The effectiveness of physical therapy for temporomandibular disorder: A systematic review

Data source and search strategy

The PubMed, SCOPUS, and Web of Sciences databases were searched. The database used search terms from the Medical Subject Headings (MeSH) vocabulary and was last searched on July 31, 2023. The keywords used for search on PubMed were [(“TMD” or “temporomandibular joint disorders” or “temporomandibular disorder”) AND (“physical therapy” or “physical exercise” or “postural therapy” or “manual therapy”)]. The keywords used in the Web of Science were ((TMD OR temporomandibular joint disorder OR temporomandibular disorder)) AND AB=(physical therapy OR physical exercise OR postural therapy OR manual therapy). The keywords used for search on Scopus were TITLE-ABS KEY (“TMD” OR “temporomandibular joint disorder” OR “temporomandibular disorder”) AND (“physical therapy” OR “physical exercise” OR “postural therapy” OR “manual therapy”) AND (“clinical trial” OR “randomized controlled trial”) AND ( LIMIT-TO (SRCTYPE, “j”)) AND ( LIMIT-TO (OA, “all”)) AND (LIMIT-TO (PUBSTAGE, “final”)) AND (LIMIT-TO (DOCTYPE, “ar”)) AND (LIMIT-TO (LANGUAGE, “English”)).

Study selection and data extraction

Two authors (ANKP and DAA) removed duplicate studies using EndNote^TM20 (version 20.4.0.18004) software. Only studies in English were included and review article restrictions were placed on the publication date. Study selection was conducted in two stages. Article titles and abstracts were reviewed in the first stage to assess eligibility based on predetermined inclusion and exclusion criteria. Subsequently, the remaining articles were searched and evaluated. Subsequently, the remaining articles were searched and evaluated.

The inclusion and exclusion criteria were determined before study identification. The inclusion criteria were as follows: randomized controlled trial (RCT) and case series design, adult population (>18 years old) with TMD diagnosis, intervention with physical therapy including physical exercise, manual therapy, postural therapy, or myofacial muscle manipulation, no comorbidities, not undergoing orthodontic treatment, never undergoing surgery, with outcome study pain relief, increased range of motion, reduced TMD signs and symptoms, improved activity of the masticatory muscles and mandibular function, and improved quality of life and sleep. The exclusion criteria were as follows: history of trauma in the TMJ area, inflammatory and rheumatic diseases (e.g., rheumatoid arthritis), congenital abnormalities, and non-human studies.

Data synthesis and analysis

Three authors (NPMS, MR and AS) reviewed the full text of relevant articles to determine the eligibility criteria. If there was disagreement among the authors, the final decision was made through discussion by majority vote. The following data were extracted: year of publication, sample size, TMD pathology, intervention groups, outcomes, results, and conclusions.

Quality assessment

Two authors (LB and GA) independently assessed the quality of the eligible studies, using 16 items from the Quality Assessment (QATSDD) Tools. Quality assessment was performed by answering all questions. Each question was scored (0-3). The risk of bias was assessed at the outcome level.

Sample population characteristics

All patients in this study complained of TMD, including orofacial and myofascial pain, headache, tinnitus, and TMJ dysfunction. Randomized controlled studies with variable sample sizes are included. The patients included in the study ranged in age from 18 to 65 years. The total sample size was 1016 patients from the 20 articles analyzed.

Intervention characteristics

The interventions investigated in the eligible studies included physical therapy, such as manual therapy, postural therapy, myofascial therapy, and home exercises, either in combination or separately. Physical exercise protocols varied widely. Protocols described included cervical-related postural correction, intraoral myofascial exercises, facial muscle relaxation, and home-based physical exercises. Some interventions were compared or combined with splint therapy, education, and hot and cold compression. Physical therapy interventions were mostly scheduled and assisted by physiotherapists. However, some studies did not specify the professional who assisted with the physical therapy.

Comparisons of interventions

Manual therapy (stomatognathic treatment) versus acupuncture

Only one study has compared manual therapy with acupuncture. Patients in the manual therapy group who underwent stomatognathic treatment were administered occlusal adjustment therapy and muscle coordination exercises for the lower jaw. Positive results were observed in both groups. The study reported pain reduction during mouth opening, lateral mandibular movements, and jaw protrusion in both groups. The study concluded that the treatment effect was similar in both groups, but those in the acupuncture group reported an irritating effect during therapy administration (Raustia and Pohjola, 1986).

Postural and cervical manipulation versus no therapy, conservative therapy (oral appliance), or suboccipital treatment

Five studies discussed manual therapy that focused on postural, cervical, and upper thorax manipulation therapy (Cúccia et al., 2010; Wright et al., 2000; Reynolds et al., 2020; George et al., 2007; Packer et al., 2015). Wright et al. (2000) investigated the effects of postural exercises under the supervision of a physiotherapist, that aimed to stretch and strengthen anatomical structures that were compromised due to poor posture. The results showed an increased mean maximum pain-free opening and improved TMD symptoms in the postural therapy group. Reynolds et al. (2020) used the cervical spine high-velocity low-amplitude thrust (HVLAT) technique, which consisted of exercises in a resting position, controlled opening, axial extension of the neck with overpressure, posture correction, and scapular retraction. This study showed that individuals with TMD who received HVLAT treatment of the cervical spine experienced significant improvements in jaw function and reduced fear of movement relative to the sham group. George et al. (2007) also used the HVLAT technique and compared it to the active release technique (ART), which focuses on the suboccipital musculus. The study reported that the degree of mouth opening between the two groups was similar.

In contrast, Cúccia et al. (2010) provided treatment directed toward the cervical region using gentle techniques, such as myofascial release, balanced membrane tension, muscle energization, joint articulation, HVLAT, and cranial-sacral therapy. There were no significant differences in the VAS, MOV, and ROM scores between the manual therapy group and the conventional therapy group treated with oral appliances. In addition, Packer et al. (2015) manipulated the upper thorax at the T1 vertebral segment in their experimental group. The patient was instructed to link the fingers behind the neck. The therapist placed the stabilizing hand under the segment to be manipulated (T2) and directed the arm caudally to encourage thoracic spine flexion. The results showed that vertical mouth opening did not differ between the manual therapy versus the sham manipulation groups. However, in the upper thoracic manipulation group, an increase in EMG activities in the left masseter and suprahyoid muscles was observed.

TMJ and orofacial muscle manipulation versus splint therapy, education, TENS, or no therapy

Six studies examined the effects of manual therapy, focusing on manipulation of the TMJ region and the orofacial muscles. Three studies compared manual therapy with splint therapy (Ismail et al., 2007; de Paula Gomes et al., 2014; Damar et al., 2022). Three other studies compared manual therapy with various therapies, namely, splint therapy and education (de Resende et al., 2021), TENS therapy (Patil and Aileni 2017), and no therapy (Vivanco-Coke et al., 2020).

Ismail et al. (2007) reported significantly higher active jaw opening after physical therapy by mobilizing the TMJ joint accompanied by jaw-lifting and muscle-blasting exercises. De Paula Gomes et al. (2014), who provided therapy with massage of the masticatory muscles, also reported maximum mouth opening, similar to that of therapy using splints. Damar et al. (2022), who provided therapy for soft tissue and joint mobilization of the TMJ and surrounding structures, reported significant results in reducing pain, increasing the range of motion and TMJ function, and improving sleep quality, relative to splint therapy.

de Resende et al. (2021) investigated manual therapy, splint therapy, education and splint therapy, and education in improving quality of life and sleep quality and reported effective short-term alleviation of TMD symptoms. Research comparing manual therapy with TENS has also shown effective results in improving mouth opening and reducing masticatory muscle and joint pain after treatment in both groups. Patients who underwent manual therapy performed an exercise program consisting of active and passive jaw opening and closing exercises, isometric jaw exercises, jaw stretching exercises, and resistive jaw exercises. Furthermore, Vivanco-Coke et al. (2020) demonstrated a clinically significant reduction in pain and dysfunction in patients who underwent manual therapy and superficial myofascial release, strain-counterstrain technique, and deep transverse massage.

Patient undertook manual therapy perfomed active and passive jaw exercises consisting jaw opening, closing, isometric, stretching, and restrictive movement (Patil and Aileni 2017). Furthermore, Vivanco-Coke et al. (2020) stated that patients who undertook manual therapy and superficial myofascial release, strain-counterstrain technique, and deep transverse massage showed a significant clinical improvement in reduction of pain and dysfunction.

Postural and cervical manipulation versus postural and cervical manipulation with TMJ and orofacial muscle manipulation

Three studies discussed additional TMJ and orofacial muscle manipulation. von Piekartz and Lüdtke (2011) compared two groups in their study. The first group received manual therapy for the cervical region, and the second group received additional manual therapy for the temporomandibular region. Additional manual therapy techniques included translational movements of the temporomandibular region and masticatory muscle techniques, such as trigger point treatment and muscle stretching. In the additional manual therapy group, treatment effects lasted for six months. Garrigós Pedrón et al. (2018) in their study compared the cervical group with the cervical and orofacial groups. Therapy for the cervical group consisted of suboccipital muscle inhibition, passive cervical joint mobilization in the supine and prone positions, co-contraction of flexors and extensors, and exercises of increasing difficulty and resistance using a latex band and nerve tissue techniques. In the cervical and orofacial groups, therapy was augmented with bilateral caudal longitudinal techniques for the TMJ, neuromuscular techniques for the masseter and frontal muscles, and coordination exercises for the masticatory muscles. The study concluded that a combination of cervical and orofacial treatments was more effective.

Delgado De La Serna et al. (2020) compared self-care manual therapy with additional cervical therapy provided by physiotherapists. This group underwent inferior glide accessory mobilization of the mandible and soft tissue mobilization of the masseter and temporalis muscles. After three and six months, the group that received additional manual therapy from a physiotherapist demonstrated significantly better clinical, psychological, and physical outcomes than self-care manual therapy.

Intraoral myofascial manipulation versus intraoral myofascial manipulation with self-care exercises and education, or self-care exercises and education

Two separate studies by the same research group discussed intraoral myofascial manipulation. The primary author also performed intraoral myofascial manipulations. In the first study, Kalamir et al. (2010) compared intraoral myofascial manipulation with intraoral myofascial manipulation plus self-care exercises and education. Three intraoral myofascial intervention techniques including intraoral temporalis release, intraoral medial and lateral pterygoid techniques, and intraoral sphenopalatine ganglion technique, were described. All treatment groups demonstrated overall improvement.

The second study compared intraoral myofascial manipulation therapy with self-care and education. The therapy protocol was the same as that used in a previous study. The results concluded that intraoral myofascial manipulation was superior in reducing pain compared with self-care and education as short-term treatment (Kalamir et al., 2013).

Intraoral myofascial manipulation versus extraoral myofascial manipulation

Only one study compared intraoral and extraoral manipulations. Intraoral myofascial manipulation uses post-metric muscle relaxation treatments (PIR), whereas intraoral myofascial manipulation uses myofascial release treatment (MR). The results of this study suggest that both PIR and MR can be used to treat TMD-associated pain and masticatory muscle tension (Urbański et al., 2021).

TMJ active exercises versus TMJ active exercises with Jog-type jaw manipulation, or masticatory muscle exercise

Two studies compared active TMJ exercises with other exercises. Bae and Park (2013) compared active TMJ and muscle exercises. These two studies also included self-care exercises. In the masticatory muscle exercise group, the patients were instructed to bring their lips together, place the front third of the tongue on the palate with the upper and lower teeth not touching each other, and then, apply a light force to push the tip of the tongue forward. The TMJ active exercise group received mouth opening and closing therapy. The results showed that TMJ pain, jaw deviations, and the mandibular range of motions improved in both groups. Nagata et al. (2019) provided active TMJ exercises to encourage condyle displacement by using simplified myofunctional therapy that pulled on the back molars. The comparison group was treated with jog-type jaw manipulation developed by the authors. The results of this study showed no statistical differences in mouth opening limitations, pain, or TMJ sounds between the two groups.