Comparative Efficacy of Non-Invasive Therapies in Temporomandibular Joint Dysfunction: A Systematic Review

Temporomandibular disorder (TMD) is a multifaceted disorder impacting the temporomandibular joint (TMJ), causing substantial discomfort and functional limitations. This systematic review aims to comprehensively assess the effectiveness of non-invasive treatment modalities for TMJ dysfunction, prioritizing a definitive protocol to ensure patient safety and enhance quality of life. Employing the PRISMA guidelines, we meticulously analyzed 20 studies from a pool of 1,417 articles sourced from databases such as PubMed, Google Scholar, ScienceDirect, and Medline. These studies underscore the multifarious nature of TMD and the varied responses to treatments such as physical therapy, laser therapy, ultrasound and electrical stimulation, splint therapy, injections, and arthrocentesis. Notably, the review highlights the paramount importance of precise diagnosis, often through surface electromyography, followed by a tailored treatment approach integrating manual therapy, counseling, and splint therapy. The systematic analysis revealed that while certain treatments such as transcutaneous electrical nerve stimulation and low-level laser therapy showed limited efficacy, combination therapies, especially those involving manual therapy, counseling, and splint therapy, demonstrated substantial improvement in reducing pain, depression, and anxiety. The findings advocate for a non-invasive, patient-centric approach, emphasizing education and symptom management before considering more invasive procedures such as injections and arthrocentesis. The review identifies the need for more comprehensive, longitudinal studies to establish a standardized, evidence-based treatment protocol for TMJ dysfunction, aiming to improve patient outcomes holistically.

can be attributed to several factors, including the physical and psychological stresses common in this age group, which may contribute to the onset or exacerbation of TMD symptoms.Approximately one-third of the population experiences at least one TMD-related symptom, such as jaw pain or clicking.TMD is often perceived as a condition influenced by repetitive movements that affect the structures involved in chewing.As with other musculoskeletal disorders, TMD patients benefit from therapeutic approaches commonly used for similar conditions [8,9].
Clinicians continue to face challenges in diagnosing and effectively managing the primary cause of nondental pain in the maxillofacial region, namely TMDs.Despite extensive clinical research efforts, TMD remains challenging to treat due to its nature as a comprehensive term encompassing various conditions with intricate origins.These conditions are further complicated by symptoms that vary widely in severity, adding to the diagnostic and therapeutic complexities [7].Interestingly, while certain signs and symptoms of TMD may spontaneously resolve without intervention, others persist for extended periods, even after exhausting all available treatment options.Furthermore, while some TMD cases have a clear physical basis, many others involve significant biopsychosocial elements, including psychological symptoms such as depression and anxiety.Over time, a multitude of treatment modalities have been suggested, with some becoming obsolete and others gaining popularity.However, a single solution for all cases of TMD is not feasible due to the diverse array of symptoms associated with the disorder.The literature reveals controversies surrounding the diagnosis and management of TMD, and treatment choices are often heavily influenced by the healthcare provider's expertise and experience [10,11].
Non-surgical treatment is considered the best and most effective approach for managing TMDs in more than 80% of patients.There are numerous non-surgical treatment options available, and they often require the collaboration of a multidisciplinary team comprising multiple specialist practitioners.This cooperative approach ensures comprehensive care that addresses the various aspects of TMD.
Published reports indicate that approximately 5% of patients receiving treatment for TMDs eventually require surgery.Currently, there is a variety of surgical procedures available for TMD, ranging from less invasive options, such as TMD arthrocentesis and arthroscopy, to more complex procedures, such as arthrotomy, which involves open joint surgery.In line with the recommendations of oral and maxillofacial surgeons who specialize in this field, patients are typically advised to exhaust non-surgical treatment options before considering surgery [12].
The primary objective of this systematic review is to critically evaluate and compare the efficacy of various non-invasive therapies for managing TMJ dysfunction/arthralgia.The main goal of the research strategy is to effectively answer the question, "Which non-invasive treatment protocol is the most effective in addressing TMJ dysfunction/arthralgia?"

Literature Search
To gather relevant articles for our systematic review, we conducted searches on PubMed, Google Scholar, ScienceDirect, and Medline using the keywords "TMD" OR "TMJ Dysfunction" OR "Treatments" OR "Therapies" AND "Non-Invasive Therapy."We adhered to PRISMA guidelines throughout the analysis to ensure precise reporting.Initially, we identified a total of 1,437 records.We applied filters to select English language publications, research articles, and clinical trials, resulting in the exclusion of book documents and review articles focused on non-invasive treatments for TMJ injuries, deformities, and dysfunctions.After applying these filters, 611 studies were screened for further relevance.
Upon a detailed examination of these studies, 229 articles were shortlisted for in-depth full-text evaluation.The remaining 442 articles were excluded for various reasons, including methodological shortcomings, poor quality or bias, inconsistency or irrelevance of outcomes, and being outdated or superseded by more recent research.After evaluating the 229 shortlisted studies, an additional 209 were excluded.Ultimately, only 20 studies met our specific criteria and were included in the review, proving to be most relevant to our study design and research objectives.To assess the efficacy of various non-invasive and minimally invasive treatments, the researchers used mandibular muscle mobility, maximum pain-free mouth opening, and pain levels as outcome measures.A total of 17 articles were removed from the selected studies based on missing information about the outcomes of interest.Next, p-values that were obtained from paired t-tests and/or ANOVA were considered for analysis.However, in some studies, other factors were also considered to compare the effectiveness of different treatment methods [13][14][15][16][17][18][19] (Table 1).In red light-emitting diode therapies and laser therapy, compared to the placebo group, there was a significant decrease in both pain levels and trigger points.In our systematic search and review process, roles were clearly defined to ensure efficiency and thoroughness.The first and last authors served as the main leaders and decision-makers.They oversaw the overall search strategy, aligning it with the study's objectives and resolving any arising conflicts or disagreements.Their role was crucial in maintaining the integrity and direction of the research.The other authors, each with their specialized expertise, conducted individual literature searches relevant to our study's scope.This collaborative effort allowed for a comprehensive and diverse data collection, ensuring thorough exploration of various topic aspects.In cases of conflicting data or differing opinions, the first and last authors would discuss these issues to reach a consensus, providing a balanced and well-considered resolution.This structured approach, with clear leadership and collaborative participation from all authors, ensured a systematic, unbiased, and comprehensive review process.This significantly contributed to the quality and reliability of our systematic review.Moreover, there are no conflicts of interest among the authors, and the research was conducted without any bias.

Analysis
Several factors were used to evaluate the effectiveness of non-invasive or barely invasive treatments in improving the symptoms of TMD: p-value, percentage of positive responses from patients, and the number of symptoms improved by a method.Different treatment methods were compared, and the effectiveness of combination therapies was also evaluated (Table 2).The study did not report any adverse effects or complications.

Results
In affected individuals, TMDs have been observed to decrease the overall quality of life.Even the most resilient patients are bothered by the distressing symptoms associated with this condition.These symptoms include persistent jaw pain, frequent headaches, and difficulties in eating and speaking, all of which can significantly impact daily life.
Given the significant challenges posed by TMDs, it is essential to adopt a treatment approach that is both cost-efficient and effective while also prioritizing patient safety.Surgical treatments are associated with various complications, making conservative and non-invasive therapies more appealing due to their inherent benefits.Consequently, these therapies have become the preferred first-line treatment for TMDs.The conservative and non-invasive approach is primarily characterized by its focus on minimizing risks and educating patients.Instead of immediately resorting to invasive procedures, this first line of therapy concentrates on empowering patients through education about their condition and providing them with tools to effectively manage their symptoms .
This systematic review analyzed 20 studies that employed a range of treatments, including physical therapy, laser therapy, ultrasound, electrical stimulation, splint therapy, injections, and arthrocentesis.Across these studies, a total of 798 patients underwent treatment using non-invasive and conservative therapies.

Physical Therapy
Physical therapy treatments for TMDs include manual techniques such as mobilizations, stretching, and manipulations of the TMJ and cervical spine.They also involve modalities that improve tissue health, exercise guidance (including self-stretching and mobility strategies), and patient education on relaxation techniques, postural instruction, and parafunctional awareness.Wright and North suggest that patients with cervicogenic headaches or forward head posture or those who have never received physical therapy for TMD should be encouraged to undergo physical therapy.Regular practice of postural exercises has been shown to improve the symptoms of TMD [34].
Functional and physiological activities involving mandibular movements, such as opening and closing the mouth, mastication, swallowing, and the occurrence of centric and eccentric occlusal contacts between the teeth of the mandible and maxilla, are crucial.These functional movements greatly affect the quality of life and are considered key oral health parameters.The movements of the bilateral TMJ, along with the presence of the articular disk, play a crucial role in ensuring proper mandibular guidance [35].
In a clinical trial involving 78 patients, Gawriołek et al. investigated the effectiveness of myorelaxation therapy in treating TMJ malfunctions [28].The study analyzed clinical findings, measurements of mandibular movement, and reported functional impairment.The findings indicated that myorelaxation therapy significantly improved efficacy.Notably, the opening and closing velocity and the range of opening and lateral movement showed considerable improvement after six months of treatment [28].The study by Gębska et al. aimed to evaluate the efficacy of surface electromyography testing and manual therapy treatments in enhancing the bioelectrical function of the masseter muscle in individuals with restricted TMJ mobility [17].The study revealed that therapeutic effectiveness could be effectively assessed using surface electromyography testing.It also emphasized including manual therapy treatments in the initial noninvasive intervention.The results indicated that manual therapy was more effective for pain relief and muscle relaxation compared to physical therapy [17].
Tuncer et al. conducted a comparative analysis to assess the effectiveness of home physical therapy versus a combination of manual therapy with home physical therapy.Their findings indicated that the combination of manual therapy with home physical therapy was more effective than home physical therapy alone [25].Osteopathic treatment, classified as a physical therapy intervention, employs fine manipulative techniques that are less invasive than other interventions.These techniques are individually tailored to the patient's tissue quality and are designed to either maintain or restore the circulation of body fluids.The concept of osteopathic treatment as a form of manual medicine was first introduced by Andrew Taylor Still in 1902.Cuccia et al. undertook a study to compare osteopathic manual therapy with conventional conservative therapy to critically assess their respective efficiencies.Their research concluded that osteopathic manual therapy was more effective compared to conventional conservative therapy [23].

Laser Therapy
The efficacy of light therapies is contingent on the absorption of photons at a cellular level.The use of LASER (light amplification by stimulated emission of radiation) technology can initiate photochemical reactions at the mitochondrial level, triggering changes in cell metabolism and protein synthesis.
Additionally, low-level light therapy is believed to stimulate the formation of new blood vessels, as well as increase collagen production and fibroblast cell activity [36].Laser therapy is beneficial in treating dentin hypersensitivity, soft tissue disorders, musculoskeletal pain, and bone regeneration.Both low-level and high-intensity laser therapy are extensively used to treat TMDs.A study investigating the efficiency of lowlevel laser therapy in patients with TMJ disorders treated 20 individuals experiencing pain with an 830 nm Ga-Al-As laser device that delivered an energy of 4 joules.However, the results indicated that the therapy was not significantly effective [14].In contrast, Ekici et al. evaluated the efficacy of high-intensity laser therapy in treating patients with myogenic TMJ disorders; 76 patients were randomized into two groups: a control group and a test group.The test group patients received high-intensity laser therapy and experienced a significant (47%) reduction in pain scores compared to the placebo group [15].
Rancan et al. conducted a clinical trial with 17 patients using stainless steel needles for acupuncture.This treatment was administered weekly for a total of 10 sessions and achieved a significant reduction in both visual analog scale (VAS) scores and TMD symptoms, thus indicating the effectiveness of acupuncture as a treatment option [37].Huang et al. evaluated the clinical effectiveness of laser acupuncture in treating TMDs.In their study, 20 patients were treated with a diode K-laser, which has a wavelength of 800 nm, once a week.The results demonstrated that 85% of the patients experienced varying degrees of pain relief [24].
Al-Quisi et al. compared the efficacy of light therapy and laser therapy in reducing pain among individuals with TMDs [16].It is proposed that low-level light therapy can potentially stimulate the formation of new blood vessels, increase collagen production, and enhance fibroblast cell activity.These effects, in addition to raising tissue temperature, can enhance microcirculation in the irradiated tissue, thereby effectively removing a majority of inflammatory mediators.The key difference between these various light therapies lies in the specific wavelength and optical power used.These factors directly influence the amount of energy delivered and the depth of light penetration through tissue [38].Both LED (light-emitting diode) and laser treatments are effective in providing therapeutic relief for the myogenous symptoms of TMDs [16,38].

Ultrasound and Electrical Stimulation
Ultrasound has been extensively researched as a potential treatment for temporomandibular joint osteoarthritis (TMJ-OA) and hypoxia-induced chondrocyte damage in TMDs.This interest stems from the fact that low-intensity ultrasound acts as a stimulator; it promotes neovascularization, facilitates the differentiation of mesenchymal stem cells, and aids in the local release of angiogenic factors.These effects then improve blood flow in ischemic tissues [39,40].In a clinical trial conducted by Ba et al., a total of 168 patients with TMD were divided into two groups for the study.The test group received ultrasound treatment.
The treatment protocol involved a single daily application for five days a week over two weeks, with each session consisting of three 5-minute blasts and a 2-minute interval between each blast.The effectiveness of ultrasound as a treatment for TMD was established in this study; only 2.63% of patients experienced a recurrence of symptoms after six months of therapy [40].The output frequency range of therapeutic ultrasound typically falls between 20 and 60 kHz.This treatment increases the stretch of the extracapsular soft tissue by generating deep heat at the joints, effectively treating joint contracture.Additionally, it aids in the stretching of soft tissue by reducing the viscosity of collagen, thereby decreasing non-acute pain, muscle spasms, and tendonitis.It also facilitates the breakage of calcium deposits in bursitis and decreases the firing of type II muscle spindles [33].The primary goals of using electrical stimulation devices for treating TMDs are to provide pain relief and address muscle hyperactivity or spasms.These devices utilize either transcutaneous electrical nerve stimulation (TENS) or high-voltage galvanic stimulation.TENS employs a low-voltage, low-amperage, biphasic current at varying frequencies, while high-voltage galvanic stimulation uses a higher voltage (>150 V), low-amperage, monophasic current at varying frequencies [41,42].Zhang et al. explored the efficacy of low-intensity pulsed ultrasound (LIPUS) in treating synovitis and masticatory myositis in TMD.They found that the therapy was effective in most tested cases after one week of LIPUS treatment [20].Zhang et al. also studied the impact of TENS on jaw movement-evoked pain in individuals with TMJ disc displacement.They observed a reduction in movement-evoked pain in TMJ patients with disc displacement without reduction (DDwoR), suggesting that TENS reduces activity-related pain in these patients [18].Donnell et al. determined the impact of motor cortex high-definition transcranial direct current stimulation (HD-tDCS) on clinical pain and motor measures in TMD patients.Twenty-four females underwent five daily, 20-minute sessions of active 2 milliamps HD-tDCS.Compared to the placebo group, the HD-tDCS group reported significant improvement in motor measurements and clinical pain [13].

Splint Therapy
One of the primary goals of splint therapy is to restore the vertical dimension of occlusion, which involves properly aligning the teeth and jaw.Occlusal splints are removable artificial occlusal surfaces used for diagnosis or therapy [41].They have several advantages, such as their ability to reduce tension, decrease muscle activity, and prevent the harmful effects caused by bruxism and TMDs.Dylina defined occlusal splint therapy as "the art and science of establishing neuromuscular harmony in the masticatory system and creating a mechanical disadvantage for parafunctional forces with removable appliances" [43].However, the use of occlusal splints prevents patients from achieving full intercuspation.As a result, patients need to position their jaws correctly, ensuring equal pressure on all teeth.This alignment helps the condyle to settle in a centric relation and encourages the development of new muscle and joint equilibrium [44].
Melo et al. evaluated the effectiveness of occlusal splint therapy, manual therapy, counseling, and a combination of occlusal splint and counseling in reducing pain in TMD patients.In the study, the combination treatment was observed to be more effective than the other treatments alone [22].Rodrigues et al. compared the effectiveness of occlusal splint therapy with low-power laser auriculotherapy in patients with TMD, and the researchers examined both physical and emotional symptoms.Intriguingly, they discovered that both treatment methods yielded similar improvements in symptom relief [30].

Joint and Muscle Injections
Joint injections and muscle injections are two types of treatments used to address TMD symptoms.Pons et al. evaluated the viability of MR-guided navigation for administering botulinum toxin injections in TMD patients.In a prospective study, six patients underwent treatment with intramuscular botulinum toxin A injections.The therapy was found to be effective in 67% of the patients [31].Vingender et al. assessed the clinical effects of platelet-rich fibrin, hyaluronic acid (HA), and platelet-rich plasma injections in the internal derangement of the TMJ.Their study concluded that there was no significant difference among the treated groups, suggesting that all injections were equally effective [29].Sipahi Calis et al. investigated the effectiveness of botulinum toxin injections in the treatment of muscular TMD.Twenty-five patients received various treatments including drug therapy, drug combined with physical therapy, occlusal splint therapy, and botulinum toxin injections.The botulinum toxin treatment showed positive results in nine patients [27].

Arthrocentesis
Performed under local anesthesia, arthrocentesis is done to flush out the superior space of the TMJ.It aims to reduce intra-articular pressure and control pain.For joint space lavage, normal saline, steroids, botulinum toxin, HA, or anti-inflammatory agents are used.The procedure encompasses three key steps: separating the joint constituents, removing inflammation, and eliminating intra-articular effusion [41].
Arthrocentesis is effective for both internal derangement and inflammatory degenerative disorders of the TMJ, making it a recommended treatment modality.Furthermore, the procedure has demonstrated favorable outcomes in both short-term and long-term results, notably improving maximum mouth opening (MMO) and alleviating pain [45].Polat and Yanik used the same arthrocentesis protocol to assess the efficacy of arthrocentesis therapy in 45 TMD patients.Arthrocentesis was found to be most effective in patients with disc displacement without reduction (DDWoR) [26].

Discussion
Even though clinical trials have identified methods with greater efficacy than others, the effectiveness of a particular treatment for TMDs varies between patients.This review describes the main findings from 20 selected studies, summarized in tables.[17,31].Half of the studies compared the effectiveness of a single treatment against a placebo group, whereas other studies evaluated multiple therapies and compared their effectiveness.The duration of the treatments varied from one week to six months.The efficacy of the treatments was assessed using various measures such as the VAS, active range of motion (AROM), MMO, and mandibular muscle mobility.
Although there are insufficient data to conclusively prioritize one treatment method over another for TMDs, some clinical trials have found that TENS [18] and low-level laser therapy [16] were not very effective in reducing pain or increasing MMO in patients.Several studies indicated that certain therapies did not show long-term results despite short-term improvement in symptoms [13-18,20-22, 24-27,30,31].These therapies include low-level laser therapy, high-intensity laser therapy, laser acupuncture, photobiomodulation auriculotherapy, LIPUS, TENS, physical therapy, occlusal splint, manual therapy, counseling, and botulinum toxin A injections.However, four studies [19,23,28,29] reported treatments that demonstrated long-term effectiveness in reducing pain, improving MMO, and enhancing mandibular muscle mobility.These effective treatments include osteopathic manual therapy, remodeling dental anatomy, myorelaxation therapy, and intra-articular injections of HA, platelet-rich plasma, and injectable-platelet-rich fibrin.
Two studies focused on using botulinum toxin to treat TMD symptoms: Calis et al. reported a 67% efficacy [27], while the other documented a 36% effectiveness [28].Additionally, two studies reported more than 90% improvement in TMD patients with combination therapies.One study found that a combination of manual therapy, occlusal splint, and counseling was highly effective in reducing pain (approximately 99%), depression (approximately 99%), and anxiety (approximately 99%) [22].The other study employed a combination of surface electromyography and physical therapy, which was effective in reducing pain and improving mandibular muscle mobility and mouth opening in 99.9% of the patients [17].
Based on the outcomes reported in these studies, it is advisable to initiate treatment for TMDs after proper diagnosis via surface electromyography.Following diagnosis, a progressive approach should be adopted, starting with counseling, manual therapy, physical therapy, and splint therapy.If pain persists despite these initial treatments, the use of more invasive methods such as injections and arthrocentesis should be considered.Optimal results are often achieved by employing a combination of treatments.For instance, the combined use of manual therapy, occlusal splint, and counseling has produced the best results in reducing pain, depression, and anxiety.Similarly, a combination of surface electromyography and physical therapy has been effective in reducing pain, improving mandibular muscle mobility, and increasing mouth opening in 99.9% of the patients.
This systematic review stands out for its comprehensive approach to evaluating the efficacy of non-invasive and minimally invasive treatments for TMDs.The breadth of the literature search, encompassing a wide range of scientific databases up to December 2023, ensures an exhaustive inclusion of relevant studies, thereby enhancing the review's coverage and relevance.The analysis spans a diverse array of treatment modalities, ranging from physical and laser therapies to ultrasound, electrical stimulation, splint therapy, injections, and arthrocentesis, offering a nuanced perspective on the therapeutic landscape for TMD.A significant strength of this review is its dual approach to data synthesis, combining quantitative measures such as VAS, AROM, and MMO, with qualitative assessments of patient satisfaction and improvements in depression and anxiety scores.This methodology provides a comprehensive evaluation of treatment outcomes, considering both objective measures of improvement and subjective patient experiences.
Moreover, the review places a particular emphasis on the efficacy of combination therapies, highlighting the potential of integrated treatment approaches to yield superior outcomes.This focus aligns with a growing recognition in the medical community of the benefits of multidisciplinary care in managing complex conditions such as TMD.By prioritizing patient safety and cost-effectiveness, the review echoes the current healthcare imperative for value-based care, advocating for conservative, non-invasive treatments as the initial management strategy.This approach is not only aligned with best practice guidelines but also reflects a patient-centered perspective, emphasizing treatments that are both effective and minimally burdensome.
The timeliness of the review, incorporating studies up until December 2023, positions it as one of the most current analyses on the topic, making its findings highly relevant for both clinical practice and future research directions.The comprehensive and meticulous methodology, combined with a focus on patientcentered outcomes and the exploration of combination therapies, underscores the review's significant contribution to the body of knowledge on TMD treatment.
Despite the comprehensive approach and significant insights provided by this systematic review of noninvasive and minimally invasive treatments for TMDs, it is not without its limitations.One of the primary constraints stems from the inherent variability in study designs, treatment modalities, and outcome measures across the included studies.This heterogeneity complicates the direct comparison and aggregation of data, potentially affecting the uniformity of the conclusions drawn.Additionally, while the review encompasses a wide range of treatment approaches, the depth of analysis for each specific treatment could be influenced by the availability and quality of the studies.The majority of included studies focus on short to medium-term outcomes, leaving a gap in our understanding of the long-term efficacy and sustainability of these treatments for TMD.
Moreover, the patient populations in the analyzed studies were not always homogeneously defined in terms of TMD subtypes and severity, which could introduce variability in treatment response and efficacy.This variability underscores the challenge of generalizing findings across the broader TMD patient population.
Another limitation lies in the potential publication bias, as studies with positive outcomes are more likely to be published than those with negative or inconclusive results.This bias could skew the overall assessment of treatment effectiveness presented in this review.
Furthermore, the review's focus on non-invasive and minimally invasive treatments, while valuable, means that comparisons with more invasive treatments were not systematically explored.This decision might limit the understanding of the full spectrum of therapeutic options available for TMD, particularly for complex or refractory cases where surgical interventions could be considered.Despite these limitations, this systematic review contributes valuable insights into the efficacy of various TMD treatments, providing a solid foundation for future research to build upon.Addressing these limitations through well-designed, longterm, multicenter studies with standardized outcome measures would significantly enhance our understanding of TMD treatment efficacy and patient care.

Conclusions
Treatments for TMDs range from simple self-care practices and conservative treatments to injections and mildly invasive procedures.It is advisable to start with conservative, non-invasive, or mildly invasive therapies and reserve surgery as a last resort.Furthermore, combining different treatments often yields the best results.For example, it has been recommended to use surface electromyography in conjunction with physical therapy or a combination of manual therapy with an occlusal splint and counseling.In TMD patients, these specific combination therapies have led to improvements of over 90%, underscoring the effectiveness of a multi-modal treatment approach.

Figure 1
Figure 1 presents a flowchart illustrating the search methodology.

FIGURE 1 :
FIGURE 1: PRISMA flowchart PRISMA, Preferred Reporting Items for Systematic Reviews and Meta-Analyses

For
done for 3 weeks using an 830 nm Ga-Al-As laser.The laser treatment delivered 4 joules of energy per session and was applied for 40 seconds at 100 mW directly to the affected area.The control group received a placebo treatment.VAS, total vertical opening, right lateral excursion, left lateral excursion, and protrusive excursion.Myogenous pain patients experienced a notable reduction in pain, as evidenced by lower VAS scores.Arthrogenous pain patients saw improvements in total vertical opening and increased protrusive and left lateral excursions.Pain intensity, jaw 2024 Alowaimer et al.Cureus 16(3): e56713.DOI 10.7759/cureus.intoa placebo group, a group subjected to red lightemitting diode therapies, and a group treated with low-level laser therapy.

TABLE 1 : Characteristics of in vivo studies on humans investigating the efficacy of non-invasive treatments in TMD patients
HA, hyaluronic acid; MMO, maximum mouth opening; NA, not reported; TMD, temporomandibular disorders; TMJ, temporomandibular joint; VAS, visual analog scale The most relevant characteristics of these studies include the number of patients enrolled, baseline characteristics, age group and gender, type of TMD, type of treatment/therapy, frequency of application, duration of intervention, description of the procedure, outcome measures, and conclusions.The first study in this review was published in 1997, with most of the clinical studies published after 2015.While most of these studies were clinical trials, some were retrospective studies.The smallest trial conducted byPons etal.enrolled a total of six patients, whereas the largest one by Gębska et al. (2023) enrolled 186 patients