Allergic reactions are becoming prevalent in the general population and the materials used for dental filling, orthodontic instruments etc must satisfy the biocompatibility specifications since they are indicated for a long time in the oral cavity. Contact allergy of the oral cavity is a T-cell-mediated (delayed) hypersensitivity reaction. The clinical manifestations vary from burning, pain and dryness of mucosa to nonspecific stomatitis and cheilitis. After reviewing the literature, we found that dental personnel have higher risk of allergy from latex gloves while patients have increased risk from metals. Therefore, this book aims to- i) Develop a systematic approach for the evaluation and monitoring of the severity of adverse reactions to dental materials available in the market ii) Give an insight into the diagnosis and management of allergy to dental materials and iii) Can help dentists to become aware of incidence of allergy; thereby preventing the progression of these allergies by early recognition and preventive strategies.