Hormones are secretory products of endocrine glands released directly into the circulation in small amounts in response to a specific stimulus and on delivery in circulation produce response on the target cells or organs. The system is specifically designed to integrate and control the human body's innumerable metabolic activities. Hormones interact with target cells via receptors which are large protein molecules with specific binding sites for specific hormones. There are 2,000 - 100,000 receptor molecules present per target cell. Any variation in the hormonal secretion from normal results in abnormal changes in the body including the oral cavity. For example increase in estrogen and progesterone during pregnancy causes pregnancy tumor (pyogenic granuloma) and puberty causes gingivitis. Likewise, parathyroid hormone fluctuations leads to defective amelogenesis which can cause enamel hypoplasia and other changes like widened pulp chamber, intra pulpal calcification, delayed eruption and blunting of apices of teeth. This book lays emphasis on Effect of Hormonal Imbalance on Oral Tissues.

Lichen Planus is an "eruption of flat topped, shiny, violaceous papules on flexor surface, male genitalia and buccal mucosa of unknown cause, may formed linear groups, microscopically characterised by a band like sub epidermal lymphocytic infiltrate."Oral Lichen Planus is a premalignant condition.They are usually bilaterally symmetrical.Oral lichen planus may coexist with lesions of the genital mucous membranes or with lesions of cutaneous lichen planus.This book aims at reviewing the pathogenesis, etiology, clinical features, histopathology and treatment of oral lichen planus.