Evaluation of Intra-articular Injection of Hyaluronic Acid Versus Radiofrequency Current in Management of Reduced TMJ Disc Displacement

Introduction Temporomandibular disorders (TMD) are a heterogeneous group of musculoskeletal and neuromuscular conditions involving the temporomandibular joint complex, surrounding muscles and bony components. It is a chronic pain disorder with a prevalence as high as 38% of the general adult population. TMD show a female predilection (2.24:1) with peak incidence around 20 - 40 years of age.

Internal derangement of TMJ is a common orofacial problem that can cause significant pain and / or dysfunction. The clinical signs of the internal derangements are abnormal mandibular kinetics with or without the presence of TMJ noises and pain. The most common form of internal derangement is anterior disk displacement with reduction. Its manifestation, include; TMJ noises (clicking) or popping sounds when the disk slide as the jaw opens or closes. It may cause pain in the area of the TMJ which may radiate to the surrounding areas especially the ear. This pain may be severe enough to interfere with normal chewing and may cause anxiety and depression and even lowering the quality of life.

There have been many options for management of this condition as:

Pharmacotherapy (1- Non-steroidal anti-inflammatory drugs ,2- Antidepressants

,3- Imotun), Physical Therapy (1-Low level laser therapy, 2- Ultrasound and electrical stimulation), Splint Therapy as (occlusal splints), Hyaluronic acid injection, Muscle Injection with BTX , Arthrocentesis and Arthroscopy. Patients with this disorder tend to exhibit a reduction in intra-articular HA concentration so lubricant is reduced, HA provides a long-term lubricating, reducing inflammatory mediators action and increasing joint mobility (movement range). A study of two HA injections at weekly intervals is more effective than placebo injections of saline and joint catabolite levels decreased significantly with a supplemental HA injection.

HA forms a layer which not only covers but also penetrates the articular surfaces. It has been proven that HA plays a significant role in the nutrition and lubrication of the TMJ articular surfaces, When the intraarticular pressure reaches sub-atmospheric values, the proteins lose contact with the articular surfaces and the HA assumes a spheroidal conformation, allowing sliding movements within the TMJ, and when it exceeds atmospheric values HA occurs in the linear form and penetrates the fibrocartilage, which is necessary for TMJ nutrition. HA found to be responsible on stabilization of TMJ component Recently, Radiofrequency (RF) has been used as a supportive treatment in this condition. RF is an electromagnetic wave with radiation frequency between 3 Hz and 3 THz, it has low or minor reaction of the nerves to high frequency alternating current as it is a good thing and that is why RF became irreplaceable therapy in all medical fields especially in dentistry .RF beneficial effect is to restore function of the muscles by improving blood circulation and thus obtain an analgesic effect. It is noninvasive method, and it should be recommended in supportive treatment of temporomandibular disorders. Due to severity of the pain combined therapy may be used for synergistic effect. Therefore, this study is attempt to evaluate clinical and radiographic effect combine therapy in management of TMJ internal derangement.