Under the restraint of the title of the book, general symptoms of OSMF, like burning in oral cavity, intolerance to temperature and spicy food, and general nutritional defciency symptoms, are excluded. Authors shall restrict to the pathological changes in oral cavity responsible for trismus. The structures classically affected are the cheek, teeth, anterior tonsillar pillar and soft palate, muscles of mastication, and temporomandibular joint. Hence, the surgeon needs to address the dense hyalinized tissues in all these areas to achieve adequate release of trismus, i.e., to improve mouth opening. The following pictures shall demonstrate all above and the factors that need to be considered before surgery. Grading is done strictly after 3 months of cessation of the injurious habits of chewing tobacco, areca nut, catechu mixed with lime, and similar offending habits. Grades are measured in centimeters of inter-incisor distance (IID). Grade 0: Symptoms of OSMF without trismus Grade 1: Inter-incisor distance equal to or more than 3 cm. Grade 2: Inter-incisor distance between 2.9 and 2 cm. Grade 3: Inter-incisor distance between 1.9 and 1 cm. Grade 4: Inter-incisor distance less than 1 cm.