Takayuki Suga
Akira Toyofuku
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- Department of Psychosomatic Dentistry, Graduate School of Medical and Dental Sciences, Institute of Science Tokyo, Tokyo, Japan
A Commentary on
By Mu, Li, Lu, Wang and Tao (2024). Front Oral Health. 5. doi: 10.3389/froh.2024.1458329
1 Introduction
Dear Editor,
We read with interest the article by Mu et al., entitled “The immediate pain relief of low-level laser therapy for burning mouth syndrome: a retrospective study of 94 cases” (1). The authors presented data suggesting a favorable immediate analgesic effect of low-level laser therapy (LLLT) in patients with burning mouth syndrome (BMS). While we commend their effort to explore noninvasive treatment modalities, we would like to raise several points of concern that warrant careful consideration before interpreting their results as definitive evidence of LLLT's efficacy.
2 Acknowledgment of LLLT advantages but insufficient placebo control
We fully acknowledge certain advantages of LLLT, including its noninvasive nature, minimal side effects, and ease of application. These features make it an attractive option for patients who are otherwise reluctant to undergo more invasive procedures or long-term pharmacotherapy. However, the authors’ study design without a placebo control group makes it difficult to rule out the possibility of a placebo effect. Although Mu et al. discussed the limitations of their study, their justifications do not exclude the likelihood that at least part of the reported immediate analgesic effect could arise from patient expectation or other nonspecific factors. In this regard, the authors' attempt to equate a short pre-post assessment interval with proper placebo control remains inadequate to definitively confirm a genuine physiological benefit of LLLT.
3 Lack of long-term efficacy evaluation
As Mu et al. primarily focused on immediate pain relief, their study design did not address the sustainability of this effect. This is reminiscent of older investigations into BMS, where nerve blocks via infiltrative anesthesia showed temporary benefits but failed to provide conclusive long-term outcomes (2, 3). Despite the possibility that a subset of patients could exhibit clinically meaningful improvements—even if partly influenced by placebo—the lack of long-term data leaves unanswered questions about whether LLLT confers sustained analgesia for BMS. In addition, BMS is recognized as a complex condition often involving psychosomatic and neuropathic components, and short-term pain relief does not necessarily translate into clinically significant long-term remission.
4 Standard pharmacotherapy in China and questionable comparisons
It is well recognized—both in our own observation and in many studies—that clonazepam and certain antidepressants are commonly used pharmacological agents for BMS in many settings worldwide (4). In China, the availability of these medications is predominantly restricted to psychiatric practices, creating a notable limitation in drug accessibility for BMS patients. Moreover, the pharmacologic treatments provided to many of their patients (e.g., mecobalamin, basic fibroblast growth factor, oryzanol, etc.) are not consistent with standard BMS medications reported elsewhere. Consequently, claiming that these participants had “standardized” pharmacotherapy prior to receiving LLLT may be an overstatement. The lack of commonly used pharmaceutical therapies (such as clonazepam) in many cases raises the question of whether these patients actually underwent what would be considered standard medical care. If, in fact, the majority of participants did not receive well-recognized treatments, concluding that LLLT succeeds where typical pharmacotherapy fails could be misleading.
5 Reports of LLLT non-efficacy and potential overstatement of conclusion
Mu et al. do acknowledge other studies indicating that LLLT may not help all BMS patients and, indeed, may exhibit results comparable to placebo (5). Nonetheless, the overall conclusion of their retrospective study appears overstated in suggesting the near-term pain reduction “proves” LLLT's effectiveness. Given that BMS is highly influenced by psychological factors, the lack of a robust control group, combined with the absence of detailed long-term follow-up, inevitably raises doubts about whether LLLT truly surpasses placebo in clinical practice. The complexity of BMS, involving overlapping neuropathic, psychological, and systemic variables, demands a more cautious interpretation of any single short-term measure of relief.
6 Conclusion and recommendations
In light of the concerns outlined above, we urge more rigorous study designs, including prospective randomized controlled trials with adequate placebo controls, standardized drug interventions, and well-defined follow-up periods. We believe such trials would more conclusively determine the extent to which LLLT confers genuine clinical benefit beyond placebo. Additionally, the interplay between psychosomatic variables and peripheral neuropathic mechanisms in BMS underscores the importance of exploring comprehensive, multidisciplinary approaches.
While LLLT may hold promise as part of a broader treatment regimen—particularly in countries where dentists who frequently treat BMS are not legally permitted to prescribe antidepressants or antiepileptic medications and for patients who cannot or prefer not to use pharmacotherapy—the current evidence, as presented by Mu et al., is insufficiently robust to warrant strong claims for routine clinical adoption.
We suggest that future investigations, in accordance with the healthcare context of each country, pay closer attention to recognized pharmacological treatments, employ randomized placebo-controlled methods, and incorporate extended observation intervals to ascertain whether the positive outcomes persist over time. Only then can the field move closer to establishing a more definitive, evidence-based consensus on LLLT for BMS.
Thank you for the opportunity to comment on this intriguing work. We believe that further discussion and additional studies can help refine our understanding of how best to manage this challenging condition.
Author contributions
TS: Writing – original draft. AT: Conceptualization, Funding acquisition, Supervision, Writing – review & editing.
Funding
The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This research was funded by KAKENHI from the Japanese Society for the Promotion of Science (JSPS), grant number 22K10141 to AT.
Conflict of interest
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Generative AI statement
The author(s) declare that Generative AI was used in the creation of this manuscript. During the preparation of this study, the authors employed the ChatGPT o1 Pro mode (OpenAI) system to translate the manuscript from Japanese into English, improve readability, rephrase text where appropriate, and ensure proper grammar. Subsequently, the authors conducted a thorough review and made any necessary editorial revisions. The authors assume full responsibility for the final content presented in this publication.
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References
1. Mu W, Li S, Lu Q, Wang J, Tao X. The immediate pain relief of low-level laser therapy for burning mouth syndrome: a retrospective study of 94 cases. Front Oral Health. (2024) 5:1458329. doi: 10.3389/froh.2024.1458329
2. Gremeau-Richard C, Dubray C, Aublet-Cuvelier B, Ughetto S, Woda A. Effect of lingual nerve block on burning mouth syndrome (stomatodynia): a randomized crossover trial. Pain. (2010) 149(1):27–32. doi: 10.1016/j.pain.2009.11.016
3. Calderipe CB, Kirschnick LB, Esteves-Pereira TC, Dos Santos ES, Vasconcelos ACU, Lopes MA, et al. Local anesthesia nerve block for managing burning mouth syndrome: a scoping review. Oral Surg Oral Med Oral Pathol Oral Radiol. (2024) 138(5):619–25. doi: 10.1016/j.oooo.2024.07.007
4. Tan HL, Smith JG, Hoffmann J, Renton T. A systematic review of treatment for patients with burning mouth syndrome. Cephalalgia. (2022) 42(2):128–61. doi: 10.1177/03331024211036152
Keywords: burning mouth syndrome, low-level laser therapy, placebo effect, Pharmacotherapy, analgesic efficacy
Citation: Suga T and Toyofuku A (2025) Commentary: The immediate pain relief of low-level laser therapy for burning mouth syndrome: a retrospective study of 94 cases. Front. Oral. Health 6:1556733. doi: 10.3389/froh.2025.1556733
Received: 7 January 2025; Accepted: 30 January 2025;
Published: 11 February 2025.
Edited by:
Rui Amaral Mendes, University of Porto, PortugalReviewed by:
Pia Lopez Lopez Jornet, University of Murcia, SpainCopyright: © 2025 Suga and Toyofuku. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Takayuki Suga, c3VnYS5vbXBtQHRtZC5hYy5qcA==