Effects of Orofascial Myofunctional Therapy and Cervical Stabilization Exercises on Jaw Pain, Range of Motion, Occlusal Load and Functional Limitation in Patients With Temporomandibular Dysfunction

Temporomandibular disorders (TMDs) are among the most common musculoskeletal conditions of the craniofacial region, characterized by pain, joint noises, and functional limitation. Anterior disc displacement is one of the most frequent TMJ disorders, classified as displacement with or without reduction (ADDwR/ADDwoR). In the RDC/TMD Validation Project, about 30% of asymptomatic participants showed disc displacement with reduction; 11% involved transient limited opening (intermittent closed locking) and 10% were displacement without reduction with limited opening, both clearly affecting masticatory function. The term "internal derangement" an intra-articular mechanical disturbance interfering with smooth joint action is reserved for stages with apparent functional consequences such as significant deviation on opening, locking, or limited opening. Axis-I, Group II-a TMD (DDwR) is a prevalent subtype: the disc displaces during jaw function but repositions on opening, often producing clicking, and repeated episodes can compromise joint mechanics, trigger pain, and produce maladaptive muscle patterns. Signs may progress to ADDwoR limited opening after the click disappears, minimal condylar translation, restricted lateral movement, and mandibular deviation toward the affected side staged as acute (≤2 months) or chronic (>2 months). Pain may eventually ease, but cartilage and subarticular bone abrasion can develop over time, prompting some to recommend disc repositioning (4).

Global TMD incidence is about 34%, concentrated in ages 18-60 with consistent female predominance, and is highest in South America (47%) versus Asia (33%) and Europe (29%). A 2021 meta-analysis showed wide variability arthralgia 5.7-17%, DDwR 2.1-33%, DDwoR without limited opening 0-0.74%, osteoarthritis 1.9-3.2%, osteoarthrosis 4.8-70% with much lower rates in children and adolescents (5), underscoring the need for standardized diagnostic and management strategies. Etiology is multifactorial and poorly understood, linked to malocclusion, trauma, emotional stress, parafunction (clenching, bruxism), sleep disorders, depression, abnormal muscle recruitment, and discal or bony morphology. The psycho-emotional component is substantial, with stress, anxiety, fatigue, and poor sleep affecting the psyche, and such patients often presenting a muscular component. Occlusal traits such as open bite, deep bite, and posterior crossbite have been linked to TMD, and greater overbite and interincisal angle to joint sounds, though some found no conclusive association Abnormal joint loading rarely stems from one factor, being compounded by parafunction, internal derangement, morphology, occlusal trauma, and childhood experiences. High-risk groups include those with repetitive masticatory use and high-stress occupations musicians, teachers, office and healthcare workers, military, and emergency services. Standardized diagnosis began with the RDC/TMD, comprising Axis I (physical) and Axis II (psychological), later refined into the DC/TMD in 2014.

Orofacial functions require coordinated activation of facial, jaw, tongue, palatal, pharyngeal, and laryngeal muscles under central control, so any occlusal, joint, or muscular change alters mastication. Masticatory efficiency reflects food breakdown, while maximum occlusal force and maximum voluntary bite force are key indicators, measurable with digital devices that detect premature contacts and TMJ problems early. Oral motor exercises aim to strengthen the articulators, with jaw-muscle synergy for speech derived from the chewing central pattern generator. OMT uses individualized oral and peri-oral exercises to retrain muscle function and stabilize the stomatognathic system, improving coordination of the jaw, tongue, lips, and cheeks, and promoting functional tongue posture, nasal breathing, lip seal, and proper mastication. Felicio's protocol enables scored evaluation of appearance, posture, mobility, functions, occlusion, and mandibular movement. Although OMT benefits conditions such as atypical swallowing, tongue-tie, and mouth breathing, its role in TMD remains underexplored.

A clear anatomical and biomechanical relationship connects the TMJ and cervical spine: cervical muscles stabilize the head and neck, enabling controlled TMJ movement essential to chewing, swallowing, speaking, and breathing, so cervical alterations affect TMJ position. Neurophysiologically, trigeminal and cervical neurons converge in the brainstem's cervical trigeminal complex, integrating nociception and allowing pain referral between regions, which justifies cervical evaluation in TMD. Postural deviations, cervical instability, and impaired neuromuscular control may worsen mandibular dysfunction and pain, and TMD patients frequently show coexisting cervical impairments. Jaw stretching, strengthening, range-of-motion, and coordination exercises improve muscle balance, pain, and mobility, and cervical exercises also help. Cervical stabilization exercises activate deep muscles and reduce surface-muscle overactivity, making them plausibly effective in TMJ disorders.

Because most OMT studies exclude complex conditions like TMD, existing evidence has limited real-world relevance, and recent reviews recommend extending OMT research to such populations. This study examines combined orofacial neuromuscular training and cervical stabilization in Axis-I, Group II-a TMD, addressing local and regional dysfunction together to guide integrated, outcome-oriented management. Current evidence remains mixed. A systematic review of ten RCTs found photo-biomodulation (PBM) plus OMT produced greater pain reduction and functional gain than either alone in seven trials, one showing raised pressure-pain thresholds at the TMJ, masseter, and temporalis. An RCT in children aged 5-14 showed EF Line myofunctional devices with myo-gymnastics improved bite patterns and orbicularis oris strength on EMG. A scoping review of 58 studies found 86% reported favorable OMT outcomes, yet only 19% were RCTs and none conclusive found OMT with active or sham laser both improved pain and oral-health quality of life, highlighting placebo effects. A study showed OMT reduced facial-aging signs, with gains regressing without maintenance. A retrospective cohort found orthodontics plus myofunctional therapy gave 25% greater PAR reduction and higher satisfaction (85% vs 60%) than orthodontics alone. Overall, OMT's direct role in TMD particularly ADDwR as a discrete entity remains limited, confounded by placebo effects and combined modalities, and weakened by small samples and poor randomization. Most studies use broadly defined TMD populations and overlook joint-level parameters such as disc position, reduction mechanics, and condylar-disc coordination, so a focused, diagnostically precise study of OMT in ADDwR is warranted.