Low level laser therapy for burning mouth syndrome

MEEFRO November 9, 2023

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Burning mouth syndrome is a complex chronic orofacial pain condition. The prevalence of burning mouth syndrome has been reported to range from 0.7% to 15% in different settings (Dental Elf – 2^nd July 2021). A recent review by Alvarenga-Brant et al (Dental Elf – 21^st Oct 2022) indicated that clonazepam, low-level laser therapy also known as photobiomodulation therapy (PBMT) and pregabalin had an impact on pain levels.

The aim of this review was to evaluate the effect of low-level laser therapy (LLLT) on burning pain, quality of life, and negative emotions in patients with burning mouth syndrome (BMS).

Methods

A protocol was registered on the PROSPERO database. Searches were conducted in the PubMed, Embase, Cumulative Index of Nursing and Allied Health Literature (CINAHL), the Cochrane Library, Web of Science, and Scopus databases. English language randomised controlled trials (RCTs) of LLLT (600 – 1100nm) for the treatment of BMS were considered. Three reviewers independently screened studies with data extraction being conducted by a single reviewer and checked by a second reviewer. Study quality was assessed using the Cochrane risk of bias tool (RoB2). Results were presented as the weighted mean difference (WMD) or standardised mean difference (SMD) with 95% confidence intervals.

Results

14 studies met the inclusion criteria.
9 RCTs involving a total of 444 patients (229 with BMS and 215 controls contributed to the quantitative analysis.
The laser wavelength ranged from 630 to 1064 nm, power (30 mW to 4 W), and irradiance (0.003 to 4 W/cm²).
2 RCTs were considered to be at low risk of bias, 5 RCTs at high risk of bias and 7 RCTs at unclear risk.
Meta-analysis showed: –
- LLLT was significantly more effective than sham LLLT in reducing pain intensity SMD = -0.92 (95%CI: -1.38 to -0.46) [10 studies].
- LLLT was slightly more effective than clonazepam (SMD = -0.47, 95% CI: -1.17 to 0.23) [1 study].
Subgroup analysis indicated that LLLT reduced burning pain intensity when the intervention:-
- duration was >4 weeks SMD = -1.12 (95%CI: -1.58 to -0.66) [5 studies].
- frequency was < or=2 times per week SMD= -1.22 (95%CI: -1.59 to -0.85) [6 studies].
Analysis suggests positive changes in
- quality of life (assessed using the Oral Health Impact Profile-14), SMD = 0.01 (95%CI: -0.58 to 0.60) and
- negative emotions (evaluated using the Hospital Anxiety and Depression Scale; SMD = -0.12, 95%CI: -0.54 to 0.30), but these effects were not statistically significant.

Conclusions

The authors concluded: –

Low-level laser therapy could reduce burning pain in patients with burning mouth syndrome and have a positive influence on the quality of life and anxiety symptoms, without serious side effects, indicating that it may be an effective therapy for burning mouth syndrome. However, given the low methodological quality of the selected studies, our results should be interpreted with caution. A long-term course of intervention, a larger sample size, and a multidisciplinary intervention design are urgently needed.

Comments

A protocol for this review was registered on PROSPERO although the question being addressed was broader being for physical therapies for the treatment of BMS rather than being specifically for LLLT. A broad range of databases were searched although the restriction to those published in English may have excluded some relevant studies. The included studies are small to moderate in size and variety of lasers are used utilising different frequencies, power, and irradiance as well as application duration and schedules. Consequently, while the findings suggest positive outcomes with LLLT use there should be interpreted cautiously. A noted by the authors in their conclusions additional high quality well reported trials of appropriate size and duration are needed to properly clarify any benefits for the use of LLLT in BMS patients. The routine use of internationally agreed common outcome measures (COMET) would also be beneficial for future comparisons.