This study determined the analgesic and myorelaxant efficacy of MT and self-therapy treatments in female patients with TMDs. The bioelectrical function of the masseter muscles and the evaluation of mandibular movements in patients with and without TMDs were also scrutinized.

When analyzing the bioelectrical function of the masseter muscle at rest and exercise, the study’s authors observed a significant difference between the control group and those with TMDs (p = 0.00). As can be seen from the diagnostic part of the study, subjects with TMDs have higher mean sEMG values of the masseter muscle at rest and during exercise. The increased bioelectrical activity of the masseter muscle is considered to influence the restriction of mandibular MMO ranges and lateral mandibular movements in the study group. As can be seen from the analysis, the mean pain intensity before PT was 6 (moderate pain) on the NRS scale. As shown by the results of studies conducted by other authors, increased muscle tension affects the range of mobility of the TMJ and contributes to pain [38].

In the treatment of patients with TMDs, an interdisciplinary treatment team consisting of, among others, an Orofacial Pain-trained dentist/pain physician specializing in TMJ treatment (prosthetics specialist, orthodontist), physiotherapist, psychologist and psychiatrist is key. When prescribing treatment, the first therapy recommended for a patient with pain and impaired joint function is MT combined with self-therapy and supplemented with behavioral therapy. Calixtre et al., in a systematic review of RCTs about studies on the effectiveness of MT in patients with TMDs, indicated that soft tissue therapy treatments applied to the masticatory muscles are even more effective than controls but as effective as botulinum toxin injections [39]. They concluded that there is very different evidence that MT relieves pain, MMO and pressure pain in people with signs and symptoms of TMDs, depending on the technique. Therefore, further RCTs evaluating the effectiveness of specific MT treatments in patients with TMDs should be conducted. Therefore, to fill this gap in the literature, the authors of this study attempted to evaluate the effectiveness of the two most commonly used soft tissue MT treatments, i.e. massage and PIR in TMD patients.

As can be seen from the study, each of the prescribed forms of physiotherapy altered the bioelectrical function of the masseter muscles, the range of mandibular mobility and the intensity of pain. Analyzing the individual parameters studied in relation to the proposed forms of therapy, it can be concluded that there were significant differences between the study groups.

Both massage, PIR and self-therapy led to a decrease in bioelectrical signals of the masseter muscle at rest as well as in exercise. When analyzing this parameter, the authors observed that no significant difference was obtained at the first time point between the TMM_TE, PIT_TE, and TE groups (p > 0.05). Only at the 2nd time point (after 5 treatments) was a significant difference obtained between the groups (p = 0.0001). The result obtained may indicate the need for at least 5 TM treatments to improve the bioelectrical function of the muscle. Analyzing the above parameter at the time endpoint (i.e. after 10 treatments), it can be concluded that, of the proposed physiotherapeutic treatments, massage combined with TE (MTM_TE) proved to be the most effective form of therapy in patients with TMDs and outperformed in its effectiveness TEPIR_TE (p = 0.0001) and TE (p = 0.0001). The result obtained may indicate that muscle massage treatments have a more substantial effect on masticatory muscle activity. Each proposed therapy showed a minimal clinically significant difference in the sEMG parameter at this endpoint. The largest MID is seen in the TMM_TE group in both resting and exercise muscle activity. The smallest MID occurred in the TE group, and in exercise muscle function, this only occurred at the second time point (after 5 treatments). Single scientific reports similarly compare the effectiveness of TE, TM, and PIR in combination with self-therapy. A study by Urbanski et al. conducted on patients with TMDs found no significant difference, in terms of myorelaxant effect, between PIR and muscle-fascial therapy. In both groups, a decrease in masseter and temporalis muscle SEMG function was observed, as well as a reduction in pain intensity. The differences between the study results may be due to the use of a different methodology for conducting the soft tissue therapy procedure in the above study [40].

Ariji et al. conducted an ultrasound study of masseter muscle features as an indicator to assess the effectiveness of massage. After the massage, the thickness of the muscle on the symptomatic side decreased significantly, the anechoic areas decreased by 85%, and the pain intensity decreased with it. According to their study, the thickness of the masseter muscle and the presence of anechoic areas may be related to the therapeutic efficacy of muscle pain [41].

We also noticed that the MT forms used effectively reduced the patients’ pain intensity. Notably, a significant difference between the therapies occurred at the second time point (after the 4th treatment). This analgesic effect may occur due to MT pain modulation via activating low-threshold Aβ fibers pathway. This inhibits nociceptive stimuli from Aδ and C supply fibers [42, 43]. MT can also elicit affective responses activating opioid, oxytocin and dopaminergic pathways [44, 45]. As TMDs are disorders involving the masticatory muscles, TMJ and related structures [44], it has been hypothesized that MT applied to craniomandibular structures positively affects pain perception [45]. However, it is essential to note that the quality of evidence supporting this hypothesis is still low and requires further research, although the available evidence supports the use of MT for pain relief in TMD patients.

When assessing the analgesic effect of MT, the authors observed that, again, the most effective form of pain management was massage combined with autotherapy, which was superior to the other two treatment groups (p = 0.0001). Analyzing the minimal clinically significant difference between the methods, it was observed that auto-therapy had an analgesic effect only after 8 treatments (a decrease of 0.5 points), while in the MTPIT_TE groups after 3 (a reduction of 0.52 points) and MTM_TE after 1 treatment (a mean decrease of 2.63 points). It is noteworthy that, from a clinical point of view, after the 7th day of massage, the mean pain score on the NRS scale was 0.889, and that of the patients subjected to PIR was 3.44. Thus, it can be concluded that, of the proposed forms of physiotherapy, massage combined with TE is the most effective therapy for treating masseter muscle pain. The therapeutic importance of massage has been extensively described in a peer-reviewed publications recently. It is related to many factors, such as local blood and lymph flow, muscle activity and the nervous system [46]. Massage is improving blood flow through small vessels because muscle tension is reduced, leading to better and faster regeneration, oxidative capacity of muscle tissue and improving the range of movement [47]. In addition, massage has analgesic properties (activation of the control gate mechanism) and has sound psychological effects, reducing stress and anxiety and improving the patient’s mood through endogenous cannabinoid/opioid system pathway, however this statement require further studies in larger cohorts [48, 49].

According to a study by Rodrigez Blanco et al., the PIR technique of the masseter muscle proved to be a more effective method than the tension/counter-tension technique in patients with pain and limited mandibular visitation [50]. In contrast, a study by Ibáñez-García et al. found no significant differences (p > 0.8) between the PIR method and tension/counter-tension in the treatment of TMJ pain and mobility [51]. Rajadurai et al. demonstrated the effectiveness of muscle energization techniques (METs) involving PIR and reciprocal inhibition in treating pain and improving MMO in patients with TMDs [52].

As shown in a study by Gomes et al. comparing the therapeutic effect of massage and splinting in an RCT in patients with TMDs, massage therapy on the masticatory muscles and the use of an occlusal splint leads to an increase in mandibular ROM similar to that in an asymptomatic comparison group in relation to maximum active mouth opening and right and left movement in TMD patients [53]. On the contrary, in a study by Shousha et al. comparing the therapeutic effect of MT and chiropractic therapy, statistical analysis showed a significant reduction in pain intensity and TMJ opening index between groups in favor of the conservative PT group. Thus, according to their study, over a treatment period of 6 consecutive weeks, conservative PT may be a better initial treatment than occlusal appliances in relieving pain and improving range of motion in cases of myogenous TMDs [54].

Another parameter assessed in this study was TMJ range of motion, which was significantly different in TMDs patients compared to healthy controls (p = 0.00).

Statistical analysis showed no significant difference in MMO between the groups at first and second-time endpoints (p > 0.5). At other time points (from the 6th treatment onwards), a significant difference was obtained between monotherapy and each form of MT, with both massage (p = 0.0001) and PIR (p = 0.0001) significantly improving the MMO range. When analyzing the minimum clinically significant difference between methods, it was observed that TE was the least effective (1 point increase on day 7 of therapy). Between the TM methods, the clinical effect was comparable both after day 1 of treatment (TMM_TE increase of 1 point; TMPIR_TE increase of 0.9 points) and at the endpoint (day 10 of therapy—TMM_TE increase of 7.4 points; TMPIR_TE increase of 7.7 points. The results obtained may indicate comparable efficacy of massage and PIR in improving mandibular abduction mobility. However, with regard to mandibular lateral movements, the authors obtained a significant difference in the proposed forms of MT, of which massage treatments were superior in their effectiveness to PIR. Thus, the above results may indicate a greater therapeutic benefit of massaging the masticatory muscles to improve TMJ function. However, these observations require the continuation of the research initiated.

A study by Toucker et al. on the evaluation of MT and therapeutic exercises showed that, when combined, both forms of therapy yield clinically significant effects on both pain and pain-free maximal mouth opening in TMD patients [55]. Also, in the authors’ study, it was observed that synergism of therapeutic agents resulted in better relaxation (p = 0.0001) and analgesic effects (p = 0.0001) and contributed to a significant increase in TMJ range of motion (p = 0.0001) compared to monotherapy.

Herrera-Valencia et al., in their meta-analysis consisting of six papers on the effectiveness of MT in the treatment of TMDs, found that significant improvements in pain and MMO were observed after manual treatment compared to baseline values. According to their analysis, MT appears to be an effective treatment for TMJ disorders in the mid-term, although the effect seems to diminish over time. However, when combined with therapeutic exercise, these effects may persist for a long time [56]. Also, De Laat A et al. demonstrated the effectiveness of a conservative approach, including counselling and physiotherapy (heat, massage, ultrasound and muscle stretching techniques, in improving pain parameters and jaw function in myofascial pain patients [57].

According to Byra et al., the PT procedure used, including MT and masticatory muscle exercises, improves TMJ range of motion and reduces pain in patients with TMJ hypomobility. Significant improvements in TMJ mobility were achieved, with an average increase of 6.6 mm (p = 0.0005) and a reduction in pain, with a decrease of an average of three points on the NRS scale (p = 0.00002) [58]. The therapeutic efficacy of TM in patients with TMDs and joint hypermobility was also confirmed in similar study by Kulesa-Mrowiecka et al. [59].

The research carried out quite clearly demonstrated the superiority of the synergism of MT methods and therapeutic exercises over monotherapy (self-therapy), at very high significance (p = 0.00), which is a major strength of this study. Similarly, is the identification of a minimal clinically relevant difference, whereby it was observed that massage treatments surpassed PIR in their effectiveness, hence producing a better and faster therapeutic effect, especially with regard to pain intensity. The results obtained are auspicious, prompting the authors to continue this type of study in the future.

According to the authors, a limitation of the study carried out was the short duration of therapy the women underwent and the small size of the treatment subgroups. In addition, there was no evaluation of how long the therapeutic effect obtained during the applied treatments persisted after the therapy cycle. Therefore, the authors see a need to continue the study conducted, focusing on the above limitations.