Oral submucous fibrosis (OSMF) is a chronic, debilitating disease characterised by juxtaepithelial fibrosis of the oral cavity. It is regarded as a precancerous and potentially malignant condition. Oral submucous fibrosis (OSMF) may be defined as an insidious, chronic disease affecting any part of the oral cavity and sometimes the pharynx. Although occasionally preceded by and/or associated with vesicle formation, it is always associated with a juxta-epithelial inflammatory reaction followed by a fibroelastic change of the lamina propria, with epithelial atrophy leading to stiffness of the mucosa and causing trismus and inability to eat. The definition by the WHO of an precancerous oral condition: “a generalized pathological state of the oral mucosa associated with a significantly increased risk of cancer” fits well with the characteristics of OSMF . The characteristic features of Oral submucous fibrosis are loss of pigmentation, blanching and leathery texture of oral mucosa, depapillation and reduced movement of tongue, progressive reduction of mouth opening and sunken cheeks. The prevalence rate in India is about 0.2–0.5 % with prevalence by gender varying from 0.2 to 2.3 % in males and 1.2 to 4.57 % in females and malignant transformation rate of 7–30 % . OSMF is a disease of middle age group with peak incidence observed in the second to fourth decade of life. The sex distribution of OSMF varies geographically. The most common oral site for OSMF is buccal mucosa and retromolar region, followed by soft palate, faucial pillars, floor of mouth, tongue, labial mucosa and gingiva. Clinical presentation depends on the stage of the disease. Initially, most patients present with a burning sensation or intolerance to spicy food, and they may have vesicles, particularly on the palate. Ulceration and dryness of the mouth is later followed by fibrosis of the oral mucosa, which leads to rigidity of the lips, tongue, and palate, and trismus. A useful clinical sign is pain on palpation in the sites where submucosal fibrotic bands are developing, and trismus is caused mostly by fibrosis in the dense tissue around the pterygomandibular raphae. Fibrosis of the eustachian tube may lead to deafness. When the fibrosis involves the nasopharynx or oesophagus, patients may experience referred pain to the ear, a nasal voice, and dysphagia to solids; usually these are features of more advanced disease. The etiology of OSMF is obscure, although various hypotheses are proposed, suggesting multifactorial origins, such as chewing of areca nut and its flavored formulations (most common), chronic nutritional deficiencies (especially iron, Vitamin B complex and protein) and genetic predisposition, autoimmunity Excessive use of areca nut and its flavored formulations disrupts the hemostatic equilibrium between synthesis and degeneration. The copper ion in areca nut increases the activity of lysyl oxidase leading to unregulated collagen production, thereby causing oral fibrosis. This leads to the production of free radicals and reactive oxygen species, which are responsible for high rate of oxidation– peroxidation of polyunsaturated fatty acids. OSMF is a disease of middle age group with peak incidence observed in the second to fourth decade of life. The sex distribution of OSMF varies geographically. The most common oral site for OSMF is buccal mucosa and retromolar region, followed by soft palate, faucial pillars, floor of mouth, tongue, labial mucosa and gingiva To predict scoring index, OSMF where O— corresponds to interincisal mouth opening, S—involvement of site in the oral cavity, M—malignant changes if any and F denotes severity of fibrous bands . Submucous Fibrosis (OSMF) is categorized into distinct grades based on clinical and functional staging criteria, providing clinicians with valuable insights into disease severity and progression. One widely accepted classification system divides OSMF into several grades, each associated with specific mouth opening ranges. Grade I, representing the early stage, is characterized by subtle clinical signs such as blanching of the oral mucosa and palpable fibrous bands, often accompanied by mild symptoms like a burning sensation during mastication. Progression to Grade II, the moderate stage, is marked by more pronounced mucosal changes, including restricted mouth opening (trismus) and increased rigidity, with the mouth opening range typically mildly reduced, often between 30-35 mm. Grade III signifies the advanced stage, featuring severe fibrosis and functional impairment, with significantly restricted mouth opening, typically between 20-25 mm, and widespread thickening of fibrous bands. Finally, Grade IV, the severe stage, reflects extensive fibrosis, complete oral vestibule obliteration, and severe trismus, severely compromising oral function, with mouth opening range being severely restricted, often less than 10 mm or even absent. Physiotherapy is a non invasive modality which may aid in the symptomatic treatment of patients with OSMF . The aim of this study is to assess the effectiveness of laser therapy versus ultrasound in combination with soft tissue mobilization and mouth opening exercises for managing trismus in oral submucosal fibrosis.

Null Hypothesis

 H₀¹ -There will not be any significant effect of low intensity laser therapy combined with soft tissue mobilization and mouth opening exercises in managing trismus in patients with oral submucous fibrosis.

H₀^2- There will not be any significant effect of low intensity laser therapy combined with soft tissue mobilization and mouth opening exercises in patients with oral submucous fibrosis for managing mouth opening and tongue protrusion.

H₀^3- There will not be any significant effect of low intensity laser therapy combined with soft tissue mobilization and mouth opening exercises in managing pain, cheek flexibility, strength of facial muscles, maximum bite force and quality of life in patients with Oral submucous fibrosis.

Alternate Hypothesis

H¹ -There will be significant effect of low intensity laser therapy combined with soft tissue mobilization and mouth opening exercises in managing trismus in patients with oral submucous fibrosis.

H^2- There will be significant effect of low intensity laser therapy combined with soft tissue mobilization and mouth opening exercises in patients with oral submucous fibrosis for managing mouth opening and tongue protrusion.

H^{3 -} There will be significant effect of low intensity laser therapy combined with soft tissue mobilization and mouth opening exercises in managing pain, cheek flexibility, strength of facial muscles, maximum bite force and quality of life in patients with Oral submucous fibrosis.