Effectiveness of extracorporeal shock wave therapy for temporomandibular disorders: a systematic review and meta-analysis

1. Introduction

Temporomandibular disorders (TMD) refer to a group of musculoskeletal disorders affecting the temporomandibular joint (TMJ), masticatory muscles, and surrounding anatomical structures [1, 2]. Patients commonly present with clinical symptoms such as irregular jaw movement, facial pain, restricted mouth opening, joint noise, and headaches. These manifestations significantly impact quality of life, particularly due to pain during chewing [3, 4]. The etiology of TMD is multifactorial and sometimes controversial, involving traumatic injuries, abnormal muscle hyperactivity, intra-articular disc disorders, systemic diseases, hormonal influences, and psychological factors [5, 6, 7]. Alrizqi AH et al. [8] reported that 30%–50% of the global population may be affected by TMD, with a higher prevalence in women, and that its onset may be associated with psychological status. The condition typically affects individuals aged 20 to 50, although it can also occur in adolescents [3].

Management of TMD involves a range of approaches, with primary objectives including pain relief, improved mouth opening, and enhanced quality of life for patients [9]. Treatment options encompass jaw physiotherapy, medications, patient education and self-care, occlusal appliance therapy, behavioral therapy, psychotherapy, minimally invasive procedures (e.g., arthrocentesis and intra-articular injections), and TMJ surgery [10, 11]. Despite the variety of treatments, they all have certain limitations. For instance, nonsteroidal anti-inflammatory drugs (NSAIDs) may cause gastrointestinal issues and negatively affect liver and kidney function, while occlusal splint therapy is contraindicated in patients with obstructive sleep apnea. Minimally invasive interventions, such as intra-articular injections, carry risks of local infection or tissue irritation [11], and surgical options are costly, invasive, and involve prolonged recovery times [12].

Extracorporeal Shock Wave Therapy (ESWT) is a non-invasive physical therapy technique that uses high-energy shock waves to target specific tissues, promoting healing, alleviating pain, and improving function. Initially developed for the treatment of kidney stone in the 1980s [13], ESWT was serendipitously found to induce an osteogenic response in animal models, which led to its application in treating musculoskeletal disorders [14, 15]. Although the precise therapeutic mechanism of ESWT remains unclear, its effectiveness in treating musculoskeletal conditions, such as proximal plantar fasciitis, lateral epicondylitis of the elbow, calcifying tendinitis of the shoulder, patellar tendinopathy, and Achilles tendinopathy, is well-established [14, 15].

As early as 2002, ESWT was explored for the treatment of TMJ locking [16, 17]. In this context, the ESWT probe, coupled with gel, is applied to TMJ tender points or adjacent masticatory muscles, while avoiding the facial nerve to minimize risks, in accordance with clinical guidelines [18]. A typical session lasts 5–10 minutes at a moderate energy level, enabling shockwaves to reach the TMJ synovium and articular cartilage [19]. Reported side effects are mild and transient, such as local erythema, slight pain, and edema, with no severe complications, such as nerve injury or joint damage, reported to date [18]. Recent studies have demonstrated that ESWT may offer a protective effect on subchondral bone structure and cartilage in rat models of TMJ osteoarthritis [20]. Clinical studies comparing ESWT with other treatment options for TMD are also ongoing.

To date, no systematic reviews or meta-analyses have been conducted on this topic. This study aims to evaluate the efficacy of ESWT in the treatment of TMD based on available RCTs, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

2. Materials and methods

This systematic review and meta-analysis was registered in PROSPERO (International Prospective Register of Systematic Reviews, CRD42025631405) and conducted in accordance with PRISMA guidelines (Supplementary material 1).

3. Results

3.1 Study selection

A total of 64 potentially relevant records were retrieved from the databases. After removing duplicates, 29 records remained. Nine records were excluded after title and abstract screening due to irrelevant interventions or incomplete outcome data, leaving 20 full texts for further eligibility assessment. Of these, 6 were excluded based on predefined eligibility criteria: 3 had incomplete outcome data, and 3 reported inadequate interventions. Ultimately, 14 studies were included in the meta-analysis [21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34]. The study selection process is outlined in Fig. 1.

Fig. 1.PRISMA flow diagram. The PRISMA flow diagram illustrates the study selection process. A total of 64 articles were retrieved from the bibliographic search, and 14 articles were included in the review. PRISMA: Preferred Reporting Items for Systematic Reviews and Meta-Analysis; PubMed: US National Library of Medicine; Embase: Excerpta Medica Database; CNKI: China National Knowledge Infrastructure; VIP: Chinese Science and Technology Periodical Database; SinoMed: Chinese Biomedical Literature Database; Wanfang: Wanfang Data Knowledge Service Platform.

3.3 Risk of bias assessment of included studies

The risk of bias of the included studies was assessed using the Cochrane Risk of Bias Tool, with the results presented in Fig. 2 and Supplementary Fig. 1. Most studies exhibited an unclear risk of bias across multiple domains. While all 14 studies employed randomization for participant allocation, none specified whether allocation concealment was implemented. Only 2 studies [21, 33] provided details on the blinding method, both being assessed as having a high risk of performance bias but a low risk of detection bias. Complete outcome data were reported in only 1 study [28], and the risk of attrition bias remained unclear for the remaining 13 studies. Two studies [21, 33] were deemed to have a low risk of reporting bias, with the risk of reporting bias remaining unclear for the others.

Fig. 2.Risk of bias summary. The judgments for each bias item from the risk of bias assessment tool were made for all included studies. +: low risk of bias; −: high risk of bias; ?: unclear risk of bias.

3.4 Meta-analysis result

3.4.1 Treatment effect of ESWT alone

Of the 14 RCTs included in the qualitative synthesis, 2 were subjected to meta-analysis to assess the efficacy of ESWT alone. In these studies, the control groups received shortwave diathermy and/or ultrasound therapy [33, 34]. Given the small number of included studies (n = 2), sensitivity analysis and publication bias assessment were not performed, as these methodological evaluations lack statistical validity and meaningful interpretability with such a limited sample size. Therefore, the certainty of evidence for these outcomes is very low (Supplementary Tables 1,2), primarily due to the small sample size and insufficient data to assess key quality aspects. Considering the limited number of trials, this subgroup analysis should be regarded as exploratory, and the results must be interpreted with caution.

3.4.1.1 Pain

Both RCTs used the VAS to measure pain changes before and after treatment. The meta-analysis results revealed no statistically significant difference in pain reduction between the ESWT group and the control group (MD = −0.81; 95% CI = −1.77–0.16; p = 0.06; I² = 0.0%; Fig. 3).

Fig. 3.Forest plot of ESWT alone for pain. Pooled mean differences were calculated using a random effects model. CI: confidence interval; MD: mean difference; SD: standard deviation.

3.4.1.2 Maximum mouth opening (MMO)

Both RCTs also used MMO as an outcome indicator to assess improvements in TMJ function. The meta-analysis results for MMO indicated that, compared to the control group, the ESWT group did not show a statistically significant improvement in MMO (SMD = −1.84; 95% CI = −18.43–14.74; p = 0.39; I² = 97.5%; Fig. 4).

Fig. 4.Forest plot of ESWT alone for maximum mouth opening. Pooled mean differences were calculated using a random effects model. SMD: standardized mean difference; CI: confidence interval; SD: standard deviation.

3.4.2 Effects of ESWT in conjunction with other treatments

Of the 14 RCTs included in the qualitative synthesis, 12 were analyzed to evaluate the effectiveness of ESWT combined with other therapies [21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32]. Among these, 10 RCTs incorporated manual therapy as the adjunctive intervention, 1 combined ESWT with electroacupuncture [22], and 1 combined ESWT with NSAIDs, antispasmodic drugs, and splint therapy [21]. According to the GRADE assessment, the certainty of evidence for this subgroup was rated as low to very low (Supplementary Tables 1,2).

3.4.2.1 Pain

All 12 RCTs used the VAS to compare changes in TMD-related pain between the control group and the combination treatment group. Meta-analysis results indicated that, compared to the control group, the combination treatment group (ESWT + other therapies) significantly alleviated pain, with low certainty of evidence (MD = 0.94; 95% CI = 0.61–1.26; p < 0.0001; I² = 19.5%; Fig. 5). Leave-one-out sensitivity analysis confirmed the stability and robustness of the pooled results, as sequential exclusion of individual studies did not alter the core findings (Supplementary Fig. 2). Publication bias was negligible: the funnel plot (Supplementary Fig. 3) showed a roughly symmetric distribution of studies, and Egger’s linear regression test yielded t = 0.29, degrees of freedom (df) = 10, p = 0.7800, with a small bias estimate of 0.2739 (Standard Error (SE) = 0.9546).

Fig. 5.Forest plot of ESWT in conjunction with other treatments for pain. Pooled mean differences were calculated using a random effects model. CI: confidence interval; MD: mean difference; SD: standard deviation.

3.4.2.2 Maximum mouth opening (MMO)

Ten of the 12 RCTs [21, 22, 23, 24, 25, 27, 28, 29, 30, 32] reported MMO as an outcome indicator to assess TMJ functional improvement. Meta-analysis results showed that the combination treatment group (ESWT + active therapy) significantly increased MMO compared to the control group, with very low certainty of evidence (SMD = 0.69; 95% CI = 0.48–0.90; p < 0.0001; I² = 45.5%; Fig. 6). Leave-one-out sensitivity analysis (Supplementary Fig. 4) confirmed the robustness of these findings, as sequential exclusion of individual studies did not alter the direction or significance of the pooled SMD. For publication bias, the funnel plot (Supplementary Fig. 5) displayed a roughly symmetric distribution of studies, and Egger’s linear regression test (t = −1.26, df = 8, p = 0.2415) further suggested no significant publication bias (bias estimate = −1.7686, SE = 1.3982).

Fig. 6.Forest plot of ESWT in conjunction with other treatments for maximum mouth opening. Pooled mean differences were calculated using a random effects model. SMD: standardized mean difference; CI: confidence interval; SD: standard deviation.

4. Discussion

This is the first meta-analysis to systematically compare the efficacy of ESWT monotherapy and adjunctive therapy for TMD. Analysis of the included studies revealed that, compared to the control treatment group, the ESWT monotherapy group showed no statistically significant improvements in either VAS scores or MMO. In contrast, the combination treatment group (ESWT combined with other therapies) demonstrated statistically significant improvements in both VAS and MMO outcomes compared to the control group.

While most RCTs suggest that ESWT is effective for TMD, its precise mechanism of action remains unclear [35]. A study using an animal model to investigate the effect of ESWT on chondrocytes and TMJ osteoarthritis in rats found that ESWT downregulates the expression of pro-inflammatory factors [20, 36]. Another study identified three main pathways through which ESWT alleviates musculoskeletal disorders: first, by acting on nerve fibers to reduce pain; second, by stimulating angiogenesis to promote tissue healing; and third, by regulating calcium deposition [35, 37].

Notably, treatment parameters and device-dependent factors influence the efficacy of ESWT: energy flux density (EFD) determines the depth of penetration, with suboptimal levels (either too low or too high) potentially limiting efficacy or increasing tissue irritation; wavelength affects penetration efficiency, with shorter wavelengths facilitating deeper tissue reach [18]; treatment duration (5–10 minutes per session) balances energy accumulation and patient tolerance; and applicator design influences energy distribution. Focused-output applicators ensure concentrated delivery to targets, while design variations may contribute to heterogeneity in treatment efficacy [18]. As previously noted, ESWT delivered at a moderate clinical EFD can penetrate to a depth sufficient to reach the core anatomical structures of the human TMJ region. This is supported by in vitro evidence showing its ability to traverse soft tissues and superficial bone. This penetration depth aligns with the TMJ’s anatomical layers (skin, subcutaneous tissue, fascia, joint capsule, and articular disc), ensuring energy reaches key pathological targets to relieve pain, release intra-articular fibrosis, and reduce synovial inflammation [19].

Although ESWT can treat musculoskeletal diseases through multiple mechanisms, the results of this meta-analysis indicate that its therapeutic effect is not statistically significant when used alone. Several factors may explain this finding. First, the control interventions in the ESWT monotherapy subgroup were limited to ultrashort wave therapy and/or ultrasonic therapy. Ultrashort wave therapy promotes vasodilation, accelerates blood circulation, and improves the nutritional supply and metabolism of local tissues [38]. Ultrasonic therapy, through its mechanical and thermal effects, alleviates pain and promotes soft tissue regeneration [39]. The therapeutic effects of these control therapies overlap with those of ESWT, which may explain why ESWT alone did not show a statistically significant advantage over the control group in treating TMD. Furthermore, the studies included specifically enrolled patients with Type I TMD, whose primary symptom is pain. The lack of significant differences in treatment outcomes might therefore be attributed to the fact that ESWT, ultrasonic therapy, and ultrashort wave therapy are all established modalities for pain relief, potentially leading to similar effect profiles in this context.

In contrast, the meta-analysis revealed a statistically significant therapeutic effect when ESWT was combined with other treatments. Notably, 10 of the 12 studies in this subgroup employed manual therapy. Various manual therapy techniques, including TMJ mobilization, soft tissue manipulation, and massage of the masticatory and cervical muscles, are commonly used in TMD management. These techniques reduce connective tissue and muscle stiffness, thus improving functional capacity [40]. The addition of ESWT is believed to accelerate pain relief by modulating anti-inflammatory mediators and endorphins, enhancing patient compliance and tolerance for subsequent manual therapy [36]. Moreover, some patients with TMD experience involuntary contractions of the masseter and temporalis muscles during joint movement, which limits the therapist’s ability to improve joint range of motion [41]. By exerting anti-fibrotic effects and alleviating muscle spasms, ESWT promotes muscle relaxation, facilitating deeper and more targeted manual therapy [42, 43]. This synergistic effect has been observed in other musculoskeletal conditions, such as frozen shoulder [44], where ESWT, as an adjunct to conventional treatment, has shown statistically significant benefits in pain reduction and functional improvement.

This study has several limitations that must be considered when interpreting the results. First, the sample size of the ESWT monotherapy subgroup is severely limited, with only two studies (totaling 160 participants) meeting the inclusion criteria. As a result, the findings should be interpreted with caution. Second, all included studies were of overall low methodological quality, with an unclear risk of bias, primarily due to insufficient blinding of participants and researchers, as well as short follow-up durations. Third, substantial clinical heterogeneity existed across the included studies, including inconsistent TMD diagnostic subtypes and varying concomitant interventions, which may limit the generalizability of the pooled results. Fourth, heterogeneity in ESWT treatment parameters, including intensity, frequency, and total number of sessions, may have contributed to variations in therapeutic effects.

Despite these limitations, this meta-analysis provides clinicians with a structured synthesis of the available evidence on ESWT’s efficacy. The primary goal is not to establish definitive clinical recommendations but to clarify the current evidence profile and identify key research gaps. Rigorous methodological assessments were employed to ensure transparent reporting of limitations, enabling readers to accurately interpret the certainty of the findings. In light of these limitations, future research should prioritize well-designed, multicenter RCTs with large sample sizes, rigorous blinding, and long-term follow-up to definitively determine the therapeutic role of ESWT.

5. Conclusions

Compared to conventional treatments, ESWT monotherapy did not demonstrate a significant advantage in pain relief or improvement in mouth opening for patients with TMD; however, this finding is constrained by the low methodological quality and small sample size of existing studies. In contrast, ESWT as adjunctive therapy showed statistically significant benefits. Nevertheless, given the overall low certainty of available evidence, definitive conclusions regarding its efficacy cannot yet be established. Our results provide a structured synthesis of current evidence synthesis to inform clinical decision-making and highlight the need for future high-quality trials to establish conclusive evidence.

Availability of data and materials

Some or all data generated or analyzed during this study are included in this published article or the data repositories listed in the References section.

Author contributions

SYL—designed and conducted the study. DDW—provided methodological assistance and advice. YLS and LY—performed the statistical analyses. SYL, YZW and SQT—drafted the manuscript. All authors participated in the editing and revision of the manuscript. All authors have read and approved the final manuscript.

Ethics approval and consent to participate

Not applicable.

Acknowledgment

Sincere gratitude is extended to Dandong Wu for her guidance and to family members and friends for their continous support.

Funding

This research was funded by the Chongqing Medical Scientific Research Project (Joint Project of Chongqing Health Commission and Science and Technology Bureau), grant number: 2024GDRC001.

Conflict of interest

The authors declare no financial affiliations (including research funding) or involvement with any commercial organization to disclose.

Supplementary material

Supplementary material associated with this article can be found, in the online version, at https://files.jofph.com/files/article/2054075010740305920/attachment/Supplementary%20material.zip.