Effect of pain science education administered condensed or longitudinally associated with manual therapy and exercises on pain intensity and disability for Temporomandibular Disorders: a randomized controlled trial

Abstract

Background

Temporomandibular Disorders (TMD) are musculoskeletal disorders that affect the chewing structures and has a complex and multifactorial etiology. A biopsychosocial approach is recommended for the management of these disorders considering the multifactorial nature of TMD etiology. The aim of this study is to compare the effect of condensed Pain Science Education (PSE) program (2 initial sessions of 75 min) versus longitudinally administered PSE (6 sessions of 25 min) combined with manual therapy and neck motor control exercises (NMCE) on primary outcomes—pain intensity and disability—and secondary outcomes – mandibular range of motion, pain self-efficacy, fear of movement, global perceived effect of improvement, empathy, knowledge about pain neuroscience, beliefs about pain, exercise adherence, and pain catastrophizing—in patients with painful TMD.

Methods

This study will be a randomized controlled trial with a sample of 148 participants. Participants will undergo a screening process to identify TMD according to the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD), aged 20 to 60 years, of both sexes, and then the volunteers will be randomized into two groups (G1: Condensed PSE + Manual therapy/orofacial and NMCE vs. G2: Longitudinal PSE + Manual therapy/orofacial and NMCE). The exercise intervention will take place once a week for 8 weeks, conducted by a physiotherapist, with each session lasting 1 h. The interventions will be administered by trained care providers. The primary outcomes will be pain intensity and disability, assessed using the numeric pain rating scale and the Craniofacial Pain and Disability Inventory (CF-PDI), respectively. For statistical analysis, a linear mixed models considering time and groups as factors will be used. A significance level of p < 0.05 will be considered.

Discussion

To date, no randomized controlled trial has yet been conducted to compare the effect of different modes of PSE delivery on pain intensity and disability in patients with painful chronic TMD.

Trial registration

NCT06259344. Registered on February 14, 2024. https://classic.clinicaltrials.gov/ct2/show/NCT06259344

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-025-09320-9.

Introduction

Background and rationale

Temporomandibular disorders (TMD) are complex musculoskeletal disorders and its etiology is described as multifactorial, encompassing both biological and psychosocial factors [1, 2] including comorbidity with other disorders, such as neck pain and headaches [3, 4]. Besides neck pain and headaches, TMDs can cause pain in the jaw, face, earache, clicking, popping, or crepitus in the temporomandibular joint, and impaired mandibular function [5]. An estimate of 30% of acute TMD may become chronic (pain lasting more than 3 months) [6] and women are more likely to be affected than men [7]. A previous systematic review with meta-analysis reported a prevalence of chronic TMD diagnoses in the general population as 38% considering Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) [8].

Among the array of therapeutic modalities, physiotherapy stands out as a valuable intervention for alleviating musculoskeletal pain and restoring normal function [9]. Manual therapy (MT), encompassing joint mobilization, manipulation, and soft tissue treatments, has also demonstrated efficacy in restoring range of motion, enhancing sensorimotor function and promoting hypoalgesia [10, 11]. Studies on therapeutic interventions involving MT underscore the importance of integrating exercise into treatment protocols [10].

A recent clinical guideline recommended a couple of interventions to manage TMD, including therapeutic exercise and MT[5]. Additionally, a network meta-analysis showed that interventions to promote coping and encourage movement and activity were found to be most effective for reducing chronic TMD pain, with moderate or high certainty of evidence [12]. Craniomandibular and cervical MT showed a decrease in short-term pain intensity and pain-free mandibular mouth opening, but such interventions showed low-quality evidence, for treating patients with TMD [13]. Moreover, incorporating pain education and physical exercises into treatment regimens is recommended for managing chronic painful musculoskeletal conditions [14].

It is recognized in the literature that TMD, like all other chronic pain conditions, was better understood, diagnosed, and treated from the perspective of an evidence-based biopsychosocial model rather than from the more limited biomedical model [15]. Hence, treatment programs should incorporate psychosocial interventions like educational approaches. Pain Science Education (PSE) [16] aims to enhance patients' understanding of pain mechanisms through metaphorical explanations, interactive activities and games which can facilitate the reconceptualization of pain-related beliefs [17]. Pain reconceptualization has been defined as shifting people's beliefs towards the understanding of four key points: 1) that pain does not provide a measure of the state of the tissues; 2) that pain is modulated by many factors from across somatic, psychological and social domains; 3) that the relationship between pain and the state of the tissues becomes less predictable as pain persists; and 4) that pain can be conceptualized as a conscious correlate of the implicit perception that tissue is in danger [18].

Meta-analytical findings suggest that integrating PSE with other interventions yields favorable outcomes in terms of pain intensity, disability, and pain catastrophizing [19] for patients with chronic musculoskeletal disorders. There are previous studies in which pain education was associated with exercises and MT to treat TMD [20, 21]. However, only one previous study evaluated the additional effect of adding PSE to MT and therapeutic exercises [21] for TMD patients. The findings showed reductions in disability post-treatment and at the follow-ups, as well as pain intensity decrease, improved pain self-efficacy and lower levels of fear of movement at the follow-ups which favor the group submitted to PSE [21].

However, despite promising findings, the study of Aguiar et al. [21] also highlighted certain limitations, including short follow-up, lack of control for changes in pain beliefs, and absence of fidelity analysis—a crucial aspect to be controlled in the context of psychosocial interventions like PSE [22]. In addition, the optimal dosage and method to deliver PSE remains a subject of debate [23, 24]. Some evidence suggests a minimum duration of PSE for eliciting minimal effects on anxiety and fear of movement [23] and a recent study found that a dose of 200 and 150 min of PSE added to an exercise programme was estimated to exceed the minimum clinically important difference for pain intensity and disability [24]. Nevertheless, there is no previous study that compared two different methods to PSE delivery for TMD patients, like a condensed vs. longitudinal mode in which the content is delivered in small blocks along all the treatment time. We suggest that PSE administered longitudinally will show better improvements in pain intensity and disability due to a better learning effect which in turn could facilitate the reconceptualization of maladaptive beliefs and, consequently, triggering behavioral changes.

In light of such considerations, this study will compare the effect of two different modes of PSE delivery, a condensed mode in which the PSE will be administered in two sessions, or a longitudinal mode, comprised of 6 sessions of 25 min, associated with craniocervical MT and exercises on pain intensity and disability (primary outcomes) in patients with painful chronic TMD. In addition, pain intensity and disability will be assessed at the 3-month and 6-month follow-ups. As secondary outcomes, we will assess mandibular range of motion, pain self-efficacy, fear of movement, global perceived effect of improvement, empathy, pain neurophysiology knowledge, pain beliefs, exercise adherence, and pain catastrophizing at the follow-ups. We hypothesized that PSE delivered in a longitudinal mode will show clinically meaningful improvements in pain and disability post-treatment, when compared to the group submitted to the condensed mode.

Methods

This study will be a superiority randomized controlled trial with two parallel arms, adhering to the guidelines outlined in the Consolidated Standards of Reporting Trials (CONSORT) [25], Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) [26] and Template for Intervention Description and Replication (TIDieR) [27] (Fig. 1). The description of interventions as recommended by SPIRIT can be found in Table 1.

Fig. 1.

Flow chart demonstrating the randomization process to be adopted in the present study. PSE C = Condensed Pain Science Education administration, PSE L = Longitudinal Pain Science Education administration MT: Manual Therapy, TE: Therapeutic Exercises (Mandibular and Neck Motor Control Exercises)

Table 1.

 Study phases, time points, interventions administered, and outcomes assessed

	Study Phases
	Enrolment	Allocation	Baseline	Sessions 1 and 2	Session 3	Session 4	Session 5	Session 6	Sessions 7 and 8	Post-intervention	Follow-up 3 months	Follow-up 6 months
TIMEPOINT	-t1	0	t1							t2	t3	t4
ENROLMENT:
Eligibility screen	X
Informed consent	X
Randomization		X
Allocation		X
INTERVENTIONS:
PSE (G1)				X
PSE (G2)				X	X	X	X	X
Orofacial Manual Therapy (G1)				X	X
Orofacial Manual Therapy (G2)				X	X
Mandibular exercises (G1)					X	X	X	X	X
Mandibular exercises (G2)					X	X	X	X	X
Neck Motor Control exercises (G1)						X	X	X	X
Neck Motor Control exercises (G2)					X	X	X	X	X
ASSESSMENTS:
Socioeconomic Assessment			X
DC/TMD	X	X
GAD-7			X							X	X	X
PHQ-9			X							X	X	X
NPRS	X		X							X	X	X
CF-PDI			X							X	X	X
TSK/TMD Br			X							X	X	X
GPE										X	X	X
PSEQ			X							X	X	X
CARE										X
NPQ			X							X	X	X
COPI-adult			X							X	X	X
Mandibular Range of Motion			X							X
EARS-Br										X	X	X
Br-PCS			X							X	X	X

G1 = Condensed Pain Science Education administration and G2 = Longitudinal Pain Science Education administration

PSE Pain Science Education, NPRS Numeric Pain Rating Scale, CF-PDI Craniofacial Pain and Disability Inventory, TSK/TMD Br Tampa Scale for Kinesiophobia for Temporomandibular Disorders, GPE Global Perceived Effect of Improvement, PSEQ Pain Self-Efficacy Scale, GAD-7 Generalized Anxiety Disorder Scale, PHQ-9 Patient Health Questionnaire, CARE Consultation and Relational Empathy, NPQ Neurophysiology of Pain Questionnaire, COPI-ADULT Concept of Pain Inventory for Adults, EARS Br The Exercise Adherence Rating Scale, Br PCS Pain Catastrophizing Scale

Study setting

Volunteers will be invited from the community to participate at the Movement and Pain Research Laboratory (LabMovePain) (Physiotherapy Department, Federal University of São Carlos - UFSCar) for data collection and interventions. The source population for recruitment consists of individuals residing in the São Carlos metropolitan area who responded to advertisements and recruitment campaigns. 

Eligibility criteria

Participants from both sexes must be aged between 20 and 60 years, as this demographic group represents the highest prevalence of temporomandibular disorders [28]. Chronic painful TMD must be confirmed through the DC/TMD assessment by a dentist, with a minimum pain intensity score of 3 on a scale of 0 to 10, persisting for at least 3 months [29, 30].

Participants will be excluded if they report a history of tumors in the orofacial region, current central or peripheral neurological diseases, current uncontrolled psychiatric illnesses, current pregnancy, toothache at the time of the study recruitment, current neuralgia, or other chronic painful conditions in the head, orofacial, or systemic pain regions at the time of study recruitment (e.g., fibromyalgia, osteoarthritis, rheumatological diseases) (excluding temporomandibular disorders and headaches), history of orthognathic surgeries, history of temporomandibular joint surgeries, or post-orofacial trauma corrections, history of major trauma involving the cervical or craniofacial region, and under physiotherapeutic treatment within 6 months prior to the study commencement. Participants with a Mini-cog score below cutoff values (score ≤ 3) [31] will also be excluded from the study. The Mini-cog is a cognitive function assessment comprising two parts: short-term memory (a three-word registration and recall task) and executive/visuospatial function (the Clock Drawing Test). The total score ranges from 0 to 5 [31]. Illiterate people will also be excluded. This study was approved by the Ethics Committee for Research Involving Human Subjects at the UFSCar (CAAE: 77.273.924.9.0000.5504). The informed consent form used in the current study is available as supplementary file. One researcher will clarify all details of the research and will obtain informed consent from all volunteers before allocation. Participants will be informed that they have the right to withdraw from the trial at any time without penalty. The trial has been registered prospectively on the ClinicalTrials.gov (NCT06259344).

Procedures

This study aims to compare PSE delivered in longitudinal and condensed modes. We expect that PSE delivered longitudinally will show clinically meaningful improvements in pain and disability post-treatment, when compared to the group submitted to the condensed mode. We suppose that more opportunities of interaction between the educator and the learner, with opportunities to review the content covered, would lead to a greater observed effect from the intervention, which in turn could facilitate the reconceptualization of maladaptive beliefs and, consequently, triggering behavior changes.

Baseline assessment, allocation, and study groups

Participants will be randomized into two groups: G1 = condensed PSE + Manual therapy/orofacial and neck motor control exercises (NMCE) and G2 = Longitudinal PSE + Manual therapy/orofacial and NMCE (Fig. 1). In both groups, participants will be submitted to craniofacial manual therapy and a program of NMCE and orofacial exercises (Table 2). Participants will also receive individual PSE workshops. The PSE program will last a total of 150 min, in 6 sessions of 25 min or 2 sessions of 75 min. Once a week the PSE program will be applied at the beginning of the session (Table 2). Participants will first be evaluated for eligibility, and those deemed eligible will then undergo the baseline assessment before being allocated to the study groups.

Table 2.

Detailed description of the interventions for each group. Neck Motor Control Exercises (NMCE). G1 = Condensed Pain Science Education administration and G2 = Longitudinal Pain Science Education administration

Sessions	G1	G2
Week 1 – Outpatient clinic	Pain Science Education – 75 min	Pain Science Education – 25 min
	Myofascial release	Myofascial release
Week 1 – Home Exercises
Week 2 – Outpatient clinic	Pain Science Education – 75 min	Pain Science Education – 25 min
	Myofascial release	Myofascial release
Week 2 – Home exercises
Week 3—Outpatient clinic	NA	Pain Science Education – 25 min
	Myofascial release/Mandibular exercises	Myofascial release/Mandibular exercises
	NMCE – Bracing	NMCE – Bracing
Week 3 – Home exercises	NMCE – Bracing	NMCE – Bracing
Week 4—Outpatient clinic	NA	Pain Science Education – 25 min
	Mandibular Exercises	Mandibular Exercises
	NMCE – Bracing	NMCE – Bracing
Week 4—Home exercises	Mandibular Exercises	Mandibular Exercises
	NMCE – Bracing	NMCE – Bracing
Week 5—Outpatient clinic	NA	Pain Science Education – 25 min
	Mandibular Exercises	Mandibular Exercises
	NMCE – Dynamic	NMCE – Dynamic
Week 5—Home exercises	Mandibular Exercises	Mandibular Exercises
	NMCE – Bracing	NMCE – Bracing
Week 6—Outpatient clinic	NA	Pain Science Education – 25 min
	Mandibular Exercises	Mandibular Exercises
	NMCE – Dynamic	NMCE – Dynamic
Week 6—Home exercises	Mandibular Exercises	Mandibular Exercises
	NMCE – Bracing	NMCE – Bracing
Week 7—Outpatient clinic	NA	NA
	Mandibular Exercises	Mandibular Exercises
	NMCE – Functional	NMCE – Functional
Week 7—Home exercises	Mandibular Exercises	Mandibular Exercises
	NMCE – Bracing	NMCE – Bracing
Week 8—Outpatient clinic	NA	NA
	Mandibular Exercises	Mandibular Exercises
	NMCE – Functional	NMCE – Functional
Week 8—Home exercises	Mandibular Exercises	Mandibular Exercises
	NMCE – Bracing	NMCE – Bracing

Intervention period

Two physiotherapists will administer the NMCE, orofacial exercises, manual therapy, and PSE program. The care providers in charge of manual therapy and exercises will be submitted to a training comprised of 30 hours of didactic and practical/supervised sessions. After allocation, since both groups will receive the same intervention, no changes in group assignment are expected. For 8 weeks, individuals will be monitored, within the protocols described for each intervention group. As an attempt to increase adherence of the participants in the study, the physiotherapist responsible for the exercises will record the exercise sessions, making it easier for the individual to reproduce them at home. For all groups, adherence will be confirmed through clinical log sheets maintained by the care providers. The sheets will record the participant's presence and the duration of each scheduled session, and the procedures delivered. Adherence will be calculated as the percentage of completed procedures and sessions relative to the total number of sessions/procedures defined in the protocol.

Post-treatment period and follow-ups

After this period, the primary and secondary outcomes will be collected immediately after the last treatment session and at the 3-month and 6-month follow-ups, to assess the medium and long-term effects of the multimodal interventions administered. After completing the 8-week intervetions, patients will be encouraged to continue performing the exercises prescribed during the treatment period. The exercise adherence will be monitored by the Exercise Adherence Rating Scale (EARS-Br) [32, 33].

No significant adverse reactions are anticipated in the study, but these will be monitored (e.g.: pain flare-ups). If the participant presents any kind of symptoms, the research team will offer attendance for as long as the symptoms persist. The intervention is planned to be discontinued if there is withdrawal of participant consent. During the application period of this protocol, participants will be allowed to use analgesic medication. Participants will not be allowed to undergo concomitant non-invasive or invasive treatments for TMD. During the treatment and follow-up time points, analgesic medication consumption used by the participants will be monitored (self-report) [34].

Interventions

Orofacial exercises and manual therapy

A protocol of Orofacial Exercises and Manual Therapy previously reported [35] will be adopted in the present study. The manual therapy techniques: intraoral temporalis muscle release, intraoral medial and lateral pterygoid (origin) muscles technique, and intraoral masseter and medial pterygoid release (sphenopalatine ganglion technique) (Fig. 2). And three mandibular exercises: Mandibular body condylar cross- pressure chewing technique and post-isometric relaxation stretches in jaw lateral movement and jaw opening (Fig. 2). Each exercise will be executed for 10 repetitions per session.

Fig. 2.

The manual therapy techniques: A Intraoral temporalis myofascial release. B Intraoral medial and lateral pterygoid (origin) technique. C Intraoral sphenopalatine ganglion technique. Mandibular exercises: (D) Mandibular body—condylar cross-pressure chewing technique. Post-isometric relaxation stretches – jaw laterotrusion (E) and jaw-opening (F)

Neck motor control exercises (NMCE)

The NMCE protocol reported by Aguiar et al. [35] and Celenay et al. [36] will be adopted in our study. The exercise program has three levels: (1) cervical bracing, (2) neck dynamic isometric exercises, and (3) neck functional exercises. The cervical bracing exercises include four hierarchical levels in neurodevelopment stages (supine, prone, quadrupedal, bipedal) for the cervical spine (Fig. 3). The intermediate level exercises will consist of upper and lower extremity range of motion exercises while maintaining a stable spine in four-, three-, or two-point kneeling (Fig. 3). The high-level exercise will be the cervical bracing in the upright position (Fig. 3).

Fig. 3.

Neck motor control exercises program: Cervical Bracing on neurodevelopment stage positions (A- C). The cervical bracing with extremity range-of-motion movements (D, E). Cervical Bracing in the standing position (F). Neck dynamic isometric exercises were performed directly forward (G), obliquely, toward right (H) and left (I), and directly backward by maintaining a stable spine with elastic resistive bands (J and K). Neck motor control exercises Functional exercises—Functional training on unstable surface was performed in combination with cervical bracing over the ball (L-N), with ball in standing position (O, P) and with ball and elastic resistance (Q)

The neck dynamic isometric exercises (five hierarchical levels) will be carried out directly forward, obliquely, toward right and left, and directly backward by maintaining a stable spine with elastic resistive bands (Fig. 3). Finally, neck functional exercises will include functional training with elastic resistance and exercise balls on unstable surfaces (eight hierarchical levels) (Fig. 3).

The criteria to progress in each level (cervical bracing, neck dynamic isometric exercises, and neck functional exercises) will be holding the contraction, for 10 s, 10 times. The progression of the exercises adopted will follow the sequence described in Fig. 3. Participants will be oriented to contract deep neck flexor muscles only during the exercises, not throughout the day as described in the protocol of the original paper [36].

Pain Science Education (PSE)

The PSE program used in our study has already been described and administered in previous published studies [35, 37]. The educational program will last a total of 150 min since a previous study reported that a minimum dose of 150 min of PSE added to an exercise programme was estimated to exceed the minimum clinically important difference for pain intensity and disability [24]. One group will receive the PSE in 2 sessions of 75 min (G1) and the other group in 6 sessions of 25 min (G2). The researcher responsible for the application of the PSE program will be trained to carry out the sessions (60 h of training). The content of the educational program will cover thematic topics described on the book Explain Pain [16] and the book Explain Pain Supercharged [38]: (i) What is pain and how we perceive it, (ii) How the brain works, (iii) The sensitized brain, (iv) The areas of the brain related to pain, (v) Why the pain become chronic and (vi) How can we train our brain to desensitize it. The PSE program content was updated considering the results of a recent study [39]. These sessions will be a combination of didactic and active learning experiences with facilitated problem solving and discussion. Active learning experiences will include activities such as “teach it back”, activity with protectometer, operationalizing key concepts within their individual context, critical reflection on the experience of others and quizzes. The PSE program will be administered in individual workshops.

Fidelity analysis

As a strategy to control the fidelity of the interventions administered in both arms of the study, we will follow the structure developed by the National Institutes of Health (NIH); Behavior Change Consortium (BCC) [40]. To track intervention administration, therapist-patient interaction time and the components of the intervention administered, video recordings throughout the study will be recorded. In addition, regular meetings will be held to discuss clinical cases.

A researcher not involved in any stage of the study will analyze the recorded videos in order to confirm the adequacy of the administered education program in terms of content, methods, and format in relation to what was initially proposed. Furthermore, we will investigate the consistency of the PSE program administered to different patients, with the aim of identifying possible differences in the treatment delivered between study participants. If any problem is identified, the study will be suspended until the issue is fixed.

Outcomes

The primary outcomes will be pain intensity and disability. As secondary outcomes, we will assess mandibular range of motion, pain self-efficacy, fear of movement, global perceived effect of improvement, empathy, pain neurophysiology knowledge, pain beliefs, exercise adherence, and pain catastrophizing. At the baseline assessment, a dentist will administer the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) [41, 42], the Patient Health Questionnaire 9-item (PHQ-9) [43, 44], the Generalized Anxiety Disorder 7-item scale (GAD-7) [45, 46], the Numeric Pain Rating Scale (NPRS) [47], the Craniofacial Pain and Disability Index (CF-PDI) [48, 49], the Tampa Scale for Kinesiophobia for Temporomandibular Disorders (TSK/TMD-Br) [50, 51], the Pain Self-Efficacy Questionnaire (PSEQ) [52, 53], the Neurophysiology of Pain Questionnaire Revised (NPQ-R) [54, 55], the Concept of Pain Inventory for Adults (COPI-Adult) [56, 57] and the Pain Catastrophizing Scale (PCS) [58, 59]. The primary and secondary outcomes will be collected immediately after treatment protocol and at the 3-month and 6-month follow-ups. The NPRS [47] and the CF-PDI [48, 49] will be used for the measurement of primary outcomes, will be administered in the immediate post treatment assessment and at 3-month and 6-month follow-ups. For the secondary outcomes, the mandibular range of motion [41, 42], the TSK/TMD-Br [50, 51], the GPE scale [47], the PSEQ [52, 53], the Consultation and Relational Empathy (CARE) [60–62], the NPQ-R [54, 55], the COPI-Adult [56, 57], the Exercise Adherence Rating Scale (EARS-Br) [32, 33] and the PCS [58, 59] will be administered immediately after treatment protocol.

The questionnaires administered in the study are Patient-reported Outcome Measures (PROM) which are self-reported tools. The DC/TMD involves a clinical assessment to establish the diagnosis of TMD. The researcher involved in obtaining this data has extensive experience in conducting the necessary clinical examinations.

Baseline assessment

Patient Health Questionnaire 9-item (PHQ-9)

The PHQ-9 [43] is a nine-item questionnaire designed to screen for depression in primary care and other medical settings. These items incorporate the nine criteria of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) depression criteria with other leading major depressive symptoms into a brief self-report instrument. The standard cut-off score for screening to identify possible major depression is 10 or above. It was adapted and validated to Brazilian Portuguese [44].

The Generalized Anxiety Disorder 7-item scale (GAD-7)

The GAD-7 [45] is a 7-item self-report measure of generalized anxiety symptoms grouped into one factor of generalized anxiety. Respondents score each item in a 4-point scale based on how often they have been bothered by the described symptoms over the last two weeks (not at all = 0; several days = 1; more than half the days = 2; nearly every day = 3). Total score ranges from 0 to 21, with higher scores reflecting higher severity levels of anxiety. It was adapted and validated to Brazilian Portuguese [46].

Diagnostic Criteria for Temporomandibular Disorders (DC/TMD)

The clinical examination and the diagnosis of TMD will be conducted always by the same calibrated dentist using the DC/TMD [41], translated and validated into Brazilian Portuguese [42]. The dentist responsible for administering DC/TMD Axis I examination has 10 years of clinical experience in Orofacial Pain and TMD and has received specialized training on the DC/TMD protocol. To ensure the reliability of the clinical data, an inter-rater calibration process was conducted comparing the findings of the dentist trained with the reference examiner (an experienced orofacial pain specialist with previous training on DC/TMD). The calibration involved the independent and successive examination of 20 patients with TMD. The examiners were blinded to each other’s findings. The dentist trained was considered successfully calibrated after reaching agreement with the reference examiner, following a detailed review of any discrepancies until consensus was reached for all 20 cases. Maximum jaw range of motion with and without pain, the examination of muscle pain with palpation and temporomandibular joint (TMJ) sounds will be assessed in all mandibular movements. Incisal relationships, maximum opening, and jaw movements will be measured with a ruler. TMJ noises will be detected bilaterally via palpation. Calibration of the palpation pressure will be conducted using a digital algometer. The DC/TMD pain diagnoses are based on self-reported pain during the last 30 days that is modified (i.e., aggravated or relieved) by jaw function. The DC/TMD allows the diagnosis of TMD in three subgroups: pain-related TMDs: (i) myalgia, (ii) local myalgia, (iii) myofascial pain, iv) myofascial pain with referral, (v) arthralgia and (vi) headache attributed to TMD and joint disorders: (vii) disc displacement with reduction, (viii) disc displacement with reduction with intermittent locking, (ix) disc displacement without reduction with limited opening and (x) disc displacement without reduction with limited opening and (xi) degenerative joint disease and (xii) subluxation. To be included in the study, participants must present at least one pain-related diagnosis.

Primary outcomes

Numeric Pain Rating Scale (NPRS)

The NPRS [47] will be used to assess pain intensity in this trial and consists of a sequence of numbers from 0 to 10, in which 0 represents "no pain" and 10 represents "worst pain imaginable”. The between-group minimal clinically important difference (MICD) for pain intensity considered in the study will be 1.0 point [63].

Craniofacial Pain and Disability Index (CF-PDI)

The CF-PDI evaluates pain, disability, and functioning of the craniofacial region through 21 items divided into two subscales: "pain and disability" and "functional status of the jaw." Each item offers four response options, with higher scores indicating greater disability related to orofacial pain [48]. The Brazilian Portuguese version showed acceptable measurement properties [49]. It consists of 21 items, with scores ranging from 0 to 63 points. Each question is scored on a 4-point ordinal scale, ranging from 0 to 3. A higher score reflects higher disability levels [49]. The MICD for CF-PDI was not reported in the literature. The smallest detectable change is 5.1 points [48, 49].

Secondary outcomes

Tampa Scale for Kinesiophobia for Temporomandibular Disorders (TSK/TMD-Br)

TSK/TMD [50] assesses fear of movement related to temporomandibular disorders through 12 items. Higher scores indicate greater fear of movement [51]. Each item is scored on a 4-point Likert scale, ranging from “strongly disagree” (score = 1) to “strongly agree” (score = 4). Responses are summed to produce a total score in which higher values ​​reflect greater fear of movement (12–48 points) [51]. The Brazilian Portuguese version showed acceptable internal consistency (Cronbach's α > 0.70) and reliability for all domains (Intraclass Correlation Coefficient [ICC] > 0.75) [51].

Global Perceived Effect (GPE) of Improvement

Participants rate the perceived effect of treatment on an 11-point scale ranging from -5 (much worse) to + 5 (completely recovered), with higher scores indicating greater perceived improvement [47].

Pain Self-Efficacy Questionnaire (PSEQ)

This questionnaire assesses beliefs about one's ability to function despite pain through 10 items rated on a 7-point scale. Higher scores indicate stronger self-efficacy beliefs [52]. Each item is rated by selecting a number on a 7-point scale, where 0 equals ‘‘not at all confident’’ and 6 equals ‘‘completely confident’’. A total score is calculated by summing the scores for each of the 10 items, resulting in a maximum possible score of 60. Higher scores reflect stronger self-efficacy beliefs. The measurement properties of the questionnaire in Brazilian Portuguese showed acceptable [53].

Consultation and Relational Empathy (CARE)

Considering the principle that the degree of perception of empathy by patient can influence the effectiveness of the health interventions, the CARE instrument consists of 10 items, to assess patient's perception of empathy [60–62]. The scores range from 1 “poor” to 5 “excellent”. All item values are then added together, providing a final score between 10 and 50. The version translated into Brazilian Portuguese has a Cronbach's alpha coefficient of 0.86 [62].

Neurophysiology of Pain Questionnaire Revised (NPQ-R)

The NPQ tool assesses cognitive learning related to the application of education programs on pain neurophysiology [64]. Each item has the following response options: true, false, undecided. Each correct question receives a score of 1. Incorrect answers and/or answers marked as undecided are not scored. The NPQ was revised and a new version with twelve items was recommended [54]. This 12-item version was translated into Brazilian Portuguese [55].

Concept of Pain Inventory for Adults (COPI-Adult)

The COPI-adult was derived from an instrument that assesses the concept of pain in children, which was developed to assess concepts about pain in adults [56]. This instrument consists of 13 items. The items are presented on a 5-point likert scale: 0 strongly disagree; 1 disagree; 2 I'm not sure; 3 agree and 4 strongly agree. Higher COPI-adult scores reflect greater alignment with contemporary pain science (total scores can range from 0 to 52) [56]. Translation and validation into Brazilian Portuguese are ongoing [57]. The original version of the instrument presented acceptable internal consistency (α = 0.78) and good test–retest reliability (ICC = 0.84) [56].

Exercise Adherence Rating Scale (EARS-Br)

It evaluates the behavior of adherence to the prescribed exercise and has 5 possible answer options (0 = completely agree to 4 = completely disagree), the total score varies from 0 to 24 points, the higher the score, the greater the exercise behavior adherence [32, 33]. The EARS-Br scale showed acceptable internal consistency (α = 0.88) and excellent reliability (ICC = 0.91) [33].

Pain Catastrophizing Scale (PCS)

The PCS is comprised of 13 items, which are divided into 3 subscales; Rumination, Magnification and Hopelessness [58]. The questionnaire is filled out based on the patient's thoughts and feelings related to pain. The scale is based on 5 points ranging from: 0 (minimum); 1 (mild); 2 (moderate); 3 (intense); and 4 (very intense). The final PCS score varies from 0 to 52 points, with the psychological risk being directly proportional to the increase in the score. The version translated and validated into Brazilian Portuguese has good internal consistency (Cronbach's α values ​​of 0.93 [helplessness], 0.88 [enlargement] and 0.86 [rumination] for the respective subdomains). Confirmatory factor analysis (CFA) supported the three-factor structure [59].

Mandibular range of motion

The mandibular range of motion will be assessed before and post-treatment according to DC/TMD [41] recommendations in the following movements: pain-free jaw opening, maximum unassisted or assisted jaw opening, lateral (right and left), and protrusive movements. Pain during the movements will also be registered.

Sample size

The study was designed to detect a between-group difference of 1 point in pain intensity measured by the NPRS [47], with an estimated standard deviation of 2 points. For disability, a between-group difference of 5 points measured by the CF-PDI [48, 49] (considering the Smallest Detectable Change of CF-PDI Brazilian version [49]). We will adjust for multiplicity of the co-primary outcomes by using a significance level of 0.025 for each outcome of the study (pain intensity and disability), for an overall significance level of at most 0.05 [65]. Therefore, 63 participants per group will be needed. Other specifications: power of 80%, alpha of 5%, effect size f = 0.25 for both primary results (medium effect) [66]. Considering a potential loss of 15%, 148 participants (74 participants per group) will be recruited. The GPower software was used to calculate the sample size (GPower 3.0.10, University of Kiel, Germany).

Volunteers will be recruited from the city of São Carlos (SP state) through spontaneous demand, and participants will be consecutively included. To publicize the recruitment of participants, announcements will be published on social networks, social media, television news, and dissemination networks within the university.

Allocation

Sequence generation

Participants will be allocated to both intervention groups using an electronic randomization process conducted by an assistant researcher not involved in other study stages. To ensure balanced distribution in terms of TMD diagnoses we will create two separate allocation groups: (i) Participants with single painful diagnosis (n = 74) and (ii) Participants with multiple diagnoses (painful + other diagnoses) (n = 74). After being diagnosed by the dentist (screening), participants will be allocated to one of the two options in each group: condensed (n = 37) or longitudinal PSE (n = 37) modes. The allocation sequence in both groups will be implemented at the intervention assignment using sequentially numbered, opaque, sealed envelopes.

Blinding

The assessor responsible for the initial and follow-up assessments (conducted after treatment, 3-month and 6-month follow-up) will be blinded to the participants' group assignments. The two physiotherapists who will be responsible for the intervention will not be blinded because the scheduling organization of the study will reveal the group to which the patient is allocated (participants receiving longitudinal education will have appointments with in every session, whereas those receiving only initial treatment sessions will not have the same commitment).

Participants in this study are not blinded, it is not a placebo-type study and there are no interventions that are inactive. However, participants will not be informed about the nature of the research question to prevent suggestion and to introduce a potential bias in the study. We do not believe that participant unawareness of the research question has ethical implications since the same interventions will be administered in both study arms.

Data collection

To mitigate attrition bias, participants will be contacted during the assessment period following the intervention via phone calls. This strategy aims to collect primary outcomes when participants are unable to attend an in-person assessment. This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Data management

Participant confidentiality will be strictly maintained. Each participant will be assigned a unique study identification code, and all study data will be registered, stored, and analyzed under this code rather than personal identifiers. Identifiable information (e.g., names, contact details) will be kept separately from study data in password-protected files, accessible only to the research team. Hard-copy documents (e.g., consent forms) will be stored in locked cabinets within the research facility. No identifiable information will be included in reports, publications, or presentations arising from the study. Data will be retained for five years after study completion and then securely destroyed in accordance with institutional and national regulations.

Statistical methods

Statistical methods for primary and secondary outcomes

All randomized participants will be analyzed according to the intention-to-treat (ITT) principle, with participants retained in their originally assigned groups regardless of adherence or protocol deviations. Missing data will be handled using multiple imputation under the assumption of missing at random.

Baseline characteristics

Baseline characteristics will be summarized by the treatment group. Categorical variables will be presented as frequencies and percentages, while continuous variables will be expressed as means with 95% confidence intervals (95% CI). No formal hypothesis testing will be conducted on baseline characteristics.

Primary outcome analysis

The primary outcomes will be evaluated using linear mixed models to assess the effect of group allocation (Exercises/Manual Therapy + 2 sessions of PSE vs. Exercises/Manual Therapy + 6 sessions of PSE), time (pre- and post-treatment), and the group-by-time interaction. The analysis will be adjusted for baseline values of the outcome where appropriate. Results will be reported as effect estimates with corresponding 95% CIs and p-values.

Secondary outcomes

Secondary outcomes will be analyzed using linear mixed models. Results will be presented as effect estimates with 95% CIs. Given the exploratory nature of secondary analyses, no adjustment for multiplicity will be applied; findings will be interpreted with caution and emphasis on effect sizes and clinical relevance rather than formal statistical significance.

Mediation analysis and subgroup analyses

Potential mediating effects, including treatment expectations, will be explored using structural equation modeling (path analysis) in AMOS (SPSS, version 22, IBM Corp., Chicago, IL, USA). Subgroup analyses are exploratory and will be clearly identified as such.

Sensitivity analyses

Sensitivity analyses will be conducted to assess the robustness of the findings, including per-protocol analyses and alternative missing data assumptions (e.g., complete-case analysis).

Software and significance threshold

All data will be coded and entered into the Statistical Package for the Social Sciences (SPSS, version 22). Analyses will be performed using SPSS and AMOS. The significance level for all analyses will be set at 0.05 (two-sided). There are no planned interim analyses with the objective of terminating the study prematurely. The interventions employed are non-invasive, with rare adverse events, not related to mortality. No compensation is planned for minor adverse effects, which are expected to be minimal and transient (e.g., temporary muscle soreness). In the unlikely event of harm directly attributable to study participation, participants will have access to appropriate medical evaluation and care at no cost. The research team will facilitate referral to specialized health services if needed, and any serious adverse events will be reported immediately to the institutional ethics committee. Post-trial, participants will continue to have access to standard care provided by the public health system (Sistema Único de Saúde – SUS).

Study coordination will be managed by the principal investigator, TCC, who assumes responsibility for the overall supervision and conduct of the trial. In accordance with the scope of this study, no independent coordinating center or trial steering committee will be established. Biweekly meetings are scheduled to monitor the research processes and the three researchers, along with the coordinator and the team. The study was approved by the institution's ethical board committee.

No formal external auditing of trial conduct is planned, given that this is an investigator-initiated and non-funded study. Oversight of the trial will be the responsibility of the principal investigator, who will conduct regular internal checks to ensure adherence to the approved protocol, accuracy of data entry, and compliance with ethical standards. Any protocol deviations or adverse events will be documented and reported to the institutional ethics committee in accordance with national regulations.

If any modifications in the protocol occur during the trial, we will report them in the publication of the study results. However, we do not intend to modify the protocol that has been published prospectively.

Access to the full protocol, participant level-data and statistical code will be shared under reasonable request. To communicate the trial results to participants, healthcare professionals, the public, and other relevant groups, the research team intends to publish in peer-reviewed journals and present at conferences.

Trial status

Enrollment of participants began in September 2024 and will proceed until September 2026, with a target of 148 participants. Protocol version: November 2025.

Discussion

The aim of this study is to evaluate the effect of two different forms of PSE administration on pain and disability in participants with chronic painful TMD. We hypothesized that PSE delivered in a longitudinal fashion will show clinically meaningful improvements in pain and disability post-treatment, when compared to the group submitted to the condensed fashion.

The theory of spiral learning advocates that learning is a continuous and iterative process, and concepts should be revisited and reinforced over time [67]. This approach can lead to better retention of information and a deeper understanding of the topics proposed to an individual in the learning process [67]. Since the first publication regarding PSE in 2003 [16], researchers have observed the need for continuous evolve of the educational program to adapt it to the distinct demands of patients suffering from chronic painful conditions. Patients with chronic pain commonly complain about seeking help from several different professionals without success, however, treatments focused on pain coping strategies, self-efficacy, and self-management of the painful condition are not commonly offered to such patients [39, 64]. Instead, passive treatments are much more commonly delivered. In this study, we aim to encourage patients to self-manage their symptoms and reconceptualize maladaptive beliefs, to improve pain and disability indirectly [39]. Additionally, the present study is testing a biopsychosocial intervention since the management of TMD focusing solely on biological issues is unlikely to be effective [68].

We are focused in overcome a couple of limitations of a previous study conducted by our research group [21], as follows: (i) using DC/TMD instead of Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) to diagnose patients, (ii) longer follow-up, (iii) assessment of misconceptions and maladaptive beliefs about pain after the PSE program, (iv) assessment of catastrophizing/empathy and (v) implementation of fidelity analysis.

Limitations

Participants in this trial will not be blinded to the group's allocation. In the design of the present study, participants will be aware that they have been allocated in the condensed or longitudinal mode of PSE delivery. Another challenge is the adherence to the sessions and the follow-ups. A potential limitation of this study can be the loss to follow-up. To maximize participant adherence and minimize the negative effects of the attrition bias, the research team will adopt the use of exercise videos and phone calls.

Future directions

TMD is a common, prevalent painful condition. This study will provide insights into different forms of PSE delivery that can inform a body of educational research into clinical training of healthcare professionals and provide support to healthcare services in the decision-making process. Additionally, this study will bring insights to a better understanding of the feasibility of PSE delivery modes as an educational intervention and support its implementation, acceptability, and provide effectiveness indicators.

Abbreviations

TMD

Temporomandibular disorders

PSE

Pain Science Education

DC/TMD

Diagnostic Criteria for Temporomandibular Disorders

CF/PDI

Craniofacial Pain and Disability Inventory

MT

Manual therapy

TE

Therapeutic exercises

CONSORT

Consolidated Standards of Reporting Trials

SPIRIT

Standard Protocol Items: Recommendations for Interventional Trials

TIDieR

Template for Intervention Description and Replication

SP

São Paulo

UFSCar

Federal University of São Carlos

PHQ-9

Patient Health Questionnaire 9-item

GAD-7

Generalized Anxiety Disorder 7-item scale

NPRS

Numeric Pain Rating Scale

TSK/TMD-Br

Tampa Scale for Kinesiophobia for Temporomandibular Disorders – Brazilian version

GPE

Global Perceived Effect of Improvement

PSEQ

Pain Self-Efficacy Questionnaire

NPQ-R

Neurophysiology of Pain Questionnaire Revised

COPI-Adult

Concept of Pain Inventory for Adults

PCS

Pain Catastrophizing Scale

EARS-Br

Exercise Adherence Rating Scale

DSM-IV

Diagnostic and Statistical Manual of Mental Disorders

TMJ

Temporomandibular joint

ICC

Intraclass correlation coefficient

CFA

Confirmatory factor analysis

NIH

National Institutes of Health

BCC

Behavior Change Consortium

CI

Confidence intervals

SPSS

Statistical Package for the Social Sciences

IL

Illinois

IBM

International Business Machines Corporation

RDC/TMD

Research Diagnostic Criteria for Temporomandibular Disorders

NMCE

Neck Motor Control Exercises

PROM

Patient-reported Outcome Measure

Authors’ contributions

JHPS and TCC wrote and drafted the study protocol. TCC developed the study concept and is the researcher coordinator. JHPS, TCL, RBRP and TCC will be involved in the trial design and data collection. The authors have read and approved the final version of the manuscript.

Funding

Not applicable.

Data Availability

The data supporting the findings of this randomized controlled trial will be available upon request from the corresponding author.

Declarations

Ethics approval and consent to participate

This study was approved by the Ethics Committee for Research Involving Human Subjects at the Federal University of São Carlos—UFSCar (CAAE: 77273924.9.0000.5504). Furthermore, all participants will be subject to sign an informed consent form after receiving written and verbal information about the trial.

Consent for publication

Not relevant for the present protocol.

Competing interests

The authors of the present protocol declare that they have no financial or non-financial competing interests in the conduct or reporting of the protocol.