examined the use of LLLT treatment for BMS were included. The methodological quality of the included trials was assessed using the Cochrane risk of bias tool for randomized controlled trials (RCTs). A meta-analysis was performed to evaluate burning pain, quality of life, and negative emotions. Sensitivity, subgroup, and funnel plot analyses were also carried out.

Results: Fourteen RCTs involving a total of 550 patients with BMS met the inclusion criteria. The results showed that LLLT (measured by the Visual Analog Scale; SMD: -0.87, 95% CI: -1.29 to -0.45, P < 0.001) was more effective for reducing burning pain than placebo LLLT or clonazepam. LLLT improved quality of life (evaluated by the Oral Health Impact Profile-14; SMD: 0.01, 95% CI: -0.58 to 0.60, P = 0.97) and negative emotions (evaluated by the Hospital Anxiety and Depression Scale; SMD: -0.12, 95% CI: -0.54 to 0.30, P = 0.59), but these effects were not statistically significant.

Conclusions: The meta-analysis revealed that LLLT may be an effective therapy for improving burning pain in patients with BMS, and producing a positive influence on quality of life and negative emotions. A long-term course of intervention, a larger sample size, and a multidisciplinary intervention design are urgently needed in future research.

Trial registration: PROSPERO registration number: CRD42022308770.

Keywords: Burning mouth syndrome; Burning pain; Low-level laser therapy; Meta-analysis; Negative emotions; Quality of life.

Fig. 1

PRISMA flowchart of the studies included in this review

Fig. 2

Risk of bias summary. The risk of each bias in the included studies is shown (+ , ?, and—indicate low, uncertain, and high bias, respectively)

Fig. 3

Risk of bias graph

Fig. 4

Forest plot and meta-analysis of changes in pain intensity. Subgroup analysis with different intervention methods as moderators

Fig. 5

Forest plot and meta-analysis of changes in pain intensity. Subgroup analysis with different intervention durations as moderators

Fig. 6

Forest plot and meta-analysis of changes in pain intensity. Subgroup analysis with different intervention frequency as moderators

Fig. 7

Forest plot and meta-analysis of changes in pain intensity. Subgroup analysis with different wavelengths as moderators

Fig. 8

Forest plot and meta-analysis of changes in pain intensity. Subgroup analysis with different irradiances as moderators

Fig. 9

Forest plot and meta-analysis of changes in quality of life. Subgroup analysis according to different intervention methods

Fig. 10

Differences in HADS scores (negative emotions) following LLLT compared with other forms of interventions

Fig. 11

Sensitivity analysis for burning pain measured by the Visual Analog Scale. Forest plot and meta-analysis of changes in pain intensity after removing the studies of Sikora et al. and Skrinjar et al.

Fig. 12

Sensitivity analysis for quality of life measured by the Oral Health Impact Profile-14. Forest plot and meta-analysis of changes in quality of life after removing the studies of Bardellini et al. and Spanemberg et al.

Fig. 13

Funnel plot summary for outcomes before and after interventions (burning pain, measured by the Visual Analog Scale)

Fig. 14

Funnel plot summary for outcomes before and after interventions (quality of life, measured by the Oral Health Impact Profile-14)

Fig. 15

Funnel plot summary for outcomes before and after interventions (negative emotions, measured by the Hospital Anxiety and Depression Scale)