A New Intraoral Appliance for Trismus in Oral Submucous Fibrosis


Trismus is the most common sequelae of various pathological processes leading to compromised nutritional state in addition to physical and psychological disabilities. Therapeutic interventions are available to relieve trismus, which range from oral usage of pharmacological agents to intralesional steroid therapy. Intraoral appliance therapy can be employed as an alternative or adjuvant treatment for radiotherapy-induced fibrosis and autoimmune disorders.

Case Report

A male patient, aged 39 years, presented to a private clinic with a chief complaint of difficulty in mouth opening since one and half years. The patient had a habit of chewing gutka for the past eight years. It was observed that there is noticeable decline in mouth opening of 17 mm (intercanine distance) and tongue protrusion of 10 mm.


On intraoral examination, generalized blanching of the oral mucosa with grayish black pigmentation was seen. And also, multiple vertical palpable fibrous bands with loss of elasticity and leathery in texture were noticed. OSMF was diagnosed, and the patient was treated with conventional intralesional steroid injections. Since the patient has been under similar treatment for over a period of time with no recognisable change or relief, he requested for an alternative therapy. Intraoral appliance therapy was considered, and prior consent was obtained from the patient. 


The patient was duly provided with necessary precautions regarding the usage of appliance and weekly follow-up without discontinuing the treatment. The treatment was carried out for a total period of 8 weeks and a follow-up of two months after completion of the therapy.


Trismus is defined as a prolonged tonic spasm of the muscles, which results in restricted mouth opening. OSMF is a potentially malignant, chronic, progressive disorder seen mostly in people from Asia and is found to affect most of the parts of the oral cavity that includes the lips, tongue, palate, pharynx, and even the upper third of the oesophagus.In later stages, further stiffening occurs due to myofibrosis of the subepithelial and submucosal tissues, thereby resulting in limitations in the mouth opening and tongue protrusion causing difficulty in eating, swallowing, and also phonation-related issues. Various treatment modalities such as physical oral therapy, intralesional corticosteroids, ultrasound therapy, and surgical modalities were tried till date.In the present case series, a newer treatment procedure is tried on patients suffering from OSMF. An appliance that can be easily fabricated was designed and used in patients with trismus due to any noninfectious pathology.For patients who are not comfortable or given consent for treatment with intralesional steroids, this appliance therapy could be an alternative treatment modality. Moreover, cost and the adverse effects are involved in this treatment when compared with steroid therapy. Yadav et al. believed that protecting surgically reconstructed defects using flaps is vital, and the authors fabricated an appliance in order to avoid trauma to the flap in the postoperative period.It is further believed that physiotherapeutic effect is a probable mechanism behind appliance therapy, which causes remodelling of the tissues for improving mouth opening.From design, the appliance works by causing mechanical force which then induces the stretching of the elevator and depressor muscles. Based on the design, these appliances are classified into externally and internally activated types. Externally activated appliances exert force by stretching the elevator muscles and depressing the mandible whereas internally activated appliances employ the force on the depressor muscles to stretch the elevator muscles.They impart forces which are continuous or intermittent, elastic or nonelastic, and light or heavy. The force generated by the elevator muscles is greater than that by the depressor muscles. The amount of force delivered depends on the strength, frequency, duration of stretching, and motivation of the patient.The activation cycle is unique to the appliance. The key which is provided for opening up the hyrax screws during rapid palatal expansion is used for activation purposes in relieving the trismus. Each full turn is equal to approximately 0.2 mm and total number of 4 full turns is given which account to 0.8 mm per week. The patient is followed up every week for 8 weeks. The approximate mouth opening hypothesized ranges from 5 mm to 1.5 cm.In the present case series, the appliance emits intermittent and bilateral forces, which help to depress the mandible and make the maxillary and mandibular teeth apart thereby relieving the trismus. Physical therapy improves the range of motion of temporomandibular joint, reduces pain, prevents hypomobility, avoids fibrosis formation, strengthens the musculature, and improves flexibility, tissue elasticity, and blood circulation.The appliance can be fabricated in patients who are completely edentulous and also in those partially edentulous patients. As the appliance is passive over the teeth and does not cause functional tooth movements, it can be comfortably worn in patients with missing dentition. As the occlusion is undisturbed, there is elimination of alteration in the occlusion sequence. Caution has to be maintained when there are periodontal compromised teeth. Excessive vertical forces may further breakdown the periodontium.Periodontal assessment has to be carried out before the appliance fabrication. Teeth with excessive mobility and poor prognosis should be managed prior to appliance insertion. Mild-to-moderate periodontitis is not a contraindication for appliance fabrication.Patil et al. from their study concluded that the use of mouth exercising device appears to be effective for the separation of collagen fibers and increased the subcutaneous matrix area leading to improved blood circulation. Oswal et al. fabricated an oral screen prosthesis to stabilize the secured flaps and to prevent it from being bitten into occlusion, and the same can also be used as an oral stent to prevent relapse.Similarly, Li et al. fabricated a EZBite open mouth device and conducted a 12-week structured open mouth training program and stated a marked improvement in mouth opening.Till date, there are two jaw-exercising devices used in palliative care. “TheraBite” is a mechanical device with lever system which assists mouth opening by squeezing the handle of the device and is able to control the extent of the stretch to the tissues.Another appliance is “Dynasplint trismus system” which is used with a low-torque and prolonged duration stretch designed to lengthen connective tissue. Both of these appliances are used effectively to relieve trismus due to various causes. TheraBite is a lever system which is patient dependent, and the maximum opening claimed is almost 41 mm.Dynasplint trismus system is bulkier compared to the presently described appliance. The present appliance is not visible outside the oral cavity unlike the two above-described systems. The mandibular range of motion may not be achieved with the present model, and modifications may be required to assess the same in further fabrication


New Intraoral Appliance, Trismus, Oral Submucous Fibrosis

Author : Nallan C. S. K. Chaitanya et al