An investigation of the effect of progressive neck motor control exercises on craniocervical pain, posture, function and kinesiophobia in different types of temporomandibular disorders: a randomised controlled study protocol

Abstract

Background

Temporomandibular disorder (TMD) is a musculoskeletal problem that affects the masticatory muscles, temporomandibular joint (TMJ) and other related structures and has many different subtypes. Different types of TMDs are known to cause different symptoms. This study will examine the effect of progressive neck motor control exercises on different types of TMD.

Methods

This randomised controlled study will investigate the effects of progressive neck motor control exercises on craniocervical pain, posture, function and kinesiophobia in individuals with myofascial TMD, TMJ disc displacement with reduction and TMJ disc displacement without reduction. Participants will be divided into groups using a block randomization method. A total of six groups will be included in the study, comprising participants who consented to participate and met the inclusion criteria. The groups will include participants with one of the three distinct types of TMD, as well as a control group for each group. The same treatment will be administered to the study groups for a period of six weeks, while the control groups will receive only patient education. All assessments will be conducted prior to the treatment, within a maximum of one week following the end of the treatment, and 1 month after the treatment.

Discussion

Despite the utilisation of craniocervical exercise approaches in individuals diagnosed with TMD, existing evidence has yet to ascertain the most efficacious intervention. This will be an inaugural study to assess the efficacy of a progressive exercise program in individuals with varying TMD types and the associated differential outcomes. The findings of this study will provide valuable information on the relationship between the jaw joint and the cervical region as well as the effect of exercise on various types of TMD.

Trial registration

The study was prospectively registered at ClinicalTrials.gov National Library of Medicine at 11. November 2023 under ID NCT06148818 (https://clinicaltrials.gov/study/NCT06148818?term=NCT06148818&rank=1).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-026-07775-z.

Introduction

Temporomandibular disorders (TMD) are a problem involving the masticatory muscles, temporomandibular joint (TMJ), or associated orofacial structures and are accompanied by various symptoms [1]. TMD is considered a subclassification of musculoskeletal disorders [1]. The prevalence is approximately 31% in adults and 11% for the child/adolescent, peaking between ages 20–40 and occurring twice as often in women [2, 3]. The subtypes of the disease are divided into intra-articular disorders and muscular (myogenic) disorders, including TMJ disc displacement, arthralgia, arthritis, and arthrosis, according to Axis I of the TMD Diagnostic Criteria (DC/TMD). Disc displacement with reduction is the most common internal derangement (≈ 41%), while the without reduction type occurs in 2–8% of cases.

TMDs are affected by biological, environmental, social, emotional, and cognitive factors [3, 4]. It has been demonstrated that the cervical region and TMJ are anatomically, physiologically, and biomechanically interrelated [5]. The position of the spine can affect the mandible, and conversely, a change in the position of the mandible can lead to craniovertebral extension [6]. A further rationale for this relationship is the convergence of trigeminal and upper cervical afferent inputs in the trigeminocervical nucleus, in addition to the neurophysiological connections between the cervical spine and the temporomandibular region [7].

Diagnosis relies on clinical examination and imaging, with findings such as abnormal mandibular movement, reduced range of motion, masticatory muscle tenderness, pain on loading, bruxism, crepitus, clicking, locking, and malocclusion [3, 8]. Furthermore, it is indicated that additional symptoms may manifest, including tenderness in the cervical region and shoulder muscles, movement restrictions in the cervical region, loss of strength, impaired proprioception and endurance, and alterations in posture [9, 10]. Although TMD subtypes exhibit some common symptoms, different levels of involvement have also been observed [11, 12]. de Abreu Figueirêdo et al. analysed individuals with muscular, articular, and mixed TMD and showed that neck disability was higher in the mixed and articular TMD groups [12]. In the study by Kıno et al., in which myofascial pain, disc displacement, arthralgia, and osteoarthritis types were examined, although some characteristics differed between the four subtypes, the majority of these characteristics were similar. In the same study, depression levels and duration of pain were higher in participants with myofascial type pain [13]. Similarly, the results of the meta-analysis by Reis et al. show that the frequency and severity of anxiety and depression are increased in patients suffering from myofascial pain compared to patients with other subtypes of TMD [11]. In line with these studies, it will be important to examine the etiological factors underlying these types in order to be more successful in symptom management in different TMD types.

In addition to biomechanical influences, it is also common for individuals with TMD to experience higher levels of psychological and emotional stress, greater depression, increased feelings of distress, catastrophizing, and heightened somatic awareness [14, 15]. The role of kinesiophobia as an overlooked factor about these psychosocial influences [14] has not been adequately addressed in the extant literature, with no study examining kinesiophobia in TMD subgroups being identified. Recent studies have indicated that kinesiophobia is a significant predictor of disability and craniofacial pain in individuals with TMD [14, 16]. It is therefore of clinical importance to evaluate and treat individuals with TMD who present with movement-related symptoms, such as limited mouth opening and clenching, for kinesiophobia [16].

The primary objectives of TMD treatment are to reduce pain, improve TMJ function, and reduce muscle spasm and pain associated with chewing [17]. Current practice has shifted from surgical to conservative, non-invasive approaches, with exercise therapy being a key component [18–20]. These exercises may include stretching, relaxation, coordination, strengthening, and endurance techniques [21], yet evidence guiding the most effective protocols remains limited [18, 19, 22]. Craniocervical flexor training, often used for cervical disorders, is also applied in TMD [23]. The deep and superficial cervical flexors contribute to segmental motion and postural control [24], both of which are often impaired in TMD [25]. Motor control exercises targeting these muscles can restore neuromuscular function, increase stability, reduce overload, and improve symptoms [26, 27]. In addition, exercises positively affect sensorimotor organization by regulating sensory inputs in the central nervous system of people with chronic pain [28]. Since jaw and neck muscles co-activate during jaw movements [29], enhancing their endurance, strength, and neuromuscular control can improve both regions’ function [30, 31].

Evidence supports the use of oral and postural exercises to relieve symptoms, but further research is needed to determine optimal prescriptions and adapt them to clinical practice [32, 33]. In consideration of the aforementioned literature, it becomes evident that the various TMD subtypes exhibit differing degrees of effect. This situation highlights the importance of carrying out a thorough assessment of patients and identifying the most effective exercises for each type of TMD when planning optimal treatment. This study will examine the effect of progressive neck motor control exercises on different types of TMD. The secondary aim of the study will be to investigate the differences between the effects of progressive neck motor control exercises on different types of TMD.

Materials and methods

The protocol was prepared in line with Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) guidelines (Appendix 1). This study is a randomised controlled parallel group study. It will investigate the effects of progressive neck motor control exercise therapy on craniocervical pain, posture, function, and kinesiophobia in individuals with different types of TMD, namely, myofascial, disc displacement with reduction, and disc displacement without reduction.

Randomization and group

The study will include participants who have been diagnosed with TMD by a dental practitioner according to one of three recognized categories. The participants will be divided into groups using a block randomization method, with the allocation determined by the random allocation software program. A total of six groups will be included in the study, comprising participants who consented to participate and met the inclusion criteria. The groups will include participants with one of the three distinct types of TMD, as well as a control group for each group. Of the TMD types included in the study, myofascial and TMJ disc displacement with reduction were selected because they are the most common. Osteoarthritis and mixed types, which appear in various articles in the literature, were not selected. Additionally, to reduce clinical heterogeneity and potential confounding effects, individuals with mixed TMD diagnoses were excluded from the study, as overlapping pathophysiological mechanisms may mask subtype-specific relationships. The type of TMJ disc displacement without reduction was selected because there are very few studies examining the effects of exercise in these individuals. The same treatment will be administered to the study groups for a period of six weeks, while the control groups will only receive patient education. The flow diagram of the study is presented in Fig. 1.

Fig. 1.

Flow diagram

Participants

Patients presenting to the Faculty of Dentistry, Department of Oral and Maxillofacial Surgery at Karadeniz Technical University will be classified according to the Research Diagnostic Criteria of Temporomandibular Disorders (DC/TMD) following a clinical examination conducted by a qualified dentist (Professor or Associate Professor) [34]. The participants will be allocated to either the study group or the control group in accordance with the randomisation process. Following this, they will be referred to a specialist physiotherapist (MSc or PhD student) for evaluation and treatment. Those who consent to participate in the study and meet the inclusion criteria will be included in the study. No invasive procedures will be employed. Written informed consent will be obtained from all participants by the physiotherapist. The study will be conducted in accordance with the ethical principles set forth in the Declaration of Helsinki. In order to conduct the study, ethical approval was obtained from the Scientific Research Ethics Committee of Karadeniz Technical University, Faculty of Dentistry (protocol numbers 2023/15 and 64529847/17). The study was registered with the Clinical Trials Registry (NCT06148818).

The study will include individuals aged between 18 and 55 years who have complaints related to TMJ dysfunction for a minimum of three months, have been diagnosed with TMD as a result of clinical and radiological evaluation by a dentist. Individuals with cognitive impairment, who use splints, have any systematic joint or muscle disease (e.g., fibromyalgia, rheumatoid arthritis), have serious systemic diseases, or have any neurological disorder (e.g., trigeminal neuralgia), pregnant or breastfeeding, received treatment for TMJ or orofacial muscle pain in the last 3 months, had surgery/trauma to the cervical region and/or TMJ, and positive vertebrobasilar artery test will not be included in the study. Participants included in the study will be asked to refrain from taking medication 48 hours prior to the assessments. All assessments will be conducted before treatment, within a maximum of one week following the end of treatment, and 1 month after treatment. The study periods are presented in Table 1. A reminder will be sent out at least one day before the appointment date to encourage participants to come to the session and follow up. Appointment times will be arranged according to participants’ availability. Participants will also be asked to mark their home program on the follow-up form.

Table 1.

Study period

Outcome measurements

The sociodemographic characteristics of the participants, such as age, height, body weight, occupation, background and family history, will be recorded. The following will be evaluated: the severity of TMD; pain intensity; pain threshold; the range of motion of the cervical and TMJ regions; proprioception in the cervical region; deep neck flexor endurance; posture; mandibular function; and kinesiophobia. The primary outcome measures in individuals with TMD are a reduction in pain intensity, and an increase in pain thresholds, TMJ range of motion, and mandibular function following a six-week exercise program. Secondary outcome measures include an increased cervical range of motion and deep neck flexor endurance, improved proprioception and posture, and reduced kinesiophobia.

All assessments will be conducted by the same physiotherapist. Each participant will be given a data code, and the results of the assessment will be recorded in this way. The date and time of each assessment and treatment session will also be recorded. Once the protocol has been implemented, the principal investigator will record all data collected in an Excel file and back it up using Google Drive. The protocol and data will not be made public. Only the results will be analysed, compiled into an article, and shared. Participants will be informed of this, too.

Assessment of the severity of temporomandibular disorders

The Fonseca Anamnestic Index, which has been demonstrated to be a reliable and valid instrument for assessing the severity of TMDs, will be employed in this study. The index is comprised of ten items, each of which presents three response options. The response options are “no” (0 points), “sometimes” (5 points), and “yes” (10 points). The total score ranges from 0 to 100. The score classification of the index is as follows: no TMD (≤ 15), mild TMD [20–40], moderate TMD [45–65], and severe TMD (70–100) [35]. The Turkish validation was conducted by Kaynak et al. [36].

Pain assessment

The intensity of pain will be evaluated using the Numerical Pain Scale. The scale allows for the rating of pain intensity on a scale from 0 (no pain) to 10 (the worst pain imaginable). Participants will be required to rate the intensity of pain experienced in the jaw and neck [30].

Pressure pain threshold assessment

The pressure pain thresholds of the TMJ, the masseter (1 cm above and 2 cm anterior to the mandibular angle), the anterior temporalis (2 cm above the line extending from the lateral margin of the eye to the anterior part of the helix), the SCM (2 cm below the mastoid process), and the upper trapezius muscles (midway between C7 and the acromion) will be assessed using an algometer device with a 1 cm rubber tip (BASELINE^®) [37]. Pressure will be applied at a rate of 0.5 kgf/sec. Patients will be in a seated. Once the patient has indicated that they perceive pain, the pressure applied to the defined points will be removed from the body by the removal of the algometer. The pressure force value (kg/cm²) displayed on the screen will then be recorded. Three measurements will be taken, and the mean pressure will be recorded. All evaluations will be conducted separately for the right and left sides. Before the test, a trial will be performed on a muscle distant from the evaluated points [37].

Temporomandibular joint range of motion assessment

The maximum painless mouth opening width and lateral deviations from the distance between the two front incisors on the lower and upper palate will be measured with a calliper three times, and the average value will be recorded [38].

Cervical region joint range of motion assessment

The “Cervical Range of Motion” (CROM) device will be used to assess the cervical region joint range of motion [39]. The assessment will encompass mobility in the sagittal, frontal, and transverse planes. The mean of three trials will be employed [40]. Furthermore, the cervical flexion rotation test will be employed to ascertain the range of motion in the upper cervical region. In the flexed position, the head and neck are passively rotated to the greatest extent possible within the limits of pain or physiological stiffness, and then the range of motion is recorded. The finding is considered positive when the range of motion is less than 32° in at least one of the directions of motion. The mean of the three range of motion measurements for each side will be calculated and will represent the final score for the left and right ranges of motion [6].

Cervical proprioception assessment (Joint position error test)

The joint position sense will be assessed using the CROM device with the angle repetition test. The participant’s head is gradually positioned in a pre-established target position, which represents 50% of the maximum range of motion (ROM) for that individual [41]. The participant’s head is maintained in the target position for three seconds, during which time the individual is encouraged to memorise the position. Subsequently, the participant’s head is returned to the initial position. The person is asked to close their eyes and repeat the movement. No visual or verbal feedback will be given to the subjects during the test. Once this has been achieved, the displacement accuracy is measured in degrees. The difference between the two positions is expressed as joint position sense error. The test is performed in four directions: flexion, extension, left and right rotations, and lateral flexion. The order in which the movement directions were tested was randomised. Three trials will be performed in each movement, and the main error margins will be recorded [41, 42].

Deep neck flexor endurance assessment

This will be evaluated with the craniocervical flexion test [43]. In this test, the patient is positioned in a neutral state while supine with the hips at 45° of flexion and the knees at 90° of flexion. A pressure stabilising feedback device is placed beneath the individual’s neck, and the pressure is set to 20 mmHg. Before performing the test, the patient is shown the exercise. The patient is asked to perform the movement to increase the pressure by 2 mmHg and hold this position for 10 s while observing the manometer. This will be repeated at each of the five levels (22, 24, 26, 28, and 30 mmHg). Upon completion of the tenth repetition, progression to the subsequent level is achieved. The test is concluded when the total pressure reaches a maximum of 30 mmHg [43, 44]. The highest pressure reached and the number of repetitions will be recorded. Activation score and performance scores will be calculated and analysed. If the participant was able to achieve a 4 mm Hg increase in the test, the activation score would be 4, and if they were able to successfully perform a maximum of 6 repetitions at this level, their performance score would be 24 (4 × 6). The highest possible performance score is 100 (10 mmHg x 10 repetitions) [43, 44].

Posture assessment

Head and neck posture will be assessed using photographic techniques. The images will then be analysed [37, 45]. The participant’s photograph will be taken with a digital camera while they are standing. Markers will be placed on anatomical reference points (C7, tragus, pogonion, eye corner, acromion). The patient will be instructed to assume the posture they are accustomed to, and to maintain gaze in the forward direction until the test is complete. In this position, a photograph will be taken with a digital camera placed on a tripod that can be adjusted in length. The camera will be positioned at shoulder height and 3 m away from the patient, with the hair endpoint forming the upper limit. The lines connecting the markers will be drawn on the photograph, which will then be transferred to the computer. The angles between them will be measured using a software program. The craniovertebral angle (the angle between the line connecting C7 and the tragus and the horizontal plane) and the eye-tragus-horizontal, pogonion (the most protruding point of the chin)-tragus-C7, tragus-C7-acromion angles will be evaluated using this measurement [37, 46]. A craniovertebral angle of 53.1°−56.8° is indicative of a normal head posture, while a value of 46.9°−49° suggests a mild degree of anterior head posture, and a value of 40.7°−43.2° indicates a moderate-to-severe degree of anterior head posture [47].

Mandibular function assessment

The Mandibular Function Impairment Questionnaire was developed for the purpose of assessing the level of jaw impairment (MFIQ). The questionnaire enables the classification of TMJ problems in terms of the severity of functional limitation. It comprises 17 questions and two dimensions that score the difficulty in a specific jaw function on a scale of 0 to 4 points (0 = no difficulty; 1 = some difficulty; 2 = significant difficulty; 3 = severe difficulty; 4 = very difficult or impossible without assistance). The initial 11 items constitute the Functional Capacity dimension, while the subsequent six items comprise the Nutrition dimension. A high total score on the questionnaire is indicative of a high level of jaw dysfunction [48].

Kinesiophobia assessment

The Tampa Kinesiophobia Scale (TKS-TMD) will be employed for the assessment of kinesiophobia. The scale was developed for TMD based on the Tampa Kinesiophobia Scale and is used to evaluate the fear of movement in individuals with TMD. Although the scale comprises 18 items, it was proposed that a shorter version comprising 12 items would be more appropriate. The total score ranges from 12 to 48 [49]. The validity and reliability study of the Turkish version of the TKS-TMD-12 was conducted by Küçük and Tonga [50].

Treatment methods

Participants in the study will receive patient education and will be required to complete a six-week program of progressive neck motor control exercises. The control group will only receive patient education. The educational content will encompass information regarding the disease and its symptoms, recommendations for mastication, dietary modifications, parafunctional habits, activities to be avoided, and postural guidance [51, 52]. A comprehensive brochure containing all the requisite information will be provided to the participants (Appendix 2).

The exercise program will be conducted as a single session on two occasions per week for a period of six weeks. Participants will be instructed to perform the exercises at home on the remaining days of the week. All sessions will be conducted by the same physiotherapist. Each session will comprise an approximately 10-minute warm-up period, a 40-minute session of neck motor control exercises, and a 10-minute cool-down period. Each exercise will be performed in two sets of ten repetitions. A period of rest, lasting between two and three minutes, will be allotted between each set. Neck motor control exercises comprise craniocervical flexion exercises conducted in a variety of positions with the application of pressure, performed with the aid of a stabilising device. The advancement of the exercise regimen will be achieved through the incorporation of extremity movements and resistances, as well as the augmentation of pressure in exercises that utilise stabilisers. The exercises are structured in a manner that allows for progression in accordance with the neurodevelopmental stages, which include supine, prone, quadrupedal, and bipedal positions [53, 54]. Progression will occur at the end of each two-week phase. Details of the exercise program are presented in Table 2 and Appendix 2. The exercises will be supplemented with the use of Theraband to provide resistance. The program will begin with the red Theraband (3.7 pounds). Upon successful completion of two sets of 10 repetitions without signs of discomfort or fatigue, participants will progress to the next level of resistance, using the green (4.6 pounds) and subsequently the blue Theraband (5.8 pounds).

Table 2.

Progressive neck motor control exercises

Week 1–2	Number of sets	Number of repetitions
Craniocervical flexion exercise with stabiliser 20 and 22 mmHg	2	10
Chin tuck in supine position	2	10
Chin tuck+ upper extremity exercises in supine position	2	10
Chin tuck+ upper+ lower extremity exercises in supine position	2	10
Chin tuck on forearms	2	10

Week 3–4
Craniocervical flexion exercise with stabiliser 24 and 26mmHg	2	10
Chin tuck in quadrupedal position	2	10
Chin tuck+ upper extremity exercises in quadrupedal position	2	10
Chin tuck+ upper+ lower extremity exercises in quadrupedal position	2	10
Chin tuck in standing position	2	10
Wall angle exercise with Chin tuck	2	10

Week 5–6
Craniocervical flexion exercise with stabiliser 28–30 mmHg	2	10
Resistive chin tuck in quadrupedal position	2	10
Chin tuck + Y exercise on Swiss ball	2	10
Resistive chin tuck in standing position	2	10
Chin tuck with Swiss ball in standing position	2	10
Resistive upper limb exercise with Swiss ball and chin tuck + Theraband in standing position	2	10

Craniocervical flexion exercises with stabilizer

Patients will perform craniocervical flexion exercises in the supine position. This involves flexing the cranium over the cervical spine while maintaining the back of the head in contact with the supporting surface. The aim of this exercise is to facilitate activation of the deep craniocervical flexor musculature while minimising the activity of the superficial cervical flexors (sternocleidomastoid and scalene muscles) [55]. The pressure created by contraction will be monitored on the screen of the stabilizer device. It will stay at the specified level for 10 s and will be repeated 10 times [54]. Initial stabilizer pressure will be set at 20 mmHg and increased by 2 mmHg each week. If a participant can complete two sets of ten repetitions at the current pressure level, they will progress to the next level. If they cannot tolerate the increase, they will continue exercising at the level immediately below.

Chin tuck exercises

The Chin tuck exercise will be conducted initially in the supine position. A 10-second interval will be observed between each repetition, with the total number of repetitions being 10. Subsequently, the movements of the extremities will be incorporated and executed. Participants will be instructed to perform the designated exercise for the upper and lower extremities while maintaining the chin tuck position [56]. Progress will continue with the patient positioned prone on the forearms, performing the chin tuck exercise. In the third and fourth weeks, quadrupedal and standing chin tuck exercises will be continued, and in the fifth and sixth weeks, resistance will be added to these exercises using Theraband [57].

Exercises in the quadripedal position

The Chintuck exercise will be performed first in this position. Then, exercises for the upper and lower extremities will be included. While maintaining the chin tuck position, the participant will extend one arm forward, hold it there for 10 s, then return the neck to the starting position while lowering the arm. This movement will then be repeated with the other arm. The exercise will then continue by extending the crossed arm and leg. All exercises will be performed in two sets of ten repetitions [56, 58]. At the final level, the chin tuck exercise will be performed in the same position with added resistance using a Theraband. If the participant is unable to tolerate the resistance, the exercise will continue with a lower-resistance Theraband.

Wall angle exercise

The wall angel exercise is performed in a standing position while maintaining the chin tuck posture. Beginning with the elbows flexed and the shoulders abducted, the participant raises the arms overhead into shoulder elevation, ensuring continuous contact with the wall throughout the movement. The arms are then returned to the starting position [59, 60].

Swissball exercises

While the participant is on their knees with their body supported by the Swissball, the Y exercise with Chintuck will be performed Then, the chin tuck exercise will be performed in a standing position, with a Swiss ball placed between the wall and the back of the participant’s head. The participant will be asked to keep the Swissball balanced behind their head for 10 s while performing the Chintuck. This movement will be performed in two sets of 10 repetitions. Progression will continue with a resistant upper extremity exercise performed in the same position. The participant will perform bilateral shoulder elevation with the Theraband while maintaining the Chintuck position against the Swissball. They will be asked to raise their arms as high as possible against the resistance of the band, keeping their elbows straight. Then, they will hold this position for 10 s and perform the movement in two sets of 10 repetitions [53, 58].

Statistical analysis

G*Power software version 3.1.9.4 (Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany) was used to calculate the sample size [61]. A repeated-measures ANOVA (within–between interaction) was chosen as the statistical test, considering 6 groups (e.g., patients vs. controls) and three time points (baseline, post-treatment, follow-up). The analysis was performed with a significance level (α) of 0.05, a power (1 – β) of 0.80, and effect size of 0.25 (f) [23, 62]. The results indicated that a total of 54 participants would be sufficient to detect a statistically significant interaction effect. Considering an approximate 10% chance of data loss, it was planned to include at least 60 people in the study.

Per-Protocol, which is one of the basic methods recommended for maintaining the effect of randomisation and preventing attrition bias, will be applied. Analyses will be performed using SPSS version 24 software (IBM SPSS Statistics for Windows, Version 24.0. Armonk, NY: IBM Corp.). The conformity of the variables to normal distribution will be examined using visual (histogram and probability plots) and analytical methods (Shapiro-Wilk tests). Mean and standard deviation will be used for descriptive analyses, and number and percentage will be used for nominal variables. A Chi-square test will be employed for the purpose of conducting a comparison of categorical variables. In the analysis of differences between three different groups, if the data are normally distributed, a One-Way ANOVA test will be used; if not normally distributed, a Kruskal-Wallis test will be used. In the analysis of differences between the study groups and the control group, if the data are normally distributed, an independent samples t test will be used; if not normally distributed, a Mann-Whitney U test will be used. Analyses of differences between repeated measurements of groups will be done using Repeated Measures ANOVA if the data are normally distributed, and Friedman test if the data are not normally distributed. Statistical significance level will be accepted as p < 0.05. Details regarding the statistical analyses to be performed are presented in Fig. 2.

Fig. 2.

Statistical analysis flow diagram

Discussion

This study will examine the effect of progressive neck motor control exercises on different types of temporomandibular disorders. Although craniocervical exercise approaches have been utilised in individuals diagnosed with TMD, current evidence has yet to determine the most effective intervention. Investigating the impact of progressive motor control exercises on different TMD presentations would provide new insights into the existing literature. This study will be the first to evaluate the effectiveness of a progressive exercise program for individuals with different types of TMD and associated differential outcomes.

It is believe that the research results will guide the limited evidence by ensuring homogeneity in the included groups. We believe that by showing the effect of cervical region treatment on different TMD types, the focus of the treatment program can be determined more accurately; thus a more effective treatment can be applied. Given that not all treatment strategies yield the same outcomes for various TMD subgroups [63], determining the optimal treatment method for each TMD subgroup is of great importance [64]. In this context, it is anticipated that this study will provide valuable guidance by employing a randomised controlled trial design and ensuring the homogeneity of the study sample through classification according to TMD type. This approach demonstrates the strength and potential of the study tin contributing to the existing evidence base research. One limitation of the study is the inability to blind participants and intervention providers.

A systematic review on TMD, published in 2023, noted that methodological problems in many of the studies reviewed made it difficult to draw definitive conclusions about treatment methods and that better controlled randomized controlled trials with appropriate methods are needed [18]. Furthermore, considerable heterogeneity between the number of studies on different TMD subgroups has been identified as a significant issue [18]. Although treatment approaches focusing on the craniocervical region have been shown to be effective in reducing pain due to the relationship between the cervical region and TMD [9, 65], the evidence is insufficient and randomized controlled trials are needed [55, 66]. It is believe that by ensuring homogeneity in the included groups, the research results will provide limited evidence. We believe that by demonstrating the effect of cervical region treatment on different types of TMD, the focus of the treatment program can be determined more accurately; thus, a more effective treatment can be applied. Because not all treatment strategies have the same effect in different TMD subgroups [63], determining the optimal treatment modality in each TMD subgroup is of great importance [64]. In this context, it is believed that the findings will inform the existing evidence base by conducting a randomised controlled trial and ensuring the homogeneity of the study sample through the classification of subjects according to TMD types.

The exercise training employed in the studies referenced in the literature is typically conducted in conjunction with other treatments, in a single position, without being progressive, or is provided as a home program [23, 67]. The study by Calixtre et al. is noteworthy because it is the first to examine the effects of a combination of manual therapy and motor control/stabilisation exercises in participants with TMD [23]. This study included only women, no specific type of TMD was selected, and only an exercise study with a biofeedback stabilizer was performed.

The results of this study will be limited to individuals with myofascial TMJ disorder (TMD), disc displacement with reduction, and disc displacement without reduction. Therefore, this should be taken into consideration when generalizing the results. Future studies examining other types of TMD, along with studies examining the effectiveness of exercise therapy in individuals with TMD, will be important. In addition, participation in treatment sessions and compliance with home exercises are also important. Therefore, the relationship between adherence percentages and changes in parameters or the effect of initial symptoms on adherence can be analysed.

Conclusion

The evidence presented in this study is of a high level of quality due to the randomised controlled trial design. It is anticipated that this initiative will offer support to clinicians and academics engaged in related disciplines within our country and across the globe. This will provide an innovative perspective and facilitate solution development to address contemporary needs. The findings of this study will provide valuable insights into the relationship between the jaw joint and the cervical region, as well as the impact of exercise on various types of TMD. It is hypothesised that this will reinforce the notion that exercises targeting the cervical region should be employed in the management of TMJ disorders rather than solely exercises tailored to the jaw joint.

Authors’ contributions

NK designed the research study. OY and YTK are responsible for patient recruitment and diagnosis. NK prepared the main draft of the study and OY, YTK and GC contributed to the study design. All authors were involved in critically revising the manuscript and approved the final manuscript as submitted.

Funding

The Scientific and Technological Research Council of Türkiye (TÜBİTAK) 1002-A Short Term Support Module (Project Number:323S251): Financial support for the purchase of assessment materials.

Data availability

No datasets were generated or analysed during the current study.

Declarations

Ethics approval and consent to participate

The ethical approval was obtained from the Scientific Research Ethics Committee of Karadeniz Technical University, Faculty of Dentistry (protocol numbers 2023/15 and 64529847/17).

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.