Temporomandibular Disorders and Traditional Chinese Medicine: Part II – Evidence-Based Analysis on Acupuncture

Journal of Complementary Therapies in Health ISSN 2975-9323 |eISSN 2975-9552 Journal of Complementary Therapies in Health 2025:3(3). doi:10.5281/zenodo.17390852 institutoptc.com/journal-complementary-therapies Review Temporomandibular Disorders and Traditional Chinese Medicine: Part II – Evidence-Based Analysis on Acupuncture. Paula Silva1*, Luísa Almeida1, José Ferreira de Oliveira2, Tony Bastos de Oliveira2, Alexandre Penelas Constantino1. 1 Independent researcher; 2 ABS – Health Level, Atlântico Business School, Vila Nova de Gaia, Porto, Portugal. * Correspondence: [email protected] Abstract Background: Temporomandibular Disorder (TMD) is a multifactorial condition with high prevalence that affects the temporomandibular joint (TMJ), masticatory muscles, and associated structures. It is characterised by pain, functional limitation, and joint sounds, representing a significant burden for both healthcare systems and patients. Although conventional approaches, such as physiotherapy, occlusal splints, and pharmacotherapy, are widely used, they often show limited effectiveness, which has encouraged the search for complementary therapies, including Traditional Chinese Medicine (TCM). Objectives: The aim of this work is to explore TMD with a focus on the TCM approach, particularly evaluating the effectiveness of acupuncture and its variants in the treatment of this condition. Methods: A comprehensive review of the literature was performed. Results: Scientific evidence suggests that acupuncture is effective in reducing pain, improving mandibular function, and decreasing muscle tension in patients with TMD. In several studies, acupuncture showed results superior or equivalent to conventional therapies, such as occlusal splints, physiotherapy, or pharmacotherapy. Specific variants, such as warm-needle acupuncture, laser acupuncture, and acupotomy, demonstrated additional benefits. Conclusions: Overall, the studies reviewed reported a favourable safety profile, reinforcing the safety of the technique. The acupuncture points most used were also analysed. Thus, TCM, particularly acupuncture, represents an effective and safe therapeutic approach for TMD, and may be integrated as a complementary option to conventional treatments. Despite the promising results, methodological limitations of the available studies restrict the generalisation of conclusions, highlighting the need for more robust and well-designed clinical trials to strengthen the existing evidence. Keywords: Temporomandibular Disorder; Temporomandibular Joint; Traditional Chinese Medicine; Acupuncture. 1. Introduction TMD is a multifactorial condition affecting the TMJ, the masticatory muscles, and related structures 1. Dysfunction in these components can lead to pain, restricted mandibular movement, and joint noises such as clicking or crepitus 2. Given its complex aetiology and high prevalence, TMD represents a considerable economic burden for both healthcare systems and affected individuals 3-5. Management typically requires a multidisciplinary approach, encompassing conservative therapies and, in more severe cases, invasive interventions 6,7. Citation: Silva P., Almeida L., de Oliveira J.F., de Oliveira T.B., Constantino A.P. Temporomandibular Disorders and Traditional Chinese Medicine: Part II – Evidence-Based Analysis on Acupuncture. Journal of Complementary Therapies in Health. 2025;3(3) 10.5281/zenodo.17390852 Academic Editor: Jorge Rodrigues Received: 25 August 2025 Reviewed: 15 September 2025 Revised: 29 September 2025 Revised: 10 October 2025 Accepted: 16 October 2025 Published: 19 October 2025 Publisher’s Note: IPTC stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Copyright: ©2025 by the authors. Submitted for open access publication under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/). Journal of Complementary Therapies in Health 2025: 3(3). 2 of 10 Silva P., Almeida L., de Oliveira J.F., Oliveira T., Constantino A.P. Temporomandibular Disorders and Traditional Chinese Medicine: Part II – Evidence-Based Analysis on Acupuncture doi:10.5281/zenodo.17390852 To enhance treatment outcomes, there is growing interest in complementary therapeutic strategies. Acupuncture, which involves the insertion of fine needles into specific points along meridians through which qi is believed to circulate, has been proposed as one such approach 8,9. This technique aims to modulate the nervous, circulatory, endocrine, and exocrine systems, ultimately promoting overall well-being 10. Accordingly, this article seeks to build upon Part 1 11 by examining the available scientific evidence on the efficacy of acupuncture in the management of TMD. 2. Methodology This study conducted a review of the scientific literature to evaluate the efficacy of acupuncture for the treatment of TMD. A literature search for meta-analyses that investigated acupuncture in TMD patients was performed. To analyse actual results and methodologies, the timeframe was set to studies published between 2020 and 2025. 3. Acupuncture for Temporomandibular Disorders 3.1. Meta-Analytical Evidence on Acupuncture Among the therapeutic techniques of TCM, acupuncture has received the greatest attention for the management of TMD 12. This section explores the most recent evidence provided by systematic reviews and meta-analyses published in the past five years. The study by Park et al. 13 investigated the efficacy and safety of acupuncture in the treatment of TMD. The authors screened 32 randomised clinical trials from 11 databases, of which 22 studies with 471 participants were included in a quantitative meta-analysis. The analysis was stratified according to the type of control group used: inactive control (placebo), active control (other treatments, such as physiotherapy), or adjunctive treatment ("add-on"). The certainty of the evidence was evaluated using the GRADE methodology. Both qualitative and quantitative analyses revealed significant findings. Compared with active controls, acupuncture produced significantly better treatment outcomes, with a relative risk (RR) of 7.00, and reduced pain intensity as measured by the Visual Analogue Scale (VAS). When applied as an adjunctive therapy, acupuncture also yielded significant improvements, with an increased treatment response (RR: 1.36) and a reduction of 1.23 points in the VAS. Based on these findings, the authors concluded that acupuncture is effective in the treatment of TMD, both when compared with active treatments and when used in combination with other therapies. Similarly, Ha et al. 14 evaluated and compared the efficacy and safety of various East Asian traditional medicine approaches, such as acupuncture, electroacupuncture, moxibustion, and herbal medicine, for TMD management. Their objective was to identify which therapies provided the most benefit for pain relief and improvement of functional restrictions. The review included 45 randomised clinical trials with a total of 2,211 participants, retrieved from multiple databases up to November 2023. A network meta-analysis was performed to compare the effectiveness of different therapies, even when not directly compared in the same trial. The analysis showed that acupotomy and acupuncture were particularly effective in alleviating pain. Acupotomy is a modern acupuncture technique that integrates traditional acupuncture principles with surgical concepts, using a scalpel-shaped needle 15. Both acupotomy (mean difference: –5.07) and acupuncture (mean difference: –1.18) demonstrated significant pain reduction compared with sham treatments. In the efficacy ranking, acupotomy was rated the most effective therapy, followed by electroacupuncture, acupuncture, manual therapy, laser therapy, and, lastly, occlusal splints. Among the 12 studies reporting adverse events, no serious events were observed. Consequently, the authors concluded that acupotomy and acupuncture may be more beneficial for pain relief than sham treatments and potentially superior to occlusal splints. Di Francesco et al. 16 reviewed the available literature to evaluate the clinical efficacy of acupuncture and laser acupuncture in reducing TMD-related pain. Eleven randomised Journal of Complementary Therapies in Health 2025: 3(3). 3 of 10 Silva P., Almeida L., de Oliveira J.F., Oliveira T., Constantino A.P. Temporomandibular Disorders and Traditional Chinese Medicine: Part II – Evidence-Based Analysis on Acupuncture doi:10.5281/zenodo.17390852 clinical trials were analysed, identified from three electronic databases up to July 2023, with a particular focus on comparisons with placebo. Their findings indicated that acupuncture is effective in reducing short-term pain intensity in muscular TMD. The metaanalysis showed that both acupuncture and laser acupuncture achieved higher efficacy rates than placebo. Importantly, the study emphasised the strong potential of laser acupuncture as a therapeutic approach for TMD. With a more specific focus, Liu et al. 17, examined the effectiveness of Warm Needle Acupuncture (WNA) for TMD, aiming to provide a robust evidence base for this increasingly used technique. In WNA, a burning moxa cone is placed on the handle of an inserted acupuncture needle, allowing heat to be conducted into deeper tissues through the needle. This warming stimulus is believed to dispel Wind and Cold, thereby alleviating pain 17. The analysis included 10 randomised clinical trials comparing WNA with other therapies, such as manual acupuncture, electroacupuncture, pharmacotherapy, and ultrasound therapy. A total of 670 patients were included across nine databases searched up to May 2021. Results indicated that WNA was superior to the other therapeutic approaches. Specifically, WNA achieved higher overall effectiveness rates (RR: 1.20) and significantly higher recovery rates (RR: 1.82) compared with acupuncture alone, acupuncture combined with TDP therapy, drug therapy, or ultrasound. The authors concluded that WNA is an effective therapeutic option for TMD, with promising clinical outcomes. General Considerations Overall, the systematic reviews and meta-analyses examined in this work consistently indicate that acupuncture is an effective therapy for the management of pain and dysfunction associated with TMD. Acupuncture has been shown to be superior to sham (placebo) treatments and, in many cases, as effective (or even more effective) than conventional therapies (active controls), such as occlusal splints and pharmacological interventions. Furthermore, specialised techniques such as Warm Needle Acupuncture (WNA) and acupotomy appear particularly promising, yielding results superior to conventional acupuncture and other therapeutic approaches. Laser acupuncture has also emerged as a highly effective option. Importantly, none of the reviewed studies reported serious adverse effects, suggesting that acupuncture is a safe therapeutic modality. Nevertheless, a critical limitation emphasised across all reviews is the generally low methodological quality of many existing studies. Although the conclusions are encouraging, they remain preliminary. Future randomised clinical trials with more rigorous designs, larger sample sizes, and standardised methodologies are consistently recommended to validate these findings more definitively. In summary, current evidence strongly supports the use of acupuncture and its variants as valid and beneficial therapeutic interventions for TMD. However, the urgent need for high-quality research remains a central issue. 3.2. Methodology and Mechanisms of Acupuncture for Temporomandibular Disorders Although acupuncture has a history spanning more than 3,000 years, it is now widely recognised in modern medicine, particularly for pain management 18. This explains the growing number of scientific studies in recent decades aimed at elucidating both its mechanisms of action and its clinical efficacy across biological systems 19. In the context of TMD, research has focused on the effects of specific groups of acupuncture points 13,16. Di Francesco et al. 16 reported that the most commonly used points are ST1 (4 studies), ST8 (3 studies), ST5 (2 studies), ST7 (1 study), and ST29 (1 study). With the exception of ST29, all of these are located on the face (Table 1). Journal of Complementary Therapies in Health 2025: 3(3). 4 of 10 Silva P., Almeida L., de Oliveira J.F., Oliveira T., Constantino A.P. Temporomandibular Disorders and Traditional Chinese Medicine: Part II – Evidence-Based Analysis on Acupuncture doi:10.5281/zenodo.17390852 Table 1. Name and location of points reported by Di Francesco et al. 16. Acupuncture point Location (according to World Health Organization 20) Stomach 1 - 承泣/Chengqi Figure 1. Location of ST1. Stomach 8 - 頭維/Touwei Figure 2. Location of ST8. Stomach 5 - 大迎/Daying Figure 3. Location of ST 5. Journal of Complementary Therapies in Health 2025: 3(3). 5 of 10 Silva P., Almeida L., de Oliveira J.F., Oliveira T., Constantino A.P. Temporomandibular Disorders and Traditional Chinese Medicine: Part II – Evidence-Based Analysis on Acupuncture doi:10.5281/zenodo.17390852 Stomach 7 - 下關/Xiaguan Figure 4. Location of ST 7. Stomach 29 - 归来/Guilai Figure 5. Location of ST 29. By contrast, Park et al. 13 highlighted a different group of frequently used points, namely LI4 (18 studies), ST6 (11 studies), ST7 (10 studies), SI19 (6 studies), and GB20 (5 studies). These are presented in Table 4, with the exception of ST7, which was already included in Table 2. Table 2. Name and location of points reported by Park et al. 13. Acupuncture point Location (according to World Health Organization 20) Large intestine 4 - 合谷/He Gu Figure 6. Location of LI 4. Journal of Complementary Therapies in Health 2025: 3(3). 6 of 10 Silva P., Almeida L., de Oliveira J.F., Oliveira T., Constantino A.P. Temporomandibular Disorders and Traditional Chinese Medicine: Part II – Evidence-Based Analysis on Acupuncture doi:10.5281/zenodo.17390852 Stomach 6 - 頰車/Jiache Figure 7. Location of ST 6. Small intestine 19 - 聽宮/Ting Gong Figure 8. Location of SI 19. Gallbladder 20 - 風池/Feng Chi Figure 9. Location of GB 20. From a localisation perspective, and in contrast with Di Francesco et al. 16, the most frequently used point overall was the distal point LI4. Both studies, however, reported Journal of Complementary Therapies in Health 2025: 3(3). 7 of 10 Silva P., Almeida L., de Oliveira J.F., Oliveira T., Constantino A.P. Temporomandibular Disorders and Traditional Chinese Medicine: Part II – Evidence-Based Analysis on Acupuncture doi:10.5281/zenodo.17390852 that the most commonly selected points generally included four local points and one distal point, with only ST7 appearing in both sets. This suggests that, for TMD, local points around the TMJ are particularly relevant. The proposed local mechanism of acupuncture is based on micro-lesions induced by needle insertion, which stimulate peripheral nerve endings and receptors, thereby activating the axon reflex 21. This reflex leads to vasodilation and increased local blood flow, promoting the release of healing substances such as neuropeptides and adenosine. Needle stimulation also triggers a localised immune response, recruiting immune cells such as mast cells and macrophages that release biomolecules, facilitating tissue repair and pain reduction 22-24. Acupuncture may also relieve tension in shortened muscle fibres associated with trigger points, thereby reducing musculoskeletal pain 25. Despite this, the most frequently used point for TMD treatment is distal: LI4. Located on the dorsum of the hand, between the first and second metacarpal bones 26. LI4 is widely used for treating facial disorders. It is the Yuan-source point of the Large Intestine Yangming meridian of the hand 27. This meridian passes through the cheek and crosses the contralateral nasolabial groove before reaching the opposite side of the nose. Accordingly, acupuncturists often choose the contralateral LI4 point to treat facial conditions, in line with the anatomical trajectory of the Yangming meridian 27. Functional MRI studies 27 have demonstrated that acupuncture at LI4 (compared to sham) activates brain regions such as the left middle temporal gyrus, right supramarginal gyrus, left inferior temporal gyrus, and the posterior lobe of the left cerebellum. These results support the specificity of acupuncture points, suggesting that its effects are mediated by distinct neural pathways. In this context, LI4 stimulation influences orofacial brain regions despite being anatomically distant, highlighting a neurological mechanism beyond local effects. The stimulation sends afferent signals to the brain that modulate complex neural networks. Additionally, LI4 stimulation has been linked to the release of endogenous analgesic substances. According to Cabıoğlu et al. 28, stimulation at LI4 increases endorphin release, thereby reducing pain and muscle tension. Clinical studies have shown significantly higher plasma levels of β-endorphin in patients treated with acupuncture at LI4 compared with sham controls 29. Moreover, LI4 stimulation enhances secretion of dynorphin and met-encephalin, further contributing to pain relief 29. Other studies have reported that LI4 stimulation promotes the release of neurotransmitters involved in pain modulation, including serotonin 30,31 and noradrenaline 32, as well as exerting anti-inflammatory effects through adenosine release 33 , albeit locally. Collectively, these findings suggest that acupuncture at LI4 exerts a multifaceted and scientifically substantiated impact on TMD. Its therapeutic action is not limited to local effects but involves two main pathways: neurological (central nervous system modulation) and biochemical (release of endogenous analgesic and anti-inflammatory mediators). 4. Conclusions This work demonstrates that TCM, particularly acupuncture, represents a promising therapeutic approach for TMDs. The analysis of the available scientific evidence indicates that acupuncture provides consistent benefits in pain relief, improvement of mandibular function, and reduction of muscle tension, being in several cases superior or equivalent to conventional therapies such as occlusal splints, physiotherapy, or pharmacotherapy. Complementary techniques, including warm-needle acupuncture, laser acupuncture, and acupotomy, have also shown relevant results, reinforcing the versatility and effectiveness of these interventions. Another important aspect is the safety of acupuncture, as studies suggest the absence of serious adverse effects, positioning it as a viable and lowrisk treatment option for TMD. Journal of Complementary Therapies in Health 2025: 3(3). 8 of 10 Silva P., Almeida L., de Oliveira J.F., Oliveira T., Constantino A.P. Temporomandibular Disorders and Traditional Chinese Medicine: Part II – Evidence-Based Analysis on Acupuncture doi:10.5281/zenodo.17390852 Despite the robustness of these conclusions, the literature still lacks high-quality clinical trials that could definitively consolidate the existing evidence. Therefore, future investigations with greater methodological rigor and larger sample sizes are essential to validate and standardise therapeutic protocols. In summary, TCM, with emphasis on acupuncture, proves to be an effective and safe therapeutic tool for the management of TMD, with the potential to complement conventional treatments and contribute to a broader, multidisciplinary approach to this condition. Author statement: Conceptualisation, P.S.; Methodology, P.S.; Software, H.M.S. and J.A.M.; Validation, P.S.; Formal analysis, P.S.; Investigation, P.S., L.A., J.F.O., T.O., and A.P.C.; Resources, T.O., and A.P.C.; Data Curation, P.S., and L.A.; Writing - Original Draft, P.S.; Writing - Review & Editing, P.S., L.A., J.F.O., T.O., and A.P.C.; Visualisation, P.S.; Project administration P.S., L.A., and J.F.O. All authors have read and agreed to the published version of the manuscript. Funding: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Conflict of Interest: The authors declare that there are no conflicts of interest. Institutional Review Board Statement: Not applicable. Informed Consent Statement: Not applicable. Data Availability Statement: The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding author. References 1. 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