BoNT is an exotoxin that is produced by gram-positive, anaerobic bacterium Clostridium botulinum, naturally found in soil, water, plants, and gastrointestinal tract of animals (17). It was first discovered by Belgian microbiologist Emile Pierre Marie van Ermengem, who concluded that it is a causive agent of, until then known as a very common and deadly disease, botulism. The possibility of using this toxin for therapeutic purposes was first proposed by doctor Alan Scott, while conducting experiments on mice and proving its effectiveness in treating strabismus. In 1989, the United States Food and Drug Administration issued a permission to use BoNT in treatments for strabismus and blepharospasm, making it the first toxin to be approved for therapeutic purposes (3). To date, seven serotypes of BoNT have been known, which are denoted by the letters A-G. The mechanism of its action is based on blocking the release of neurotransmitter acetylcholine through the presynaptic membrane, which is achieved by the cleavage of SNARE proteins that are necessary for its exocytosis. Such sequence of events results in the paralysis of the affected muscles (11, 12). The spectrum of indications in which BoNT is used is significantly larger today and it is constantly increasing. It is used in numerous conditions of the orofacial region, including facial paralysis, treatment of migraine, trigeminal neuralgia, trismus and TMD, while doctors of dental medicine use it to treat gummy smile, sialorrhea, as additional therapy in orthodontics and implantology and in numerous cosmetic treatments. It is important to note that certain indications have been officially approved, however BoNT is also known to be used outside those recommended indications (off-label use) (8, 16).