Effect of Active Mandibular Techniques and Specific Cranio-cervical Therapeutic Exercise in Patients With Temporomandibular Disorders and Bruxism (AMaCe-TB)

Instituto de Investigación Biomédica de Salamanca60 enrolled

Overview

Temporomandibular Disorders (TMD) are a common source of pain and functional limitation affecting the stomatognathic system. They frequently lead to difficulties in mastication, decreased quality of sleep, limited mandibular mobility, and restrictions in daily activities. These symptoms are often aggravated in patients with associated bruxism. Chronic involvement of the temporomandibular joint and surrounding structures can also negatively influence cervical posture and motor control due to the neurophysiological connections between the cranio-cervical region and mandibular biomechanics. This study is designed to evaluate whether active mandibular techniques, specifically the Muscle Energy Technique (MET) applied with the support of the jaw motion rehabilitation system, combined with a cranio-cervical therapeutic exercise program, may improve pain, function, and motor behavior in patients with chronic TMD and bruxism. The trial will be conducted as a randomized controlled study with two parallel groups. The experimental group will receive a mandibular MET intervention delivered once weekly for four weeks, using an active resistance and controlled movement protocol based on three cycles of isometric contraction and passive stretching. In addition, participants will perform daily cranio-cervical motor control exercises at home, with weekly supervision. These exercises aim to enhance neuromuscular regulation of deep cervical flexors and extensors and improve cervical dissociation, symmetry, and alignment. The control group will receive standard clinical care supplemented by a single session of a modified suboccipital inhibition technique acting as a placebo procedure. They will also perform non-specific cervical mobility exercises at home over a four-week period. The primary outcome will be the change in Pressure Pain Threshold (PPT) measured with a pressure algometer at trigger points located in the trapezius, masseter, external pterygoid, and digastric muscles. Secondary outcomes will include maximum mouth opening, pain intensity using a visual analog or numeric rating scale, craniocervical postural control assessed through standardized motor control evaluations, and mandibular movement behavior analyzed through visual or device-assisted kinematic assessment. Measurements will be taken at baseline, immediately after the intervention period, and during a follow-up assessment. Participants will be adults aged 18 to 65 years with a clinical diagnosis of TMD associated with pain for at least three months and bruxism. All participants must provide informed consent prior to inclusion. Individuals with congenital malformations or cervical spine pathology, acute infectious or inflammatory disease, vestibular dysfunction, technical contraindications, recent manual therapy treatment (within one month), or recent use of analgesic, muscle relaxant, or anti-inflammatory medication (within eight hours) will be excluded. The study aims to determine whether the application of active mandibular techniques combined with specific cervical motor control training results in superior improvements in function and pain compared to standard clinical management. Furthermore, the analysis will consider sex-related differences in baseline characteristics and treatment outcomes. Results from this trial may provide clinically relevant evidence to guide physiotherapeutic approaches for patients with TMD and bruxism, potentially improving therapeutic decision-making and long-term patient outcomes. The findings will be disseminated through publication in high-impact international journals and presentation at scientific conferences.

Interventions

Mandibular Muscle Energy TechniquePROCEDURE

The mandibular muscle energy technique lasts approximately 3-4 minutes. The physical therapist stands next to the patient to use the jaw motion rehabilitation system, which will allow the technique to be applied through a system of controlled opening and resistance to closure, with a real assessment of the balance of mouth opening. The patient will be asked to open their mouth and it will be gently increased, while the patient's forehead is fixed, up to the patient's joint opening range. From this position, the patient will be asked to perform an isometric contraction of the masticatory muscles for approximately 3-5 seconds. This procedure will be performed in three cycles, with three contractions per cycle and a rest period between contractions of approximately 3-5 seconds. Patients will perform specific craniocervical motor control exercises for 4 weeks and will be monitored during weekly visits, where manual treatment will be performed using the mandibular muscle energy technique.

Modified suboccipital inhibition techniquePROCEDURE

The modified suboccipital inhibition technique will be performed at the beginning as a placebo technique. This technique will last 5 minutes. For this technique, the patient will lie on the table. The aim of this technique is to provide a stimulus as similar as possible to the original suboccipital inhibition technique, but without the force of movement. The patient will keep their eyes closed for the duration of the technique.

Outcomes

Primary Outcomes

Pressure Pain Threshold (PPT / UDP)

The primary outcome will be the change in pressure pain threshold (PPT), also referred to as Umbral de Dolor a la Presión (UDP), measured in kg/cm² using a handheld pressure algometer at clinically relevant trigger points of the upper trapezius, masseter, external pterygoid, and digastric muscles. An increase in PPT indicates improved pain sensitivity. The objective is to determine whether the mandibular muscle energy technique combined with cranio-cervical control exercise leads to superior improvements compared to standard care and placebo suboccipital inhibition techniques

Time frame: After 4-week intervention and 12 week follow up.

Secondary Outcomes

Maximum Mouth Opening (MMO)

Maximum mouth opening will be measured in millimeters using a digital caliper or equivalent device. Measurements will be taken during active mandibular depression without pain-provocation, and repeated at baseline, after 4 weeks of treatment, and at follow-up. Improved range of mandibular motion is an indicator of enhanced temporomandibular functionality. Previous research cited in the protocol indicates that motor interventions directed at the cervical spine and mandibular musculature have been associated with increases in mouth opening capacity.

Time frame: Baseline, after 4-week intervention, 12 week follow up.

Pain Intensity

Pain intensity will be quantified using a validated subjective scale such as Visual Analog Scale (VAS) or Numeric Pain Rating Scale. VAS is a simple, 1-dimensional measurement tool used to assess subjective experiences like pain, fatigue, or mood, typically a 10-centimeter line with descriptive anchors (e.g., "no pain" to "worst imaginable pain") at each end, where patients mark their current feeling, and clinicians measure the distance from the start to get a score (0-10 or 0-100). The NPRS is a simple 11-point scale (0-10) where patients rate their pain intensity, with 0 being "no pain" and 10 being the "worst pain imaginable", helping clinicians track pain levels and treatment effectiveness. Pain reduction is expected as a direct result of the active mandibular and cervical therapeutic exercises, which have previously demonstrated improvements in patients with temporomandibular disorders.