The occurrence and evolution of the disease depend on the properties of the organism, the cortical inhibition prevents the development of anaphylactic shock in humans. In some people, the increased and altered sensitivity manifests itself in the form of idiosyncrasy. In idiosyncrasy, the reactivity of the organism is altered from different substances of antigenic nature These substances can be food (milk, strawberries, eggs) or drug substances (iodine, iodoform, bromine, etc.) (drug idiosyncrasy whose symptoms are not related to the specific pharmacodynamic properties of the substance), plastics (prostheses, babies�dummy, etc.). The allergic reaction can be divided into two successive stages: a first stage of allergy, characterized by the formation of allergic type antibodies, their spread and fixation on certain tissues, and the second stage, of antigen -antibody, which represents the reaction In both stages there are both phases of immunological specificity (antibody production, antigen binding to the antibody) as well as non-specific phases in which the allergen and the antibody behave banal, non-immune (enter the body, circulate) or participate in reactions without immunological specificity (histamine release, etc.) The allergy therapy will appropriately include both specific methods and non-specific methods. Specific methods are only two: stopping the allergen input (allergen deficiency) and specific desensitization.Material and Method: A sample of 183 patients was studied in the present study between 2013 and 2017 with suspicions of hypersensitivity to dental materials for local or general symptoms. Results and discussions: A more severe allergy can be manifested in the dental office, is caused by the local anesthetic. The dentist has several local anesthetics, and through a well-done questioning, he will decide which type of anesthesia is the one indicated. For these reasons, an allergic reaction to the anesthetic is less common, but its manifestations are rather severe if it does not intervene in time. Conclusions:Dental biomaterials, in addition to mechanical and chemical resistance, should not contain toxic diffusible elements in the general circulation, elements with allergic or carcinogenic potential.