William Stewart Halsted is considered to be one of the most influential and innovative surgeons the USA has ever produced. His contributions to surgery are abundant, ranging from sophisticated surgical techniques in the field of breast surgery, surgery of the digestive apparatus and traumatological interventions, to the introduction of gloves in the operating theatre. Here we present Dr Halsted, together with his aide Dr Hall, as the discoverers of the technique for blocking the inferior alveolar nerve and the antero-superior dental nerve using cocaine as an anaesthetic. The anaesthetic technique, described perfectly by both surgeons in 1885, has been revolutionary in the practice of odontology since its introduction, offering dentists the possibility of performing invasive interventions to the maxillary without pain.